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The aim of this study was to investigate the properties of concrete with waste paper ash (WPA) as cement replacing material. The chemical composition of WPA was reported, and Portland cement was partially replaced with 0%, 5%, 10%, 15%, and 20% of WPA to explore its effect on both fresh and hardened properties of C—25 concrete. The result of this study indicated that the chemical compositions of WPA were not classified as Pozzolanic material. Setting times of blended cement paste with WPA were lengthened and its consistency was also increased. The cement paste with replacement up to 10% showed a normal consistency within the standard range. The workability of concrete was tested immediately after preparing the concrete mix, whereas the compressive strength was tested after 7 and 28 days of curing. The results indicated that the workability of concrete containing WPA decreases as the WPA content increases. This study also revealed that there is a significant improvement in the compressive strength of concrete. Replacement of ordinary Portland cement by WPA up to 10% results in better compressive strength than that of the control mix. An improvement of 5.6% & 1.2% was observed, respectively, when compared with the 28-day compressive strength of the control mix. But the compressive strength decreases as the WPA replacement increases over 10%. Maximum compressive strength of 37.89 MPa was obtained for concrete containing 5% of WPA. [ABSTRACT FROM AUTHOR]

In order to improve the widening technology of cement concrete pavement of rural highway, this paper further studies the blockage simulation process of permeable concrete pavement. Moreover, this paper separately studies various external conditions such as sediment gradation, horizontal runoff velocity, seepage velocity, porosity, etc., and reveals the mechanism of pore blockage in permeable pavement. After decades of self-gravity consolidation and the effect of traffic load on the subgrade of the rural old road, the consolidation of the old road has been basically completed. At the same time, after the new road is built, due to its own load and vehicle load, it gradually generates its own settlement, resulting in differential settlement of the old and new subgrade. In addition, this paper explores this difference through digital simulation, and puts forward several suggestions in combination with the simulation model. Finally, on this basis, this paper verifies the method proposed in this paper through experimental research. The research results show that the improvement strategy proposed in this paper is suitable for the widening construction of cement concrete pavement of rural highway. [ABSTRACT FROM AUTHOR]

Concrete, a widely used building material, should minimize its environmental impact to align with the construction sector's Sustainable Development Goals. Researchers worldwide are investigating the possibility of e-waste in building materials incorporating various recyclable elements. This paper conducts a thorough review of research on e-waste as a building material. Various E-waste products are used as fine and coarse aggregate replacements in concrete. The study uses a bibliographic approach with the Scopus database to delve into the literature discussing E-waste in construction materials from 2007 to 2022. Data are extracted specifically from Scopus, which identifies 731 papers based on the keyword "Electronic waste used as building materials". The second step involves scientometric analysis, which focuses on patterns within the articles, such as the most prolific countries, sources, frequently used keywords, and reports containing relevant research. Each research phase contains a summary of the results obtained at various stages. Detailed quantitative and qualitative discussions are also conducted to achieve the three primary goals: a summary of quantitative data, a discussion of the existing application, and identifying future research directions. These findings will be useful for subsequent academic studies on transforming e-waste into building materials. The scientometric review provides a path for researchers from various countries to share new ideas and information while encouraging research collaboration. [ABSTRACT FROM AUTHOR]

This paper describes deep neural network (DNN) models based on hyperparameter optimization for the prediction of the compressive strength of concrete. The novelty of this research lies in the implementation of optimized hyperparameters to train the DNN models with the aim to enhance their predictive accuracy. Utilizing the Keras Tuner library, the most effective hyperparameters for the DNN models were identified. These models are then trained and evaluated using an experimental dataset of 1030 instances, encompassing nine quantitative variables that include various concrete mix ingredients and age. The target variable for all models is the compressive strength of concrete. The assessment of model performance, based on metrics like mean squared error (MSE) and R² values, was conducted on previously unseen test data. The optimal configuration for the hidden layers in the model was identified as five layers, containing 12, 16, 16, 40, and 26 neurons, respectively. The optimal learning rate for the model was 0.001. With this set of optimal hyperparameters, the best DNN model achieved an MSE of 28.76 and an R² value of 0.89 on the testing data. The results demonstrate a significant improvement in the DNN models' performance when trained with the optimized hyperparameters. In comparison to the regression model, the performance of the DNN models was significantly better. Adopting the predictive models developed in this research offers the potential for substantial cost and time savings by circumventing the need for labour-intensive and time-consuming laboratory tests. [ABSTRACT FROM AUTHOR]

MWCNTs and ultra-fine steel microwires double-doped RPC are researched to determine the modification law of flexural strength and post-folding compressive strength in order to investigate the impact of nanoscale admixtures on the strength of high-rise building concrete. This research also examines the elastic modulus of the prismatic specimen as well as the flexural toughness and compressive toughness of the load-displacement curve. Through theoretical calculations of composite materials, this paper also investigates how MWCNTs and ultra-fine steel microwires double-doped fillers improve the mechanical properties of RPC. Additionally, this work uses experimental techniques for material preparation, performance analysis and simulation research in conjunction with intelligent models. The method suggested in this research has a certain effect, and has a certain promotion effect on the subsequent performance improvement of concrete materials, as can be observed from the data statistics. [ABSTRACT FROM AUTHOR]

This paper proposes a mathematical model approach to predict the Ultrasonic Pulse Velocity (UPV) of concrete. This paper presents the formulation, calibration, evaluation, and validation of the proposed UPV model. An experimental program was developed to calibrate and evaluate the proposed model. Furthermore, the model was validated using a separate group of measurements in the experimental program, to test its accuracy and generalization capability. Analysis of the results reveals that the proposed model provides a good fit to the experimental data and does not contain outliers or discerning pattern. The corresponding standard error and determination coefficient are 45 m/s and 0.92, respectively. Model validation demonstrates high predictability and generalization capability. The corresponding standard error and determination coefficient are 74 m/s and 0.91, respectively. [ABSTRACT FROM AUTHOR]

