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This study evaluates the laboratory performance of Warm-Mix Asphalt (WMA) containing locally sourced Steel Slag (SS) and limestone (LS), focusing on stiffness and moisture sensitivity. Four asphalt mixes were tested: Hot mix with limestone (HL), hot mix with steel slag (HS), warm mix with limestone (WL), and warm mix with steel slag (WS). The binder used for all mixes was AC 60/70 penetration grade, and Aspha-min served as the warm mix additive. Testing included Marshall Stability, boiling water, indirect tensile strength, moisture-induced damage (TSR), and dynamic modulus. Image Analysis quantified the aggregate-retained coated area after the boiling test. Despite performance differences, all mixes met Egyptian code requirements for asphalt concrete mixes. Visual inspection and image analysis demonstrated the effectiveness of using steel slag to mitigate asphalt mix stripping. The retained coated area for limestone mixes ranged from 60 % to 75 %, while SS mixes exhibited over 95 %. Dynamic modulus tests indicated no significant stiffness difference with SS, and stability increased by 8 % and 14 % with and without the warm additive. Economic study confirmed the feasibility of utilizing SS. In conclusion, combining Aspha-Min and steel slag improves AC mix production and construction processes, offering a sustainable and advantageous option in Egypt. [ABSTRACT FROM AUTHOR]

Recently, the use of supplementary cementitious materials (SCMs) as a partial replacement of Portland cement has become necessary to minimize CO 2 emissions associated with concrete, while the wide variations in their types and properties make predictions of the final products difficult, requiring a significant experimental effort. In this research, machine learning (ML) algorithms were explored to predict the major phases of Portland cement blended with SCMs. An artificial neural network ML algorithm was used for prediction in order to provide adaptable input that can be utilized for various SCMs. The application of the model was validated by forming and analyzing the relationship between the phases, water-to-cement ratio, and main oxide compositions of SCMs. The results demonstrated that ML models can be used effectively to predict phases of SCM-blended cements. The outcome of this study is expected to provide valuable information for concrete mix designs involving the use of SCMs. [ABSTRACT FROM AUTHOR]

This paper studies the fresh and mechanical properties of high-strength concrete (HSC) by incorporating recycled concrete aggregates (RCA) of varying sizes and concentrations. The recycled aggregate concrete (RAC) was prepared by partially replacing RCA with natural coarse aggregate (NCA) at 0%, 15%, 30%, and 45%, with aggregate sizes ranging from 5 to 12 and 12–20-mm. Fresh concrete properties, such as slump, Kelly ball, compacting factor, K-slump, and fresh density, were tested to determine the influence of RCA size and concentration. In addition, the mechanical properties were studied through the execution of compressive, split-tensile, and stress-strain tests. The test results revealed that increasing the RCA concentration declines the fresh and hardened properties of HSC. In the fresh concrete experimentation, the 12–20 mm aggregate size RAC mixes exhibited greater workability than the 5–12 mm aggregate mixes. On the contrary, 5–12 mm aggregate mixes RAC had higher compressive and split-tensile strength and a higher modulus of elasticity than 12–20 mm aggregate mixes concrete. When it comes to sustainability, the study found that the smaller size range of RAC produces inferior embodied CO 2 (eCO 2) and provides a cost-effective and sustainable solution for the construction industry. [ABSTRACT FROM AUTHOR]

Due to the brittle nature of ceramic, the ceramic and construction industry produces a large volume of waste that imposes a severe environmental threat due to its non-biodegradability. In this study, the suitability of ceramic waste as a replacement of natural coarse and fine aggregate in concrete has been investigated by evaluating engineering properties such as bulk density, water absorption, workability, etc. with respect to different concrete samples made with different mix proportions. Furthermore, a prediction model is introduced to predict compressive and splitting tensile strength using the machine learning tool support vector machine (SVM). A data set containing 108 records either for compressive or tensile strength was used for the training and testing purposes of the SVM model. A total of 9 mix proportions was selected and cast cylinders were cured for 7, 28, and 56 days. Four different kernel functions were used to optimize the results and different accuracy parameters like the value of R2, mean absolute error, mean square error, root mean square error, etc. were compared to find the best kernel function for this study. By primarily evaluating the coefficient of determination (R2), SVM showed an acceptable result with an accuracy of over 90%. Moreover, in terms of other accuracy measurement parameters result indicates that the SVM is an effective tool to predict the compressive and splitting tensile strength of concrete comprised of different proportions of ceramic content. [ABSTRACT FROM AUTHOR]

Concrete has experienced significant improvements in recent decades, resulting in lower Portland cement consumption as well as a lower carbon footprint through CO2 injection while keeping comparable fresh, mechanical, and durability performance. The use of CO2 injection in concrete (CarbonCure) in the United States and Canada has enabled advances such as green concrete under normal and severe conditions. While incorporating novel developments, this study focuses on CarbonCure concrete modification in the extreme weather of the Arabian Gulf region. This is a relatively new option that has entered the field in the Middle East. The materials, process, and fresh and hardened properties of the CarbonCure concrete made and field cured in the Arabian Gulf region will be considered here and evaluated in detail. Along with adding CO2 to the mix, the cementitious material was lowered without impacting the quality or performance of the structural concrete. The developed green mix included up to 0.2% CO2 by mass of cementitious material. Because of the benefit of early carbonation, which strengthened the concrete product even with less cementitious material, this green concrete mix retained a 28% increase in slump compared to the standard concrete mix without CO2, a 28-day compressive strength of 48 MPa, low water absorption of 1.3%, and resistance to aggressive chemicals, all within the limits defined by the standard codes. Due to these benefits, and because this green concrete was tested against the severe coastal climate, it would be ideal for maritime applications. [ABSTRACT FROM AUTHOR]

This paper focuses on the investigation of fresh, mechanical, and durability properties of concrete with the influence of fly ash and polypropylene fiber. In this study, cement was partially replaced by 15 % and 30 % fly ash content in weight, whereas polypropylene fiber was incorporated in concrete mixes at 0.06 %, 0.12 %, and 0.18 % by volume. Twelve concrete mix proportions were developed, and slump, density, ball penetration, and compacting factor tests were conducted to examine the fresh concrete properties. Besides, mechanical characteristics, including the uniaxial compressive and splitting tensile strength of concrete, were evaluated at 7, 28, and 90 days. Further tests of concrete durability, including rapid chloride permeability test, sorptivity, and water penetration, were performed at 90 days. The results exhibited that the incorporation of fly ash developed fresh concrete properties, while polypropylene fiber decreased the fresh characteristics of concrete. Furthermore, the combination of fly ash and polypropylene fiber in concrete was substantially attained to improve the mechanical and durability characteristics compared to the control mix. Mix proportion of 15 % fly ash and 0.12 % polypropylene fiber exhibited a pronounced influence on compressive strength, chloride permeability, sorptivity, and water penetration compared to other concrete mixtures. [ABSTRACT FROM AUTHOR]

Alternative substitutes to convectional building and construction materials which pose environmental challenges, will be a bonus to the construction industries. This research investigates the suitability of calcined termite mound as partial substitute for cement and recycled concrete aggregate as aggregates substitute in the production of concrete. Termite mound clay in its natural state was obtained, calcined, and pulverized to the fineness of 75 µm. Various concrete mixes were formulated in which Ordinary Portland cement was partially replaced with Calcined Termite Mound (CTM) from 0% to 25% replacement at a step size of 5%, and recycled concrete aggregates (RCA) was also used as a partial replacement of the coarse natural aggregate (NA) at 20%, 40%, 60%, 80% and 100% by weight replacement. Compressive strength test, setting time test, slump test, scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR), were used to characterize the test materials and the concrete specimens. The results show that addition of either RCA or CTM will lead to reduction in the compressive strength. However, when RCA is combined with CTM, the optimum combinations suitable for structural load bearing members were found to be 60% RCA, 40% NA with 5% CTM. Other comparable mixes were also discovered. [ABSTRACT FROM AUTHOR]

Paper crumb (PC) is a type of paper sludge residue from the wastepaper recycling industry. It is a by-product from the various fiber purification stages that is particularly composed of short cellulose fibers, lignin, organic compounds and inorganic filler residues. Despite representing a reject material for the paper recycling sector, this feedstock can be turned into a bioresource to enable cross-sector industrial symbiosis in the form of a more sustainable concrete, hence an opportunity for novel Net Zero supply chains. This study sought to valorise the PC by the sequential anaerobic digestion to produce methane (CH 4) from the organic compounds, followed by utilization of the digestate as a water replacement in concrete. The 21-day digestion of PC yielded 163 ml CH 4 per gram volatile solids and the resulting digestate improved concrete compressive strength up to 50% water replacement grade, meeting the requirements for structural grade (C32/40) applications with substitution grades up to 50% and 25%, with and without the addition of plasticiser respectively. In a minor capacity, the digestate reduced workability of the concrete mix, however we demonstrate this issue can be resolved by the addition of plasticiser or increased water to cement ratios. The admixture addition is important to facilitate pumpability on site and ensure satisfactory compaction. This study highlights the potential of anaerobic digestate as a concrete supplement (additive), which would improve the sustainability of both the construction and the paper sector. [Display omitted] [ABSTRACT FROM AUTHOR]

