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Natural rubber latex (NRL) and cellulosic fibre are promising additives for improving the performance and sustainability of cement composite. This study investigated the optimised inclusion of NRL into waste paper pulp (WPP)-ordinary Portland cement (OPC) composites to enhance mechanical and durability properties. Three mixing methods were compared, revealing pre-mixing WPP with OPC before adding diluted NRL as the most effective. Both high-ammonia NRL (HA-NRL) and prevulcanised NRL (PV-NRL) significantly reduced water absorption, with PV-NRL slightly outperforming HA-NRL. Flexural properties were optimised at an NRL/OPC/WPP ratio of 10/700/300 parts by dry weight, although excessive NRL content reduced modulus. NRL also enhanced fire resistance through a synergistic effect, forming an ash-char layer, with HA-NRL exhibiting superior performance due to chemical distinctions. Failure modes and crystal formation were analysed using FE-SEM. Overall, optimised NRL and WPP incorporation improved water resistance, flexural performance, and fire resistance, suggesting their potential for sustainable construction. Further research could explore additional performance aspects and optimise NRL and WPP dosages for broader applications. • NRL incorporation significantly enhances flexural strength and modulus, promising structural applications. • Optimised composite formulations with natural rubber latex and waste paper pulp offer sustainable construction materials. • Synergy between NRL and waste paper pulp enhances fire resistance, resulting in the formation of a ash-char layer, suggesting suitability for fire-prone environments. • Exceptional water resistance ensures durability and resilience against moisture-induced degradation. [ABSTRACT FROM AUTHOR]

This study investigates the impact of incorporating lime mud (LM) as a filler material to develop sustainable, cementless ultra-high performance concrete (UHPC) by replacing silica powder (SP) and silica sand (SS) at varying percentages. Flowability analysis reveals that LM, with its distinctive particle size, influences flow characteristics differently at different replacement levels. Compressive strength was improved by 5.4% with 30% SP replacement, showcasing the role of LM in nucleation, as well as its particle size advantage. The heat of hydration analysis indicates that LM likely influences the early curing stages, enhancing reactivity and nucleation. TGA analysis also confirms that LM plays a role in hydration reaction, influencing weight loss and hydration peaks. The mercury intrusion porosimeter results show the impact of LM on pore distribution, with 30% for SP and 50% for SS replacements, favoring denser matrices. Life cycle assessment (LCA) demonstrates reduced CO 2 emissions and favorable environmental performance, highlighting the sustainability potential of LM replacements. Overall, the incorporation of LM in UHPC shows promise in terms of enhancing its mechanical properties and environmental sustainability. [Display omitted] • Lime mud (LM) in UHPC boosts material strength, leading to denser, more effective concrete. • LM enhances hydration, flowability, and refines pore structure. • High LM ratios in UHPC increase sustainability and reduce CO 2 emissions. • LM's use in UHPC significantly advances its mechanical properties and eco-friendliness. [ABSTRACT FROM AUTHOR]

The increasing global waste generated by industrial activities poses significant environmental challenges. Eco-waste management emerges as an economically viable solution for converting, valorizing, and repurposing these byproducts, aligning with circular economy principles, and aiming to reduce greenhouse gas emissions. Construction, known for its unsustainability due to high energy consumption, non-renewable resource utilization, waste generation, and greenhouse gas emissions, particularly from cement production, has led to the exploration of alternative materials. Magnesium oxide (MgO)-based cement, an alternative to Ordinary Portland Cement (OPC), has gained attention, leveraging Brazil's prominence as a major magnesite producer. This study explores the valorization of waste from kraft pulp mills of the paper industry, specifically lime sludge (LS) and lime slaker grits (grits), to produce magnesium oxysulfate (MOS)-based fiber cement boards. The effect of accelerated carbonation on cementitious composites produced with formulations containing grits and LS was investigated. Replacing 25% of the limestone with grits showed no noticeable differences in the properties of the boards, and MOR values close to 11.17 MPa were obtained. However, the physical-mechanical performance showed a decrease with the use of LS and higher concentrations of grits, associated with Na 2 SO 4.XH 2 O formation in the system and ITZ structure formed around the aggregated particle, respectively. Carbonation in a saturated atmosphere led to the carbonation of the 5–1–7 phase, which was related to the decrease in mechanical strength of the boards after the curing process. The thermal decomposition of the Hydrated Magnesium Carbonates (HMCs) formed during accelerated carbonation corroborated with the changes in the physical properties of the composites, demonstrating that the carbonation products are formed within the voids and pores of the material and contribute to the reduction in water absorption of the boards. • Global waste requires innovative environmental solutions for sustainability. • Investigation on eco-waste management aligns with circular economy principles, reducing environmental impact. • Article focuses on MgO-based cements as an alternative to Ordinary Portland Cement, highlighting global magnesite production. • Research emphasizes valorization by utilizing waste from kraft pulp mills (such as LS and grits) for MOS-based fiber cement production. • Exploration of accelerated carbonation impact on cementitious composites with LS and grits unveils shifts in physical-mechanical performance. [ABSTRACT FROM AUTHOR]

Recycled Aggregate Concrete (RAC) has attracted considerable attention for its potential to conserve natural resources and mitigate carbon emissions. Nevertheless, the widespread adoption of RAC in the construction industry faces challenges associated with its inherent performance deficiencies, including the formation of pores and microcracks in the recycled aggregate (RA) generated during the crushing process, as well as the presence of dual interfacial transition zones (ITZ) within the internal structure of RAC. The incorporation of fibres as reinforcement offers a promising solution to improve the performance of RAC. The paper begins with a comprehensive examination of various fibre properties and recycled aggregates. Then, summarizing the impact of fibres on RAC's performance. Special emphasis is placed on analyzing the influence of mixed fibres on the mechanical properties of RAC. The introduction of a blend of low-strength and high-strength fibres demonstrates the potential for further improving the mechanical properties of RAC beyond the benefits offered by individual fibres. This blending strategy also enhances the multiscale crack resistance of RAC, attributed to the collaborative effects of various fibres at different load stages. The reinforcing mechanism at the micro-scale of RAC is also discussed. Finally, the paper outlines perspectives for future research. [Display omitted] • A comprehensive review of hybrid fibre reinforced recycled aggregate concrete. • The effects of a single type of fibre on mechanical properties and microstructure. • Combining high-strength and low-strength fibres shows positive effects. • Blended fibres induce a dense C-S-H gel phase, enhancing cracking resistance. • The economic and environmental impacts are discussed. [ABSTRACT FROM AUTHOR]

This paper presents a series of experimental investigations into the flexural fatigue performance of rubberised concrete (RuC). A detailed account of fatigue response of reference conventional concrete materials (CCM) and RuC under flexural loading is presented. The experimental arrangement is described as well as the constituent materials, and the volumetric rubber replacement ratio of both fine and coarse aggregates varies between 0 % and 20 % in this study. The effect of three different stress ratios (R = 0.1, 0.3 and 0.5) on the flexural fatigue response are studied. It is found the static flexural strength of RuC with the rubber contents (ρ rv) of 10 % and 20 % show a reduction of 12 % and 24 % compared to their counterpart of CCM, respectively. A stress level of 0.9 is embedded in this study while despite the uncertainty of fatigue life of concrete materials, the increase of stress ratio from 0.1 to 0.5 lead to an increase of fatigue life of RuC in general. It is notable that the inclusion of rubber in concrete increases the fatigue life uncertainty whereas significantly increases the fatigue life of RuC at the same time, i.e. the average fatigue life of RuC with 20 % rubber content shows an increase of 170 % compared to its counterpart of CCM when R = 0.5. Based on the experimental results in this study, a series of three-parameter Weibull distribution models are proposed to describe the failure probability of RuC under fatigue flexural loadings, which consider the effects of ρ rv , stress ratio, stress level, and loading frequency on the probability of failure (PF) of RuC. This paper presents the attempt to investigate the possibility distribution of fatigue life of RuC, and all numerical calculation curves are in good agreement with the experimental results carried out in this study. • Flexural strength and fatigue behaviour of conventional and rubberised concrete were tested. • Cyclic flexural tests at different stress ratios were carried out. • The fatigue life probabilistic model of rubberised concrete is established. • The three-parameter Weibull distribution is introduced as a cumulative failure model. • Effect of stress ratio and rubber content is included. [ABSTRACT FROM AUTHOR]

During coal preparation, a substantial volume of coal gangue (CG) is generated, leading to severe environmental and health concerns stemming from its massive accumulation. Comprehensive research has been conducted on the utilization of CG in various engineering applications. Transforming it into supplementary cementitious material (SCM), geopolymer, and concrete aggregate holds pivotal significance in engineering applications, aligning with the imperatives of sustainable development. However, there are notable deficiencies in current research related to the grading, categorization, and standardization of CG for its optimal utilization based on its basic properties, which need to be addressed for further study and development. This paper takes the mineral composition of CG as a starting point, delving into an analysis of physical and chemical characteristics determined by the composition. Based on these characteristics, the effects of five main activation methods including mechanical, chemical, thermal, microwave, and composite treatments are comprehensively reviewed with a focus on their interaction mechanisms with CG. Subsequently, the fresh properties, mechanical properties, and durability of cementitious materials and aggregates prepared by CG were summarized and analyzed. Research suggests that contingent upon the degree and purpose of treatment (activation), CG can be applied in SCM (partially replacing cement), geopolymer (completely replacing cement), and concrete aggregate, with distinct treatment conditions influencing its engineering characteristics. This paper offers a systematic perspective and insights into the high-capacity utilization and value-added applications of CG. It highlights the issues encountered in the utilization of CG while further providing novel perspectives for its scaled utilization in engineering. [Display omitted] • Utilization of coal gangue in engineering is an ecological and sustainable way. • The pretreatment intensity varies across different utilization methods. • Progressed coal gangue exhibits excellent engineering utilization effect. • Numerous issues were identified, and some suggestions were proposed. [ABSTRACT FROM AUTHOR]