The Mechanical properties of concrete significantly deteriorate when exposed to fire, with explosive spalling posing a major threat to structural integrity. This highlights the need for effective insulation systems to protect concrete structures in fire conditions. However, current insulation solutions are typically installed externally, requiring additional labour and materials. This review explores the potential of incorporating Phase Change Materials (PCMs) directly into concrete as an embedded insulation system. As a latent heat storage material, PCM offers promising fire-resistant properties, reducing the need for external insulation while improving the fire performance of concrete. This paper presents a bibliometric analysis and a systematic review of recent publications on the use of PCMs in concrete and their fire performance applications. One thousand two hundred and four publications retrieved from Scopus© and Web of Science databases were passed through the PRISMA flowchart to obtain a database of recent literature on the study area. The current trend of research shows a shift towards inorganic PCMs in concrete. There is a significant lack of studies on using inorganic and eutectic PCM in concrete for fire applications and existing studies show inorganic PCM can be a viable solution. Commercial availability and lack of synthesised encapsulated PCM were found to be barriers to research. [ABSTRACT FROM AUTHOR]

This paper investigates the flexural behaviour of hybrid reinforced concrete (RC) beams having aramid fibre reinforced concrete (AFRC) in the tension zone and high-strength concrete (HSC) in the compression zone. In two series of experimental investigations, the depth of AFRC layer and the concrete strength in the compression zone were varied. The hybrid beams were tested in series 1 to explore the effects of the depth of AFRC layer on load-carrying capacity and flexural toughness. The effects of compressive strength of the concrete in the top half of the hybrid beams on load-deflection behaviour, failure mode and cracking pattern were studied in series 2. The experimental results reveal that the use of AFRC only in the bottom half of the beam enhanced load-carrying capacity and flexural toughness by 62.44% and 87.66%, respectively, compared to the control specimen with no AFRC. The hybrid beam with AFRC-HSC exhibited 5% higher load-carrying capacities, 45% higher ductility and better cracking behaviour than the conventional RC beam. These enhanced structural performances are beneficial for specific purposes such as structures in marine environment where rebar corrosion is the main concern, or structures under extreme loadings where high ductility is required. [ABSTRACT FROM AUTHOR]

Carbon materials engineered electrically conductive cement concrete (ECCC) is typically prepared by directly adding carbon-based conductive filler into the cement matrix and then mixing cement with aggregates. With such a strategy, ECCC possesses a high conductivity and strain/stress sensitivity and thus can be used for snow and ice melting, ohmic heating, cathodic protection system, electromagnetic shielding, structural health monitoring, and traffic detection. This paper aims to provide a systematic review on the development and applications of ECCC, especially the progress made in the past decade (from 2012 to 2022). The composition and manufacture of ECCC are first introduced. Then, the electrical performance of ECCC and its potential applications are reviewed. Finally, the remaining challenges for future work are discussed. [ABSTRACT FROM AUTHOR]

This paper conducted an experimental investigation on the effects of dispersed basalt fiber (BF) on lightweight expanded clay concrete (LWECC). The objective is to evaluate the strength, density of LWECC containing dispersed BF with comparison on the strength derived from research of similar work. Experiments were performed on LWECC 100 × 100 × 400 mm prism for flexure and 100 × 100 × 100 mm cube for compression and split tensile tests. Additives were added to enhance the concrete strength. The compressive strength ðfcÞ, density (ρÞ, flexural strength ffð Þ, split tensile strength ðfstÞ were obtained from LWECC containing 0%, 0.9%, and 1.6% BF, respectively. The experimental results on day 28 show that fC recorded the highest at 1.6% BF content, and lowest at 0% BF content while with incorporation of 0.9%BF, the fC of ECC increased by 121.82%, with incorporation of 1.6% BF the fC of ECC increased by 162.79% and ECC containing 1.6% BF showed ρ of 1410 Kg/m³ while the ff is highest with 1.6% BF at 6.54 MPa followed by 0.9% BF at 4.01 MPa and lowest at 0% BF at 3.72 MPa. The fst is higher with 1.6 BF at 5.41 MPa. Incorporation of BF in ECC proved to have positive effect of ECC. [ABSTRACT FROM AUTHOR]

This paper presents the results of a testing program to examine the possibility of using crushed clay bricks as fine aggregate in concrete and mortar mixtures. A total of 90 specimens of concrete and mortar were cast at different percentages of crushed bricks (0, 25, 50, 75, and 100)% by weight as replacement of fine aggregate. Mechanical and physical properties of the specimens were conducted and presented in this paper. The experimental results indicated a decrease in compressive strength and splitting tensile strength of the concrete specimens. Also, the presence of crushed bricks aggregate in mixtures reduces the workability and flow ratio compared to the reference mix due to high water demand of the recycled aggregates than the normal aggregate. It can be noted that crushed bricks concrete is a convenient replacement in treading and finishing areas in buildings and in high floors in order to reduce the dead loads. [ABSTRACT FROM AUTHOR]

The durability of the self compacting concrete is one of the prominent areas of concern in recent years since it has become prevalent due to its ease of handling in the construction industries. However, there is a lack of detailed durability study of M-sand self compacting concrete with polypropylene fibres in the literature. In this paper, self compacting concrete made by Portland pozzolana cement with natural sand and M-sand, different percentages of volume fraction (0%, 0.1%, 0.15% and 0.2%) polypropylene fibres with M-sand is thoroughly investigated for fresh properties, hardened properties, drying shrinkage, water absorption, permeability, acid resistance and corrosion crack initiation time. Further, SEM analysis was carried out to know the effect of polypropylene fibre on the concrete microstructure. The results confirmed that the use of M-sand has improved the fresh, hardened and durability properties of the self compacted concrete than natural sand. Also, it is observed that the addition of polypropylene fibres has reduced the fresh properties of self compacted concrete. However, M-sand with 0.15% polypropylene fibres has slightly improved the strength of self compacting concrete, compression strength by 6.97%, split tensile by 8.68% and flexure strength by 3%. Further, it has reduced the drying shrinkage by 40%, water absorption by 30%, water penetration by 33.33%, and increased the chemical resistance, surface crack initiation period than the natural sand self compacting concrete. Finally, this study concludes that M-sand with 0.15% polypropylene fibres improves the durability of self compacting concrete by reducing effect from aggressive environments and in turn contributes to increased corrosion resistance of reinforcements embedded in concrete. Thus, the study supports the use of self compacting concrete with M-sand and optimum amount of polypropylene fibres to achieve required sustainability in terms of strength and durability. [ABSTRACT FROM AUTHOR]

