Search Results (29)

This study investigates the combined use of fly ash (FA) and plastic waste (PW) as partial replacements for cement and coarse aggregates in the production of paver blocks. Experimental mixes were developed with a substitution level of FA (10% to 30%) and PW (3% to 15%). The performance of the modified concrete block was evaluated in terms of compressive strength (CS), flexural strength (FS), ultrasonic pulse velocity (UPV), water absorption (WA), Cantabro abrasion resistance (CAR), and rapid chloride permeability test (RCPT). Experimental results revealed that the optimal mixture, containing 25% FA and 12% PW (M4), exhibited superior performance. Compared with the control mix, the 56-day compressive and flexural strengths increased by 14.1% and 15.3%, respectively. The UPV value increased to 5.1 km/s, indicating improved concrete quality and matrix densification. Durability performance was significantly enhanced, with water absorption reduced by 25.4%, Cantabro abrasion mass loss decreased by 23.7%, and chloride ion penetrability reduced by 50.0% at 56 days. Statistical analysis using two-way ANOVA confirmed that FA and PW contents significantly influenced paver block performance (p < 0.05). The economic assessment further demonstrated cost savings of up to 3.0% compared with conventional concrete paver blocks. The study demonstrates that FA and PW can be effectively valorized in paver block production, offering both economic and environmental benefits. This green approach supports sustainable construction practices and promotes efficient waste management. Full article

To promote the resource utilization of high-titanium blast furnace slag (HTBFS) and advance the development of lightweight prefabricated structures, this study developed a lightweight HTBFS concrete composite beam (HTC composite beam) by replacing natural gravel and sand in concrete with HTBFS coarse and fine aggregates, and incorporating fly ash ceramsite to reduce self-weight. Symmetrically two-point bending tests were conducted on five HTC composite beams with different reinforcement ratios and precast heights, one Integrally cast HTC beam, and one ordinary concrete composite beam. The failure modes, load-carrying capacities, and deformation characteristics were evaluated. The loading process was also simulated using Abaqus, and the numerical results were compared with experimental data for validation. The results indicate that HTC composite beams satisfy the plane-section assumption; increasing the reinforcement ratio improves the load-carrying capacity, and the precast height has positive effect of HTC composite beams’ load-carrying. Compared with the ordinary concrete composite beam, the HTC composite beam exhibited a 12.30% higher load-carrying capacity, smaller deflection, and better deformation capacity. Multiple energy-based indices demonstrated that HTC composite beams possess favorable post-cracking plastic deformation capacity and stiffness retention. The difference between the finite element simulations and experimental results was less than 5%, confirming both the reliability of the numerical model and the accuracy of the experimental data. An economic analysis revealed that this structural system has significant potential for carbon reduction and cost savings, with an overall saving of approximately 141,000–500,000 CNY. These findings provide theoretical and engineering support for the application of HTC composite beams in prefabricated construction and have positive implications for reducing project costs and promoting the industrialization and low-carbon development of prefabricated buildings. Full article

The increasing demand for sustainable construction materials has driven research into low-carbon geopolymers that mitigate both cement-related emissions and plastic and glass waste accumulation. This study explores the development of geopolymer concrete incorporating fly ash (FA), slag (S), and FA + S blends, with 10% recycled crushed glass (RCG) and recycled plastic waste (RPW) as partial coarse aggregate replacements. Compressive strength testing revealed that FA + S-based geopolymers (25FA + S) with 100% ordinary Portland cement (OPC) replacement achieved a 7-day strength of 24.6 MPa, representing a 98% improvement over control specimens. Slag-based geopolymers demonstrated water absorption properties comparable to OPC, indicating enhanced durability. Microstructural analyses using SEM, XRD, and EDS confirmed the formation of a dense aluminosilicate matrix, with slag promoting FA reactivity and reinforcing interfacial transition zone (ITZ). These effects contributed to superior mechanical performance and water resistance. Despite minor shrinkage-induced cracking, full OPC replacement with S or FA + S geopolymers outperformed control specimens, consistently exceeding the target strength of 15 MPa required for low-impact, single-story housing applications within seven days. These findings underscore the potential of geopolymer systems for rapid and sustainable construction, offering an effective solution for reducing carbon footprints and repurposing industrial waste. Full article