Shotcrete was prepared by using micro-nano bubble water as mixing concrete water in cooperation with air-entraining agent (AOS-R) and superabsorbent polymer (SAP), and its frost resistance performance was experimentally studied. The results show that the incorporation of AOS-R and SAP will reduce the 28-day strength of concrete, but MNBW can compensate for the strength loss to a certain extent. The frost resistance of concrete mixed with alkali accelerators is inferior to that of concrete mixed with the alkali-free accelerator. The incorporation of AOS-R or SAP into shotcrete can improve its frost resistance to in some degree as well. Given the frost resistance of concrete mixed with SAP is not as effective as AOS-R, MNBW can play a synergistic effect to improve the frost resistance of concrete. The main reason why the AOS-R improves the frost resistance of concrete is that it generates a large number of small bubbles to isolate the water transmission channel which manage to relieve the crystallization pressure of water. MNBW improves the frost resistance of concrete, because it refines the pore structure and increases the density of concrete. [ABSTRACT FROM AUTHOR]

In this paper, experimental studies were conducted to examine the shear behavior of reinforced concrete beams, including a combination of crumb rubber (CR) and rice husk ash (RHA). One of the key objectives of the concrete industry is to reduce global emissions and provide environmentally friendly concrete. Twelve RC beams with four replacement levels of CR (0 %, 5 %, 10 %, and 20 %) by fine aggregate (FA) and three substitution ratios of RHA (0 %, 10 %, and 20 %) by cement (one beam from each mix) with dimensions of 120 × 250×2000 mm were cast and tested under four-point loading conditions. The experimental outcomes display that incorporating a combination of CR and RHA reduces workability. The introduction of RHA enhanced both the compressive and tensile strengths. Conversely, the inclusion of CR significantly impacted the loss in concrete strength. The shear capacity, stiffness, and toughness of the tested beams were noticeably enhanced with the addition of RHA up to 10 %, then dropped with the addition of 20 % RHA but remained higher than those of the reference beam. On the contrary, the introduction of CR had a negative effect on the shear capacity and stiffness of tested beams, and incorporating RHA up to 10 % enhanced these effects. To maintain environmental sustainability and preserve natural resources, the ideal substitution ratios for the concrete mix are 10 % CR and 10 % RHA, which produce an acceptable shear capacity with a slight drop of approximately 4.0 %. Additionally, a comparison was conducted between the predicted shear capacity of four design code equations (ACI 318–2019, ECP 203, BS8110, and Euro-2) and the experimental results obtained from all test beams. • Mechanical properties of concrete comprising CR and RHA as FA and cement replacement, respectively, were investigated. • The shear behavior of RC beams comprising RHA as cement replacement was studied. • The introduction of RHA can mitigate the negative effect on concrete strength caused by CR. • The optimum substitution ratios for the concrete mix are 10 % CR and 10 % RHA [ABSTRACT FROM AUTHOR]

Current service life prediction models for concrete sewer design, including the widely used Life Factor Method (LFM), do not efficiently incorporate certain key corrosion contributing factors, such as material selection, concrete mix design, and sewer environment. This paper describes an advancement of the LFM model to cover these factors, broaden its usage, and improve concrete sewer design and applications. By integrating the first principles of the original LFM model, advanced knowledge from the literature, and results from field performance studies of various sewer concretes, a practical and relatively simple LFM model was advanced. With concrete mix design, oxide composition of all concrete ingredients, and sewer environmental and hydraulic conditions, the so-called 'advanced LFM model' could predict the corrosion rate of various concrete mixes. The model emphasised the influence of various modern binders, including calcium aluminate and calcium sulpho-aluminate cements, and various aggregate types including siliceous, calcareous, and alumina-based aggregates, when subjected to different sewer environments. • We aim to advance the Life Factor Method (LFM) for sewer concrete structures. • We highlight LFM limitations in integrating key corrosion-contributing factors, i.e., material and sewer environment factors. • We refine the LFM by addressing its limitations through insights derived from literature and fielde studies. • We present the advanced LFM, accounting for the impact of various binders and aggregates in concrete under varied sewer environments. • The advanced LFM is a simple-use and effective tool for predicting corrosion rate of sewer concrete. [ABSTRACT FROM AUTHOR]

This research focuses on the development of the Anti-freezing Durability-Oriented Carbon Emission Indicator (CEI) system for assessing concrete's carbon footprint with an emphasis on durability, particularly in freeze-thaw conditions. This novel approach reduces the environmental impact of concrete by integrating durability metrics into carbon emission evaluations. The paper presents experimental findings on mix designs for high-strength, low-carbon concrete, which demonstrate improved freeze-thaw durability. And found out that concrete mixes using sulfate-resistant cement with GGBS outperform those with FA and OPC in terms of low-carbon performance, in the newly developed 19 mixes, concrete mix incorporating air-entraining agents with sulfate-resistant cement and 40% GGBS as a supplementary cementitious material, namely the HPC1-P•HSRF-S group, demonstrates a distinct low-carbon advantage across various indicators. Overall, the inclusion of fibers is shown to improve freeze-thaw durability, though with limited impact on compressive strength. The research underlines the importance of optimizing concrete mix designs for both environmental and durability considerations, presenting a significant step towards more sustainable construction practices. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) has shown promise in improving concrete strength. Despite its frequent use in cement composites, its effect on concrete properties is less explored. The influence of GO on concrete remains unclear due to various interactions among constituents such as GO type and percentage, Superplasticiser (SP) type and percentage, dispersion technique, and curing age. Therefore, making prediction of compressive strength using simple mathematical formation is challenging. This study represents the first-ever attempt at developing a comprehensively validated machine learning model to predict GO-concrete's compressive strength characteristics by considering all key variable parameters. A comprehensive laboratory experiment program was conducted to collect the data required for training the machine learning (ML) models. Once the ML models were trained, they were used to predict the relationship of each of those input variables towards the compressive strength properties. Four machine learning models—(a) multiple linear regression (MLR), (b) k-nearest neighbour (KNN), (c) random forest (RF) and (d) extreme gradient boost (XGB)—were utilised to model the relationship between input parameters and compressive strength. Also, explainable machine learning (XML) methods were employed to elucidate the impact of mixed constituents on the compressive strength of GO concrete. The results from test predictions showcase that the XGB has attained a coefficient of determination (R2) of 0.981, coefficient of correlation (R) of 0.99, mean square error (MSE) of 0.9, mean normalised bias (MNB) of 0.004, scatter index (SI) of 0.2 with mean absolute error (MAE) of 0.8 MPa for the predictions, outperforming the remaining models. XML highlighted the true impact of GO and the remaining variables, emphasising that the presence of GO significantly improves compressive strength. The optimum GO content and optimum superplasticiser content observed from the experimental work agreed with results obtained from the XML analysis, showing the consistency of the explanation with the experimental results. This implies the superiority of using XML methods in concrete mix design applications in industry. [Display omitted] • Compressive strength of GO-added concrete was predicted using XML. • XGB model achieved the highest accurate compressive strength predictions. • SHAP revealed the impact of GO on concrete. • Developed an XML-based predictive tool for GO-added concrete. [ABSTRACT FROM AUTHOR]

Oil-based Drilling Cutting Pyrolysis Residue (ODPR) is a waste produced during oilfield drilling using oil-based mud. Recycled Fine Powder (RFP) consists of particles less than 0.16 mm, crushed and sieved from waste concrete. China's solid waste is characterized by high production, low utilization rates, and high pollution levels. This study explores the feasibility of preparing ceramsite from ODPR and RFP. By examining the effects of varying temperatures and proportions on the macroscopic and microscopic properties of ODPR-RFP ceramsite (ORC), the optimal process was determined: ODPR: RFP = 7:3, 2 % borax flux, 10 minutes ball milling, 1200℃ sintering temperature, and 30 minutes insulation. The resulting ORC, with a bulk density of 1120 kg/m³, cylinder compression strength of 10.50 MPa, and water absorption rate of 7.8 %, meets the "Lightweight aggregates and its test methods (GT/B17431.2)" standard. Batch production of ORC products of various sizes was conducted to evaluate their practical application in LC30 lightweight aggregate concrete. Replacing the aggregate in lightweight concrete with ORC yielded a concrete with excellent mixing performance, reaching a maximum strength of 31.2 MPa after 7d and 44.8 MPa after 28d. The damage pattern of ORC lightweight concrete is characterized by longitudinal splitting, with varied crack initiation and expansion paths. In the interfacial transition zone of ORC concrete, the ORC form a strong bond with the cement mortar, enhancing the strength of the lightweight concrete. Additionally, the leaching of heavy metals (HMs) from the ORC was examined to assess potential environmental pollution. The results indicated that preparing ORC from these two types of solid waste can effectively immobilize HMs, with a solidification rate of up to 92.10 %. Pb with high content is mainly solidified in the form of solid solution to form (Ba, Pb) SO 4. The ecological risk assessment method for HMs shows that using this solid waste and process to prepare ORC does not pose HMs risks and is an environmentally friendly building material. • Basic properties of ODPR-RFP ceramsite was carried out. • Microsintering mechanism of ODPR-RFP ceramsite was parsed. • Lightweight concrete application and heavy metals solidification were analyzed. [ABSTRACT FROM AUTHOR]

Additive manufacturing in construction demands an in-depth understanding of the rheological properties of fresh concrete. However, the abundant data in this field remains underexplored. This conventional fragmented approach has hindered broader progress and innovation. This study aims to develop rheological models for 3D printable concrete through a comprehensive, data-driven paradigm, emphasizing the urgent need for a unified, large-scale dataset. By compiling data spanning a decade, we have created an open-access dataset that contains mix designs and experimental results on the rheological behaviors of additive construction concrete. A machine learning-based model and explicit polynomial expressions for estimating rheological properties were developed. The developed machine learning model can take nineteen different parameters as inputs to predict the rheological behavior of printed concrete, showing superiority over models considering a few parameters. Our model can predict the properties of unexplored mix designs, with tailored expressions for practical engineering in additive construction. This enhances understanding of concrete mix design and rheology, highlighting the importance of data-driven method in unveiling the complexity of concrete. • Analyzed the rheology of 3D printing concrete through the lens of data. • Identified research gaps in the area of mix designs for 3D printing concrete. • Developed novel predictive models for 3D printing concrete and explained the models using game theory. • Developed novel explicit equations for rapid estimation of rheological properties based only on the mix design. [ABSTRACT FROM AUTHOR]

