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Many challenges persist with traditional self-sensing cementitious composites, such as selecting conductive fillers, determining optimal aspect ratios, controlling dosage, achieving filler dispersion, designing practical electrodes, and overcoming fabrication difficulties. Therefore, this paper proposes a novel self-sensing technique for cementitious composites by incorporating a 2-dimensional (2-D) carbon-fibre textile network to address these challenges. Additionally, instead of using the entire composite volume as the sensor, an alternative approach is explored, which involves utilising the interlaminar interface by incorporating the 2-D carbon-fibre textile network. This approach provides an integrated self-sensing system, including electrical leads and conductive pathways, which can be tailored based on the design requirements. The paper introduces fundamental concepts and measurement circuit design, followed by a comprehensive study covering measurement techniques, electromechanical properties, and microstructural analysis. Furthermore, it discusses the impact of ambient conditions, such as temperature and relative humidity, on the measurements. Experimental results demonstrate a remarkable maximum fractional change in contact resistivity, reaching up to 70%. The reversibility during cyclic compression is excellent, with a maximum negative gauge factor of − 2500. These findings represent a significant step toward achieving a practical and simplified method for manufacturing self-sensing cementitious composites and open avenues for self-sensing, sustainable textile-reinforced concrete structures (TRC). [Display omitted] • A novel self-sensing system for cementitious composites has been introduced. • The system can be considered as an integrated solution, encompassing the essential components required for self-sensing. • A simplified equivalent circuit model and an equation to calculate the overall contact resistivity have been proposed. • A remarkable maximum fractional change in the overall contact resistivity, reaching up to 70%, has been achieved. • The reversibility during cyclic compression has been excellent, with a maximum negative gauge factor of − 2500. [ABSTRACT FROM AUTHOR]

This paper performed the research on the autogenous shrinkage mitigation mechanism and mechanical properties of alkali-activated high strength mortar (AAHSM) incorporating hydroxypropyl methylcellulose (HPMC). The increase in HPMC content causes the lower slump flow and the longer setting time of AAHSM due to the flocculation effect of HPMC. Because of strong interaction between the hydroxyls of HPMC and water, the higher internal relative humidity is achieved, leading to the much lower capillary pressure. The unreacted precursors and reaction products are wrapped by the HPMC molecular network, causing that the depolymerization-polymerization reaction is prevented, which leads to the lower reaction degree. The increase in HPMC content promotes less generation of C(N)-A-S-H gels and more generation of hydrotalcite. The adhesion forces between reaction products particles are enhanced by the flocculation effect caused by the HPMC molecular network, indicating that the AAHSM containing HPMC has larger resistance to the deformation. Adding HPMC has a slight effect on the element compositions of reaction products and the pore types and a slight adverse effect on the Yang's modulus of reaction products micro region. Thus, the 56 days autogenous shrinkage of AAHSM is reduced by 22.2 % when the HPMC content is 2.0 wt%. Although the proportion of meso pore is increased by adding HPMC, the higher porosity and coarser pore structure are achieved, thus the autogenous shrinkage is still reduced. The lower reaction degree and generation of C(N)-A-S-H gels caused by adding HPMC lead to the higher porosity, which is related to the lower compressive and flexural strength. When the HPMC content is 2.0 wt%, the 28 days compressive and flexural strength of AAHSM are 89.2 MPa and 8.2 MPa, which are decreased by 17.3 % and 16.3 % compared to that of AAHSM without HPMC. At longer curing age, the reaction degree is improved and more Ca-rich C(N)-A-S-H gels are generated regardless of with or without HPMC, causing the lower porosity and higher Yang's modulus of reaction products micro region, which leads to the improvement of mechanical properties. ● Alkali-activated high-strength mortar (AAHSM) with strength of over 90 MPa was prepared. ● Autogenous shrinkage mitigation mechanism of HPMC for AAHSM was revealed. ● Mechanical properties effects of HPMC for AAHSM was studied. ● Compressive strength of AAHSM was slight reduced and the flexural strength and toughness were improved by HPMC. ● Autogenous shrinkage of AAHSM was reduced due to the lower capillary pressure and stronger adhesive force between gel particles caused by HPMC. [ABSTRACT FROM AUTHOR]