Traditional systems for strengthening concrete structures, such as externally bonded reinforcement-fiber reinforced polymers (EBR-FRP) encounter difficulties associated with premature FRP debonding from the concrete surface. To overcome this challenge, this research introduces a novel strategy referred to as externally bonded reinforcement on grooves (EBROG). This innovative approach aims to efficiently tackle the issue of premature FRP debonding, thereby delaying or averting such occurrences. Despite extensive research on EBROG joints, their behavior under cyclic fatigue loading remains unexplored. In a pioneering effort, this paper provides an empirical exploration into the behavior of carbon FRP (CFRP)-to-concrete bonded joints employing the EBROG installation approach under low and high-cycle fatigue loading by using wide specimens. Twenty-three specimens underwent reinforcement through the EBROG approach with diverse groove dimensions, while an additional five specimens received strengthening via the EBR method. Subsequently, these specimens underwent single-lap shear tests under both monotonic and varying fatigue loading amplitudes. The results revealed that wider concrete specimens exhibited more capacity compared to previous research. Furthermore, the EBROG method significantly extended the fatigue life of CFRP-to-concrete joints within the same loading range as EBR. Conversely, tests indicated that the fatigue life of EBROG specimens is contingent on the loading amplitude and can be enhanced by reducing the maximum load level of cyclic loading. In a pioneering step, the paper introduces a formula to forecast the fatigue life of strengthened FRP/concrete joints employing the EBROG method. • The paper studied the fatigue behavior of FRP-to-concrete bonds using EBROG methods under various loading amplitudes. • It proposed a new equation to predict fatigue life for CFRP-to-concrete joints bonded with EBROG. • EBROG installation significantly increased the fatigue life of bonded joints. • The effect of concrete block width on EBROG bond capacity was examined. [ABSTRACT FROM AUTHOR]

This paper addresses two important worldwide environmental concerns: disposal of waste tyres and attenuation of trains induced vibration. To this end, use of the waste materials in construction of railway concrete slabs for reduction of train induced vibration is investigated in this research. For this purpose, rubber tyre particles with different dosages were used in the concrete mixtures of test specimens. Extensive laboratory tests were conducted on the rubberized concrete specimens to measure their compressive strength, density and damping of the specimens. The effect of rubberized slab track on attenuation of vibration propagated from slab track was investigated by numerical modeling using results of laboratory tests as the input data. The laboratory results obtained indicate that adding rubber particles to the railway slab causes up to 96% increase in damping ratio (for concrete with 10% rubber). Results of numerical analysis elucidates that the rubberized slab track causes up to 21% reduction of the train induced vibration. By compromising between compressive strength and damping of vibration, it is shown that the optimum amount of crumb rubber in the concrete of railway slabs is 2.5% by which the best performance of the railway slabs is obtained. • This paper addresses two important environmental challenges in the world. • A method for recycling waste tyres and reducing railway vibration is developed. • Optimum amount of crumb rubber integrated into railway concrete slab is derived. • Environment-friendly solution for mitigation of train induced vibration is derived. [ABSTRACT FROM AUTHOR]

To scientifically and efficiently utilize reclaimed asphalt pavement (RAP) generated during asphalt pavement maintenance, and to promote resource recycling and sustainable development, this paper developed and evaluated the Fiber-enhanced RAP interlayer for HMA overlay and preservation treatments. In this paper, RAP interlayer was designed based on the Response Surface Methodology (RSM) and the pull-out strength and the shear strength of were tested. Through double-objective optimization and analysis, the recommended proportions were determined as 2.22 kg/m2 of rubber asphalt, 10.57 kg/m2 of aggregate, and 30% RAP content. Subsequently, the effects of different basalt fiber contents on the pull-out strength, shear strength, flexural strength, fatigue life, and permeability coefficient of asphalt mixture with interlayer containing RAP were investigated. The results indicated a significant improvement in these properties with an 80 g/m2 basalt fiber content. The performance of asphalt mixture with Fiber-enhanced RAP interlayer was obviously superior to the asphalt mixture with interlayer without fiber and RAP. According to the test results of Digital Image Correlation (DIC), it was found that basalt fibers effectively reduce stress concentration, delaying the initiation and propagation of cracks. • Fiber- enhanced RAP interlayer is developed. • The RAP content reaches 30%. • Basalt fibers delay the propagation of cracks. [ABSTRACT FROM AUTHOR]

In this paper, an orientation method with pre-tensioning at both ends is proposed to successfully prepare continuously directional steel fibre reactive powder concrete (DSFRPC). The tensile and fracture properties are determined by splitting tensile, axial tensile and three-point notch fracture tests. The paper sets three different groups named C0, Group S and Group D, which presents non-fibre, randomly distributed fibre and directional fibre, respectively. The test results showed that: the splitting strength of Group D specimens increased quite significantly with the increase of fibre dosage. Compared to the Group S, the splitting strength of Group D was improved by 46.5%, 69.8%, and 66.1%, respectively. The specimens of C0 and Group S in the axial tensile test suffered typical single-seam brittle failure, which showed obvious strain softening characteristics. With the increase of fibre dosage, the damage mode of specimens in Group D changed from single-seam brittle damage to multi-seam ductile damage, showing better energy dissipation capacity. Under the same converted fibre dosage, the fracture energy enhancement ratios of Group D specimens were 14.7, 18.9 and 19.55, respectively. At a lower water-cement ratio, the toughening effect of continuous directional steel fibre specimens is more obvious. The toughening effect of the reactive powder concrete (RPC) of with continuous directional steel fibre is mainly reflected in the directional distribution of steel fibre produced by the interfacial adhesion and friction caused by the increase in energy dissipation, as well as the maintenance of a stronger grip between the "dispersed rebar" and the matrix. Based on current study, the future research should be focused on a wider range of materials, structural design, and environmental conditions to verify the effectiveness and reliability of DSFRPC in various applications. • A novel directional method to prepare a new type of directional steel fibre concrete material. • The method can reduce the cost and improv the reinforcing and toughening effect of steel fibre. • The properties were experimental studied by splitting tensile, axial tensile and three-point notch fracture tests. • The research reveals the reinforcement mechanism of continuous directional steel fibres on RPC. [ABSTRACT FROM AUTHOR]

The blending degree between aged and virgin asphalt in recycled asphalt mixture has a significant impact on the high and low temperature performance of recycled material, as well as its resistance to moisture damage. To comprehend the blending state and its interaction mechanism, this paper presents a comparative review of state-of-the-art studies concerning the blending theories, models, and characterization of virgin and aged asphalt. Firstly, the definition and significance of the blending phenomenon of recycled asphalt are analyzed. Next, three types of diffusion and blending theories and their derived models are discussed, accompanied by a comparison of their advantages, disadvantages, and applicability. Furthermore, this paper presents a comprehensive summary of multi-scale characterization approaches for asphalt blending, spanning from macro-scale to micro-scale. These approaches are categorized based on the measurement principles, and their respective limitations are analyzed. It is identified that the macroscopic evaluation methodologies are flawed and fail to explain the blending mechanism. In contrast, the microscopic measurement instruments can be effectively applied to investigate the microscopic effects of diffusion and blending processes, thus visualizing the miscibility interface. Finally, the challenges and suggestions for further research are proposed in this paper, which provides significant references to the development of blending characteristics and design theories of recycled asphalt, ultimately contributing to promoting a resource-saving and environment-friendly society. • The diffusion theories and their advantages and disadvantages are introduced. • The blending and diffusion can be assessed by combining a staged extraction method. • The selection of chemical solvents for extraction remains a primary concern. • Understanding the blending and diffusion will benefit recycled asphalt pavements. [ABSTRACT FROM AUTHOR]

Glass Fiber-Reinforced Polymer (GFRP) bars can enhance the flexural bearing capacity and durability of concrete beam members under sustained loading and alkaline environment over an extended period. However, addressing the challenges related to durability and deformation resistance remains crucial for long-term service. In this paper, the flexural performance of GFRP-reinforced concrete beams with different glass fiber contents under the coupling action of the alkaline environment and continuous load is studied, and the mechanism of improving the flexural performance of GFRP-reinforced concrete beams by dispersed fibers is analyzed from a microscopic point of view by scanning electron microscope (SEM) test. In addition, the finite element analysis software was used to simulate and verify the improvement effect of singly dispersed fiber on the bending of GFRP-reinforced concrete beams. The results demonstrate that GFRP-RC beams containing 0.5%, 1.0%, or 1.5% glass fiber exhibit a reduction in deflection ranging from 11% to 23% compared GFRP-RC beams without glass fiber, thereby improving their deformation resistance. The optimal glass fiber content is 1.5%. Simulation analysis demonstrates that the model exhibits enhanced resistance to deformation when the glass fibers are randomly dispersed. Specifically, increasing the random scattering of fibers at the bottom of the beam by two to three times results in a reduction of 7%-12% in mid-span displacement of the model. Additionally, within the cracked area, the fibers bear greater tensile stress compared to those in other uncracked regions, effectively preventing further cracking of GFRP-RC beams. This study offers valuable design guidance for enhancing performance of GFRP-RC members during long-term service. • This paper studied glass fiber GFRP-RC beams. • The working condition is the coupling of sustained loading and alkaline environment. • The influence of fiber on the flexural property of beam was investigated by finite element method. • The corrosion age of alkaline environment is 450 d. [ABSTRACT FROM AUTHOR]

In February 2024, Construction and Building Materials published the paper "Nondestructive measurement of the capillary water absorption coefficient and water transport behaviors of porous building materials by using single-sided NMR", which claims to measure the capillary absorption of moisture in brick, sandstone, mortar and concrete by means of moisture content profiling with the 'NMR mouse', a low-field, single-sided, open-magnet NMR instrument. This critique formulates several serious concerns on the study's outcomes and conclusions. The excessively large similarity of the capillary absorption behaviour of the four materials is peculiar, since it disregards the differences in their open porosities and pore sizes. The overly large capillary moisture contents are equally abnormal, as they exceed the moisture storage limit of the material's pore structure. There appears to be an inconsistency between the moisture content profiles and the overall moisture masses. Finally, it is shown that the lengthy time interval necessary for a single NMR pass limits the applicability of the NMR mouse for capillary absorption coefficients of porous building materials. • this post-publication review formulates concerns on a previously published paper. • several of the study's quantitative outcomes are physically/internally inconsistent. • the paper's method moreover is solely fit for implausibly slow capillary absorption. [ABSTRACT FROM AUTHOR]