The South China Sea contains many coral reefs, and there is a lot of discussion about the best way to dispose of them. Finding ways to use these materials effectively in marine engineering could help address the shortage of natural aggregates in coastal engineering. One potential solution is using coral concrete, which offers cost-effective and enhanced properties. A type of coral fiber concrete using sea sand is created by combining coral rock, sea sand, seawater, PVA fiber, and PP fiber. The findings indicate that by utilizing the optimal ratio of the two fibers (3 kg PVA + 1 kg PP and 2 kg PVA + 2 kg PP), the cubic and axial compressive strength of the new concrete can be increased by 10 % and 20 %, respectively compared to ordinary coral concrete. Furthermore, incorporating these fibers can also reduce axial displacement, resulting in an elastic modulus that is 30–50 % higher than non-fiber variants while enhancing axial toughness. Finally, this study examines stress-strain curves at three different stages through analysis of macroscopic and microscopic failure mechanisms. It was found that there exists a correlation exceeding 0.9 between two mathematical models and measured stress-strain curves from this study. The effective use of composite plastic fiber significantly enhances concrete material performance while providing valuable data support for marine economic facilities construction. • Two different compressive strengths of coral concrete materials mixed with two kinds of plastic fibers were tested, and their macroscopic failure forms were linked. Finally, the microscopic mechanism was analyzed. • Coral aggregate fiber concrete with better performance than ordinary concrete is developed, and various stress-strain data indexes are analyzed and simulated effectively. • This paragraph presents a proposed solution for marine construction concrete that utilizes coral stone as an alternative to freshwater river sand and seawater sand, thereby addressing the issue of material scarcity. [ABSTRACT FROM AUTHOR]

The thermal energy accumulated by the concrete cover exposed to fire is several orders of magnitude larger than the elastic energy entailed by thermal stress. Water vaporization can quickly convert this huge energy source into the mechanical work required to drive the fracturing and acceleration of concrete shards, namely the explosive spalling phenomenon. In order to fully understand the role of moisture content in this mechanism, a novel small-scale screening test setup was developed, where a planar crack is triggered in a heated concrete disk by the high thermal dilation of an embedded polymer ring. The concurrent pore saturation level is changed by the heating rate, the addition of polypropylene fibre, and the preliminary drying of samples, with direct effects on crack instability. The ability of this setup to categorize the inherent spalling sensitivity of different concrete mixes was validated against standard fire tests on prestressed slabs. [ABSTRACT FROM AUTHOR]

Considering the shortcomings of traditional tunnel support methods like shotcrete, including large rebound, poor water retention, and dust pollution, this paper proposes an innovative method to use mold-bag concrete (MBC) for initial tunnel support. Through macroscopic mechanical tests and microscopic structural characterization, a high-fluidity mix ratio of MBC suitable for actual construction conditions has been developed. To clarify the mechanical properties of MBC, compressive tests were conducted, leading to important conclusions: 1) Mold-bags can significantly enhance the compressive strength and ductility of MBC. The specimens of mold-bag concrete of PP (MBC-PP) fail first but have good ductility, while specimens of mold-bag concrete of SNG-PET (MBC-SPET) have the best compressive performance but poor ductility; 2) Without pressurized drainage, mold-bags can increase the compressive strength of MBC due to the water permeability characteristics, with MBC-SPET having the largest increase in compressive strength, 69.1 %; 3) MBC-SPET tests show that increasing pressure has a better effect than increasing drainage time, with 90 s and 20 kg pressurized drainage being the best increase effect. These findings highlight the potential of MBC in addressing the limitations of traditional methods, providing strength enhancement, environmental benefits, and practical feasibility for tunnel support. ● An innovative approach to utilize mold-bag concrete for the initial support of tunnels is proposed. ● A high-fluidity mold-bag concrete mix and corresponding testing protocols have been formulated to meet on-site construction requirements. ● The impact of different mold-bag material and weight on concrete at 3, 7, and 28 days is investigated under identical drainage conditions. ● The impact of pressurized drainage on the compressive strength of concrete is investigated under consistent mold-bag conditions. [ABSTRACT FROM AUTHOR]

In previous literature on predicting compressive strength (CS) using machine learning (ML), the focus has primarily been on algorithm-specific improvements, with less emphasis on improving the data perspective of CS prediction. Departing from these conventional investigations, this study presents data-centric enhancements. A systematic and comprehensive methodology is adopted, involving series of steps. Firstly, a large dataset (> 24,214 datapoints) comprising 26 input features relating to mixture proportions, engineered ratios and atmospheric parameters is prepared and processed. Feature engineering is then performed for selection and processing of data features. Subsequently, six scenarios are designed and investigated for CS prediction, focusing on distinct combinations of input features. Finally, CS predictions for all six scenarios are compared using five well-known ML model, and results are validated using statistical hypothesis testing. The results show significance improvements in CS prediction, with a 12.8 % increase in coefficient of determination (R2) and a 61 % reduction in root mean square error (RMSE) achieved by incorporating engineered and atmospheric parameters in conjunction with mixture proportion as inputs in CS prediction. Based on CS prediction in six scenarios, the study presents useful discussions focusing on concrete data perspective, role of engineering ratio and atmospheric features, and interaction and influence of input features in CS prediction. In conclusion, this work emphasizes the importance of enhancing data management practices for concrete performance assessment to have a more efficient, realistic, and sustainable outcomes in the concrete industry. • Evaluates the compressive strength prediction considering mixture proportions as well as atmospheric parameters. • Design and investigates six modeling scenarios and five widely used machine learning methods. • Statistical hypothesis testing based evaluation of ML methods is achieved. • An improved prediction of concrete strength in terms of model fitness and accuracy. [ABSTRACT FROM AUTHOR]

Concrete production, ubiquitous in global construction, exerts significant environmental strain, notably through cement manufacturing's carbon footprint and natural sand depletion. As a response, researchers are exploring eco-friendly alternatives, including Waste Tyre Rubber (WTR) aggregates which replace natural sand in concrete. This study investigates the impact of WTR particle sizes (ranging from 0.2 to 4 mm) and volumetric replacements (0–54 %) on Rubberised Concrete Mortar (RuCM) and Rubberised Concrete (RuC) mechanical properties. Additionally, Waste Tyre Steel Fibre (WTSF) reinforcement effects (volume dosage between 0 % and 3 %) are examined and compared with Commercial Steel Fibre (CSF). The study optimizes RuCM and RuC mixes via particle packing theory, incorporating Ground Granulated Blast Furnace Slag (GGBS) and Fly Ash (FA) as cement replacements. Mechanical tests reveal the compressive and flexural strength reduces with an increasing WTR dosage, attributed to the inherent softness of WTR and the weak interfacial bonding between WTR particles and surrounding matrix. Utilizing an optimized RuC mixture with a 10 % WTR replacement yields substantial mechanical improvements, showcasing a remarkable 195 % surge in compressive strength and a noteworthy 61 % elevation in flexural strength over conventional concrete (CC). However, when compared to the control mix devoid of rubber replacement, there is a modest reduction of 16 % in compressive strength and 4 % in flexural strength. Moreover, the incorporation of WTSF reinforcement proves beneficial in mitigating compressive strength losses post rubber particle inclusion and brings about a substantial increase in flexural strength with 3 % volumetric additions. Quantitative analysis reveals the reinforcement effect from WTSF is comparable to the effect of CSF reinforcement. These findings underscore the intricacies and potential opportunities in harnessing WTR and WTSF for the development of resilient and sustainable concrete formulations. • Optimized rubberised mortar and concrete mixes are developed via particle packing theory. • Impact from rubber particle sizes (0.2–4 mm) and volumetric replacements (0–54 %) is studied. • Noteworthy elevation in flexural strength is observed from waste tyre fibre reinforcement. • Reinforcement effect from waste tyre fibre is comparable to the commercially available new steel fibre. [ABSTRACT FROM AUTHOR]

This experimental study aims to advance sustainable construction practices by exploring the recycling potential of steel fibre reinforced concrete with 4D Dramix® fibres from the company Bekaert. In this research steel fibres from reinforced concrete specimens with varying fibre quantities of two 4D Dramix® fibre types, more precisely, the 55/50 BG and 65/50 BG fibres are recycled. A jaw crusher at the recycling company AC Materials (Flanders, Belgium) and an impact crusher at the research and development company CTP (Wallonia, Belgium) are employed to optimize the quantity and quality of the recycled fibres. Subsequently, the recycled steel fibres are reintegrated into fresh concrete mixes. The recycling process of the fibres results in a general decrease of the residual tensile strength capacity for the concrete mixtures with recycled fibres (RSFRC) compared to those with new fibres (NSFRC), and the deviation increases with increasing crack mouth opening displacement (CMOD). It was found that fibres recovered by the impact crushing process are (generally) shorter than those obtained from the jaw crusher, which results in a fibre reinforced concrete (FRC) with a somewhat lower post-cracking tensile strength. Nevertheless, most recycled fibres retain 75 % of their original capacity, considering the mean residual tensile strength of the FRC mixtures. Consequently, current findings show promising results for the recycling potential of steel fibres and the residual strength behaviour of RSFRC compared to NSFRC. Additionally, this study highlights the potential for an improved constitutive tensile model for FRC mixtures, where the design parameters k a and k c can be estimated based on the f R 3 k / f R 1 k -ratio. • The settings of the impact crusher largely influence the recycled fibre quality. • The jaw crusher distorts the fibre hooked-ends more than the impact crusher. • As CMOD values increase, recycled fibres show greater residual strength loss. • Most recycled fibres show a residual tensile strength capacity of 75 %. • The constitutive tensile model can be predicted based on the f R3k /f R1k ratio. [ABSTRACT FROM AUTHOR]