This paper investigates the synergic effect of both hydrated lime and guar gum stabilisation on the mechanical, thermal and hygroscopic properties of a compressed earth material for building applications. The stiffness, strength and compression energy at failure of both unstabilised and stabilised earth samples were measured at different curing times by means of compression tests. The moisture-dependent thermal conductivity was instead determined via the hot disk technique at a constant temperature of 25 °C and at the three different relative humidity levels of 0 %, 50 % and 95 %. The specific heat capacity was measured by means of calorimetry tests at the three temperature levels of 32–34 °C, 34–36 °C and 36–38 °C. The moisture adsorption-desorption curves were measured by performing a cyclic variation of relative humidity between 0 % and 95 % at a constant temperature of 25 °C via the dynamic vapour sorption (DVS) technique. Results from the experimental campaign show that the proposed stabilisation methods increase both the peak compressive strength and compression energy at failure while the addition of the biopolymer guar gum induces a progressive reduction of stiffness. The thermal properties of the earth are only marginally affected by the addition of hydrated lime and guar gum, with stabilised samples exhibiting similar levels of thermal conductivity and specific heat capacity to those of the unstabilised ones. Finally, the biopolymer stabilised samples exhibited a similar hygroscopic behaviour to that of unstabilised ones, whereas the addition of hydrated lime deteriorates the moisture adsorption capacity of the material. • Earth samples are stabilised with hydrated lime and the biopolymer guar gam. • Biopolymer stabilisation increases strength and compression energy while reducing stiffness. • Lime stabilisation increases stiffness and strength but reduces ductility. • Lime and guar gum stabilisations marginally affect the thermal properties of the earth. • Moisture adsorption is preserved by guar gum stabilisation and reduced by lime stabilisation. [ABSTRACT FROM AUTHOR]

Cement-based materials with addition of superabsorbent polymer have attracted widespread attention due to their excellent shrinkage resistance and durability. This paper investigated the effects of three internal curing materials with different swelling behavior on mortar related shrinkage, corresponding durability at 50% humidity. The composite microgel with high water retention and controllable water release kept the relative humidity inside the mortar at a high level, and the total shrinkage in the low humidity condition decreased by 126.22 µm/m compared with the reference sample. The correlation analysis showed that the composite microgel reduced the autogenous shrinkage of mortar at the early hydration stage, and significantly alleviated the drying shrinkage with the reduction of internal relative humidity. Composite microgel compacted the microstructure of mortar, and compressive strength is higher than that of microgel modified mortar. At the same time, the role of composite microgel in refining microstructure prevented the water penetration of mortar, and the freeze-thaw resistance of mortar can be better improved by entrained air void of composite microgels. • The influence of SAP with different water absorption behaviors and chemical structures on the shrinkage of mortar has been studied. • The correlation between IRH and shrinkage of mortar was analyzed. • The freeze-thaw resistance, impermeability property of cement mortar at 50% RH can be promoted by composite microgel. [ABSTRACT FROM AUTHOR]

This manuscript focuses on the use of foam glass aggregates (FGAs) as insulator to protect pavements against frost action. The ultimate objective of the paper was to develop design tools for the thermal design of pavements insulated with FGAs. A mathematical model was outlined to describe the complex thermal behavior of FGAs and calculate temperature levels within a domain representing a pavement insulated with FGAs. The formulation is based on the one-dimensional heat equation which was discretized with a forward finite-difference technique and subsequently coded in Fortran90. This code was executed to successfully replicate temperature measurements collected within an experimental pavement insulated with FGAs, enabling the validation of the model. The model was then re-executed to perform three different sensitivity analyses and investigate the effects of the pavement geometry, layers humidity, and FGAs' effective particle size on the maximal frost front penetration. Compared to a pavement without insulation, utilizing FGAs reduced the maximal frost front depth. The sensitivity analyses were summarized in design charts to guide the utilization of FGAs for the thermal design of pavements. The code utilized to generate these charts is freely available on GitHub. • Foam glass aggregates (FGAs) layers can mitigate frost action in flexible pavements. • A thermal model is outlined to obtain temperature levels in FGAs-insulated pavements. • Conduction, radiation, and convection are considered within the model. • The model is successfully validated against a full-scale FGAs-insulated pavement. • The model is made freely accessible and design guides are provided. [ABSTRACT FROM AUTHOR]