This study systematically reviews 62 papers on the use of rotational rheometry to assess the fresh state behavior of Portland cement-based materials. The research highlights the wide variation in test methods and aims to provide a comprehensive overview. Findings reveal that 50.0% of studies employed vane geometry, despite its limitations in providing transformation equations. Regarding dynamic shearing tests, 67.0% followed a consensus using a pre-shearing step and a step-wise routine with stabilization times ≥ 10 s. While the Bingham model is commonly used, the study emphasizes the importance of considering shear-thinning behavior in cementitious materials. Models like Herschel-Bulkley and modified Bingham may be more appropriate. This review offers insights into testing conditions for rotational rheometry of cementitious materials, serving as a foundation for future research in the field. • The 62 papers that conducted rotational rheometry trials were systematically reviewed. • The Vane rotor type is the most employed geometry in studies. • There was a trend of step test protocols with stabilization times of at least 10 seconds. [ABSTRACT FROM AUTHOR]

This work focuses on how different aspects of design, testing, and field implementation of fiber-reinforced polymer (FRP) in concrete have gained attention from the scientific research community. FRP composites have gained significant recognition after being implemented in civil engineering applications over the past three decades. This paper conducts a comprehensive survey of the existing literature on FRP in concrete from different engineering aspects. Since its advent, FRP research has resulted in numerous peer-reviewed papers available in various scientific databases such as Elsevier, ASCE, Springer Nature, ACI, and MDPI. Researchers investigated the use of FRP in concrete from different aspects, including material systems, element types, and applications, accounting for 35.8%, 50.3%, and 13.9% of the research publications, respectively. This paper aims to present an overview and summarize the use of FRP based on highly cited literature and to support FRP's continued growth and development in concrete applications. Consequently, this paper is expected to offer advantages to stakeholders involved with FRP use, such as owners, engineers, and professionals, by emphasizing the number of available research publications, which can increase confidence in adopting FRP. It offers scholars and researchers the opportunity to become acquainted with the use of FRP in the application of concrete. • Interest in fiber-reinforced (FRP) in concrete is growing within the scientific research community. • Research on FRP in concrete focuses on material systems (35.8%), element types (50.3%), and applications (13.9%). • The paper provides an overview of FRP use in concrete, citing influential works and promoting its ongoing growth. • The study identifies research gaps, helping academicians and scientists understand the challenges in incorporating FRP into concrete. [ABSTRACT FROM AUTHOR]

Accumulated construction and demolition waste (CDW) can occupy much land and cause environmental pollution. To dispose of CDW and slow down the depletion of natural resources, the use of recycled aggregates (RA) prepared from CDW as a substitute for natural aggregates (NA) in preparing concrete materials has become an essential trend in the construction materials industry. RA has high porosity, which affects concrete's mechanical strength and durability. In this paper, it is concluded that chemical modification-removal of adhered mortar (AM), physical modification to enhance AM, biological modification, and composite modification can improve the performance of RA to varying degrees. Then, the performance of recycled aggregate concrete (RAC) can be further enhanced by various forms of curing. Meanwhile, combining factors such as economic efficiency and carbon emissions, it is also found that the replacement rate of RA and the transport distance are the main factors limiting the large-scale application of RAC. This paper addresses three aspects of RA modification, RAC maintenance, and RAC application. The study results help RAC to be applied accurately and on a large scale in practical projects, reducing environmental damage and lowering carbon emissions. [Display omitted] • This review explores enhancing RA performance through CDW properties. • Discussion internal curing's impact on RAC durability and crack reduction. • Study highlights localized processing to cut economic and environmental costs. • Review advocates systematic CDW recycling via advanced technology and local centers. [ABSTRACT FROM AUTHOR]

Efficiently and actively dissipating accumulated heat within asphalt pavement is crucial for reducing pavement distress and improving subgrade stability. This paper proposed a novel inverted "T" shaped heat induced structure (IT-HIS) that facilitates the rapid transfer of heat from the pavement to the subgrade and shoulders. The IT-HIS consists of two components: a vertical gradient thermal conductivity structure utilizing steel slag, and a horizontal oriented carbon fiber heat induced structure. The heat transfer behavior of the IT-HIS was analyzed using a finite element heat transfer model created in ABAQUS, and the results were validated through indoor irradiation experiments. The findings demonstrated that the IT-HIS enhanced heat flow and promoted secondary aggregation in the vertical direction, while facilitated lateral heat dissipation. Compared to the ordinary group (OG), the heat flux of IT-HIS at depths of 5 cm and 6.5 cm increased by 19.8 % and 64.6 %, respectively. The indoor irradiation experiment results indicated that during the heat absorption period, the IT-HIS reduced temperatures at depths of 0 cm, 2 cm, and 5 cm by 1.5 ℃, 1.7 ℃, and 1.1 ℃, respectively. During the heat dissipation period, the IT-HIS reduced temperatures at depths of 0 cm, 5 cm, and 10 cm by 0.9 ℃, 0.7 ℃, and 1.8 ℃, respectively. The IT-HIS enhanced the cooling effect during daytime and inhibited heat upward during nighttime based on the gradient thermal conductivity structure. The proposal and validation of this structure provide a fundamental approach to forming large-scale high-speed microchannel heat dissipation within asphalt pavements, and is expected to provide experimental and theoretical foundations for the development of directional active cooling technologies. • In order to reduce heat accumulation within asphalt pavement, this paper proposed a novel inverted "T" shaped heat induced structure (IT-HIS). • IT-HIS enhanced heat flow and promoted secondary aggregation in the vertical direction, while facilitated lateral heat dissipation. • IT-HIS enhanced the cooling effect during daytime and inhibited heat upward during nighttime. [ABSTRACT FROM AUTHOR]

Stone coal leaching slag (SCLS) and bauxite residue (BR) are hazardous solid wastes generated during the extraction of vanadium and aluminum from stone coal and bauxite. High heavy metal contents and corrosivity make SCLS and BR hard to use safely in building materials. In this paper, a lightweight ceramsite called LSBC was successfully made using SCLS, BR, and feldspar as raw materials. The optimal preparation conditions for the ceramsite were found to be a ratio of SCLS: feldspar: BR = 65 %: 20 %: 15 %, and sintering at 1180 °C for 20 min with a heating rate of 7.5 °C/min. Under optimal conditions, the LSBC met Chinese standard requirements (GB/T 17431.1–2010) for the 600-grade ceramsite with a bulk density of 594.3 kg/m3, compressive strength of 7.33 MPa, and 1 h water absorption of 4.96 %. The numerous micropores endowed the ceramsite with a specific surface area of 3.99 m2/g. Furthermore, the formation of the liquid phases contributed to the solidification of heavy metals in the SCLS and BR, resulting in a much lower leaching concentration of heavy metals within the ceramsite than the specified value in the Chinese standard (GB 5085.3–2007). This paper provided a feasible and effective manner for the safe co-utilization of SCLS and BR. [Display omitted] • Lightweight ceramsite was prepared with SCLS and BR as raw materials. • The ceramsite showed high compressive strength and low bulk density. • The leaching concentration of heavy metals was lower than the standard. • Co-utilization of SCLS and BR for the preparation of lightweight ceramsite. [ABSTRACT FROM AUTHOR]

Past earthquakes revealed that the brittle nature of unreinforced masonry (URM) structural walls often leads to extensive cacking and shear damage, which can seriously affect the structural integrity and thus compromise the safety of the entire building. Hence, finding an effective seismic retrofitting solution that can increase the safety of existing masonry building stock is of great importance. This paper explores the potential of alternative seismic retrofitting solutions for URM masonry walls - near-surface mounted austenitic stainless-steel helical bars. Being cold rolled from a plain round wire and subsequently tensioned through a free-twisting process, such a reinforcement can not only offer high durability, but also superior mechanical and bond properties, as well as effective redistribution of loads through the retrofitted masonry. In addition, the relatively high flexibility of the bars allows them to be mounted continuously along the joints of the wall, leaving the aesthetic of the retrofitted masonry intact. A total of nine single-leaf clay brick walls were tested under cyclic displacement reversals to examine the seismic performance of the reinforcement in terms of increasing in-plane shear capacity and ductility. Test specimens comprised cantilever walls with various retrofitting patterns, including flexural and shear helical reinforcements installed in the mortar joints or into the vertical slots cut into the masonry. The results showed considerable improvements in the ductility and energy dissipation of the walls after the retrofitting. For most of the retrofitted walls the value of q factors exceeded 4.0, which is greater than the typical q factors for reinforced masonry, thus indicating that large increases in ductility were achieved. The paper highlights the potential of helical stainless-steel bars as a seismic retrofitting reinforcement capable of preserving the structural integrity of masonry structures at increasing displacement demands without affecting the aesthetic of the surface of the walls. • Helical reinforcement for URM offered desirable balance between flexibility, strength, and bond. • URM walls retrofitted with helical bars showed improved ductility and energy dissipation. • Novel retrofitting patterns utilising "wiggled" vertical bars were investigated. • Retrofitting with helical bars allows for preserving natural aesthetics of masonry. [ABSTRACT FROM AUTHOR]

The outbreak of the COVID-19 epidemic has led to a large number of waste disposable medical face masks (DMFMs) worldwide, which seriously pollute the environment and threaten human health. In this paper, waste DMFMs were recycled as mask fiber and mixed into self-compacting recycled aggregates concrete (SCRAC) to form a mask fiber reinforced self-compacting recycled aggregates concrete (FRSCRAC). The effects of recycled coarse aggregate (RCA) replacement ratio, DMFM fiber content, and length on the working and mechanical properties of FRSCRAC were investigated. The results show that the specimens meet the requirements of self-compacting concrete (SCC) in terms of working and mechanical performance, but the RCA and DMFM fiber could reduce the workability of the FRSCRAC, and the higher the amount of RCA and DMFM fiber, the more obvious the reduction. At the same time, the mechanical properties of FRSCRAC increased as the decreasing RCA replacement ratio and growing DMFM fiber content. Compared with specimens without DMFM fiber reinforcement, the compressive strength, split tensile strength, flexural strength, and elastic modulus were increased by 1.3%-9.6%, 1.46%-8.6%, 24.4%-54.69%, and 0.65%-4.73%, respectively. Moreover, the reduction of the DMFM fiber length is favorable to the mechanical properties of FRSCRAC as well. Furthermore, the X-ray CT and scanning electron microscope (SEM-EDS) techniques were applied to analyze the microstructure of typical specimens. The results showed that the DMFM fiber and surrounding mortar could form a multiphase composite, which reduces the porosity and improves interfacial stress transfer efficiency, thus enhancing the mechanical properties of FRSCRAC. In addition, based on the experimental results, the mechanical strength index of FRSCRAC and the calculation formula of its mutual conversion relationship were proposed. The research conclusions of this paper can provide a reference for the application of waste DMFM fibers in FRSCRAC. • Waste disposable medical face masks were recycled as fiber and mixed into self-compacting recycled aggregate concrete. • Parameters were investigated to make clear the influential mechanisms of waste fiber on recycled concrete performance. • The mechanical strength index of FRSCRAC and the calculation formula of its mutual conversion relationship were proposed. [ABSTRACT FROM AUTHOR]