The present study investigated the effect of the lightweight aggregate content on the carbonation response of concrete according to its compressive strength and water-to-cement ratio. Twenty-five concrete mixes containing structural lightweight aggregates produced using artificially expanded bottom ash and dredged soil granules were tested in a controlled chamber with a temperature of 20 ± 2 °C, a relative humidity of 60 ± 5 %, and a CO 2 concentration of 5 ± 0.2 %. Nonlinear regression analyses were conducted to examine the effect of the 28-day compressive strength and density of the concrete on the propagation of carbonation and CO 2 diffusion coefficients at different exposure times. The experimental and regression results clearly revealed that the propagation of carbonation was somewhat affected by the density as well as the compressive strength of the concrete. The increase in the lightweight aggregate content slightly delayed the diffusion of CO 2 within the concrete. Consequently, lightweight aggregate concrete (LWAC) exhibited a slightly lower carbonation depth compared to normal-weight concrete with a similar mixture proportion to achieve the designed compressive strength. The proposed empirical equations also show promise for the assessment of carbonation depth and CO 2 diffusion coefficients for LWAC exposed to a controlled carbonation environment. • This study presents compelling experimental data on carbonation response of LWAC. • We formulated CO2 diffusion coefficients exposed at different times for LWAC. • We found that lightweight aggregate content slightly delays the diffusion of CO2. • We demonstrated that the carbonation depth was lower for LWAC than for NWC. [ABSTRACT FROM AUTHOR]

Meeting the requirements of the construction market and addressing the scarcity of virgin materials pose significant challenges in increasing the required concrete amounts for construction projects. This study explores the workability, density, and strength properties of sustainable concrete containing partial replacement of natural sand with iron ore waste (IOW) as a fine aggregate. In the first group, four concrete mixtures were prepared using different percentages of IOW (0 %, 15 %, 30 %, and 60 %) to replace natural sand. Basalt fiber was added into the second group of four concrete mixtures to enhance fiber-reinforced concrete (FRC) in the volume of 2 % of the cement weight. High volume of supplementary cementitious materials (SCMs) including fly ash (FA) and silica fume (SF) were used to replace cement in proportions of 35 % and 15 %, respectively to achieve sustainable concrete with low cement content. The results obtained show that an increase in replacement levels of IOW led to a decrease in the slump value of the concretes, from 120 mm to 80 mm, with a reduction rate of 33 %. The addition of 30 % IOW as fine aggregate led to an increase in the compressive strength of concretes by 47.34 %. Scanning electron microscopy (SEM) images revealed that the high porosity of IOW contributed to these changes in concrete properties. It is recommended to optimize concrete mixes based on the specific needs of civil engineering applications. This includes selecting different mix designs tailored for the desired structural performance, durability, and environmental conditions. Using IOW as fine aggregate in the concrete mix will help conserve resources for the next generations and enhance waste management, leading to greater sustainability in the construction industry. • The iron ore waste (IOW) and basalt fiber were used to enhance the concrete strength. • The workability, density, and strength properties of sustainable concrete have been studied. • The supplementary cementitious materials were used in 50 % to replace cement and obtain sustainable concrete. • The slump value of concretes reduced from 120 to 40 mm due to the use of IOW and basalt fiber. • The compressive, flexural, and tensile strengths increased due to use of IOW and basalt fiber. [ABSTRACT FROM AUTHOR]

The construction industry plays a pivotal role in the treatment and reuse of used tires, and the research on rubberized concrete holds immense potential. The present study employs micro- calcium carbonate (MCC) for the modification of the crumb rubber (CR) concrete substrate and its application in 3D concrete printing technology (3DCP). Firstly, the lightweight and thermal insulation properties of 3D printed rubber concrete are explored by testing the thermal conductivity and density of the mixtures materials. Then the performance enhancement mechanism of MCC on 3D printed rubber concrete is analyzed through mechanical property tests. Ultimately, the compatibility of the mixtures with the self-developed concrete 3D printer is verified by the fluidity test, buildability test and interlayer bond strength test and obtained the optimal ratio of MCC modified 3D printed rubber concrete. This study is helpful to increase the application of recyclable rubber materials in the construction industry and reduce the environmental pollution caused by rubber and provide a reference for the application of micron-material-modified rubber concrete in 3D construction printing. • Recycled rubber is adopted as a substitute for sand and applied in 3DCP. • An excellent thermal insulation lightweight concrete material is explored. • The mechanism of MCC improving the strength of CR concrete is explored. • The printability of MCC modified rubber concrete is verified. • This study is of significant importance for waste recycling and green buildings. [ABSTRACT FROM AUTHOR]

The concrete used in building nuclear facilities is of a special nature in terms of properties and compositions, which gives it support in sustainability and withstanding the harsh conditions that are generated during the operation periods inside the nuclear power plant. Consequently, the main purpose of this research is to investigate the suitability of some concrete components to produce "high performance heavyweight concrete-M60 grade", which can provide high durability against the impacting surrounding environment. The concrete mixtures containing the coarse aggregates of hematite (Ht), ilmenite (Il), air-cooled slag (ACS) and dolomite (Do) were designed. To fulfill the requirements of high performance concrete (HPC-grade M60), some pozzolanic materials such as granulated blast furnace slag (GGBFS), fly ash (FA-class F) and silica fume (SF) are added to Portland cement. Under normal conditions, the workability and compressive strength of all concretes were monitored after curing in tap water at 7, 28 and 90 days. In some mixtures, the sand was completely replaced with the fine aggregates of hematite, ilmenite and air-cooled slag to raise the density to 3 ton/m3, and then the compressive strength was determined after similar curing times. The effect of aggressive seawater on concrete designs was studied by measuring the compressive strength for all mixes up to 6 M. Phase composition and microstructure of concretes were investigated using XRD and SEM techniques. Corrosion of reinforcement is considered to be a predominant factor causing widespread premature deterioration of concrete construction worldwide, especially for the structures located in the coastal marine environment. In this regard, concrete mixes made with dolomite, hematite, ilmenite and air-cooled slag were designed and cured in different curing media, including saturated Ca(OH) 2 solution, tap water and seawater for 28 days. Then, the corrosion behavior of steel in concrete was studied by applying two types of electrochemical measurements, namely open-circuit potential and galvanostatic anodic polarization. The findings indicated that, the concrete mixture incorporating ACS supplemented with 10 % SF exhibited superior physico-mechanical properties before and after exposure to seawater solution compared to the other concretes. Additionally, it achieved more durability and confronting the harsh environment, while protecting steel rebar from corrosion upon exposure time. • Under normal conditions, the optimal mechanical properties was achieved with the inclusion of ACS aggregate. • Under marine conditions, ACS-concrete mixtures achieved values exceeding by 35, 48 and 52 % over M60 requirement. • Confronting the harsh environment, while protecting steel from corrosion was achieved with inclusion of ACS aggregate. • Hematite in Egypt cannot satisfy the requirements for heavy HPC (grade M60) needed for NPPs construction. [ABSTRACT FROM AUTHOR]

The existing models for the service life design of concrete structures exposed to chloride lack the possibilities to consider the effect of accelerated aging due to load-induced microcracks, since the respective formation of the cracks (widths, length, shape) cannot be summarised in generally valid factors. Thus we propose an approach related to the level of the applied load and not to the properties of appearing cracks to consider this effect. We therefore designed a set-up to determine the impact of external loading on the non-steady-state chloride migration coefficient D nssm of various concrete and mortar mixes. We were able to point out a correlation between the applied load level and increasing D nssm -values and a influence of the aggregate size on the intensity of this effect. A final comparative study directly quantifies the impact of load-related increasing migration coefficients on the service life of concrete and mortar components. • External load effects the chloride migration resistance of concrete and mortar in dependency on the size of the aggregates. • The developed test set-up enables a precise adjustment of certain load and stress levels on classic RCM-specimens. • By making a sample calculation, the impact of external load was directly referred to a a loss in service life. [ABSTRACT FROM AUTHOR]

Polycarboxylate superplasticizer (PCE) is one of the most widely-used chemical admixture in concrete, which is generally added during the mixing stage of concrete. However, part or major of the PCEs would be consumed during the initial rapid hydration resulting in the reduce of efficiency. Encapsulation of PCEs is an effective strategy to inhibit the undesired effects. However, due to retarding effect, low loading rate (high dosage required), and large capsule size (∼101-102 μm), most of the polymer and inorganic shell materials are not beneficial for the mechanical strength of concrete. Herein a type of silica matrix-microcapsule containing PCE were synthesized by the hydrolytic condensation of silane in an water/oil (W/O) emulsion. The loading rate could achieve ∼70 wt% based on the total weight of capsule. The size, specific surface area of the capsule could be well-regulated, which enabled the tunning of the release process within hours in simulated pore solution. Microcapsules containing PCE can significantly enhance the fluidity retention property of cement paste. The capsules also promote hydration due to silica, which could react with Ca(OH) 2 and yield calcium silicate hydrate gel. The strength of mortar showed that capsule improved the mechanical properties of mortar. [Display omitted] • Microcapsules containing PCE were prepared by the hydrolytic condensation. • The release process of microcapsules can be adjusted within hours. • Microcapsules enhance the fluidity retention property of cement paste. • Microcapsules improved the mechanical properties of mortar. [ABSTRACT FROM AUTHOR]