The water status within concrete under low air pressure (AP) condition has been reported to affect the long-term properties of concrete in plateau regions, however, the underlying mechanism for the microstructural changes is not fully understood yet. In this paper, the confined water statuses within cement pastes curing at 98% RH and different APs (i.e. 101 kPa, 60 kPa, and 20 kPa) were first demonstrated and then correlated to the nanomechanical property changes of calcium-silicate-hydrates (C-S-H) phase by means of the 1H NMR relaxometry and nanoindentation techniques. The results show that low AP conditions increase the evaporable water content and drive the water movement from interlayer spaces to gel pores during wetting at 98% RH. According to the nanoindentation investigations, low AP conditions increase the volume fraction of high-density (HD) C-S-H and improve the nanomechanical and creep characteristics and bending strength of hardened cement pastes, which is attributed to the water redistribution within C-S-H phase. • Water statuses within cement pastes were identified by 1H NMR relaxometry. • Low air pressures drove water redistribution from interlayer space to gel pores. • Low air pressures changed nanomechanical characteristics of cement pastes. • Nanomechanical characteristics changed with water statuses of cement pastes. [ABSTRACT FROM AUTHOR]

• Rh6G fluorescent molecules can visualize the humidity evolution of mud-based materials. • As humidity evolves, the polymeric state transition of fluorescent molecules leads to changes in fluorescence intensity, which peaks at 65 %RH under the ACQ effect. • The temperature sensitivity is weakened by the methyl action of the molecules and the thermostatic properties of the insulation board. • The fluorescent molecules maintained good fluorescence intensity stability under multiple temperature and humidity cycles. In situ detection technology for cement-based materials typically produces unclear physical meanings, which limits research on durability issues such as heat-moisture transfer, dry-wet cycles and microcrack propagation. Taking the external thermal insulation system of building exterior walls as an example, this paper explores in-situ fluorescence sensing techniques for moisture evolution of cementitious materials using the quenching effect caused by the aggregation of fluorescent molecules. This study includes the monitoring of fluorescence intensity under humidity evolution and a stability study of fluorescence intensity under different temperatures and humidity cycles. Results showed that the gradual transition of the polymeric state of fluorescent molecules led to the first increase and then decrease of fluorescence intensity with increasing humidity (0 % RH-95 % RH). The fluorescence intensity peaked at 65 % RH, decreases at high humidity due to aggregated caused quenching effects, and maintained good stability after 8 humidity cycles. With regard to ambient temperature, the fluorescence intensity decreased with increasing temperature (5 °C – 40 °C), and the fluorescence intensity peaked at 5 °C. The temperature sensitivity of the fluorescence is weakened by the methyl effect of the rhodamine 6G fluorescent molecules and the thermostatic properties of the insulation boards. Fluorescence sensing technology for humidity evolution of cement-based materials has moisture sensitivity and fluorescence stability, and thus has a wide range of applications in the sensing of humidity evolution of civil engineering materials. [ABSTRACT FROM AUTHOR]

• Including SF into the AAFA mixture decreased workability, whilst STPP increased it. • Including 5–15% SF or/and 4% STPP in AAFA increased compressive strength. • Exposing specimens to outdoor natural weathering showed an adverse effect on their strength. • The adverse effect of weathering could be decreased with including up to 15% SF and 4% STPP. As known, exposure of any material to outdoor natural weathering, which has varied changes in temperature, relative humidity, percentage of sunny/cloudy, precipitation, CO 2 and polluted air may adversely affect its properties compared to its unexposed counterpart cured at the lab. This paper aims to evaluate the effect of one year of outdoor natural weathering exposure on the properties of neat alkali-activated fly ash (AAFA) mortars and those modified with silica fume (SF) and sodium tripolyphosphate (STPP). To increase the resistivity of AAFA mortars to weathering exposure, the FA was partially substituted with 5–20 wt% SF. To further improvement, a fixed ratio of 4% STPP was added to the neat FA mortar specimens and those containing SF. After initial curing, half of the specimens were cured inside the lab for one year (unexposed specimens), whilst the other half were exposed to outdoor natural weathering conditions for the same period. The variations in the compressive strength, mineral composition, hydration products and microstructure were compared. The results showed that exposing specimens to natural weathering has a negative effect on their compressive strength. This negative effect can be mitigated by introducing SF up to 15%. To further reduce this negative effect, 4% STPP can be added. [ABSTRACT FROM AUTHOR]