In recent years, with the improvement of construction safety requirements in deep well mining, the backfill mining method has been widely used. However, the strength of paste filling acquired in quarry often surpasses the design strength determined in laboratory settings. In view of the problems that indoor conditions cannot restore deep mining environment, and the mechanism of coupling effect under multiple fields is unclear. This paper has carried out relevant research work through theoretical analysis and indoor experiments. First of all, after completing the preparatory experiments, this paper analyzed the strength difference of backfill under different curing stress and drainage conditions, and studies the influence of different curing conditions on the strength. Secondly, MPS-6 and 5TE sensors were used to monitor the electrical conductivity, pore water pressure, porosity and other parameters of backfill during the stress-drainage curing process, and changes of parameters during curing process were analyzed. Finally, the relationship among relevant parameters and strength properties of paste backfill was analyzed, as to clarify the influence mechanism of stress-drainage curing conditions on the strength formation for paste backfill. Research shows that both stress-undrained and stress-drained conditions can effectively increase the strength of backfill. Under stress-drainage conditions, the internal porosity of backfill will decrease, and the pore water pressure of backfill will first increase slightly and then continue to decrease. Under this condition, the electrical conductivity of backfill will first increase and then continue to decrease. The entire research has important positive significance for reducing mining costs, optimizing mining processes, and developing mining technology. • The instrument is a self-developed equipment, which can monitor changes of backfill in real time. • The test blocks were cured under different stress and drainage conditions. • Binarize the scanned image of samples, and then use ImageJ to analyze the processed image. • Combined with two sensors, the relationship between microscopic parameters and strength can be explored. [ABSTRACT FROM AUTHOR]

To study the differences in material performance between HRB400E steel and conventional strength steel, this paper performed monotonic and cyclic loading tests on HRB400E and Q355B steels under a series of loading protocols. Additionally, the self-designed fixtures were used to achieve large strain rate loading. The ductility, monotonic behavior and hysteretic characteristics of HRB400E and Q355B steels were assessed, along with the energy dissipation capacity evaluated through the energy dissipation coefficients. The cyclic skeleton curves of both steels were fitted using the Ramberg-Osgood model, with further investigation into the influence of kinematic hardening parameters on hysteretic curves. The combined hardening parameters of the Voce-Chaboche model were calibrated based on the experimental results, and the hysteretic curves were simulated under different loading protocols via ANSYS. The analysis results reveal that the energy dissipation coefficients of HRB400E steel are larger than that of Q355B steel, yet smaller than those of Q460D, LYP100, LY100, LY160, and LY225 steels. Both HRB400E and Q355B steels demonstrate significantly improved material strength under cyclic loading. Excellent agreement between simulated and experimental curves is achieved when using four pairs of kinematic hardening parameters. Additionally, the hysteretic performance of HRB400E and Q355B steels under different cyclic loading protocols can be precisely simulated by employing calibrated combined hardening parameters. Through this paper, the cyclic behavior and constitutive relations of HRB400E steel are comprehensively understood, which provides a reliable theoretical basis for engineering design and structural analysis. Furthermore, this research provides a scientific basis for material applications of HRB400E steel. • HRB400E steel and conventional strength steel are compared in material performance. • Monotonic and cyclic loading tests are conducted. • Ductility, monotonic property, and hysteretic performance of HRB400E and Q355B steels are assessed. • Self-designed fixtures are utilized to achieve large strain rate loading. • The hysteretic property of the HRB400E steel can be accurately simulated. [ABSTRACT FROM AUTHOR]

Reinforced concrete is a commonly used material for constructing basements in low-rise buildings or residential houses in Canada, and as the use of cross-laminated timber (CLT) advances, the door to think of an alternative basement material to offset greenhouse gas emissions associated with reinforced concrete is open. However, the evaluation of CLT durability in below-grade environments, specifically concerning moisture and mould development, remains an unexplored field in research. Hence, this paper aims to analyze CLT's moisture response and mould growth risk in below-grade environments using field and laboratory experiments. A laboratory experiment was carried out to test a waterproofing membrane solution selected to compose the wall assembly in the field experiment. A large-scale experimental CLT basement was built at a cohesive soil site in Edmonton, Canada. The field experiment involved monitoring the relative humidity, temperature, and soil volumetric water content of the CLT panels, which measure 3 m by 6 m in plan and 2 m deep. Data was collected for an extended period from June 2022 to July 2023. The VVT model, developed by Hukka and Viitanen (1999) and updated by Viitanen et al., 2011 to estimate the mould growth level, was used to predict the risk of mould growth. The laboratory experiment showed that the waterproofing membrane is suitable for protection against moisture in a still-water setup. Field experiment results suggested that the primary moisture source was below the basement floor when the floor was finished inadequately. The moisture content of CLT walls was significantly increased by floor flooding and decreased by heating the basement interior. The acceptable mould index of three was surpassed during periods of abundant water below the basement floor due to flood events, showing that the CLT panels were at risk of mould growth development. • CLT use inbasements is in research stage. This paper contains insights for developing future research on this subject. • CLT in basement construction requires robust envelope with waterproofing membranes that perform well below grade. • Elevated moisture levels could pose structural and biological risks to the CLT basement and its occupants. • CLT basement walls take time to dry, and during this period, the walls may be exposed to risky levels of mould growth. [ABSTRACT FROM AUTHOR]

Grouting is one of the most commonly used methods to control water inrush disasters in fractured rock mass. At present, most of the research on the diffusion process of fracture grouting is carried out on the hypothesize that the groundwater was completely displaced by the slurry, which is lack of sufficient theoretical basis. Therefore, a one-dimensional visual fracture grouting experimental system was developed and a new characterization method of slurry concentration based on the image gray level was proposed in this paper in order to characterize the variation law of slurry-water mixing region during the grouting process. Results show that there exists slurry-water mixing region at the frontal surface of the diffusion slurry in the grouting process in fractured rock mass. The slurry-water mixing region can be characterized by the gray level of the images captured by cameras. The relationship of water to cement ratio of slurry (w/c) and image gray level of slurry (G) conforms to linear function, which can be expressed by G = 19.17 w/c when w/c is between 0.8 and 10. In addition, slurry concentration decreased linearly along the diffusion flow path in the slurry-water mixing region. The size of slurry-water mixing region is positively related to grouting flow rate, the mass ratio of water to cement (w/c) and fracture aperture when the grouting flow rate is between 0.6 L/min to 2.4 L/min, w/c is between 0.8 and 1.6 and fracture aperture is between 1 mm to 5 mm. Furthermore, the ratio of slurry-water mixing region size to hypothetical diffusion radius (RSR) was proposed to characterize development degree of slurry-water mixing region. The stable value of RSR was between 0.04 and 0.24 under the experimental conditions in this paper. The index of RSR can be used to provide theoretical basis for the simplification of the interface between slurry and water. The distribution rules of the slurry-water mixing region can be applied to predict the diffusion range more accurately and perfect the grouting theory. • Image gray level method was introduced to characterize the variation of slurry-water mixing region during grouting process. • Experimental system for simulation of one-dimensional visual fracture grouting was presented. • The ratio of slurry-water mixing region size to hypothetical diffusion radius was developed. [ABSTRACT FROM AUTHOR]

3D printing technology revolutionizes construction by creating custom building components with increased efficiency and reduced waste. This paper reviews advancements in the 3D printing of cementitious materials, focusing on integrating mineral additives (MAs) like metakaolin, micro-silica, slag, and fly ash to address environmental and economic challenges linked with high-Portland cement content in 3D concrete printing (3DCP). MAs enhance the pumpability, printability, and buildability of 3DCP while reducing its environmental impact. The review emphasizes optimizing cement mixtures, including alkali-activated materials, to enhance sustainability and performance. It discusses the mixture design's importance, balancing mechanical properties and environmental impacts, and examines MAs' influence on rheological properties, mechanical performance, and 3DCP durability, including layer bond strength. The paper also discusses global 3D printing technology adoption in construction and challenges in additive manufacturing implementation. By analyzing printing parameters, mixture proportions, and materials' effects on long-term performance, this review highlights 3D printing's potential for economically viable and eco-friendly structural elements. It aims to guide future advancements in 3D printable cementitious materials, meeting modern construction demands while addressing traditional concrete production's environmental challenges. • Using recycled mineral additives reduces 3D-concrete printing's environmental impact. • Optimizing printing parameters strengthens layer bonds in 3D-concrete printing. • Recycled materials promote sustainability and innovation in 3D-concrete printing. [ABSTRACT FROM AUTHOR]

This paper investigates the behavior of reinforced concrete (RC) arch beams with shear weaknesses strengthened with fiber-reinforced polymer (FRP) composites, using two different methods: the externally bonded reinforcement (EBR) and grooving method (GM) in the form of externally bonded reinforcement on grooves (EBROG) method. Additionally, two different patterns of shear strengthening including two-sided and U-shaped were utilized. Nine arch beam specimens were tested, each having a square cross-section of 150 mm and a span length of 947 mm. Among these, two specimens were strengthened using the EBR method, while six specimens were strengthened using the EBROG method. The paper explores the impact of the strengthening method and pattern on the load-carrying capacity, failure mode, energy dissipation, and strain distribution of the specimens. The results indicate that the EBROG method significantly increased the load-carrying capacity of the arch beams compared to the EBR method in both patterns. The results also show that the U-shaped pattern was more effective than the two-sided pattern in increasing the load-carrying capacity of the specimens. The specimen with intermittent U-shaped FRP demonstrated 34.8% and 47.3% higher load-carrying capacity than the non-strengthened specimen when using the EBR and EBROG methods, respectively. The paper also introduces an analytical approach to estimating internal forces, such as flexural moment, axial force, and shear force, along the arch beam. The comparison between the experimental and theoretical results confirms the accuracy of the analytical approach. • The behavior of RC arch beam with shear weakness was investigated. • EBR and EBROG methods were adopted for strengthening of the arch beam. • PIV method was utilized to obtain the strain distribution, validate the displacements, etc. • An analytical procedure was conducted to validate the experimental results and investigate the performance of the strengthening methods. [ABSTRACT FROM AUTHOR]