Geopolymer concrete is gradually assuming significance from the point of sustainability in the concrete industry. The reinforced concrete corbels are used for supporting the precast beams. This paper presents an experimental investigation on the interface shear strength of reinforced geopolymer concrete corbels. A total of forty-five symmetric double cantilever reinforced GPC corbels were cast and tested. The parameters of the study include the compressive strength of GPC and the percentage of secondary reinforcement i.e. closed loop ties crossing the interface. The experimental shear strength at the interface of reinforced geopolymer concrete corbels obtained is compared with available analytical models and design codes applicable to the conventional concrete. The results of the study indicated that the interface shear capacity of geopolymer concrete was evaluated based on conventional concrete analytical models that underestimates the shear capacity of GPC corbels. Further the experimental shear strengths of corbel are about 9% higher than the predicted interface shear strength of GPC corbels using the analytical expression proposed in this paper. [ABSTRACT FROM AUTHOR]

To investigate the long-term performance of the packaged fiber Bragg grating (FBG) sensors embedded in civil infrastructure for strain monitoring, in this paper, the influence of host matrix's creep effect on the behavior of the FBG sensors was systematically studied through theoretical, numerical, and experimental analysis. A theoretical strain transfer analysis between the optic fiber, packaging layer, and host matrix to consider the creep effect of the host matrix was performed accordingly for long-term strain monitoring. Parametric studies were carried out using numerical analysis for FBG sensors packaged with glass fiber reinforced plastic (GFRP), also known as FBG-GFRP sensors in concrete, as an example. The results show that embedded in a creep medium, an acceptable long-term performance of packaged FBG sensors requires the packaging layer to have a minimum length and maximum thickness. Laboratory long-term creep tests using epoxy resin and concrete as host matrix for FBG-GFRP sensors also clearly demonstrated that the influence of creep effect cannot be ignored for strain measurements if the host matrix has a creep potential and the developed correction model performed well to reduce measurement errors of such sensors in creep medium. [ABSTRACT FROM AUTHOR]

Expanded polystyrene (EPS) concrete has high environmental and economic benefits. However, the difference in physical and chemical properties leads to a weak interface between EPS and concrete, which limits the use of EPS concrete. Based on the macro experiment of Ethylene Vinyl Acetate Copolymer (EVA) modified EPS concrete, two molecular dynamics interface models of EPS/C-S-H and EPS/EVA/C-S-H were constructed by molecular dynamics simulation, and their interface strengthening mechanism was discussed. The results of interfacial interaction analysis show that EVA increases the interfacial interaction energy and binding energy between EPS and C-S-H, and improves the adhesion between EPS and cement base. The results of radial distribution function analysis show that in the model with the modifier, there are not only Van der Waals forces and hydrogen bonds in the model without the modifier, but also strong interactions such as Ca - = O and OT - = O. The results of mechanical property analysis show that the elastic modulus of EPS concrete interface model after adding modifier is improved, and its interface properties are improved. The molecular dynamics simulation carried out in this paper shows that EVA acts as a bridge between EPS and C-S-H and enhances its interfacial properties. This study can provide basic theoretical support for the application of EPS concrete and reference for the development of high-performance composite cement-based materials. [ABSTRACT FROM AUTHOR]

Most hydraulic concrete structures are in complex stress state. In order to study the effect of dynamic action on properties of hydraulic concrete under biaxial tension-compression, hydraulic concrete specimens were subjected to dynamic biaxial tension-compression tests were conducted at 6 different tension-compression ratios of 0 (uniaxial compression), 0.05:-1, 0.1:-1, 0.25:-1, 0.5:-1, ∞ (uniaxial tension) as well as 4 different strain rates of 10−5/s, 10−4/s, 10−3/s and 10−2/s. The failure mode, ultimate strength, peak strain and stress-strain curve under different tension-compression ratios and strain rates were measured. According to test data, the ultimate strength, as well as deformation properties, was analysed in terms of tension-compression ratio and strain rate. The failure criterions of hydraulic concrete under dynamic biaxial tension-compression stress state were established in principal stress space and octahedral stress space, respectively, providing experimental and theoretical reference for the design and maintenance of hydraulic structures. The results of the research on the ultimate strength and failure criterion of ordinary concrete, wet sieve concrete and air-entrained concrete under biaxial stress state were compared with the experimental results of this paper, proving the feasibility of the failure criterion proposed in this paper. [ABSTRACT FROM AUTHOR]

Self-sensing uses the cement-based material without sensor incorporation to sense itself. This paper reviews self-sensing cement-based materials, with coverage of the well-studied resistance-based sensing as well as the less-studied capacitance-based sensing. This review is the first that covers capacitance-based self-sensing. Capacitance-based sensing is advantageous over resistance-based sensing in that no particular admixture is required, so that it is applicable to both existing and new structures. In contrast, resistance-based sensing that is comparable to capacitance-based sensing in stress/strain sensitivity requires conductive admixtures, such as carbon fiber. Resistance-based strain sensing is based on piezoresistivity, which is associated with the resistance increasing upon tension and decreasing upon compression. Capacitance-based strain sensing is based on piezopermittivity, which is associated with the permittivity decreasing upon tension and increasing upon compression. Damage causes the resistance to increase and causes the permittivity to decrease. Increase in temperature decreases the resistance but increases the permittivity. This review also covers the methodology of the electrical measurements. [ABSTRACT FROM AUTHOR]

Development and commercialization of self-healing concrete is hampered due to a lack of standardized test methods. Six inter-laboratory testing programs are being executed by the EU COST action SARCOS, each focusing on test methods for a specific self-healing technique. This paper reports on the comparison of tests for mortar and concrete specimens with polyurethane encapsulated in glass macrocapsules. First, the pre-cracking method was analysed: mortar specimens were cracked in a three-point bending test followed by an active crack width control technique to restrain the crack width up to a predefined value, while the concrete specimens were cracked in a three-point bending setup with a displacement-controlled loading system. Microscopic measurements showed that with the application of the active control technique almost all crack widths were within a narrow predefined range. Conversely, for the concrete specimens the variation on the crack width was higher. After pre-cracking, the self-healing effect was characterized via durability tests: the mortar specimens were tested in a water permeability test and the spread of the healing agent on the crack surfaces was determined, while the concrete specimens were subjected to two capillary water absorption tests, executed with a different type of waterproofing applied on the zone around the crack. The quality of the waterproofing was found to be important, as different results were obtained in each absorption test. For the permeability test, 4 out of 6 labs obtained a comparable flow rate for the reference specimens, yet all 6 labs obtained comparable sealing efficiencies, highlighting the potential for further standardization. [ABSTRACT FROM AUTHOR]