• The hygrometric properties of homogeneous and dual composite bio-sourced materials were investigated. • The moisture content, moisture transfer resistance, moisture flux and the adsorption, diffusivity decreases. • Water content, sorption capacity and volumetric water content were correlated using the Freundlich model. • The bio-sourced material moisture diffusivity distribution is investigated versus relative humidity. With the world's population increasing and energy demand on the rise, innovative materials are becoming one of the most important solutions for building designers. This paper focuses on the hygrometric properties of bio-sourced materials, specifically new cob mixes used for insulation and load-bearing wall elements, those materials consist of various mixes of French soils and fibers with different water contents. Experiments are conducted using the isothermal sorption and the one-sided moisture transmission tests in transient and steady states. The hygrometric properties of the homogeneous bio-sourced samples (a thermally insulating material, and a structurally mechanical material), and composite bio-sourced materials (both structural and insulating materials) were investigated. Five salt solutions were used to measure distribution of the relative humidity in each material. The moisture content and moisture transfer resistance of the insulating material is more important than the structural material. The composite material has the lowest moisture flux and the adsorption is influenced by the multilayers. Results show that as much as the material contains fibers, as much as its impermeability increases and its diffusivity decreases. Diminution of the bio-sourced material density increases its resistance to the moisture transfer. Using the Freundlich isotherm model, the volumetric water content, sorption capacity and water content were correlated for all the tested samples. The Moisture diffusivity for the studied bio-sourced materials drops strongly in the dry region where the relative humidity is lower than 30%. In the wet state, the moisture diffusivity decreases slightly. [ABSTRACT FROM AUTHOR]

The paper characterizes concurrent effects of gamma-irradiation and presence of water in Portland cement pastes. An extensive nanomechanical quantification (Young's modulus, hardness, and creep compliance) at two scales is performed after exposure to two gamma-ray doses and a wide range of relative humidities (RH 0%–100%). Competing microstructural mechanisms such as water radiolysis, hydration, carbonation and drying were identified and their effects de-coupled with the aid of nanoindentation and other supporting techniques. Maximum radiation resistance was found for samples in medium humidities (33%–57%). Samples irradiated below 11% RH exhibited compaction of C-S-H phases at the level of 100 nm, ∼ 25% increase of Young's modulus and decrease of creep compliance due to water radiolysis and drying. The compaction resulted in microcracking at higher paste scale and caused ∼ 17% decrease of elastic modulus. Samples irradiated in water showed large (∼ 26%) decrease of Young's modulus and increased creep compliance accompanied by 9%–10% Portlandite loss. • Nanomechanical properties of irradiated cement pastes studied at various humidities. • Medium humidity helps cement pastes best withstand gamma radiation. • Radiolysis and drying leads to cement paste microcracking but also C-S-H compaction. • Gamma-irradiation counteracts with the hydration process of cement paste. • Decreased paste stiffness but increased creep is caused by radiation in the water. [ABSTRACT FROM AUTHOR]

• The multiphysics model is proposed for non-shrinkage concrete early age behavior. • The coupling simulation is built with chemical, humidity and mechanical process. • The differences between material behavior and structural performance are tested. • The mulitphysics behaviors of clustered shearing connector pocket is simulated. • Numerical optimizations are conducted about material, curing and structural design. Early age behavior of shearing connectors is of great significance for the performance of composite structures. To improve the structural mechanical state and reduce the risk of shrinkage cracks, the non-shrinkage concrete and the clustered shearing connector pocket are used in engineering applications, but the existing empirical model can hardly describe the physicochemical process in the actual structure. Focusing onresponsestiphysics mechanism of concrete shrinkage and the contribution of expansion additive, a comprehensive model is proposed for non-shrinkage concrete in this paper, and the processes of the hydration reaction, the humidity transport, and the mechanical response are included. The free shrinkage test regresses the parameter of material shrinkage, and the corresponding structural test verifies the multiphysics model of the clustered shearing connector pocket. With the volume increasing along the hydration reaction of expansion additives, the −120 με shrinkage of normal concrete is compensated to the 160 με expansion. In the clustered shearing connector pocket, the slight expansion of non-shrinkage concrete can keep the structural compression state and eliminate the risk of local cracks. According to structural test, the early age behavior is constrained by the prefabricated deck, reinforcement and clustered studs greatly, and the expansion strains at the pocket upper and bottom are reduced by about 16% and 72%, respectively. In the multiphysics simulation, not only the time-dependent shrinkage strains at different positions are predicted accurately, but also the detailed distributions of hydration ratio, relative humidity and mechanical stress are also presented. Eventually, the numerical comparison discusses the improvement of non-shrinkage concrete, the influence of relative humidity in the curing environment and the design modification of stud layout, and the peak stress in stud bodies can be reduced by about 18.42%, which is significant and practical for improving related construction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Compressive strength and modulus of elasticity of earthen materials are linearly correlated with the relative humidity. • Strength and deformation characteristics of earth masonry do not depend on the temperature at constant relative humidity. • Influence of relative humidity on the strength and deformation characteristics can be approximated by a suggested equation. • The correlation is generally applicable to unstabilised earth masonry without high contents of organic aggregates. • Influence of the material moisture content can be considered in structural design without extensive testing. The mechanical properties of unstabilised earthen building materials are distinctively influenced by changes in material moisture content. However, this moisture-dependency often remains unconsidered in the calculation of the load-bearing capacity of earth constructions. This paper aims to derive a convenient way to sufficiently consider the impact of different material moisture contents on the mechanical properties of unstabilised earth masonry. Therefore, the influence of relative humidity and temperature on the strength and deformation characteristics of unstabilised earth blocks, earth mortar and earth masonry is evaluated by conducting compression tests under various climate conditions. The results show that the compressive strength and the modulus of elasticity are linearly correlated with the relative humidity, whereas changes in temperature at constant relative humidity have no significant influence. To account the distinct moisture-dependency, a general applicable modification factor for unstabilised earthen materials is provided, which enables the adjustment of the compressive strength and the modulus of elasticity in dependency of arbitrary hygroscopic material moisture contents. [ABSTRACT FROM AUTHOR]