This paper studies the effect of high temperatures (20℃, 200℃, 400℃, and 600℃) and stress ratios ( σ 2 / σ 3 ) (0.15, 0.3, 0.45, and 0.60) on biaxial compressive strength and strain development patterns of high-strength geopolymer concrete (HGPC). Experimental observations indicate that HGPC exhibits laminar damage similar to ordinary Portland concrete (OPC) before and after exposure to high temperatures, under biaxial compression. Unlike OPC, damage in HGPC initially passes through coarse aggregates at room temperature but shifts predominantly to the aggregate-mortar interface at 600℃. The biaxial compressive strength envelope of HGPC expands with rising temperatures. The increased multiple of biaxial compressive strength ( σ 3 / f m ) for HGPC at room temperature rises and then falls with increasing stress ratios, peaking at a stress ratio of 0.45 and surpassing the values for OPC and high-strength concrete (HSC). Before high temperature, the modulus of elasticity of HGPC is higher than that of OPC and decreases with increasing temperature, decreasing by about 45–60% for every 200°C increase, and the reduction is greater than that of OPC. The existing failure criterion is not suitable for HGPC after high temperature, this paper develops a new biaxial compression failure criterion for HGPC before and after high temperature based on Kupfer's criterion, taking into account the effect of temperature. The proposed failure criterion calculation results are well in agreement with the experimental data. A damage constitutive model for HGPC considering the effect of temperature and lateral pressure is also proposed, combining the Weibull distribution model for the ascending branch and a modified empirical model for the descending branch. This combined model effectively predicts the stress-strain relationship of HGPC under various temperature conditions. • The axial behavior of HGPC is tested at different temperatures and lateral pressures. • A failure criterion for biaxial compression of HGPC taking into account the effect of temperature is proposed. • A damage constitutive model of HGPC considering the effect of temperature and lateral pressure is established. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of bond in post-tensioning strands in the presence of grout injection defects. In particular, the paper describes a campaign of experimental pull-out tests with a single 7-wire steel strand in the centre of a galvanised sheet metal duct with no grouting defects and with 25% and 50% defects, i.e. voids in the cross-section area of the grout. The grouted length is short in order to obtain a local bond–slip relationship. This relationship has an initial branch followed by a jump descent and a subsequent growing branch in the form of a sawtooth. The experimental data are used to define a specific bond–slip relationship that takes into account the presence of defects. The results show that the obtained bond–slip law is very different from those proposed in the literature for the case of ribbed steel bars. Furthermore, the defects cause a decrease in bond stresses and a flattening of the shape of bond–slip curves. • Bond of post-tensioning strands is studied. • Experimental pull-out tests are performed. • Effect of grout injection defects is investigated experimentally. • A bond-slip relationship for post-tensioning strands with defects is proposed. [ABSTRACT FROM AUTHOR]

This paper focuses on the experimental and analytical behavior assessment of novel sandwich panels fabricated with recycled glass-fiber/polyester resin (GFRP) core and PVC face sheets. The originality of the present work is based on sustainable development and waste recovery to design lightweight and eco-friendly structures. In this respect, the panels cores were fabricated using fully recycling of fiber-glass waste issued form the boats building. Accordingly, a set of sandwich panels with various core configuration and fibers orientation were manufactured and tested up to failure under three-point bending to characterize flexural and shear properties. In addition, validated analytical equations were advocated to assess the bearing capacity of the studied panels. The obtained results in terms of mechanical, thermal and physical features are emphasized, discussed and confronted with a good agreement to literature ones. A principal component analysis was conducted to optimize the effect of the geometrical parameters on the panel failure mechanisms. As main outcomes, the work can provide environmental and economic solutions for the design of sandwich structures. • Lightweight and eco-friendly sandwich structures-based GFRP waste core were designed • Validated analytical equations were advocated to assess the bearing capacity of the studied panels under bending • A principal component analysis was conducted to optimize the geometric parameters of the panels • The paper results provide environmental and economic solutions for the design of sandwich structures [ABSTRACT FROM AUTHOR]

Engineered Cementitious Composites (ECC) utilize the bridging effect of high toughness fibers to improve the brittle failure of concrete materials, achieve the effective control of cracks in cementitious materials, and significantly improve the deformation capacity. In view of the multi-stage crack-blocking effect of different fibers incorporated in ECC materials, 91 ECC specimens of steel-polypropylene hybrid fiber by mixing steel fiber (SF) and polypropylene fiber (PPF) into cement-base are made in this paper. The specimens are tested in compression, tensile, bending and damping properties, respectively, which is of great significance to study the response of ECC structures under the earthquake action. The effects of the volume content of SF and PPF on the mechanical properties of ECC are studied in this paper. The results show that the cube specimen has better ductility than the prismatic specimen under monotonic compression, and there is no obvious brittle failure. With the increase of the volume content of SF to PPF, the compressive strength and elastic modulus of hybrid fiber ECC gradually increase, while the corresponding strain and axial compressive toughness gradually decrease; the tensile strength and tensile modulus increase, while the bending strength and damping ratio decrease. According to the test results, constitutive models of monotonic and repeated loading of hybrid fiber ECC suitable for finite element (FE) analysis are proposed. This investigation provides a theoretical basis and an experimental reference for further study of steel-polypropylene hybrid fiber ECC. • Steel fiber and polypropylene fiber are mixed as hybrid fiber of ECC. • The mechanical properties of ECC are investigate. • Volume content of steel-polypropylene hybrid fiber has influence on concrete material. • The hybrid fiber ECC cube has better ductility than that of prismatic. • Constitutive models of hybrid fiber ECC are suitable for finite element analysis. [ABSTRACT FROM AUTHOR]

The maintenance design for existing asphalt pavements, characterized by their typical structure and material composition, falls short of meeting the diverse requirements of pavements. There is an urgent need for a more rational design approach that can achieve accurate pavement design while also reducing construction costs. This paper focuses on selected conventional road surface structures and conducts an analysis of how pavement structure and materials impact fatigue life and construction expenses. It employs Python to perform three-dimensional finite element road modeling, analysis, and data extraction at specific locations, using normalized fatigue equation to calculate pavement fatigue life. The optimization variables selected are the modulus E and thickness h, with pavement maintenance cost serving as the optimization target function. The particle swarm optimization algorithm is employed for optimizing these variables. A comparative analysis is carried out for five improved optimization algorithms, optimizing combinations of inertia weight, learning factors, particle speed, number of particles, and iteration times. The results reveal that the enhanced optimization algorithms significantly improve iteration trends, featuring velocity limitations and natural selection mechanisms. Between 0 and 20 iterations, all algorithms search for the optimal solution over a wider interval with greater fluctuations. Between 20 and 30 iterations, each algorithm gradually converges towards its solution, stabilizing in the later stages. Based on optimization speed and actual engineering cost benchmarks, the NDPSO algorithm is selected, resulting in a 52.8% reduction in actual engineering costs. Adjustments to the particle count and iteration number of the NDPSO algorithm are made based on computational cost and optimization accuracy, thus choosing 20 particles and 50 iterations as the recommended parameter combination. By combining automated finite element modeling, analysis, and particle swarm optimization, this paper offers a novel and effective automated design reference for extending the lifespan of asphalt pavement structures. • An improved particle swarm optimization model for fatigue life with consideration of the modulus E and thickness h. • The automation of finite element modeling, calculation and data extraction is completed by using further development. • Normalized fatigue equation is used to calculate pavement fatigue life. • A novel and effective automated design reference for extending the lifespan of asphalt pavement structures is proposed. [ABSTRACT FROM AUTHOR]

This paper presents a thorough investigation into utilizing hybrid fibers, comprising both steel and polymeric fibers, to enhance the compressive and tensile behaviors of ultra-high-performance concrete (UHPC). Flowability tests revealed potential usability challenges with polymeric fibers, emphasizing the necessity for careful consideration. Compressive strength results demonstrated that hybridizing straight steel fibers with short hooked steel fibers results in performance similar to that of reduced steel fiber content. Elastic modulus trends correspond with those of the compressive strength, and unexpectedly positive effects on the ultimate strain capacity under compression are observed with long polyvinyl alcohol fibers. Tensile behavior analysis highlights the superiority of both short and long hooked steel fibers, with the latter contributing the highest tensile strength. However, the use of polymeric fibers significantly decreases the tensile strength owing to insufficient dispersion and low tensile strength. Scanning electron microscopy images of UHPC with polymeric fibers reveal debonding and surface damage, with potential advantages observed for polypropylene fibers through methods such as surface moisture coating. In conclusion, this paper provides insights into optimizing fiber content and types for UHPC, emphasizing a balance between reduced fiber content and maintained performance. The proposed hybrid reinforcement approach, particularly with short hooked fibers, is promising for practical usability and cost-effectiveness in construction applications. • Addition of hybrid fibers, particularly polymeric fibers, results in a decrease in flowability. • Hybridizing with hooked fibers decreases the fiber content by 0.5 % given similar strength levels. • Long PVA fiber is effective in increasing elastic modulus of UHPC due to limited deformation. • Hybrid use of straight and hooked steel fibers exhibits improved tensile performance of UHPC. • Introduction of PVA and PP fibers causes a decrease in the tensile strength of UHPC. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the variation rule of coarse aggregate and pore structure of shotcrete by adding MWCNTs. In the paper, X-ray computed tomography scans are used to study the coarse aggregate distribution and pore structure of the preparation of shotcrete, high-temperature curing shotcrete and shotcrete with MWCNTs. The distribution pattern of coarse aggregate and pore of shotcrete is obtained. The results show that: the coarse aggregate loss of shotcrete is serious within 30 mm from the wall and the coarse aggregate increases significantly in 30–70 mm. The addition of 0.03% MWCNTs increased the coarse aggregate of shotcrete by 36.63% and the volume of coarse aggregate by 25.64%. The largest increase is in coarse aggregates of 5–7 mm. This show that MWCNTs can improve mortar adhesion and reduce aggregate rebound. The number of shotcrete pores decreases with the increase of pore diameter. The proportion of small pores is up to 85%, the proportion of large pores is only 2%, but the volume of large pores reaches 87%. The addition of 0.03% MWCNTs can reduce the number of small pores in the shotcrete and reduce the mean pore diameter, resulting in a decrease in the porosity of the shotcrete. When the curing temperature is 80℃, the porosity of shotcrete increases, and the pores decrease due to interconnection. The pores around the coarse aggregate account for over 70% of the total porosity, with pores larger than 1 mm accounting for 75%. This paper has a good reference value for the development of shotcrete and the selection of coarse aggregate in the actual working conditions. • The coarse aggregate distribution and pore structure characteristics of shotcrete were revealed. • The influence of MWCNTs on the rebound of shotcrete coarse aggregate was analyzed. • The relationship between pore distribution of shotcrete and coarse aggregate distribution is discussed. [ABSTRACT FROM AUTHOR]