The impact of high temperatures on calcined clay-limestone cement concrete (LC3) and calcined clay-marble stone cement concrete (MC3) is studied in this paper. In the present study, M25 and M35 grades of concrete was prepared using LC3 and MC3 cement and ordinary Portland cement (OPC). After 28 days of moist curing, prepared cubes of size 100 × 100 × 100 mm3, which were subjected to 100°C, 200°C, 400°C, 600°C and 800°C temperatures. Scanning electron microscopy (SEM), mass loss, surface texture and compressive strength (CS) were studied before and after specified temperatures. The X-ray diffraction (XRD) patterns, thermogravimetric analysis (TGA) and Fourier transformed infrared (FTIR) spectroscopy have been studied over M25-OPC, M25-LC3 and M25-MC3 concrete. The result shows that when the temperature exceeds 400°C, the mass loss in OPC was more than LC3 and MC3 concrete. CS was more in LC3 and MC3 concrete than OPC concrete at all high temperatures. The SEM results reveal that M25-LC3 and M25-MC3 concrete specimens have a sound structured C–S–H gel at high temperatures as compared to M25-OPC concrete specimens. [ABSTRACT FROM AUTHOR]

Concrete is poorly tensile in strength and susceptible to cracking. Therefore, researchers have explored the incorporation of PET fibres into concrete as reinforcement. PET is a polymer commonly used in food and beverage packaging, and textile industry. This study reviews the fresh and hardened properties of recycled PET fibre-reinforced concrete (rPET-FRC). The workability, compressive, tensile, and flexural strength are investigated under factors such as rPET fibre volume, dimensions, water–cement ratio, and the use of blended cement. This review includes experimental results of previously conducted rPET-FRC research along with results gained from rPET-FRC where the rPET fibres are obtained from the same recycling plant. Furthermore, the experimental results are broadly elaborated by explaining the reasons behind the obtained results. This review is a valuable reference that offers insights into the effectiveness of rPET fibres in enhancing concrete's overall mechanical properties. By highlighting the most effective rPET fibre volume fractions, water-cement ratios, and the influence of blended cement, this review enables researchers to optimise the design and application of rPET-FRC, promoting sustainable and innovative solutions in the global infrastructure sector. Further studies to be carried out in the future are recommended and existing research gaps related to rPET-FRC are also highlighted. [ABSTRACT FROM AUTHOR]

This paper presents the behaviour of hollow and concrete-filled mild steel tubular columns under static and impact loading. A total of three test series have been carried out recently at the University of Western Sydney and the University of Wollongong to investigate the performance of steel hollow and concrete-filled steel tube (CFST) columns subjected to static as well as impact loading. The test results reported in this paper are from the first test series, where mild steel was used and no axial load was applied to the columns. In the next two series, the effects of a combined axial and transverse impact loads, the steel type, as well as the location of the impact loading, were considered. At the same time, steel impact property tests using a split Hopkinson's pressure bar were conducted at Hunan University, China. These test results are also reported in this paper. This paper also reports detailed results from a numerical model using ABAQUS to simulate those static and impact experiments. A non-linear finite element modelling explicit time domain dynamic approach has been used for the simulation. The main objective of this paper is to compare the performance of experimental results with numerical results for mild steel hollow and CFST columns and to provide design guidance. Moreover, the behaviour of in-filled tubes under impact loading is also compared with that of hollow sections. Generally, a reasonable level of agreement has been observed between the numerical and experimental results. [ABSTRACT FROM AUTHOR]

The use of the near-surface mounted (NSM) fibre reinforced polymer (FRP) strengthening method in civil construction applications has gained considerable popularity worldwide, and can produce confident strengthening and repairing systems for existing concrete structures. The response of concrete structures rehabilitated using the externally bonded (EB) FRP method under monotonic and fatigue loading has been well reported. On the other hand, the monotonic and fatigue response of NSM FRP-rehabilitated concrete structures is less known. This paper reviews current research on concrete members retrofitted using the NSM FRP technique and subjected to monotonic and fatigue loading. It provides an outline of FRP composites and the fatigue behaviour of concrete, steel and FRP materials. In addition, the review focuses on the bond characteristics between NSM FRP, adhesive and concrete substrate, and on the flexure behaviour of NSM FRP-strengthened and repaired reinforced concrete (RC) beams. Furthermore, the paper reviews the failure modes, factors affecting NSM FRP systems, codes and guidelines for the use of FRP in concrete structures, damage accumulation and residual strength, stress limits in steel reinforcement, and the limitations of using epoxy and polymer-based cementitious adhesives for strengthening of concrete members. [ABSTRACT FROM AUTHOR]

This paper proposes the use of sleeve joints for the steel connection of concrete-filled, square, tubular columns to H-beams. To study the influence of the sleeve height and thickness, three joint specimens were designed and subjected to low-cycle loading tests. The effect of these size parameters is evaluated in terms of specimen stiffness, load-bearing capacity, energy dissipation capacity, ductility performance and shear deformation of the joint. The experimental results show that under the reciprocating load, the ultimate failure modes of the connection are tearing of the joints at the beam-sleeve interface and the welded column-sleeve interface. Increased sleeve thickness significantly increases the bearing capacity, stiffness, energy dissipation capacity and ductility of the members and joints, by reducing the strength degradation and stiffness degradation of the members. The joint strength and stiffness degradation is stable, with good ductility and energy dissipation capacity that meets seismic requirements. [ABSTRACT FROM AUTHOR]