• Thermal and hygric characteristics of novel insulation prototypes. • Development and characterisation of prototype insulation using maize pith, recycled bedding, and wheat straw insulating. • Large-scale thermal conductivity and hygric investigations were conducted on bio- and waste-based insulating materials. • Insulation protypes with a timber framed wall was studied under steady state and variable environmental conditions. A growing awareness of the environmental impact of construction materials is leading to development of more sustainable building products, with particular attention focussed on bio-based resources and circularity. In recent years the market share of bio-based building products has grown significantly, supported by research on materials such as wood fibre, hemp, and straw bale. At the same time there has been growing awareness of the potential for greater circularity in construction, prolonging the life of existing products and materials, thus minimising embodied carbon emissions of future projects, as well as reducing reliance on primary resources and impact on landfill. This paper presents results of an investigation into the thermal and hygric characteristics of three novel insulation prototypes developed from bio-based or waste-stream materials. The experimental development and characterisation of insulation using maize pith, recycled bedding (polyester duvet) materials, and wheat straw insulating prototypes are presented. Hygric and thermal performance are compared to a mineral wool insulation product. As part of this work a series of large-scale thermal conductivity and hygric investigations were also conducted in which the performance of each insulation product with a timber framed wall was studied under steady state and variable environmental conditions. This work was part of a larger international research project aimed at developing insulating materials from bio-based and waste streams and will support market development of novel materials and products into mainstream construction. [ABSTRACT FROM AUTHOR]

• CatBoost regression model for prediction of surface chloride level. • The regression model has MAE and RMSE scores of 0.11 and 0.16 respectively. • Increase in chloride ingress with the increase in temperature and humidity. • Exposure zone has a significant effect on chloride ingress. • Temperature and humidity of RCP 2.6 and RCP 8.5 considered for analysis. This paper presents the effect of climate change on the long-term reliability of concrete structures due to chloride ingress. The impact has been demonstrated for three regions across the globe for the best and worst-case climate change scenarios. The methodology adopted here can be divided into three main steps. The first one is the development of a machine learning regression model using CatBoost for estimation of surface chloride levels, which is a function of temperature, concrete material properties, exposure conditions, and chloride levels in the seawater. The CatBoost model fitted over the experimental data has a mean absolute error (MAE) and root mean square error (RMSE) value of 0.11 and 0.16, respectively, and a high R2 value of 0.82. The second step is solving the coupled non-linear partial differential equation for temperature, humidity, and chloride ingress in concrete with time. A parametric study considering the effect of external parameters (temperature, humidity, exposure condition, and chloride levels in water) reveals the complexity and the dependencies of the chloride ingress process on external parameters. The final step involves the reliability analysis to estimate the time for chlorides to reach threshold levels at the rebar level using the numerical model. The input for the numerical model is temperature and humidity condition for different representative concentration pathways (RCP) scenarios, the material properties of concrete, and the exposure conditions. The reliability analysis shows that, for the concrete structure located in Dubai, UAE, and Cascais, Portugal, the mean time to corrosion initiation decreases due to climate change and it increases for the structure located in Tasmania, Australia. Further, the structures that are built in the future may have lower service life compared to the structures that were built in the past. Based on the study it concluded that it is necessary to consider the impact of climate change on service life to design resilient structures. [ABSTRACT FROM AUTHOR]