Transparent bamboo (TB) stands as a promising biomass composite material, offering a range of merits including a straightforward preparation, high light transmittance, environmental sustainability, superior mechanical properties, and low thermal conductivity. These characteristics position TB for versatile application spanning energy-efficient building materials, decorative elements, and optoelectronic devices. This comprehensive review aims to elucidate the optical synthesis mechanism of TBs, delving into their functionalization improvement and exploring the potential applications across various domains. This paper serves to furnish readers with a profound understanding of the evolving landscape of TBs and their potential transformative impact. • This paper reviews the synthesis mechanism, preparation process, functional improvement of Transparent bamboo (TB). • The structure, properties and functional characteristics of TB are discussed. • The potential applications of TB in building materials, interior decoration and optoelectronic devices are summarized. • The prospects and challenges for the development of TB are discussed. [ABSTRACT FROM AUTHOR]

Utilizing nano-SiO 2 (NS) to reinforce the old mortar and the weak interfacial transition zone (ITZ) in recycled coarse aggregate (RCA) is a productive approach to enhance the quality of RCA. Throughout this paper, RCA was immersed in NS solutions with different concentrations (2, 5, 10 and 30 wt%). Subsequently, a systematic evaluation of the crushing index and water absorption of the treated NS modified recycled coarse aggregate (SRCA) was conducted. In addition, the calcium hydroxide (CH) content of RCA before and after modification was analyzed by Thermogravimetric and Differential Thermal Analysis (TG-DTA) curves. This study finds that the performance of SRCA modified with 2% concentration achieves comparable modification effects to other concentrations. Additionally, this paper delves into the impact of NS powder on the slump characteristics and compressive strength of concrete. Considering the above research and economic costs, this study adopts 2% concentration of NS for RCA modification and further investigates the stress-strain relationship of NS modified recycled aggregate concrete (SRAC) with various SRCA replacement ratios. Moreover, this paper establishes mesoscopic models of SRAC for various replacement rates and proposes constitutive models corresponding to these rates. The results indicate that when the SRCA replacement rate is within 60%, the stress-strain curve shape of SRAC closely resembles that of natural aggregate concrete (NAC); when the replacement rate exceeds 60%, the descending segment of the SRAC stress-strain curve becomes more precipitous, showing a higher tendency towards fragility in the concrete. ● Nano-SiO 2 can be used to improve the properties of recycled coarse aggregates. ● NS powder affects the slump and compressive strength of recycled concrete. ● As the concentration of NS solution increases, the compressive strength of concrete increases. ● Mesoscopic models of modified recycled concrete were established and constitutive models were proposed. [ABSTRACT FROM AUTHOR]

When a slurry shield tunnel traverses through extensive deposits of silty clay stratum, a considerable amount of high-viscosity waste slurry with elevated particle content is inevitably generated. Failure to promptly address this waste slurry could have a severe impact on project progress and the surrounding environment. To address the challenge of rapid dewatering for high-moisture and high clay-content waste slurry, this paper introduces an efficient waste slurry dewatering technique: magnetic flocculation dewatering technology. Additionally, the paper explores avenues for the resource utilization of waste slurry containing magnetic particles Through conducting flocculation settling experiments, a comparative analysis was carried out on the dewatering effects of traditional flocculation and magnetic flocculation technologies. The paper discusses the dewatering mechanism of magnetic flocculation and determines the optimal process conditions for treating waste slurry utilizing magnetic flocculation. The results indicate: (1) The flocculation and dewatering process of waste slurry can be divided into two stages: a rapid flocculation settling stage and a slow consolidation stage, with the rapid flocculation settling stage playing a dominant role. (2) Under magnetic flocculation, the time required for the rapid flocculation settling stage is only 1/3 of that in traditional flocculation, and the slurry dewatering rate is 1.4 times higher than traditional flocculation. (3) The optimal sequence for adding material under magnetic flocculation is to add magnetic powder first and then the flocculant. The optimum dosage of magnetic powder is 1.0 g/L, and the most suitable magnetic field intensity is 92.0 mT. (4) The magnetically flocculated sludge obtained after magnetic flocculation treatment can be utilized for the production of construction bricks that comply with standard specifications. The research findings of this paper provide a basis and guidance for the efficient reduction and resource utilization of waste slurry. • A novel efficient technique for dewatering of waste sludge, known as magnetic flocculation dewatering technology, is introduced. • Comparative analysis between traditional flocculation and magnetic flocculation techniques is conducted to confirm the superior dewatering efficiency of magnetic flocculation. • The mechanism of magnetic flocculation technology in the dewatering process of waste sludge is elucidated, leading to the identification of optimal operational conditions for waste sludge treatment under magnetic flocculation. • A pathway for the resource utilization of waste sludge is proposed, with the feasibility of using waste sludge for the production of construction bricks without firing being validated. [ABSTRACT FROM AUTHOR]

Since 3D printed concrete has a promising application in engineering, the combination of 3D printing concrete and other building materials has become a hot research topic.This paper investigates the shear properties of 3DPM-NM specimens which use 3D printed mortar (3DPM) as the precast part and normal mortar(NM) as the cast-in-place part. Four different types of interfacial locking design were analyzed in this paper, including L-shaped, C-shaped, S-shaped and K-shaped. The shear damage law of the specimens was analyzed using digital image correlation (DIC) technology. The results show that L-shaped specimens are basically damaged along the shear surface during the loading process. Most of the initial cracks in the C-shaped, S-shaped and K-shaped specimens appeared along the interfacial bonding surface during the loading process. Then, the cracks in the C, S and K-shaped specimens continued to develop along the interfacial bonding surface or spilt through the specimens directly. The results show the shear properties of the C-shaped specimens are similar to those of L-shaped specimens. And the mechanical properties of S-shaped and K-shaped specimens are better than those of L-shaped specimens which increased by 96% (S-shaped), 78% (K-shaped) respectively. The mean slip is increased by 10% in S-shaped specimens and 28% in K-shaped specimens compared with that of L-shaped specimens. According to the AASHTO GSCB INTERIM-2003 specification, the modified formula for the shear bearing capacity of 3DPM-NM specimens is proposed in this study. The calculated resultsare in good agreement with the test results, which theoretically provide guidance for the application of 3DPM, lay the foundation for its feasibility as a structural body of a building. • Specimens with 3D printed mortar (3DPM) as a precast component and normal mortar(NM) as a cast-in-place part were tested. • Comparison of the shear performance of specimens with different types of interfacial locking design were conducted. • Theoretical analysis and modified calculations of shear strength for 3DPM-NM interfacial locking specimens were carried out. [ABSTRACT FROM AUTHOR]

This study proposed a procedure to optimize the mixture proportion of geopolymer using machine learning (ML) and multi-objective optimization (MOO) model, which enhances the compressive strength and minimizes the carbon emission and costs. The experiment was preliminary carried out to analyze the workability, compressive strength, microstructure, and pore characteristics of fly ash/slag-based geopolymer. The results showed that the higher replacement ratio of slag established positive effects on the hardening as well as porosity improvement due to the coexistence of C-S-H and NASH-type binders, especially for a ratio was no more than 60%. Considering the performance of geopolymers is often influenced by multiple factors such as material composition and curing conditions, which could not be solved by traditional methods. A database containing 836 samples was established to analyze the prediction performance of 7 ML models by using Bayesian optimization. The GPR model has good generalization ability, with R 2 being 0.99 (0.99) on the testing set (training set). Furthermore, the reliability of the ML models was evaluated by the tests conducted in this paper. The feature importance analysis utilizing SHAP method indicates that Age, HM, and SS are key parameters influencing the compressive strength of geopolymer. The proposed MOO model can effectively evaluate the trade-offs between compressive strength, carbon emission, and costs, and all Pareto solutions for bi-objective and three-objective provided the optimal mixture schemes. On this basis, the design procedure proposed in this paper can give the scheme of geopolymer materials with different requirements (given mixture scheme and given design strength). [Display omitted] • Working mechanism of different matrix on geopolymer are revealed. • SHAP method can explain the physical mechanism of parameter on the output variable. • Reliability of the intelligent prediction model is validated by experiment. • MOO model can evaluate the relationship between CS, CO 2 and costs of geopolymer. • Procedure of geopolymer mixture schemes with different design strength are proposed. [ABSTRACT FROM AUTHOR]