This study makes a significant contribution to the field of pervious concrete by using machine learning to innovatively predict both mechanical and hydraulic performance. Unlike existing methods that rely on labor-intensive trial-and-error experiments, our proposed approach leverages a multilayer perceptron network. To develop this approach, we compiled a comprehensive dataset comprising 271 sets and 3,252 experimental data points. Our methodology involved evaluating 22,246 network configurations, employing Monte Carlo cross-validation over 20 iterations, and using 4 training algorithms, resulting in a total of 1,779,680 training iterations. This results in an optimized model that integrates diverse mix design parameters, enabling accurate predictions of permeability and compressive strength even in the absence of experimental data, achieving R² values of 0.97 and 0.98, respectively. Sensitivity analyses validate the model's alignment with established principles of pervious concrete behavior. By demonstrating the efficacy of machine learning as a complementary tool for optimizing pervious concrete mix designs, this research not only addresses current methodological limitations but also lays the groundwork for more efficient and effective approaches in the field. • An ANN is provided to predict pervious concrete properties • Accurate prediction of permeability (k) and compressive strength (f C) were attained • Predictive accuracies of R2=0.98 for k and R2=0.97 for f C were achieved • Direct relationships between predicted results and PC behavior • The ANN models offered viable alternative to tedious lab tests for FRC assessment. [ABSTRACT FROM AUTHOR]

A stable cobalt-organic framework adsorbents with dense π-π stacking aryl rings rationally designed exhibits high-efficient SF 6 /N 2 mixture separation. [Display omitted] • A cobalt(II)-MOF with multiple π-π stacking aryl rings was designed. • YTU-30 shows extraordinary chemical and physical stability. • The SF 6 /N 2 breakthrough interval be up to 233.0 min/g. • The cyclic adsorption experiments show its practical application. Effective capture and separation of the greenhouse gas SF 6 from N 2 is extremely important to attenuate the greenhouse effect and bring economic benefits to the semiconductor industry. Herein, a highly stable "pillar-layer" MOF (YTU-30) with multiple π-π stacking aromatic rings as pillar in the pores was prepared by mixed ligand strategy. Static equilibrium isothermal adsorption results display that YTU-30 possesses a high SF 6 uptake capacity (68.6 cm3 cm−3), while nearly negligible N 2 adsorption (3.3 cm3 cm−3) at 298 K and 1 bar. The substance ratio of SF 6 -to-N 2 uptake reached 20.8. Dynamic breakthrough experiments also demonstrate that YTU-30 can achieve the effective separation of SF 6 /N 2 (10/90) mixture. Cycling experiments of static and dynamic were unchanged with a very simple process, which further confirmed the feasibility and directly capture SF 6 and separate the SF 6 /N 2 mixture for YTU-30. The dense aryl rings with π-π stacking in the pores not only increases the stability of MOF, but also contributes to its high SF 6 adsorption. These results provide a new strategy to achieve the construction of a stable MOF for the separation SF 6 /N 2 gas mixture. [ABSTRACT FROM AUTHOR]

Infrastructures treated with de-icing salts and those which are in direct contact with sea water are subjected to degradation by chloride ingress. Concrete composed of reactive sources of silica and used near such regions can suffer from both, alkali silica reaction (ASR) and chloride ingress subsequently. This research aims at empirically investigating the residual mechanical properties of plain and steel fiber reinforced concrete damaged by alkali silica reaction (ASR) and subsequent chloride ion ingress. Accelerated degradation tests on three concrete mixes such as plain concrete (PC,control), steel fiber reinforced concrete (SFRC) and high strength fiber reinforced concrete (HSFRC) were done. Specimens were initially damaged by ASR, and then submerged in chloride solution at temperature ranges of 5 oC, 25 oC and 40 oC. 1 mol/L NaOH solution and 3% NaCl solution were used for a period of 20 and 40 weeks. Steel fibers were found to be effective in reducing surface crack widths at 5 oC and 25 oC. Accelerated mortar bar test showed that steel fibers were able to reduce expansion by 31.5% and 65.3% using single and double hooked fibers. By examining the residual compressive and flexure strengths, it was found that exposure to chloride environment aided in hydration reaction which counter-balanced the damage due to ASR. Fiber-matrix bonding developed over time inducing friction which led to higher ductility and less damage in flexure strength in steel fiber reinforced concrete prisms. [ABSTRACT FROM AUTHOR]

• Iron slag recycled aggregate (ISRA) concrete mixes were prepared in the laboratory. • Destructive and Non-Destructive Testing was performed on ISRA concrete mixes. • Grey correlation grades and regression coefficients were calculated for validation. • Scanning electron microscopy (SEM) was performed in support of experimental outcomes. • Finest concrete mix was suggested on the basis of laboratory and statistical findings. The future construction industry will demand for sustainable concrete, either by recycling or direct incorporation of industrial by-products for effective solution of ecological concerns. The paper covers, outcomes of an investigation conducted to assess the 'performance of iron slag (0–30 %) recycled aggregate concrete (ISRA) with different levels of recycled (0–100 %) concrete aggregates (RCA)' using destructive (DT) '(compressive, split-tensile and flexure strength)' and non-destructive '(pulse velocity, electrical resistivity and rebound hammer)' testing (NDT). The strength characters were evaluated to develop statistical regression and grey co-relations. ISRA concrete resulted majorly in decrease of pulse velocities, electrical resistance (up to 28 %) and rebound numbers (by 10) at higher alteration levels. The correlation coefficients were evaluated using linear regression and grey analysis. The grey correlations resulted in visible variations, indicating disparity in magnitude of ISRA concrete. The higher regression (>0.75) and grey coefficients (GRG>0.8) postulates higher probability of accuracy, successfully validate the outcomes. [ABSTRACT FROM AUTHOR]

Addressing ecological concerns stemming from concrete usage is paramount, prompting exploration into additives for mitigation. Graphene quantum dots (GQDs) have been recognized for their potential to improve the mechanical attributes of cement composites. Additionally, the electrochemical reduction of a saturated solution of carbon dioxide (CO 2) and monoethanolamine (CO 2 -MEA) effectively removes CO 2 from the atmosphere. This study delves into the influence of GQDs on the mechanical and durability aspects of concrete. It is noted that the control mix of concrete without GQDs was specifically designed for concrete railway sleepers. Varied proportions of GQDs, ranging from 0.3 % to 1.2 % at 0.3 % increments, were incorporated to assess their impact on fresh and hardened concrete properties. Mechanical properties such as compressive strength, splitting tensile strength, flexural strength, and dynamic properties were evaluated. Durability assessments encompassing water absorption and chloride ion penetration were conducted. Microstructural analysis via Field Emission Scanning Electron Microscopy (FESEM) imaging and Energy-dispersive X-ray spectroscopy (EDS) elucidated the concrete's internal composition. Notably, an optimal GQDs percentage of 0.3 % was observed, signifying its efficacy in enhancing the performance of concrete. When 0.3 % of GQDs was added to concrete, compressive strength, split tensile strength, and flexural strength were enhanced by 10.8 %, 23 %, and 11 % respectively. The incorporation of GQDs resulted in a notable improvement in the fundamental frequencies and dynamic modulus of elasticity. Concurrently, a decrease in the damping ratio was observed for specimens containing GQDs. Additionally, the porosity and chloride penetration depth were lower by 6 % and 30 % for specimens with 0.3 % GQDs. The improvement in workability, mechanical, and dynamic properties of concrete, along with reducing CO2 from the atmosphere, makes GQDs an ideal eco-friendly material. This study is the first to open new pathways for the development of construction materials that are not only structurally superior but also environmentally responsible, marking a significant step forward in the field of civil engineering materials, especially in railway applications. • Adding just 0.3 % of GQDs significantly improves concrete's mechanical and dynamic properties. • GQD integration can reduce concrete porosity and chloride penetration depth by 6 % and 30 %, respectively. • FESEM and EDS analyses confirm GQDs' positive impact on concrete's microstructure. • GQDs enhance concrete performance and aid in atmospheric CO2 removal, boosting environmental sustainability. [ABSTRACT FROM AUTHOR]

Compression casting enhances mechanical properties, durability, and microstructure of concrete while reducing cement usage and carbon emissions. However, its brittleness restricts its widespread use. This study aims to mitigate the brittleness of compression cast concrete (CCC) through fiber reinforcement. Eleven concrete mixes with varied volumetric ratios (0, 0.05, 0.1, 0.15, 0.2, and 2 %) and aspect ratios (250, 313, and 396) of polypropylene fibers were prepared. Both compressed and uncompressed specimens were analyzed for compressive stress-strain behavior, compressive strength, modulus of elasticity, toughness, specific toughness, and microstructure. Results show that CCC specimens have steeper and shorter descending segments on their compressive stress-strain curves than uncompressed concrete, indicating brittleness. Adding polypropylene fibers significantly reduces this brittleness by enhancing the post-peak compressive stress-strain behavior of CCC. Fiber reinforced CCC specimens exhibit significant enhancements in compressive strength, modulus of elasticity, and toughness (up to 68 %, 34 %, and 38 % respectively) compared to uncompressed plain concrete. Mercury intrusion porosimetry, scanning electron microscopy, and backscattered electron imaging confirm that compression casting strengthens the interfacial transition zone of both plain and fiber reinforced CCC. Proposed empirical models accurately forecast the modulus of elasticity, compressive strength, and peak compression strain for both types of CCC. Comparisons with existing models show that Nematzadeh and GB50010–2010 models effectively predict the ascending part of the compressive stress-strain curves of plain and fiber reinforced CCC. These findings affirm that polypropylene fibers effectively reduce the brittleness of CCC, promoting its practical application. • This research focuses on mitigating the brittle behavior of Compression Cast Concrete (CCC) through fiber reinforcement. • Eleven concrete mixes with varying volumetric (0-2%) and aspect ratios (250-396) of polypropylene fibers are prepared. • Stress-strain behavior, compressive strength, elasticity, toughness, specific toughness, and microstructure is investigated. • Adding polypropylene fibers reduces brittleness and enhances post-peak stress-strain behavior of CCC. • Proposed empirical models accurately predict modulus of elasticity, compressive strength, and peak strain. [ABSTRACT FROM AUTHOR]