Alkali-activated building materials have attracted the interest of many researchers due to their low cost and eco-efficiency. Different binders with different chemical compositions can be used for their production, so the reaction mechanism can become complex and the results of studies can vary widely. In this work, several alkali-activated mortars based on marginal by-products as binders, such as high calcium fly ash and ladle furnace slag, are investigated. Their mechanical (flexural and compressive strength, ultrasonic pulse velocity, and modulus of elasticity) and physical (porosity, absorption, specific gravity, and pH) properties were determined. After evaluating the mechanical performance of the mortars, the optimum mixture containing fly ash, which reached 15 MPa under compression at 90 days, was selected for the production of precast compressed slabs. Steel or glass fibers were also incorporated to improve their ductility. To reduce the density of the slabs, 60% of the siliceous sand aggregate was also replaced with recycled polyethylene terephthalate (PET) plastic aggregate. The homogeneity, density, porosity, and capillary absorption of the slabs were measured, as well as their flexural strength and fracture energy. The results showed that alkali activation can be used to improve the mechanical properties of weak secondary binders such as ladle furnace slag and hydrated fly ash. The incorporation of recycled PET aggregates produced slabs that could be classified as lightweight, with similar porosity and capillary absorption values, and over 65% achieved strength compared to the normal weight slabs. Full article

Underground mining creates voids that require filling to prevent ground subsidence and mitigate post-mining issues. Traditionally, sand has been used as the primary backfilling material. However, the increasing demand from the construction sector and the slow natural replenishment of sand have necessitated the search for alternative materials. Researchers have explored fly ash (FA) as a potential substitute; however, its slow settling rate and the development of hydrostatic pressure limit its effectiveness. To address these issues, this study investigated the development of fly ash–plastic aggregate (FPA) as a suitable material for hydraulic backfilling by mixing FA with high-density polyethylene (HDPE) plastic in an 80:20 ratio. Initial investigations revealed that adding plastic as a binder significantly improves the physical, mechanical, and morphological properties of FA. The results further demonstrate that FPA satisfies and exceeds the standard requirements for hydraulic backfilling, as outlined in previous studies and case reports. These findings suggest that FPA is a promising alternative to both sand and FA for hydraulic backfilling applications. Full article

The rising population and demand for plastic materials lead to increasing plastic waste (PW) annually, much of which is sent to landfills without adequate recycling, posing serious environmental risks globally. PWs are grinded to smaller sizes and used as aggregates in concrete, where they improve environmental and materials sustainability. On the other hand, PW causes a significant reduction in the mechanical properties and durability of concrete. To mitigate the negative effects of PW, highly reactive pozzolanic materials are normally added as additives to the concrete. In this study, PW was used as a partial substitute for coarse aggregate, and graphene nanoplatelets (GNPs) were used as additives to high-volume fly-ash concrete (HVFAC). Utilizing PW as aggregates and GNPs as additives has been found to enhance the mechanical properties of HVFAC. Hence, this study employed two machine-learning (ML) models, namely Gaussian Process Regression (GPR) and Elman Neural Network (ELNN), to forecast the mechanical properties of HVFAC. The study input variables were PW, FA, GNP, W/C, CP, density, and slump, where the target variables are compressive strength (CS), modulus of elasticity (ME), splitting tensile strength (STS), and flexural strength (FS). A total of 240 datasets were employed in this study and divided into calibration (70%) and validation (30%) sets. During the prediction of the CS, it was found that GPR-M3 outperforms all other models with an R-value equal to 0.9930 and PCC value of 0.9929 in the calibration phase, and R-value = 0.9505 and PCC = 0.9339 in the verification phase. Additionally, during the modeling of FS, it was also noticed that GPR-M3 surpasses all other combinations with R = 0.9973 and PCC = 0.9973 in calibration and R = 0.9684 and PCC = 0.9428 in the verification phase. Moreover, in ME modeling, GPR-M3 is the best modeling combination and shows high accuracy with R = 0.9945 and PCC = 0.9945 in calibration and R = 0.9665 and PCC = 0.9584 in the verification phase. On the other hand, GPR-M3 outperforms all other models during the modeling of STS with R = 0.9856 and PCC = 0.9855 in calibration, and R = 0.9482 and PCC = 0.9353 in the verification phase. Further quantitative analysis shows that, in the prediction of CS, the GPR improves the prediction accuracy of ELNN by 0.49%, while during the prediction of the splitting tensile strength, it was also found that the GPR improved the accuracy of ELNN by 1.54%. In FS prediction, it was also improved by 7.66%, while in ME, it was improved by 4.9%. In conclusion, this AI-based model proves how accurate and effective it was to employ an ML-based model in forecasting the mechanical properties of HVFAC. Full article