This paper comprehensively reviews present research on the potential for repurposing primary categories of waste plastics. These include Polyethylene Terephthalate (PETE), High-Density Polyethylene (HDPE), Polyvinyl Chloride (PVC), Low-Density Polyethylene (LDPE), Polypropylene (PP), Polystyrene (PS), and other variants such as Acrylonitrile Butadiene Styrene (ABS), Ethylene Vinyl Acetate (EVA), Polycarbonate (PC), and Polyurethane (PU). The focus is on their use in the construction of bituminous mixes via the dry process method. This method incorporates plastic waste into bituminous mixes by modifying the mixture or replacing aggregates. This practice has consistently demonstrated improvements in pavement performance, including increased stiffness, resistance to rutting, and fatigue. When bituminous mixtures are modified with the mixture modifying approach using low melting point plastics such as LDPE, HDPE, and LLDPE, a significant reduction in OBC is observed. Furthermore, the mixture modification approach has demonstrated higher resistance to moisture damage, rutting, and fatigue damage than the aggregate replacement approach. The potential benefits of using plastics in the bituminous pavement are substantial. This includes a reduction in the amount of waste sent to landfills, a decrease in reliance on finite natural resources, and the expansion of options for constructing bituminous pavements. Economic analyses have shown that using waste plastics can reduce pavement construction costs by 10%, with a minimal probability of leaching. Despite a multifold increase in the emission of greenhouse gases, an overall reduction in environmental impact was observed from the life cycle assessment study. However, the use of PVC and dark-colored plastics is not recommended. Field studies conducted on roads constructed with waste plastic-modified bituminous pavements showed notable improvements. Most of these pavements exhibited higher Pavement Condition Index (PCI) values and lower International Roughness Index (IRI) values than conventional pavements. These findings underscore the superior riding quality and reduced deterioration associated with waste plastic incorporation. Moreover, in-plant production processes, plants require minimal modifications, as existing equipment used for feeding fibers is well-suited for adding plastics into the mixture. In conclusion, further research is essential to fully understand the impact of different types of plastics on pavement performance and to evaluate this process's potential environmental and economic implications. This paper seeks to bridge the gap in the literature by reviewing and discussing the performance of such mixes and constructed pavements in laboratory and field situations. ● The impact of different plastics on mechanical performance of bituminous mix has been reviewed. ● Plastics at OPC improves bituminous mixture's mechanical performance. ● Long term field performance studies have been reviewed. ● Pavements containing waste plastics shows better riding quality and less deterioration. ● Future studies should more focus on environmental assessment. [ABSTRACT FROM AUTHOR]

Over the past year, ChatGPT's initial applications across diverse fields have progressed amid debates on its ethical implications and inherent biases. This paper investigates the comprehension level of ChatGPT 4.0 regarding cementitious composites and initiates preliminary research into its application in cementitious composites，including ordinary Portland cement (OPC) concrete, Engineered Cementitious Composite (ECC), and Ultra-High-Performance Concrete (UHPC). Initially, the study designed forty-five progressively challenging questions to examine the readability and accuracy of ChatGPT's responses related to cementitious composites. Building on this, the research explored the feasibility of utilizing ChatGPT for the identification and analysis of ECC cracks, the design of mix proportions for cementitious composites, and the real-time analysis of carbon emissions. The results demonstrate ChatGPT 4.0's proficiency in acquiring foundational knowledge of cementitious composites, a capability verified through interactive human-computer modalities for analysing crack quantity and width, formulating preliminary material compositions, and providing instantaneous feedback on carbon emissions. However, the study also uncovers ChatGPT 4.0's limitations in understanding the complex design mathematics and mechanics underlying cementitious composites, as well as its inadequate ability to synthesise and integrate interdisciplinary knowledge, occasionally leading to arbitrary and forced responses. These findings underscore the need for further enhancements in algorithmic sophistication and database comprehensiveness. The paper concludes by projecting the future applicability of ChatGPT in the cementitious composites sector, highlighting its initial contributions while delineating avenues for subsequent research and development. • The understanding of ChatGPT on cementitious composites was investigated. • The preliminary application study of ChatGPT 4.0 was conducted. • The future application prospects of ChatGPT were anticipated. [ABSTRACT FROM AUTHOR]

All-Bamboo Aggregate Concrete (BAC) is a type of cement concrete material where all coarse aggregates are made of bamboo aggregate, a plant material that requires necessary measures to avoid or slow down its degradation in alkaline and natural environments. This paper enhances the durability of BAC materials through the treatment of bamboo aggregate with ACQ-polyacrylate (AP method). Initially, the study explores the impact of polyacrylate dilution concentration on the compressive strength and coating thickness of BAC, and based on a reasonable modification process, conducts freeze-thaw cycles, salt solution immersion, accelerated wet-dry aging, and long-term natural environment tests to assess the durability of BAC materials. The results show that a polyacrylate solution with a dilution ratio of 1:5 can form a coating thickness of 23.8μm, performing better in various durability evaluations. After 25 freeze-thaw cycles, the BAC material's loss rate of compressive strength is lower than that of Ordinary Concrete (OC). Compared with OC, BAC materials are more susceptible to salt damage after salt solution immersion. The compressive strength loss rate under 180 days of natural environment exposure is comparable to that in 10 cycles of accelerated wet-dry aging, 28 days of salt solution immersion, and 10–15 freeze-thaw cycle tests, recommending the use of freeze-thaw cycle tests for evaluating the durability of BAC materials from an experimental efficiency perspective. By exploring the durability of BAC materials, this paper provides an innovative solution in the field of construction materials, promoting the transition of the construction industry towards sustainable development. It emphasizes the feasibility and effectiveness of improving the performance of bamboo-based materials through surface treatment technology, offering a valid reference for developing more environmentally friendly and high-performance new materials in the future. • BAC materials show lower durability than traditional concrete. • Polyacrylate solution can enhance BAC durability. • Polyacrylate solution can enhance BAC durability. • Future research should optimize polyacrylate modification. [ABSTRACT FROM AUTHOR]

Building precise machine learning and deep learning models has traditionally required a combination of mathematical skills and hands-on experience to meticulously adjust hyperparameters that significantly impact the learning process. As datasets continue to expand across various engineering domains, researchers increasingly turn to machine learning methods to uncover hidden insights that may elude classic regression techniques. This surge in adoption raises concerns about the adequacy of resultant meta-models and the interpretation of findings. In response to these challenges, automated machine learning (AutoML) emerges as a promising solution, aiming to construct machine learning models with minimal intervention or guidance from human experts. This paper benchmarks AutoML solutions by providing an overview of their principles and applying them to predict the most important mechanical properties of different concrete datasets, i.e., compressive strength. Nine datasets from various concrete types, sample sizes, and features are utilized, with a detailed discussion on the benchmark dataset from high-performance concrete, applying best practices to the other eight datasets. For each case, the importance of hyperparameter tuning is discussed, alongside the ensemble and stacking models. Tree-based models are employed for each dataset to develop SHAP plots, interpret results, and understand the contribution of each component in the mix design to the overall strength of the concrete. This paper further explores three unique aspects of benchmarking AutoML in material science: (1) "reliability" by contrasting the benchmark dataset's error metric with literature collected over the past 20 years, (2) "uncertainty" by quantifying the variability in the mean and standard deviation of the error metric from different datasets and its correlation with the sample-to-feature ratio, and (3) "dilemma" by discussing the shortcomings of AutoML in specific concrete datasets. • The first comprehensive application of AutoML is presented in the concrete regression model. • Nine different concrete datasets are compared in terms of compressive strength. • AutoML's reliability, and dilemmas are evaluated in predicting concrete strength. • A benchmark problem is discussed to quantify the AutoML uncertainty in material science. • Explainable machine learning is used to identify the key contributing factors in f' c. [ABSTRACT FROM AUTHOR]

This paper not only studies the influence of fiber content on the mechanical properties of steel fiber ultra-high performance concrete (SFRUHPC), but also conducts high-speed impact tests and simulations on high-volume fiber targets with varying thicknesses to evaluate the damage characteristics of the SFRUHPC targets, such as residual velocity and penetration depth of the projectile. The results indicate that compared with ordinary concrete and low fiber content targets, the flexural strength and compressive strength of the target incorporated with 7% steel fiber reach the maximum values of 87.9 MPa and 362.9 MPa, respectively, which are significantly improved. On the other hand, the 7% steel fiber reinforced target demonstrates excellent anti-penetration performance which is evidenced by a 51.9% lower residual velocity compared to ordinary concrete targets in thin target tests, as well as a 37.4% reduction in penetration depth in thick target tests. Additionally, the rebound phenomenon of the projectile is observed during the tests. Furthermore, the three-dimensional mesoscopic numerical model established exhibits a good correlation with the experimental results. Finally, the model adopted in this paper can better predict the residual velocity and depth of penetration of the projectile. • The anti-penetration performance of three types of targets incorporating high content steel fibers were evaluated. • The high content steel fibers attribute to the better penetration resistance. • The phenomenon of projectile rebound is observed in a thick target with a steel fiber content of 7%. • The established three-dimensional mesoscopic numerical model aligns well with the experimental data. [ABSTRACT FROM AUTHOR]

This review paper presents a comparative evaluation of polymer, bacterial-based, alkali-activated, and geopolymer binders in regard to their production methods, mechanical properties, their environmental/life cycle assessment (LCA), and durability when exposed to deteriorating cycles (such as sulfates, acids, and high temperatures). The significance of this study is to compare the results of over 400 journal papers, which present an in-depth analysis of fresh and hardened state properties of various binders that are advocated in the literature. Historically, Portland cement is generally considered a binder that plays a major role in any cementitious composites because of its high availability, and relatively inexpensive cost. Despite its significant benefits, it is known that the manufacturing process of Portland cement is energy and carbon intensive, and the resulted material often has shortcomings when exposed to deteriorating causes such as sulfates, acids, and high temperatures. However, recent movement toward net-zero as well as ultra-high-performance practices has increased the need for a more sustainable and durable binding system. Based on the result of this paper, each binder presents specific advantages when compared to Portland cement for specific applications that can be a better choice for their ultra-high capabilities and ecological properties. This includes the significantly better performance of alkali-activated binders (specifically geopolymers), under high temperatures, or very rapid strength gain of polymer (e.g., epoxy, polyester, and vinyl ester) binders, making them great alternatives to Portland cement, for rapid repair and rehabilitation purposes. Similarly, bacterial concrete also have certain capabilities such as long term durability and the potential for a continued self-repair or self-healing. In terms of environmental impacts, however, polymer binders are heavily depedant on their source of energy (e.g., petroleum vs. bio-based resins) while alkali-activated concretes and geopolymers have activators' large contributions to overall LCA impact categories. For bacterial binders, the used urea and nutrition can play a key role in their LCA results. Finally, based on the highlighted capabilities of each binder, recommendations on performance-based or hybrid design methods and specifications for an optimized system are also provided. Novel areas in polymer, bacterial-based, alkali-activated, and geopolymer binders are also included. • A comparative analysis of various binding systems are provided. • Mechanical, Durability, and Ecological Properties vary significantly across binders. • Concentration, surface area, temp., and catalysts play key role in each binder. • Unique advantages and shortcomings of each binder is discussed. [ABSTRACT FROM AUTHOR]