• A novel environmental effects in terms of heating, freezing, and humidity. • The bond behaviors under temperature elevation and repeated environmental effects. • Analysis and determination of interfacial shear traction stress and separation. • Numerical simulation under temperature elevation and repeated environmental effects. This paper investigated the influences of the temperature elevation and the repeated environmental effects on the bond behavior of the notched concrete beams with CFRP externally bonded through four-point bending tests. The corresponding numerical model was established and the FE results were compared with the test results. Two failure modes were observed in the test, both of which occurred to be sudden and brittle. The failure mode of the specimens changed from concrete failure to CFRP debonding after the temperature exceeded 150 °C or the cycle number reached 50 times. The ultimate loads of the specimens decreased linearly with the increase of both the temperature and the cyclic number, and the slopes of load-displacement curves in the first phase of the specimens were also reduced by both heating and cycling. Before CFRP debonding, the average maximum interfacial shear stresses at 0–30 mm from the mid-span decreased linearly with the increase of both the temperature and the cyclic number. The average shear traction stresses and the average interface stiffnesses were decreased with the increase of both the temperature and the cyclic number. The results obtained from the FE were similar to that from the test, which confirms the suitability of the FE model in the test conditions. [ABSTRACT FROM AUTHOR]

The transport of chloride into concrete is affected by many factors, including temperature, relative humidity, load cracks, and material properties. The purpose of this paper is to analyze the influence of various factors on the chloride ingression process through a case study for Hangzhou Bay Bridge located in marine environment. Firstly, based on the concentration of free chloride in pore solution, a porous media diffusion model is derived, considering the chloride adsorption term. Then, chloride adsorption isotherm, time-varying diffusion coefficient, temperature, relative humidity, and macroscopic cracks are simulated respectively by the porous media diffusion model. The main conclusions are as follows: (1) The chloride adsorption effect and time-varying diffusion coefficient have a great influence on the numerical results, which cannot be ignored in any case. (2) The natural temperature and relative humidity conditions of the case have a small effect on the simulation results. (3) Under the marine atmospheric environment, the macroscopic load cracks have a small influence on chloride ingression in the long term. • A transport model based on free chloride in concrete pore solution is established. • Chloride adsorption isotherm of concrete is assumed to be a transient process. • Effect of air relative humidity on concrete saturation is analyzed and simplified. • A none flux boundary condition is applied to the opening of macro load crack. • Five years of natural air temperature and relative humidity data were employed. [ABSTRACT FROM AUTHOR]

• Non-uniform shrinkage of recycled aggregate concrete (RAC) is discussed. • Distribution of relative humidity through depths of RAC is monitored. • Coarse recycled aggregate (CRA) increases the shrinkage gradient of RAC. • The influence of CRA increases with the decrease of the concrete depths. • Prediction model for non-uniform shrinkage of RAC is proposed. This paper investigates the influence of coarse recycled aggregate (CRA) on the non-uniform shrinkage of concrete with a single surface exposed to the air. A 210 d experiment was conducted on 17 slabs made with recycled aggregate concrete (RAC), measuring the shrinkage strain distribution through the slab depth. The parameters considered included the replacement ratios of CRA, slab depths, and the moisture-transferring boundary conditions (MTBC). The internal relative humidity distribution through the slab depth was monitored to verify the reasonableness of the occurrence of the non-uniform shrinkage. Based on the test results, a prediction model for the non-uniform shrinkage of RAC with a single surface exposed to the air was established and validated. Based on the age-adjusted modulus method, a cross-sectional analysis was conducted on the long-term strains of composite slabs using the proposed model. The investigation results indicated that (1) the incorporation of recycled aggregate significantly increased the shrinkage gradient by 84%−102%; (2) the influence of recycled aggregate on the shrinkage distribution of single-surface exposed concrete increased with a decrease in slab depth; and (3) the proposed equations can accurately predict the non-uniform shrinkage of single-surface exposed RAC. [ABSTRACT FROM AUTHOR]