Bonding carbon fibre-reinforced polymers (FRP) to reinforced concrete (RC) flexural members has become a popular means to enhance load carrying capacity and prolong service life. Considering the type of FRP strengthening system, the near-surface mounting (NSM) technique of embedding FRP strips in saw-cut grooves within the concrete cover of RC members to flexurally strengthen beams and slabs is known to have desirable bond behaviour benefits over external bonded FRP plates. Further the NSM technique has attracted growing attention in strengthening of statically indeterminate RC members. However, little is known about the durability of the critical bond between the embedded FRP and the concrete when installed using this technique. In this paper, experimental results of continuous flexural members strengthened with NSM FRP is collated and reviewed to investigate failure modes, ductility and moment redistribution capability. Ductility and moment redistribution characteristics of strengthened RC members relies on the bond performance of reinforcement to concrete and hence this paper also reviews durability testing of NSM joints. Regression analysis shows that concrete compressive strength and steel reinforcement ratios are paramount to maintaining ductility under all strengthening schemes. [ABSTRACT FROM AUTHOR]

During the last few years, incorporating of nanomaterials in cementitious matrix has been considered as a leading approach in research work. This paper reviews the effects of including graphene oxide (GO) in the cementitious materials, as GO represents one of the well-known inclusion nanomaterials in the cementitious matrix during the last few years. This study describes in one way the improvements in the performance of the cementitious composites and in the other way the new properties that can be shaped. These two paths of improvements are largely dependent on the functionalisation behaviour of GO which results in upgrading the properties of the host matrix. Besides presenting the well-reported effect of GO on enhancing mechanical strengths, this paper emphasises on reporting the influence of GO on durability enhancement of the cementitious composites. Furthermore, it shows promising findings of using GO in fabricating new construction material. However, considerable advancement of adopting GO in scientific fields such as materials technology has achieved significant levels. Applications such as drug delivery, solar cells and super capacitors made remarkable progress through inclusion of GO. Hence, more extensive research work is essential for achieving similar progress in the construction materials which represents a considerable future challenge. [ABSTRACT FROM AUTHOR]

The Ready Mixed Concrete Dispatching Problem (RMCDP) is a generalised version of the Vehicle Routing Problem (VRP). In RMCDP however, given the particular properties of concrete, a set of additional constraints must be considered. The perishability of fresh material, for example, has to be contemplated, together with other technical issues, such as a truck can only serve a single customer and two or more customers cannot be supplied using a truck in a single trip. RMCDP can be modelled as a mixed integer problem (with soft time window) and it can be optimally solved for small and medium sized variants of the problem. However, the objective cost and similar constraints are usually calculated using spatial distances (Euclidian distance) and similar approximate travel times are used. In this paper, we propose a more realistic method for calculating travel times based on real travel distances obtained from Google Maps API. The accurate travel time information is used as input for the RMCDP, to provide results that are more convincing. This paper compares RMCDP with two different objective functions; (i) spatial distance and (ii) real distance. This research will clarify the influence that the quality of this information has on the decision-making process and whether it is relevant to regard the accurate travel time to achieve a more realistic result. [ABSTRACT FROM AUTHOR]

There are innumerable tests on small stocky circular cylinders with either internal passive encasement of the concrete with circular stirrups or spirals, or external passive encasement through fibre-reinforced polymer (FRP) wrapping or through the use of FRP tubes or steel tubes. These tests have shown that passive confinement can increase the strength but, in particular, can substantially increase the ductility of concrete cylinders. Because of these important benefits, the effect of passive confinement on the concrete stress/strain in a particular cylinder section is invariably derived from tests such that substantial member testing is required. In this paper, it is shown how the passive stress/strain of the concrete for a particular circular member can theoretically be determined directly from their partial-interaction shear-friction and partial-interaction bond-slip material properties for any reinforcement arrangement and geometry of the circular cylinder. This procedure provides tools for designing for the benefits of passive confinement directly without the need for member testing. [ABSTRACT FROM AUTHOR]

Infrastructure engineering research at the University of Melbourne covers various subjects such as safe and sustainable structures, steel connections, high-strength concrete, earthquake engineering, dynamics of structures, and protective structures. The protective structures research group focuses on development of innovative and effective mitigation technologies for the protection of infrastructure from extreme human-caused acts and natural disasters. This paper presents the developments and future challenges in protective structures research, which falls within the scope of performance of structural components subjected to accidental or intentional blast effects, and the mitigation of these effects. The research group branches out into several key areas of interest such as performance and mitigation of structures against blast pressures, and glazing façade performance assessment under blast pressures. Developments of both analytical and experimental approaches in the key areas of interest will also be presented in this paper through a review of blast trials conducted in Woomera. Firstly, the loading characteristics were established in the blast trials and the analysis phase. Secondly, once the loading conditions were established the performance of local components (such as blast panels, concrete beams and façade components) was analysed. In this part, the performances of the modelling approach were assessed in comparison to the experimental results. The final part of this paper presents a study to establish the global behaviour of structures subjected to blast effects. [ABSTRACT FROM AUTHOR]

In this paper, the mechanical properties of High-performance fiber reinforced cementitious composites containing active powders, such as metakaolin and fly ash, with a combination of carbon nanotubes (CNTs) and steel fibers have been investigated. The presence of active powders and their combination with micro-silica, increase the physical and mechanical properties of fibre concrete. Subsequently, by adding CNTs, the precise microstructural properties of concrete before and after 300 cycles of thawing-freezing, according to the ASTMC666 standard by scanning electron microscope (SEM) have been analysed. The results reveal that by adding active powders and steel fibres in the concrete, the volume of cavities reduces, and the bonding between concrete components increases. moreover, the addition of functionalised CNTs creates the crack bridge and prevents the propagation and growth of micro-cracks. This leads to increasing the mechanical properties of concrete before the cycles and decreasing the strength loss (bendingand compressive) after thawing-freezing cycles. [ABSTRACT FROM AUTHOR]

Knowledge of the precise size of unbond, debond areas and delaminations aids the assessment and evaluation of the integrity of structures retrofitted with carbon fibre-reinforced polymer (CFRP) systems. This assessment and monitoring can lead to reduced stress from over loading and keep the structure well beyond the serviceability limit. At the same time, reading the size of defects accurately can help radically with repair and maintenance. This paper investigates the ability of infrared thermography (IRT) non-destructive testing to determine subsurface defect sizes with high accuracy. Different designed defects in several specimens were measured using active pulse thermography technique IRT. These defects were located under different CFRP materials. Far distance detection and measurement of bond defects were also investigated with different pulse intervals applied to different specimens. [ABSTRACT FROM AUTHOR]