The objective of this paper is to investigate the microstructure of high-viscosity modified asphalt binder (HVA) containing high-content polymers and its effect on fatigue performance, as well as the applicability of different analytical methods and failure criteria of linear amplitude sweep (LAS) test to HVA. In this paper, two types of HVAs with different polymer contents, a commercial HVA, a conventional polymer-modified asphalt binder, and a base asphalt binder were first prepared or selected. Fluorescence microscopy tests, time sweep tests, and LAS fatigue tests were then performed on these binders. Finally, the fatigue properties of the different binders were analyzed in depth using different analytical methods and failure criteria. The results show that the polymers in HVA crosslink with each other to form a strong cross-linking structure, and the phase inversion of the polymers renders them into a continuous phase, which significantly improves the fatigue damage resistance of the HVA; moreover, the evolutions of stress with shear strain for the fatigue process of HVAs is related to the polymer network. Besides, the two-dimensional damage characteristic curve (DCC) cannot accurately reflect the evolution of the fatigue performance of HVA, and this paper suggests the use of a three-dimensional DCC curve with strain information. Furthermore, the 35% reduction in C 0 in the dissipative energy method is not a suitable failure criterion, a more accurate fatigue performance ranking can be obtained by using the yield stress as the failure criterion. Although the fatigue resistance of HVA after yield stress is theoretically considered using the pseudo-strain energy approach, HVA does not show a peak of stored pseudo-strain energy even when the strain is increased to 60% in the LAS test. Therefore, the maximum strain value (30%) in the standard LAS test is not sufficient in characterizing high-polymer HVAs because there is not enough fatigue accumulation of HVAs in this range, consequently, the maximum shear strain parameter in the LAS experiment needs to be reconsidered. • Polymer morphology and its crosslinking networks in HVA with high-content polymers were analyzed. • The fatigue properties of HVAs based on LAS test and different analytical methods are compared. • The fatigue crack length and its evolution of HVA are characterized. • The deficiencies of the LAS test to evaluate the fatigue resistance of HVA and suggestions for modifications are presented. [ABSTRACT FROM AUTHOR]

Shape memory alloy (SMA) is an innovative intelligent material, capable of restoring its shape before deformation upon reaching the critical activation temperature. This property promotes its promising applications in civil engineering. This paper proposes a novel reinforcement method and aims to investigate the reinforcing effect of iron-based shape memory alloy (Fe-SMA) plates on prestressed concrete (PC) beams through four-point bending tests on one reference beam without reinforcement and three Fe-SMA reinforced beams, as well as with three beams reinforced by carbon fiber-reinforced polymer (CFRP). The results show that Fe-SMA can effectively reduce concrete cracks, and improve stiffness and characteristic loads of beams without negative effects. Under the same loading conditions, new cracks of Fe-SMA reinforced beams were relatively fewer than those of CFRP reinforced beams. Besides, Fe-SMA exhibited superior performance when utilizing the same cross-sectional reinforcement material to enhance the bending capacity of beam, and proved more advantageous for improving stiffness and characteristic loads of beam under the identical initial tensile force. Furthermore, the reinforcing effectiveness of Fe-SMA positively correlates with the cross-sectional area (thickness) and recovery stress (pre-stretch level and activation temperature) of Fe-SMA. Increasing the thickness of Fe-SMA plates by 100%, while maintaining other parameters constant, resulted in a 33% increase in cracking load. Similarly, elevating the recovery stress from 314 MPa to 340 MPa led to a 12.5% rise in cracking load. This paper investigates the reinforcement effect of Fe-SMA plates on PC beams, and provides a reference for the application of Fe-SMA in PC beam reinforcement, laying a foundation for promoting the utilization of Fe-SMA in civil engineering. • A novel reinforcement system to strengthen PC beams employing Fe-SMA plates was proposed. • The effect of Fe-SMA plates on PC beams through four-point bending tests was compared with CFRP tendons. • Fe-SMA was more effective than CFRP in enhancing the bending capacity of PC beams. • The reinforcing effectiveness of Fe-SMA positively correlates with cross-sectional area and recovery stress. [ABSTRACT FROM AUTHOR]

Surface (microscale) roughness of coarse aggregates influence the cement suspension' viscosity and the interfacial bonding strength of concrete, but its characterization method is not consolidated and still a research challenge. 3D scanner determines accurately the shape, volume, but it is incapable of describing the roughness at microscale. Roughness at microscale (surface index – cm2/cm2) can be measured accurately using interferometry, but it cannot describe shape and volume of the particles. Once the volume of aggregate particles may vary 200% and it seems crucial to establish the (micro)roughness per volume (cm2/cm3) to better understand the effects in the properties of cementitious materials. This paper presents a method of obtaining volumetric surface area of coarse aggregates at micrometric scale by joining (cm2/cm3) both techniques. Three types of aggregates were assessed: gneiss, low-grade meta-carbonate (dolomite) and quartzite (gravel), with one hundred particles in the size range of 4.75 mm to 37.5 mm. For coarse aggregates, the larger the particles, the more of their surface area will be influenced by (mesoscale) shape and less by surface (microscale) roughness. However, the smaller the particles, SI index will differ considerably. The surface area determined by the method proposed in this paper provides a good correlation with the methylene blue method. • New method to determine volumetric surface area (VSA) of aggregates. • Light white interferometry and 3D scanning methods combined. • Shape and roughness (multiscale) morphological descriptors discussed. [ABSTRACT FROM AUTHOR]

In this paper, a thermo-mechanical sequential coupling mesoscopic simulation method was established and verified, which considered the interaction between steel tube and meso-components of concrete due to the difference in thermal parameters, as well as the low-temperature effect on mechanical parameters. On the basis of heat conduction analysis, the damage evolution and failure mechanism of CFST column under axial compression were subsequently revealed, and the effects of low temperature (20, −30, −60 and −80 °C), cross-section size (160, 320, 480 and 640 mm), width-thickness ratio (27, 36, 53 and 107) and cross-section shape (square and circular) on axial compression performance and the corresponding size effect of CFST columns were quantitatively analysed. Research results show that the low-temperature action can enhance the nominal peak strength and residual strength of CFST column, but weaken the ductility. As the cross-section size increases from 160 to 640 mm, all the nominal peak strength, nominal residual strength and peak strain of circular CFST column decrease with the maximum reductions of 16.2, 28.7 and 16.9%, respectively. Besides, the low-temperature action can enhance the size effect on nominal peak strength of CFST column with the maximum increase of 68.8%. Whether at ambient or low temperature, the size effect on nominal peak strength of square column is stronger than that of circular one. The size effect behaviour on axial compressive peak strength at various temperatures can be also well described by the previous proposed prediction formula. The research results of this paper can provide reference for the engineering application of large-sized CFST columns in the extreme low-temperature environment. • The thermo-mechanical sequential coupling method at low temperature was developed. • The effect of low temperature, width-thickness ratio, cross-section size and cross-section shape were considered. • The mechanical properties and corresponding size effect of CFST columns at low temperature were quantitatively analyzed. [ABSTRACT FROM AUTHOR]

In this paper an overview is presented on the use of diatomaceous earth (DE) as a partial substitute for binder and fine aggregate in mortars. For this purpose, this paper was divided into two sections. In the first one, concepts related to physical, chemical and microstructural properties of DE, as well as results of previous studies about its reactivity used in different construction materials (cement, concrete, mortar, bricks, phase change materials etc.) were summarized and discussed. In the next section, the effects of using DE on the fresh, hardening and durability properties of cement and lime-based mortars were discussed. In general, the results suggest that increasing DE content may reduce mortar performance due to the high porosity of its particles. However, this deficiency was observed for DE contents higher than 20%, which, however, can be compensated for by using superplasticizer additives or by volumetric dosage instead of by weight one. This critical value of up to 20% of DE was calculated using T2 statistical on the scores of principal components analysis obtained from the results collected from publish manuscripts. Nevertheless, the results of this review research may contribute to provide information on an under-explored alternative source of supplementary cementitious materials (SCMs) and therefore help mitigate the negative effects generated by the cement industry and assist in the production of mortars with a lower carbon footprint that can play an important role in the thermal behavior of buildings. • State of the art systematic review of diatomaceous earth (DE) for mortar production. • Statistical analysis of the mechanical properties of mortar with DE. • Understanding the effects of DE on properties of mortars. • When up to 20% DE is used, the mechanical behavior of mortars can be improved. • Paths for the development of new studies on mortars incorporating DE are shown. [ABSTRACT FROM AUTHOR]

To improve the fatigue behaviour of the concrete, this paper explored a potential innovative method: the joint addition of expansive agents (EA) and glass fibres (GF). It was envisaged that the addition of EA reduced additional defects caused by the addition of GF to the concrete, while the compressive prestress caused by EA enhanced the bonding between GF and the concrete, thereby improving the fatigue behaviour of the concrete. The test results indicated that the synergistic effect of EA and GF effectively improved the static bending strength, fatigue life, and deformation performance of the concrete. The synergistic effect of EA and GF on the fatigue life of the concrete was revealed qualitatively and quantitatively. The synergistic effect was further demonstrated from perspectives of the fatigue deformation and fatigue stiffness. Furthermore, P - S - N curves of EA and GF reinforced concrete were established, and the fatigue ultimate strength and conditional fatigue ultimate strength were provided as a design basis. This paper recommended adding an appropriate amount of EA to glass fibre reinforced concrete to achieve better concrete properties. • Joint addition of EA and Gf was a potential method for improving concrete. • Bending tests were used to elucidate fatigue bending performance of concrete. • Synergistic effect of EA and GF on fatigue performance of concrete was reveal. • Using two-paramater Weibull distribution, P - S - N curves were established. [ABSTRACT FROM AUTHOR]