This research provides a comparative analysis of the optimization of ultra-high-performance concrete (UHPC) using artificial neural network (ANN) and response surface methodology (RSM). By using ANN and RSM, the yield of UHPC was modeled and optimized as a function of 22 independent variables, including cement content, cement compressive strength, cement type, cement strength class, fly-ash, slag, silica-fume, nano-silica, limestone powder, sand, coarse aggregates, maximum aggregate size, quartz powder, water, super-plasticizers, polystyrene fiber, polystyrene fiber diameter, polystyrene fiber length, steel fiber content, steel fiber diameter, steel fiber length, and curing time. Two statistical parameters were examined based on their modeling, i.e., determination coefficient (R²) and mean square error (MSE). ANN and RSM were evaluated for their predictive and generalization capabilities using a different dataset from previously published research. Results show that RSM is computationally efficient and easy to interpret, whereas ANN is more accurate at predicting UHPC characteristics due to its nonlinear interactions. Results show that the ANN model (R = 0.95 and R² = 0.91) and RSM model (R = 0.94, and R² = 0.90) can predict UHPC compressive strength. The prediction error for optimal yield using an ANN and RSM was 3.5% and 7%, respectively. According to the ANN model’s sensitivity analysis, cement and water have a significant impact on compressive strength. Full article

In today’s digital age, innovative artificial intelligence (AI) methodologies, notably machine learning (ML) approaches, are increasingly favored for their superior accuracy in anticipating the characteristics of cementitious composites compared to typical regression models. The main focus of current research work is to improve knowledge regarding application of one of the new ML techniques, i.e., gene expression programming (GEP), to anticipate the ultra-high-performance concrete (UHPC) properties, such as flowability, flexural strength (FS), compressive strength (CS), and porosity. In addition, the process of training a model that predicts the intended outcome values when the associated inputs are provided generates the graphical user interface (GUI). Moreover, the reported ML models that have been created for the aforementioned UHPC characteristics are simple and have limited input parameters. Therefore, the purpose of this study is to predict the UHPC characteristics while taking into account a wide range of input factors (i.e., 21) and use a GUI to assess how these parameters affect the UHPC properties. This input parameters includes the diameter of steel and polystyrene fibers (µm and mm), the length of the fibers (mm), the maximum size of the aggregate particles (mm), the type of cement, its strength class, and its compressive strength (MPa) type, the contents of steel and polystyrene fibers (%), and the amount of water (kg/m³). In addition, it includes fly ash, silica fume, slag, nano-silica, quartz powder, limestone powder, sand, coarse aggregates, and super-plasticizers, with all measurements in kg/m³. The outcomes of the current research reveal that the GEP technique is successful in accurately predicting UHPC characteristics. The obtained R², i.e., determination coefficients, from the GEP model are 0.94, 0.95, 0.93, and 0.94 for UHPC flowability, CS, FS, and porosity, respectively. Thus, this research utilizes GEP and GUI to accurately forecast the characteristics of UHPC and to comprehend the influence of its input factors, simplifying the procedure and offering valuable instruments for the practical application of the model’s capabilities within the domain of civil engineering. Full article

The construction industry plays a significant role in global resource consumption and environmental degradation. To mitigate these negative impacts, researchers and engineers have been exploring sustainable building materials and practices. This research paper focuses on the development of Eco Bricks, a sustainable alternative to conventional clay bricks, using a combination of cement, sand, Fly ash Ground Granulated Blast Furnace Slag (GGBS), PET bottles, aggregates, shredded plastic waste, and water. This study aims to investigate the mechanical properties, environmental benefits, and feasibility of producing Eco Bricks for construction applications. Furthermore, this research explores the environmental advantages of using Eco Bricks. By diverting plastic waste from landfills and reducing the demand for traditional building materials like clay bricks or concrete blocks, Eco Bricks contribute to reduced carbon emissions and resource conservation. This paper also addresses potential challenges associated with Eco Bricks, including quality control, durability, and long-term performance in different climatic conditions. Full article