Implementation of self-consolidating concrete (SCC) leads to the evaluation of more attractive, quality-controlled concrete with improved workability in the construction sector. The aim of the paper involves the determination of the rheological properties of SCC using waste glass aggregate, which affects the concrete's rheological behaviour. In this research, the conventional coarse aggregate was substituted by the waste glass aggregate (WGA), at 10%, 20% and 30%, respectively. The consequence of adding waste glass in fresh concrete was inspected by several tests such as density, slump flow, J-ring, L-box and V-funnel test. These properties were then compared to the corresponding properties of normal-weight concrete. Test results specify that the WGA amplified the slump value of SCC thus indicates the improved workability. The decreasing density of the SCC leads it to the lightweight concrete. Subsequently, the SCC concrete shows relatively reduction in the passing ability with the addition of waste glass due to the angular shape of the glass bits. Hence, the study concludes that all of the rheological properties of self-compacting glass concrete (SCGC) made of WGA showed an impressing enhancement in the result, in comparison with the conventional SCC. [ABSTRACT FROM AUTHOR]

The deterioration of structures due to reinforcement corrosion is a major problem both in Australia and globally. The corrosion of the reinforcement can lead to rust staining, cracking spalling, and eventually structural failure if no remedial action is taken. In order to assess the condition of a structure a visual inspection is often the first step, with any defects noted. Further visual inspection or installation of monitoring equipment may then be made to identify any subsequent deterioration that occurs. These activities can often be time consuming and expensive, both in the undertaking and in the analysis of the data. This paper reports the use of laser scanning technology to monitor the condition and deterioration of reinforced concrete specimens and relate the level and rate of crack growth with a standard visual inspection. [ABSTRACT FROM AUTHOR]

The research nowadays is mainly focusing on the basic science of cementitious material at nano/atomic level. Further, researchers are continuing to improve the durability and sustainability of concrete and have realized significant increment in mechanical properties of cementitious materials by incorporating nano-silica. The review paper summarizes the effect of nano-silica addition on mechanical, durability and microstructure characteristics of paste, mortar and concrete. It provides the current development of application of nano-silica in paste, mortar and concrete. Finally, the future trend/potential and implication of nanosilica in cement-based materials is discussed. [ABSTRACT FROM AUTHOR]

In this paper, application of fuzzy logic technique using triangular membership function for developing models for predicting compressive strength of concrete with partial replacement of cement with nanosilica has been carried out. For this, the data have been taken from various literatures and help in optimizing the constituents available and reducing cost and efforts in studying design to develop mixes by predefining suitable range for experimenting. The use of nanostructured materials in concrete can add many benefits that are directly related to the durability of various cementitious materials, besides the fact that it is possible to reduce the quantities of cement in the composite. Successful prediction by the model indicates that fuzzy logic could be a useful modelling tool for engineers and research scientists in the area of cement and concrete. Compressive strength values of concrete can be predicted in fuzzy logic models without attempting any experiments in a quite short period of time with tiny error rates. [ABSTRACT FROM AUTHOR]

This paper addresses the structural performance of crumb rubberised concrete (CRC) and reinforced CRC slabs under static and low-velocity impact loads. An innovated setup was designed to investigate the impact of behaviour of concrete material based on the drop-weight test. The drop-weight velocities before and after impact were recorded through a laser system. Based on the velocity variation, the energy that was absorbed in concrete material during the test, which also was the impact resistance of the sample's failure section, had been calculated. CRC samples with rubber percentages varying from 0% to 20% were tested. Experimental results verified the advantages of using rubber on material impact behaviour. Finally, as a structural application, reinforced CRC slabs were tested under static and impact loads. Experimental results showed that CRC slabs exhibited superior post-cracking performance with member moment capacities comparable or even higher than that of reinforced traditional concrete (TC) slabs. It is believed that this unique phenomenon was due to zip-shaped cracking section along CRC slab width. At last, a series of impact tests were conducted and test results showed a significant reduction in the peak stress response in CRC slabs when compared with TC slabs. [ABSTRACT FROM AUTHOR]

In the past, a lot of research has focused on using spirals and rings to confine concrete. Yet, the effect of using spirals to confine square cross sections is not well investigated. It would appear from the above, therefore, that there is a need for a reappraisal of the material model used to describe the behaviour of concrete in the compressive zone of a beam. Its aim should be to improve the theoretical basis of the structural concrete design so as to be compatible with concrete behaviour in the experimental observation. This paper proposes an analytical confinement model that measures the stress–strain behaviour of rectangular concrete sections confined with spiral links. This research aims to provide an average equation to calculate the strength enhancement that results from confining rectangular beams with spiral links and hence this simplified model could be used for design purposes. The proposed model is capable of predicting the behaviour of normal-strength concrete as well as high-strength concrete and incorporates allowance strength variation. Comparisons are made between the proposed new model and the models of others in the literature. [ABSTRACT FROM AUTHOR]

Strengthening and retrofitting of reinforced concrete elements using FRP (fibre reinforced polymer) is currently gaining acceptance because of its merits over available conventional practices. FRP confinement enhances the load-carrying capacity of the column by increasing the ultimate strain and ductility. Study of the stress-strain behaviour of FRP-confined concrete is of prime importance to be studied for safe, economical and reliable design. In this paper, authors have attempted to study the stress-strain behaviour of carbon fibre reinforced polymer (CFRP)-confined concrete under both monotonic as well as repeated cyclic loading using analytical as well as numerical models. For numerical analysis, FE software ABAQUS is used. Stress-strain studies on FRP-confined concrete were carried out experimentally on low-strength concrete and the results were validated using existing analytical models by Lam and Teng, and Shao and the proposed analytical and numerical models are compared. [ABSTRACT FROM AUTHOR]

This paper assesses the bond-slip behaviour of Crumb Rubber Concrete (CRC) with embedded steel bars. A series of pull-out tests were conducted using CRC with 18% of the sand replaced by crumb rubber and traditional concrete (TC), with embedded steel bars of 12 mm and 16 mm in diameter. An ABAQUS model was developed to simulate the bond-slip relationship using cohesive elements and the model predictions agreed well with experimental results. The standardised bond strength of steel bars embedded in CRC is slightly lower than that of steel bars embedded in traditional concrete. The steel to concrete bond mechanism in CRC displayed similar behaviour to TC. Numerical results verified that the bond stress was uniform for short embedment bond specimens. A modified Eligehausen-Bertero-Popov model was able to satisfactorily predict the bond-slip relationship. [ABSTRACT FROM AUTHOR]