• The temperature and relative humidity variations obtained by WUFI are in good agreement with the literature experimental findings. • The excessive moisture content in straw leads to bio-deterioration, mold, and decay damage in the whole structure. • The hygrothermal issues in a straw wall depend on the interior and exterior covering layers. • Hygrothermal issues can be solved by adding the straw thickness, adding a vapor retarder layer, adding an unventilated air layer, and controlling the indoor conditions. Straw is becoming a promising alternative insulation material to improve the building energy performance because of its low cost, large availability as cereal waste, its good hygrothermal properties, and its low embodied energy. The goal of this paper is to assess the hygrothermal performance of multi-layered straw walls with different boundary conditions. The study consists of evaluating five different straw-based wall assemblies, under a continental (Arkhangelsk, Russia), a tropical climate (Brasilia, Brazil), a temperate Mediterranean climate (Nice, France), and a cold desert climate Xinjiang (China). Numerical models of the heat and moisture transfer through the walls using WUFI software are developed, calibrated, and validated through experimental results from the literature. The chosen evaluation criteria are the total water content, the drying rate, the condensation risk, the mold growth, the moisture quantity, the time lag, and the decrement factor. Results show that straw walls with cement and/or wood covering can be used in tropical and temperate climates, coated straw walls with additional air layers in dry climates, while insulated straw walls are best fitted in continental climates. In the latter, the dryness rate varies between 7 and 40% with a low condensation risk of value in the range of 0–12%. It can be concluded that the straw wall's performance strongly depends on the interior and exterior added thermal insulation layers since they affect the ability of the material to dry out. [ABSTRACT FROM AUTHOR]

• Early-age basic tensile creep of concrete with and without SAP was studied. • Inclusion of SAP in concrete resulted in increased creep. • A modified MC2010 model accounting for the effect of SAP on creep was proposed. • Mechanisms behind the effect of SAP on creep of concrete were explored. Internal curing with superabsorbent polymers (SAP) significantly affects both deformational and mechanical properties of cement-based composites at early ages. Despite substantial previous research, the impact of SAP on the basic tensile creep of early-age concrete is hardly investigated. In this paper, through direct tensile testing, the basic tensile creep of concrete with a water-to-binder ratio of 0.35 and containing 0.3% SAP (by mass of binder) loaded at early ages was studied. Concrete with SAP exhibited higher basic tensile creep than the reference concrete without SAP when first being loaded at 1 day, 6 days, and 14 days. The higher basic tensile creep of early-age concrete with SAP may be due mainly to the formation of large air voids, delayed cement hydration, and also higher internal relative humidity. The applicability of using the B3 model and the MC2010 model to predict the basic tensile creep of early-age concrete was examined. A modified MC2010 model was then proposed to more realistically reflect short-term tensile creep characteristics of early-age concrete with and without SAP. The model parameters were first determined through best-fitting with the measured creep data for reference specimens loaded at 1 day. Subsequently, the model, with parameters so determined, was used to predict the specific basic tensile creep for specimens loaded at 6 days and 14 days. The good agreement between the model predictions and test results suggests an acceptable predictive capability of the modified model. Besides, the autogenous shrinkage, compressive strength, and elastic modulus of the two types of concrete, with and without SAP, were also investigated and highlighted. [ABSTRACT FROM AUTHOR]

[Display omitted] • Efflorescence of fly ash-based geopolymer mortars was investigated by high-low humidity cycles. • Ultrasonic treatment was used for investigating the migrated fraction of cations. • When 1 wt% caltite was added in geopolymers with the w/c ratio of 0.4, efflorescence fraction was reduced by 89.34%. • Theoretical maximum compressive strength was decreased from 149.86 MPa to 132.17 MPa after efflorescence. • The ammonium stearate of caltite decreased the leached fraction of Na+ by 0.1%. The efflorescence of fly ash-based geopolymer (FG) is a significant factor of durability, which has been widely concerned in the application of civil engineering. Fly ash based-geopolymer mortars (FGMs) were fabricated by optimizing their water/cement (w/c) ratio from 0.6 to 0.4 as well as the addition of caltite solution (CS) in this paper. The characteristics and mechanism of efflorescence under the high-low humidity cycles were identified. These free cations in FGMs migrated in the direction of surface to form carbonate (Na 2 Ca(CO 3) 2 ·5H 2 O), resulting in efflorescence. The most effective way for FGMs to mitigate efflorescence from the obtained results was adding 1 wt% CS into the FGMs with the w/c ratio of 0.4. The filter membrane of alkaline stearate was formed by the reaction between CS and alkaline activator, and it adhered to the capillary to suppress migrating and leaching behavior of Na(H 2 O) n +. Efflorescence fraction was thus decreased from 92.16% to 2.82%, and the mechanical properties were simultaneously decreased by 23.17%. Adding 3 wt% CS into FGMs with the w/c ratio of 0.5 also mitigated efflorescence, the efflorescence fraction was decreased by 18.13%. With the dosage of CS increasing to 4 wt%, the efflorescence of FGMs with the w/c ratio of 0.6 could be accelerated. The results further confirmed that the trace addition of CS could obtain the optimal result for mitigating the efflorescence of the FGMs. [ABSTRACT FROM AUTHOR]