This study systematically investigated the influence of varying carbon dioxide (CO 2) dosages and steel slag (SS) replacement rates on the fresh and hardened properties of concrete through the injection of CO 2 gas during the mixing process. The composition of hydration products, degree of hydration, and the evolution of microstructural characteristics within the CO 2 -SS-cement system were analyzed. The results showed that CO 2 addition during the mixing process enhanced early strength in SS concrete. For concrete with a 10 wt% SS replacement rate, the incorporation of CO 2 ranging from 0.4 wt% to 1.2 wt% of the total mass of cementitious materials resulted in notable compressive strength increases of 1.26%–12.47%, 0.64%–6.14%, and 11.79%–18.24% at ages of 1 d, 3 d, and 7 d, respectively. CO 2 rapidly reacted with SS to form calcite-type CaCO 3 and promoted the generation of C-S-H through synergistic hydration with cement. However, a high CO 2 dosage (1.2 wt%) led to issues such as microcrack propagation and interface loosening due to CaCO 3 deposition, which could be mitigated to some extent by appropriately increasing the SS content. • CO 2 -mixing and steel slag synergistically improve early strength of concrete. • Increasing steel slag content alleviates adverse effects of high CO 2 dosage. • CO 2 -mixing enhanced the early cement hydration. [ABSTRACT FROM AUTHOR]

The manufacture of cement contributes significantly to carbon dioxide emissions; hence, the building and construction industry has focused on environmentally friendly cement substitutes. Supplementary cementitious materials (SCMs) such as calcite powder (CP) and Vitellaria paradoxa ash (VPA) offers sustainable substitutes. Thus, this study calcined shea nutshell at 700 °C for 3 h, obtaining VPA. Portland limestone cement was partially replaced by calcite powder and VPA at 5–15 wt% to produce 25 and 30 MPa concrete grades. Split tensile strength (STS), flexural strength (FS), and compressive strength (CS) of TBC samples were tested after 3–120 days of curing. Deep neural network (DNN) models, having 3 hidden layers with 5–30 nodes, were engaged to predict the strengths with respect to the concrete mix design proportions. For each strength, 108 datasets were obtained from the experimental data. Out of these values, 100 datasets were utilized to train the models, and the remaining 8 values were used to confirm the model's accuracy. The results revealed an improvement in concrete's CS, FS, and STS at 10 % VPA and 10 % CP replacements. The 7–25–25–25-1 network topologies demonstrated robust correlation for training, validating, and testing the input and output variables of CS and FS with correlation coefficients (R) of 99.92 and 99.01 % compared to other architectures. However, 7-20–20–20-1 network structure exhibited the best performance metric for predicting the STS of TBC with 99.51 % R. Strong relationships were found between the created model's validity and the raw experimental datasets, with R2 values for CS, FS, and STS yielding 98.45, 99.75, and 99.35 %. By using this technique, TBC incorporating SCMs would be of higher quality. • The sensitivity analysis of each concrete constituent on TBC are investigated. • Influence of nodes on the hidden layers of developed DNN architecture is investigated. • DNN is engaged to predict the CS, FS, and STS of TBC. • Developed DNN models accurately predicted CS, FS, and STS of TBC. • The correlation between developed DNN models and untrained datasets yield strong correlation. [ABSTRACT FROM AUTHOR]

The traditional mix ratio optimization research is affected by the operation conditions, and most of them only consider a single target, which cannot fully consider the correlation between different performance indicators. In this study, considering the multi-objective demand, to meet the basic mechanical properties of asphalt concrete requirements, to seek both economic and low carbon emissions of the theoretical asphalt concrete mix ratio. The response surface method (RSM) and non-dominated sorting genetic algorithm-II (NSGA-II) were combined to balance the economy and low carbon of hydraulic asphalt concrete. The Box-Behnken design (BBD) was used to arrange a series of experimental studies. The filler asphalt ratio X 1 , mortar aggregate ratio X 2 , and fine aggregate ratio X 3 were used as design variables, and porosity, stability, and flow value were used as response values. According to the technical indicators, the spatial constraints of the mix ratio were constructed. Through NSGA-II, the Pareto optimal solution under the goal of economy and low carbon is sought, and the linear weighted sum method is used to obtain the optimal mix ratio scheme with different biases. The research shows that:(1) The fusion of RSM-NSGA-II can effectively optimize the multi-objective optimization of the mixture ratio; (2) Regression fitting to establish the prediction model of performance with respect to mix ratio parameters is highly significant, and the established spatial constraints can greatly reduce the screening range of mix ratio parameters. (3) The optimized mix ratio of environmental protection bias is X 1 = 1.2, X 2 = 0.21, X 3 = 0.6, the optimized mix ratio of economic bias is X 1 = 1.2, X 2 = 0.22, X 3 = 0.59, and the optimized mix ratio of balanced type is X 1 = 1.2, X 2 = 0.218, X 3 = 0.6. This study has theoretical guiding significance for mix ratio design in engineering practice. • Skeleton dense hydraulic asphalt concrete aggregate gradation design. • Establishment of three-dimensional hydraulic asphalt concrete mix ratio space. • Multi-objective optimization of mixing ratios by RSM-NSGA-II. • Balancing economy and low carbon emissions in asphalt concrete mix ratios. [ABSTRACT FROM AUTHOR]

As industrial by-products, mineral admixtures can improve the crack resistance of concrete. However, the early crack resistance performance of concrete mixed with ternary minerals (steel slag powder, mineral powder and fly ash) was not fully understood. In this study, the mechanical and crack resistance performance of each group was preliminarily investigated using the slab method. Then G52 group and the control group were selected for a comparative analysis based on temperature stress testing machine (TSTM) and analytic hierarchy process (AHP) method. The results show that the ternary minerals admixtures reduced the early strength and enhanced the 28d strength of concrete. Meanwhile, they reduced the early adiabatic temperature rise, the maximum compressive stress and the influence of creep on the crack resistance performance of concrete, thereby enhancing the tensile stress at cracking of concrete. Overall, this study provided new insights into the mix proportions of ternary minerals concrete. [ABSTRACT FROM AUTHOR]

The demand for segment concrete increases rapidly with the expansion of urban rail transit and underground space, which may lead to carbon emissions (CE). In the production of segment concrete, using supplement cementitious materials (SCM) can be used to reduce CE instead of cement. However, SCM contents are usually determined by many orthogonal experiments, which are often time-consuming and only consider the limited experimental variables. Therefore, a novel hybrid intelligent algorithm combining Bayesian optimization (BO), natural gradient boosting (NGBoost) and non-dominated sorting genetic algorithm (NSGA)-III is proposed, which overcomes these disadvantages. Firstly, NGBoost model after hyperparameter optimization using BO is used to establish a nonlinear mapping relationship between segment concrete mix proportion and performance, which was used as the fitness function of the non-dominated sorting genetic algorithm (NSGA-III). Secondly, the optimal Pareto solutions were obtained through NSGA-III, and the reasonable range of segment concrete mixing proportion was obtained. Finally, a segment concrete production case was used to verify the effectiveness of the proposed algorithm. The results showed that the proposed hybrid algorithm combining proposed scheme decision strategy can obtain an optimal design scheme for concrete mix proportion. In addition, the comprehensive optimization rate of the obtained optimal scheme compared to the experimental optimal group was 11.5%. Moreover, the amount of phosphorous slag (PS) and granulated blast furnace slag (GBFS) in the optimal scheme was 26%, with a mass ratio of 1:2. Compared to the experimental optimal group, the optimal scheme can reduce the cost and CE per cubic meter by 31.64 yuan and 31.04 kg, respectively. Furthermore , the hybrid algorithm proposed can accurately obtains an optimal amount of SCM, which could be used as a supporting tool to reduce the production cost and CE of segment concrete. Overall, this research contributes to combining machine learning algorithms with actual production processes, which overcomes the data limitations of traditional experiments. It also provides a new intelligent approach and reference cases for the low-carbon design and sustainable development of building materials such as concrete. [ABSTRACT FROM AUTHOR]