Geopolymers have been proposed as a green alternative to Portland cement with lowered carbon footprints. In this work, a geopolymeric mortar obtained using waste materials is studied. Fly ash, a waste generated by coal combustion, is used as one of the precursors, and waste glass as lightweight aggregates (LWAs) to improve the thermal performance of the mortar. The experimental study investigates the effect of varying the alkali activating solution (AAS) amount on the workability, compressive strength, and thermal conductivity of the mortar. Indeed, AAS represents the most expensive component in geopolymer production and is the highest contributor to the environmental footprint of these materials. This research starts by observing that LWA absorbs part of the activating solution during mixing, suggesting that only a portion of the solution effectively causes the geopolymerization reactions, the remaining part wetting the aggregates. Three mixes were investigated to clarify these aspects: a reference mix with a solution content calibrated to have a plastic consistency and two others with the activating solution reduced by the amount absorbed by aggregates. In these cases, the reduced workability was solved by adding the aggregates in a saturated surface dry state in one mix and free water in the other. The experimental results evidenced that free water addiction in place of a certain amount of the solution may be an efficient way to improve thermal performance without compromising the resistance of the mortar. The maximum compressive strength reached by the mortars was about 10 MPa at 48 days, a value in line with those of repair mortars. Another finding of the experimental research is that UPV was used to follow the curing stages of materials. Indeed, the instrument was sensitive to microstructural changes in the mortars with time. The field of reference of the research is the rehabilitation of existing buildings, as the geopolymeric mortars were designed for thermal and structural retrofitting. Full article

This study investigates the alterations in the ratios of components such as class C fly ash (FA), blast furnace slag (BFS), and waste stone powder (WSP) types of limestone powder (LP) used in the production of geopolymer concrete. These components are meticulously examined concerning the physical and mechanical attributes of geopolymer concrete. Using the mixture-design method, 10 different mixing ratios were determined using FA, BFS, and LP, and experimental research on the mechanical attributes and workability of geopolymer mortar is presented. A series of experimental tests, including tests for compressive strength, impact strength, setting time, flow table, flexural strength, and water absorption, were carried out on the geopolymer mortars that were made using FA, BFS, and LP, to investigate and enhance their overall performance. The experimental study aimed to ascertain the extent to which variations in the materials used in the formation of geopolymer mortar affected its mechanical and physical properties. To achieve this objective, certain parameters for geopolymer mortar formulation were fixed, according to the literature (molarity: 10; aggregate/binder ratio: 2.5; plasticizer ratio: 2%; sodium silicate (SS)/sodium hydroxide (SH): 1.5; additional water content: 14.5%; alkali activators/binder: 0.5). Subsequently, mortars were produced according to the 10 different mixing ratios determined by the mixture-design method, and the experiments were completed. The samples of the 10 different mixes were subjected to air curing at an ambient temperature (23 °C ± 2 °C) for 28 days. Following the curing period, the tests revealed that mix No. 9 exhibited the best compressive, flexural, and impact strengths, while mix No. 10 demonstrated superior workability of geopolymer mortar. It was shown that impact, compressive, and flexural strength values decreased as the ratios of FA and LP increased. In contrast, the increases in the ratios of FA and LP positively influenced the workability of geopolymer mortar. Full article

The infrastructure demands for mega cities, urbanization and environmental concerns are pushing for smart and sustainable solutions. Structural lightweight concrete is gaining popularity in the concrete industry because of its intrinsic properties of resisting the load and being lighter in weight. Therefore, in this study, a green structural lightweight concrete was targeted by fabricating a plastic-based aggregate incorporating different industrial by-products to reduce the carbon tracks along with an alternate lightweight structural material. Thus, the compatibility of the different industrially by-products (dune dust, fly ash, and quarry dust) with plastic to produce a sustainable structural lightweight aggregate was evaluated in this study. The major physical characteristics of manufactured aggregates along with fresh, hardened, and durability properties of concretes were studied. Results revealed that altering the filler type had altered the texture and size of the developed aggregate. The aggregates developed with dune dust showed the largest particle size, bulk specific gravity, and strength while the ones with fly ash had the smallest size and water absorption. The decrease in the strength was found to be 24.7, 43.6, and 29% for dune dust, fly ash, and quarry dust respectively, once the filler percentage was increased from 50 to 70%. Additionally, all the concretes incorporating developed aggregates have evidently demonstrated their likely usage in structural lightweight applications by complying with ASTM C330/C330M-14 for compressive, flexural, and splitting tensile strength values, in addition to the improved durability behavior. Full article