• Engineering properties of CLSM were evaluated under two different curing regimes. • 100% and 50% humidities and three different temperatures were used for curing. • Both curing temperature and humidity significantly influence the engineering properties of CLSM. This paper outlines research conducted on controlled low strength material (CLSM) to examine the effects of curing condition and water-cementitious material (w:cm) ratio on its engineering properties, including compressive strength, elastic modulus, indirect tensile strength, drying shrinkage, and setting time. Two different curing regimes were used to assess compressive strength and indirect tensile strength. In the first curing regime, continuous curing was applied in a 100% relative humidity environment and at a temperature of 70°F (21.1 °C). In the second, continuous curing was used in a 50% relative humidity (RH) environment at a temperature of 70°F (21.1 °C). Curing the specimen at 50% RH environment remarkably decreased the rate of strength gain when compared to the 100% RH environment. The compressive strength and indirect tensile strength of CLSM, as expected, also increased as the w:cm ratio decreased from 1.0 to 0.8 for the same curing conditions and decreased as the cement amount was lowered in the mix. The bar linear shrinkage tests showed that shrinkage strain at 50% RH decreased when the w:cm ratio decreased. Tests conducted to investigate the effects of curing temperature and w:cm ratio on the setting time showed that CLSM sets faster as curing temperature increased from 50°F (10 °C) to 90°F (32.2 °C) w:cm ratio decreased from 1.0 to 0.8. [ABSTRACT FROM AUTHOR]

• A specifically designed humidity tester is employed to measure the humidity inside the specimen during the period of humidity conditioning. • A novel method for the master curve under humidity conditions is proposed to quantify the influence of water vapor on LVE properties of asphalt mixtures. • The effect of humidity on LVE properties of asphalt mixtures is analyzed from three aspects. • The three-dimensional master curves of dynamic modulus and phase angle of asphalt mixtures are constructed. It has been demonstrated that humidity, or water vapor, is a non-negligible contributor to moisture damage of asphalt pavements. However, little work has been done regarding the effect of humidity on the performance of asphalt mixtures. The objective of this paper was to investigate the linear viscoelastic (LVE) properties of asphalt mixtures under different humidity conditions. Specimens were first conditioned at four humidity levels and subsequently employed to perform dynamic modulus tests. Next, a shifting method for the master curve under humidity conditions was proposed to quantify the influence of water vapor on LVE properties of asphalt mixtures. Finally, the effect of humidity on LVE properties of asphalt mixtures was analyzed based on three aspects. The results show that the developed shift method is accurate enough to quantify the effect of humidity on master curves of asphalt mixtures since the error in any group is less than 2%, while each R2 value exceeds 0.98. The rheological parameter E e decreases, and R and m increase as the humidity levels rise. However, no obvious variation trend was found in the E g , k , and f c of different groups. The humidity factor g (H i) shows a negative increasing trend based on the rise in humidity levels. Meanwhile, according to the developed three-dimensional master curves of dynamic modulus and phase angle of the two types of mixtures, dynamic modulus decreases and phase angle increases as humidity levels rise at low frequencies (or high temperatures). No significant differences were observed on dynamic modulus and phase angle among different groups at high frequencies. Thus, the developed three-dimensional dynamic modulus and phase angle master curves can determine dynamic modulus and phase angle under arbitrary humidity conditions. [ABSTRACT FROM AUTHOR]

This paper presents an investigation of the mechanical properties of three different earth building materials manufactured by compacting two soils with distinct particle size distributions under two markedly different efforts. Multiple samples of each material have been equalised either inside a climatic chamber at different humidity levels or oven-dried, before being subjected to shearing inside a triaxial cell to measure the corresponding levels of strength and stiffness. Triaxial shearing has been performed under different levels of radial stress to investigate the effect of material confinement inside thick walls. Consistent with previous research, the study has indicated that strength and stiffness increase as ambient humidity reduces and degree of saturation decreases, though the actual variation of these properties strongly depends on the dry density and clay content of the material. Most importantly, particle grading has emerged as a key material parameter, whose impact on earth building has often been overlooked. Particle grading appears to influence strength and stiffness even more than compaction effort, dry density and average particle size, which are usually quoted as the most important variables for the design of earth building materials. [ABSTRACT FROM AUTHOR]