The present research work investigates the effect of mix parameters such as fly ash-ground granulated blast furnace slag (GGBS) blends (85 %/15 %, and 70 %/30 %), NaOH solution molarity (10 M and 14 M), different salts (i.e., 3.5 % NaCl and 3.5 % NaCl plus 3.5% MgSO 4) on workability, compressive strength, chloride content, sulfate ion concentration, and microstructure of geopolymer concrete (Gc). Cube specimens were made for compressive strength test at the age of 7, and 28 days. Further, free chloride and total chloride contents of geopolymer concrete mixes were determined. The sulfate ion concentration and pH values of pore solutions made from different geopolymer concrete mixes were also determined. The effect of mix parameters on phase composition of geopolymer concrete mixes was evaluated by X-ray diffraction (XRD) analysis and the morphology of geopolymer concrete was studied by Field emission scanning electron microscope (FESEM) analysis. The results showed that the workability of geopolymer concrete decreased with increase in GGBS content and concentration of NaOH solution. With addition of salt, the slump value of geopolymer concrete increased. The compressive strength was increased with GGBS content and molarity of NaOH solution. The control geopolymer concrete mixes exhibited higher compressive strength than that added with salt. Free chloride and total chloride contents mostly reduced with increase in GGBS content in geopolymer concrete mixes. The increase in GGBS proportion and NaOH solution concentration reduced the concentration of sulfate ions in geopolymer concrete pore solutions contaminated with chloride-sulfate salt. From the XRD analysis, albite, nepheline, anorthoclase, and C-S-H gel peak intensities were mostly increased with age and GGBS replacement level. FESEM analysis showed formation of denser microstructure in geopolymer concrete made with 14 M NaOH solution than that made with 10 M NaOH solution. Overall, the geopolymer concrete made with higher GGBS content and higher concentration of NaOH solution exhibited improved performance through formation of denser microstructure leading to enhanced mechanical property and also reduced the concentration of aggressive ions i.e., chloride and sulfate ions in the pore solution of geopolymer concrete. • The addition of chloride and sulfate salt led to increase in workability and decrease in strength of geopolymer concrete. • The increase in GGBS content led to decrease in free chloride content. • Higher GGBS content and NaOH solution molarity reduced sulfate ion concentration in mixes added with chloride-sulfate salt. • The halite and gypsum were identified in geopolymer concrete admixed with both chloride and sulfate salts. [ABSTRACT FROM AUTHOR]

This study deals with a comparison of the environmental performance of one-way slabs utilizing steel fibre-reinforced limestone calcined clay cement (LC3) concrete with the control case of Ordinary Portland cement concrete. The experimental program constituted compressive and residual strength testing of concrete mixes and beams reinforced with traditional longitudinal steel reinforcement as opposed to steel fibres. The code-compliant design of the one-way slabs confirmed that, by adding steel fibres, 45% replacement of longitudinal steel reinforcement could be achieved. The cradle-to-gate life cycle analysis proved that the use of LC3 as a binder and integration of steel fibres lowers the environmental impact of one-way slabs by 10% despite the slight increase in the concrete cover of the steel fibre-reinforced concrete slabs for carbonation resistance purposes. Several scenario analyses were carried out to confirm that the savings could reach 40% depending on concrete mix design optimization and the potential use of recycled fibres. • LC3 concrete proven for use as a C40/50 structural concrete. • Concrete cover increase for carbonation resistance has negligible carbon footprint. • The addition of steel fibres could reduce the reinforcement rebars in one-way slabs by 45%. • LC3 as a binder and steel fibre-reinforcement could save 10% carbon of one-way slabs. • Adjusted concrete mixes and the use of recycled steel fibres could increase the savings to 40%. [ABSTRACT FROM AUTHOR]

This study aims at investigating the performance of Portland cement concrete incorporating construction and demolition waste aggregate in conjunction with rubber and steel fibers from post-consumer tires. Eight concrete mixes were prepared and tested. In these, natural coarse aggregate (NCA) was replaced by 100 % recycled concrete aggregate (RCA) and/or 20 % and 40 % rubber coarse aggregate (RuCA). The contribution of post-consumer tire steel fibers (PCTSF) to the behavior of the various recycled concrete mixes was also examined. The axial compressive stress–strain, flexural stress–deflection, and splitting tensile strength behaviors together with the dry density, porosity and rapid chloride penetration for all concrete mixes were investigated and compared. The results indicated that increasing the replacement levels of RuCA resulted in a decrease in concrete strength, although the decrease was less pronounced in the concrete mixes with RCA than in mixes incorporating NCA. Specifically, the reductions in compressive, tensile and flexural strengths were respectively as much as 6.6 %, 12.9 % and 14 % less in the mixes containing RCA. Also, the addition of PCTSF substantially mitigated the reductions in strength and, more significantly, the deflection at peak stress was increased by up to 664 %. Furthermore, incorporation of these fibers maintained up to 47 % of the flexural peak strength of the concrete mix at 4 mm deflection in the post-peak region. Additionally, the porosity of the concrete mixes ranged from 6 % to 12 %, placing them in the high-durability concrete category. The dry density exhibited an inverse relationship with the rubber aggregate content, resulting in a reduction of up to 10.2 % compared to the control mix. Hence, utilizing a substantial volume of post-consumer tire materials in recycled-aggregate concrete mixes is envisaged as an ideal choice in construction applications where lower concrete rigidity is desired, for example in seismic or vibrated zones. The approach also aligns with the increasing emphasis on sustainable construction materials. • Mechanical and durability properties of concrete mixes were investigated. • Elastic modulus values were compared with the values predicted by various codes. • PCTSF retained adequate concrete strength and enhanced its post-peak behavior. • High-durability concrete mixes with porosity 9–12 % were developed. • Lightweight concrete mixes with densities less than 2200 kg/m3 were produced. [ABSTRACT FROM AUTHOR]

The integration of rubber aggregate (RA) into concrete presents a pivotal avenue for enhancing the material's sustainability and environmental impact. Despite its potential, a crucial gap persists in the field concerning the development of material models that accurately consider the influence of RA particle size on the stress-strain responses of Rubberized Concrete (RuC). To address this gap, this study explores the effects of incorporating RA into concrete on its ascending compressive stress-strain behavior. In this research, we have compiled a comprehensive database encompassing the compressive stress-strain characteristics of 80 distinct concrete mixes incorporating RA from varied sources, sizes, and attributes. The investigation also evaluated the effectiveness of recent models in predicting key parameters, including modulus of elasticity, peak stress, and strain at peak stress. We proposed more robust models to accurately capture essential features. Notably, the findings suggest that higher RA content leads to dispersed cracks and decreased stiffness, resulting in lower peak stress and strain. Moreover, compressive strength exhibits notable variations with RA content, with significant drops observed across both normal and high-strength concrete mixes. The performance evaluation of existing models underscores the superiority of Li et al.'s model for peak stress prediction and Abbara et al.'s model for elasticity modulus prediction. The proposed simplified nonlinear models in this research offer enhancements over existing ones, promising more accurate predictions. These findings have profound implications for the optimization of rubberized concrete mixes and pave the way for future research directions aimed at further refining predictive models and advancing the application of RA in concrete technology. • A new rubber replacement factor that accounts size and volume is introduced. • Novel models for rubberized concrete's stress-strain behavior are proposed. • Comprehensive database of 80 concrete mixture with rubber aggregate is constructed. • Enhanced predictions of peak stress and modulus of elasticity were achieved. • Significant variations in compressive strength with rubber content were observed. [ABSTRACT FROM AUTHOR]

The impermeability of recycled aggregate concrete (RAC) presents challenges for underground engineering, particularly concerning its larger pore. Combining crystalline admixture (CA) with waste glass powder (WGP) offers a feasible solution to enhance impermeability. To understand the collaborative mechanism of CA and WGP in improving RAC impermeability and establish an accurate mixture ratio, we conducted compressive strength tests and a series of permeability tests on WGP and CA modified recycled aggregate concrete (WRC). These tests involved different CA contents (0%, 1%, and 2%) and varying WGP replacement rates (0%, 10%, 20%, and 30%). Our findings indicated that when the WGP substitution rate exceeds 10%, the strength of the WRC decreases by approximately 23%. In contrast, the overall decline is about 5% when the CA content increases from 0% to 2%. Therefore, the WGP emerges as the primary factor influencing the compressive strength of WRC. Meanwhile, The WGP and CA play a major role in enhancing the short-term and long-term impermeability of WRC, respectively. Additionally, When the WGP substitution rate increases from 0% to 30% on same CA content, the R C increases by approximately 2%, indicating that elevated WGP content enhances the effectiveness of CA. Finally, the optimal combination to improve the impermeability of WRC is 10% WGP substitution and 1% CA content. Microscopic tests analyses show that under the influence of CA and WGP, C–S–H gel, C-A-S-H gel, and Ettringite are produced inside the WRC, effectively blocking pores and cracks, thus improving the specimen's impermeability. This research not only holds the potential to elevate impermeability but also offers a solution to the issue of waste glass accumulation, contributing to global sustainable development. [ABSTRACT FROM AUTHOR]

Conventional concrete in its existing form possesses characteristics like better compressive strength, density, resistance against moisture and enhanced performance under various exposure conditions like elevated temperature and long-term durability etc. However, some of the shortcomings such as reduced ductility, brittleness can be improved by using additives like fibers to improve its properties. The present study highlights the performance evaluation of engineering properties and life cycle assessment (LCA) of hybrid fiber reinforced concrete (HFRC) incorporating with glass and polypropylene fibers in equal proportions (0%, 0.5%, 1.0%, 1.5%, and 2.0%). In addition to these, impact resistance at first crack phase and post cracking phase i.e., at failure have also been investigated to ascertain the effect of HFRC vs conventional concrete mixes. Sorptivity studies also performed to find its effect on HFRC, and control concrete mixes prepared with and without glass and polypropylene fibers. Reduction in workability of concrete was observed with increase in hybrid fiber content. Superior performance in terms of strength and durability properties was observed at 1% hybrid fiber content. Similarly, this study also focuses on studying the impact of HFRC and conventional concrete on environment using LCA approach. For LCA, SimaPro software and EcoInvent database is used to compare environmental impact assessment of HFRC and conventional concrete mixes. Impact on environment and cost comparison on HFRC mixes exhibits satisfactory results when compared to conventional mix. Finally, this research will address the need for HFRC mixes to achieve their adaptability in construction sector to make concrete economic and environmentally friendly. [ABSTRACT FROM AUTHOR]