Evaluating the effects of using new water sources on the mechanical properties of concrete is an important issue that should be considered in practical projects such as dam construction and tunnelling. The fracture toughness as one of the mechanical properties describes the resistance of a material against the crack propagation and the effect of a new water source should be assessed on this property of concrete. This paper aims to investigate the use of domestic treated wastewater in making concrete. For this purpose, several single edges notched beam (SENB) are prepared using 5 different combinations of drinking water and domestic treated wastewater. The experimental results show that the values of fracture toughness obtained from concrete samples with wastewater have discrepancies between 2 to 6% in comparison with conventional concrete. Therefore, it is concluded that applying domestic treated wastewater as both curing and mixing water has no serious negative effect on fracture toughness. The slump of concrete samples using treated wastewater increased slightly related to using drinking water and setting time increased. Scanning electron microscope (SEM) images of the samples using treated wastewater indicated that existing ettringite, white and needle-like crystals, connected two sides of the cracks. [ABSTRACT FROM AUTHOR]

Based on experimental study correlations between change in electrical resistance and properties of concrete are reported in this paper. This study is performed on concrete cubes of 100mm size containing carbon fibres in different dosages (0, 0.5, 1, 1.5 and 2%) by mass of cement. Concrete cubes were subjected to strain-sensing and damage-sensing tests. Strain-sensing test is conducted within elastic range and the correlation is obtained between change in electrical resistance and strength of concrete. From test results, it is found that concrete specimens containing carbon fibres 1.5% produces better strain and damage-sensing characteristics and can be correlated to stress strain curve of concrete. On the basis of experimental results, it is rationally explored in this study that concrete containing micro carbon fibres induce self-sensing property in it and therefore can be effectively used for health monitoring of concrete structures. [ABSTRACT FROM AUTHOR]

When freshly cast concrete is exposed to water this can result in an increase in the pH of the water, which in turn can have an adverse effect on the local flora and fauna. The use of replacement materials and the specimen geometry have been identified as potentially reducing this impact. This paper reports the results of a study investigating the effect on leaching of fresh concrete containing fly ash replacement up to 30% and slag replacement up to 65% in cubic and cylindrical specimens. The results show that the use of replacement materials can be beneficial in reducing the impact of leaching from freshly cast concrete, with the slag being the most effective. This is primarily attributed to the reduction in the alkali oxides and the differing hydration mechanisms. The geometry was also identified as affecting the rate of leaching, with cylindrical specimens leading to higher rates of leaching. [ABSTRACT FROM AUTHOR]

Over the past few decades, enhancing the sustainability of concrete structures has become a worldwide necessity. This study proposes a mathematical model for predicting compressive strength (CS), aiming to further the objective of designing sustainable concretes incorporating silica-fume as a partial cementing replacement material. The article outlines the formulation, calibration, evaluation and validation of the proposed model. Various factors related to concrete mixture and age were considered in the formulation of the CS model, which employed multiple sub-models including a cement hydration model that considers cement chemical composition and hydration rate, along with other factors like aggregate packing density, capillary porosity, air pores, standard cement strength, paste-to-aggregate bond strength and presence of supplementary cementing materials. An experimental program consisting of 10 different concrete mixtures was designed to calibrate and evaluate the model. The model was then validated using databases from multiple literature sources, which consisted of 50 data points with diverse materials and mixture proportions, to test its accuracy and generalization capability. Results show that the proposed model closely matches the experimental data and has no sign of anomalies or distinct trends. The model's coefficient of determination and standard error are 0.97 and 4.0 MPa, respectively. Moreover, model validation demonstrates high predictability and generalization capability, with a corresponding coefficient of determination and standard error of 0.93 and 4.4 MPa, respectively. Overall, this research suggests that the proposed mathematical model is a reliable tool to predict the CS of sustainable concretes that utilize silica-fume as a partial cementing replacement material. [ABSTRACT FROM AUTHOR]

Present work contains a 3-D finite element (FE) model created in Abaqus to examine bond behavior in controlled/non-corroded reinforced concrete beams. Study evaluated the compatibility between corrosion levels and beam deflections. Cohesive surface-based interaction method is applied to the Data obtained from recent studies in which corrosion was induced by accelerated corrosion technique. The cohesive surface-based interaction approach has been found to be suitable for simulating the interfacial binding between reinforcement bars and the concrete. Analysis of Control and corroded beams along with mesh sensitivity were used for the validation of the work. It is found that maintaining uniform mesh size for steel and concrete is necessary as varying mesh size influences the load - deflection relation. The developed FE model of RC beam under corrosion could be adopted to obtain the load at failure with considerable accuracy. Hence, the model can be adopted to numerically simulate the influence of various parameters on response of corroded RC beams. This would avoid the expensive laboratorial tests. Study demonstrated that experimental and analytical research are in good agreement with considered level of corrosion and corresponding deflections. Rebar yield capacity of corroded RC beam in tension zone declined, resulting in a decrease in load-carrying capability. The modelling outcomes can be used to validate the bond behaviour of Reinforced concrete cantilever beams without considering the influence of stirrups. [ABSTRACT FROM AUTHOR]

This study investigates the chemical and physical properties of fine and coarse aggregates and their implications for concrete performance. The research employed an experimental approach to analyze various parameters, including chemical composition, chloride content, particle distribution, and slump, among others. The mixed proportions of concrete were carefully controlled to assess the influence of different aggregate compositions on concrete properties. The study utilized ASTM standards for testing procedures and calculations. Key findings of the research include the significant impact of chemical composition on concrete properties, with variations in oxides such as MgO, Al2O3, SiO2, K2O, CaO, Fe2O3 and Na2O influencing setting time and strength development. Moreover, the chloride content of fine aggregates varied across different sources, with implications for concrete durability. Particle distribution analysis revealed the importance of optimizing aggregate gradation for desired concrete properties. The study's outcomes emphasize the importance of careful mix design and aggregate selection in optimizing concrete performance and durability. Recommendations for future research include further exploration of the mechanical behavior properties of concrete and assessment of environmental sustainability considerations in aggregate production processes. This research contributes valuable insights into optimizing concrete mix designs and enhancing the durability of concrete structures. Based on the findings, it is recommended to carefully consider aggregate characteristics and sources to achieve desired concrete properties. Overall, this study underscores the significance of aggregate selection in achieving durable and sustainable concrete structures. [ABSTRACT FROM AUTHOR]