Concrete's heat of hydration can cause wide restraint cracks, delayed ettringite formation and low strength. The heat of hydration in concrete poses significant challenges in the construction industry particularly in mass concrete elements. Addressing these challenges, the utilization of supplementary cementitious materials (SCMs) such as fly ash (FA) and ground granulated blast furnace slag (GBFS) in concrete has been extensively studied for their individual contributions in modifying the heat of hydration. However, the comparative effectiveness of FA and GBFS, as well as the implications of their combined use in a ternary blend mix, remain underexplored. This study aims to bridge this gap by investigating the heat evolution profiles of concrete blends incorporating varying proportions of FA, GBFS, and general Portland cement (GPC). Through a series of semi-adiabatic tests, the study evaluates the hydration kinetics, maximum temperature rise, and time delay to peak temperature for binary and ternary mixes. The findings suggest that while individual SCMs like FA and GBFS offer distinct thermal benefits, their combined use in a ternary blend presents a synergistic effect, optimizing heat management in concrete. In essence, this study not only underlines the potential of ternary blends in enhancing concrete's thermal performance but also emphasizes their role in promoting sustainable and resilient construction practices. • Demonstrates Fly Ash (FA) and Ground Granulated Blast Furnace Slag (GBFS) significantly lower the heat of hydration in concrete. • Compares and contrasts the effectiveness of FA and GBFS in mitigating hydration heat. • Details the efficiency of a ternary blend mix using both FA and GBFS for creating a concrete mix with the lowest heat of hydration. • Provides construction professionals with actionable insights for addressing challenges related to concrete heat of hydration. • Highlights the environmental and sustainable advantages of using FA and GBFS in concrete, contributing to eco-friendly construction practices. [ABSTRACT FROM AUTHOR]

The increasing use of natural resources and pollution caused by construction industries has spurred interest in eco-friendly materials such as recycled aggregates and recycled fibers. This research focuses on evaluating the effects of incorporating varying proportions of RCA and NWFs into HPC on its engineering characteristics and emissions. The environmental effects of the formulated blends on the HPC mixes were evaluated. The system boundary was determined based on cradle-to-gate theory, and Ecoinvent 3.10 was used as the background database for assessing the impacts of concrete mixes. Life cycle Impact assessment was carried out with the help of SimaPro software using CML baseline method. The findings reveal that introducing 0.25–0.5 % NWFs optimizes STS for all RCA percentages. NWFs also effectively mitigate the negative influence of RCA on CS. Incorporating 0.25 % NWFs enhances durability aspects related to permeability. Emissions related to CS are minimized in concrete mixes with 0.25 % NWF, particularly at 75 % RCA substitution levels. Portland cement dominates emissions in concrete, constituting 84.03 % without RCA and escalating to 91.35 % at complete substitution. It significantly influences the GWP, ETP and ADP. NCA exerts the highest environmental impact on FAETP 18.53 % without RCA and notably affects ODP and HTP, while RCA proves more sustainable, with a 66 % reduction in GWP compared to NCA, due to its recycled origin and lower energy demands in production. The optimal transport distance for 75RCA ranges from 25 km to 145 km with specific limits for different impact categories. [Display omitted] • Investigates eco-friendly construction materials, RCA and NWF to address resource use and pollution in construction. • Evaluates the impact of RCA and NWF proportions on HPC concrete engineering characteristics and emissions. • Optimal STS achieved with 0.25–0.5 % NWFs, mitigating negative effects of RCA on CS. • 0.25 % NWFs enhance durability aspects, particularly permeability, while minimizing emissions related to CS. • Life cycle assessment shows RCA's lower environmental impact than NCA, with transport limits for 75% RCA substitution. [ABSTRACT FROM AUTHOR]

• Size and age effects on fracture parameters of dam gallery concrete are studied simultaneously. • Size-independent double-K fracture parameters and scale parameters are extrapolated from test results. • Equations for predicting the concrete fracture failure of any age and size are established based on Boundary Effect Model. • Double-K fracture parameters of dam gallery concrete specimens of any age and size are solved by Fracture Extreme Theory. Cracking-associated problems may occur in the construction and operation periods of dam galleries, necessitating attention to the fracture characteristics of gallery concrete. The fracture parameters of concrete exhibit size effects and also change with age. A correct evaluation of the cracking risk or crack stability of gallery structures at any given time requires a comprehensive understanding of both the size effect and time-variant characteristics of the gallery concrete fracture parameters. In the present study, 75 wedge-splitting specimens, with effective heights ranging from 200 mm to 600 mm, were cast using gallery concrete produced by the concrete mixing system at the Baihetan Dam construction site. Subsequently, fracture tests were conducted on these specimens at curing ages spanning from 7 days to 90 days. According to the test results, the fracture parameters of concrete with a specific size exhibited an increasing trend with age within 90 days, while the fracture parameters of concrete at specific ages show a significant size effect, tending to stabilize as the effective depth of specimens gradually increases. The boundary effect model was utilized for analyzing the fracture test results of concrete specimens at different ages, yielding the size-independent double-K fracture parameters and scale parameters for concrete at each age, along with their time-varying patterns. Subsequently, equations for predicting the failure loads of concrete specimens of any age and size were established. Based on the prediction results of failure loads, the double-K fracture parameters of concrete specimens of any age and size were solved by the fracture extreme theory. The predicted failure loads and fracture parameters were in good agreement with the experimental results. The findings of this study can be applied to the full lifecycle crack risk analysis or crack stability assessment of Baihetan Dam gallery structures. [ABSTRACT FROM AUTHOR]

• Air-entrained concretes incorporating blends of aggregates were investigated. • Fracture energy and durability parameters of concretes were measured. • RSM presented reliable models predicting concrete performance from R C & R F. • Strong correlations were established between G f (I) & D f and G f (I I) & f C. • Concrete with the sustainable-optimum blend gave the higher G f (I) & G f (C). Cement concrete pavements are the ground structures constructed with quasi-brittle materials which fail under fracture modes caused by traffic loading and environmental conditions. Practically, incorporating local aggregate resources is inevitable for the sustainable use of materials in construction. In this research study, a total of 15 concrete mixes with similar gradations, slump and air-content were fabricated at different substitution ratios of coarse (R C) and fine (R F) durable and non-durable aggregates. Compressive fracture energy (G f(c)) compressive strength (f c), flexural strength (f f), and elastic modulus (E) of concrete specimens were measured. Edge-notched prism bend (ENPB) specimens were also used to determine the fracture energy under pure modes (G f(I) , G f(II) , G f(III)). Additionally, the durability factor (D f) and weight loss (WL) of prismatic specimens after freeze–thaw exposure were measured as the common tests for evaluating the pavement concrete. These experimental data were then adapted to give predictive models in terms of R C & R F using the response surface method (RSM). Strong correlations were found between durability parameters, G f(I) and G f(II). Using the prediction models, the optimum substitutions were estimated at the minimum required mechanical and durability specifications. Furthermore, the higher G f(I) and G f(c) were found to be required for attaining sustainable design to enhance the concrete ductility under expansive stresses induced by frost action. [ABSTRACT FROM AUTHOR]

The use of recycled concrete aggregates for new concrete production is an important avenue to increase the sustainability of concrete. While numerous studies have demonstrated the benefit of nanosilica on recycled aggregate concrete, a connection between the enhanced properties and the properties of the calcium-silicate-hydrates is unproven. Thus, we investigate how nanosilica modifies the distribution of calcium-silicate-hydrates in fine recycled concrete aggregate mortar. Using an interdisciplinary approach of nanomechanical testing, data science, and advanced chemical, microstructural and pore structure characterization, we find that 12 wt.% nanosilica results in a 30.8% increase in the combined relative amount of high-density and ultra-high-density C-S-H, 16.7% reduction in C-S-H gel porosity, 24.4% reduction in total porosity, and 3.9% increase in fracture toughness. [Display omitted] • Fine recycled aggregate concrete was mixed using 4%–12% of colloidal nanosilica. • The fraction of high-density calcium-silicate-hydrates increased significantly. • The C-S-H gel porosity of fine recycled aggregate concrete decreased by 2.9-16.7%. • The fracture toughness increased for a large amount of added colloidal nanosilica. • The porosity of fine recycled aggregate concrete decreased by 4.9-24.4%. [ABSTRACT FROM AUTHOR]

This study investigates the performance of structural lightweight geopolymer concrete (SLWGC) exposed to chemical attack. The objective of this study is validation the ability of using light weight geopolymer concrete for structural purpose under hard conditions. The alkali activator was produced using sodium silicate, sodium hydroxide and water. Flay ash and slage as waste materials were replaced by 90% of ordinary Portland cement to produce the geopolymer concrete. Also, ordinary cement concrete produced to comparison. Three types of lightweight aggregate were used instead of normal aggregate represented by pumice stone, expanded clay and construction waste clay brick to produce SLWGC. The unit weight of produced SLWGC were in the range (1800–2100) kg/m3. Normal weight geopolymer concrete and SLWGC were produced simultaneously to compare their performance each with other. The geopolymer concrete mixes treated by heat curing at 65 °C for 24 h after removing the molds. The specimens of all mixes exposed to sulfuric acid with concentration 5% and 10% for 8 weeks. The investigated mechanical properties represented by compressive strength and flexural tensile strength. The results indicate that the geopolymer concrete exhibit better resistance for acid attack compared to OPC concrete where the strength deterioration for SLWGC lower than ORC light weight concrete after exposed to acid, crushed clay bricks exhibit superior mechanical and durability performance compared to other LWA. Finally, the results proved the ability of producing light weight geopolymer concert for structural purposed with acceptable performance of strength and durability under hard chemical conditions. [ABSTRACT FROM AUTHOR]