Large-scale manipulators, such as the boom of a mobile concrete pump, typically rely on lightweight construction to maximize their operational range. As a result, significant elastic deformations occur during operation. Various automation and control applications require computationally fast and accurate mathematical models of the manipulator's motion. In this work, a mathematical model for the boom of a mobile concrete pump with 5 individual joints is presented. This model takes into account the elastic bending in two directions and the torsion of the boom. To reach a high model accuracy, calibration is required. This is challenging due to the large dimension and the outdoor operation, which makes the accurate measurement of the boom position difficult. A camera-based measurement setup is proposed in this work that is tailored for the considered problem. It is shown by measurements that the model is able to achieve a high accuracy with rather small computational costs. [ABSTRACT FROM AUTHOR]

Sustainability issue in construction sector came forward over the last two decades due to concerns regarding using virgin materials as well as emission of greenhouse gases from production of raw materials. Cement is the prime constituents of concrete and contributes approximately 7% of global man made CO2 production. Interest in blended cements is growing because of its advantages as increased production economy, reduced CO2 emissions and fuel consumption. This paper discusses the effects of cement replacement with supplementary cementitious material fly-ash on the strength development, water permeability and rapid chloride penetration resistance of concrete over the curing age of 365 days. Three different grades of concrete M38, M33 and M28, each with seven different fly-ash replacement level, 10, 20, 30, 40, 50, 60 and 70% were used for the experimental program. Ordinary Portland cement concrete was also used as reference concrete. Coefficient of permeability as well as rapid chloride penetration resistance was determined at an age of 28, 56, 90, 180 and 365 days whereas strength at 3, 7, 28, 56, 90, 180 and 365 days. Test results show that permeability of concrete decreases with the increase of fly-ash level up to an optimum value and then start to increase, whereas strength of concrete increases with the increase of fly-ash up to an optimum level and then starts to decrease. Among all the concretes studied, the optimum amount of cement replacement is reported to be 30%. The study reveals that fly-ash concrete is less permeable and achieves higher strength due to pozzolanic activity of fly-ashes that creates more durable calcium silicate hydrate and fills capillaries and bleed water channels occupied by water soluble lime. As a result fly-ash concrete inhibits the penetration of aggressive species including chloride which can effectively reduce the corrosion of the embedded steel reinforcement. [ABSTRACT FROM AUTHOR]

There has been an extensive amount of research into determining the compressive stress-strain properties of concrete for design. Difficulty has arisen in quantifying the softening or descending stress-strain relationship as it has been found to depend on the size and shape of the specimen being tested as well as on the confinement and eccentricity of compressive load applied to the specimen. This difficulty has restricted the development of design rules for reinforced concrete members not only for strength but also for ductility particularly for confined members. In this paper, a meso-scale model, which divides concrete into a three phase composite material consisting of the mortar matrix, aggregate and interfacial transition zone, is used to explain and quantify the softening mechanism of concrete specimens. It is shown that this meso-scale model can both simulate the cracking patterns and deformations which are seen to occur in concrete while softening and also quantify and explain the effects of size, shape, confinement and eccentricity of load. This realistic simulation of the softening mechanism should allow a better understanding and quantification of the compressive failure mechanism of concrete which should lead to the development of better design rules particularly for confined concrete. [ABSTRACT FROM AUTHOR]

Post-tensioned concrete wide-band beams are used increasingly as a common floor construction method in Australia. More recently, there has been a growing need for the floor system to contribute to the seismic resistance of the building as a moment frame. However, relatively little is known about the performance of wide post-tensioned beams under this type of loading. This paper reviews the current state of knowledge in this area, and assesses several current building design codes in terms of their relevance to this type of construction. Current research shows the potential to achieve adequate drift and energy dissipation in areas of low to moderate seismicity, but research is very limited, particularly for post-tensioned wide beams. While AS3600-2009 does not contain any width limitations on beams resisting earthquake loads, other codes do limit this width for certain levels of ductility. However, these design codes focus on narrow beams, and the beam width restrictions are generally based on limited research data. Construction techniques and seismicity levels vary significantly for different countries and this affects different design codes. Therefore, the relevance and applicability of several code design and detailing requirements in relation to beam widths and detailing typically used in Australia are questionable. [ABSTRACT FROM AUTHOR]

This paper presents a study to assess the effects of site exposure on the durability of concrete cast with ordinary Portland cement (OPC), pulverised fly ash (PFA) and ground granulated blast furnace slag (GGBS) using the controlled permeability formwork (CPF). An experimental program has been undertaken in which trial specimens have been placed on exposure sites at coastal locations in Australia. Various non-destructive tests were conducted such as Schmidt hammer, water permeability, air permeability, ultrasonic pulse velocity, steel potential mapping, linear polarisation resistance corrosion rate monitoring, chloride diffusion, accelerated chloride diffusion, and resistivity. The durability data are presented to compare the effects of using CPF with those of traditional (plywood) formwork for OPC, PFA and GGBS concrete mixes, as specified on actual construction projects in Australia. The results indicate that CPF gave improved performance compared to the traditional formwork for surface properties of concrete. [ABSTRACT FROM AUTHOR]

The Ross River Bridge in Townsville is currently under construction and will be located in an aggressive environment at the river's mouth. A durability plan was developed prior to construction in order to determine appropriate concrete design and construction practices to achieve the required design life of 100 years. Possible deterioration mechanisms investigated included: chloride ingress; carbonation; alkali-aggregate reaction (AAR); sulphate attack; acid sulphate soil degradation; atmospheric corrosion and corrosion of pile casings due to sulphate reducing bacteria. This paper outlines the approach undertaken to ensure that the bridge design met the required life. The results of mathematical modelling of chloride ingress and carbonation are presented based as both deterministic and probabilistic approaches. The concrete mix design was adjusted to address AAR and sulphate attack and appropriate testing was incorporated into the project specifications. The design approach outlined resulted in some durability requirements exceeding those nominated in AS5100.5 such as increased cover requirements and the need for stainless steel reinforcement. [ABSTRACT FROM AUTHOR]