Despite the continuous improvement in the research and development of concrete precast composite slab technology, problems like easy cracks and excessive weight at the joints remain. In this study, high-titanium heavy slag was mixed with different kinds of ceramsite to prepare ceramsite lightweight high-titanium heavy slag concrete. The joint of the composite slab was optimized to develop a novel ceramsite lightweight high-titanium heavy slag concrete precast composite slab, hereinafter referred to as “CLHCPCS”. Two CLHCPCS and one ordinary concrete composite slab were prepared. This study analyzed the effects of new materials and improved joints on the flexural capacity and crack resistance of CLHCPCS. It concluded that the density of high-titanium heavy slag concrete with shale ceramsite decreased by 12.0%, and the density of high-titanium heavy slag concrete with fly ash ceramsite decreased by 10.6%. At a 30% dosage of fly ash ceramsite, the compressive strength and splitting tensile strength of concrete reached the maximum. At a 20% dosage of shale ceramsite, the mechanical properties were optimal. Finally, fly ash ceramsite was selected as part coarse aggregate of CLHCPCS. CLHCPCS 1 and 2 demonstrated superior ultimate bearing capacity and crack resistance than ordinary concrete composite slab DBS1, with its ultimate bending capacity test value higher than the average value of ordinary concrete composite slab. ANSYS established the joint model of CLHCPCS for a bending simulation test. The stress and strain distribution of the model and the ultimate bending capacity under the plastic line method were obtained, consistent with theory and experimental analysis results. Full article

This study was carried out to investigate the effect of the diamond-shaped Interlocking Chain Plastic Bead (ICPB) on fiber-reinforced fly ash-based geopolymer concrete. In this study, geopolymer concrete was produced using fly ash, NaOH, silicate, aggregate, and nylon66 fibers. Characterization of fly ash-based geopolymers (FGP) and fly ash-based geopolymer concrete (FRGPC) included chemical composition via XRF, functional group analysis via FTIR, compressive strength determination, flexural strength, density, slump test, and water absorption. The percentage of fiber volume added to FRGPC and FGP varied from 0% to 0.5%, and 1.5% to 2.0%. From the results obtained, it was found that ICBP fiber led to a negative result for FGP at 28 days but showed a better performance in FRGPC reinforced fiber at 28 and 90 days compared to plain geopolymer concrete. Meanwhile, NFRPGC showed that the optimum result was obtained with 0.5% of fiber addition due to the compressive strength performance at 28 days and 90 days, which were 67.7 MPa and 970.13 MPa, respectively. Similar results were observed for flexural strength, where 0.5% fiber addition resulted in the highest strength at 28 and 90 days (4.43 MPa and 4.99 MPa, respectively), and the strength performance began to decline after 0.5% fiber addition. According to the results of the slump test, an increase in fiber addition decreases the workability of geopolymer concrete. Density and water absorption, however, increase proportionally with the amount of fiber added. Therefore, diamond-shaped ICPB fiber in geopolymer concrete exhibits superior compressive and flexural strength. Full article

The modern energy-saving vector of development in building materials science is being implemented in a complex way through the development of new heat-insulating materials with the simultaneous exclusion of low-ecological cement from them. This article presents the results of the development of resource-saving technology for a heat-insulating composite material. The research is devoted to the development of scientific ideas about the technology and properties of effective cementless lightweight concretes. The aim of the work is to create a heat-insulating composite material based on porous granules and a matrix from mixtures of liquid glass and thermal energy waste. The novelty of the work lies in establishing the patterns of formation of a stable structure of a porous material during thermal curing of liquid glass with technogenic fillers. Studies of liquid glass mixtures with different contents of fly ash and aluminosilicate microspheres revealed the possibility of controlling the properties of molding masses in a wide range. To obtain a granular material, liquid glass mixtures of plastic consistency with a predominance of aluminosilicate microspheres are proposed. The matrix of composite materials is formed by a mobile mixture of liquid glass and a combined filler, in which fly ash predominates. The parameters of heat treatment of granular and composite materials are established to ensure the formation of a strong porous waterproof structure. The possibility of regulating the structure of composite materials due to different degrees of filling the liquid glass matrix with porous granules is shown. A heat-insulating concrete based on porous aggregate has been developed, characterized by the genetic commonality of the matrix and the granular component, density of 380–650 kg/m³, thermal conductivity of 0.095–0.100 W/(m °C) and strength of 3.5–9.0 MPa, resistance under conditions of variable values of humidity and temperature. A basic technological scheme for the joint production of granular and composite materials from liquid glass mixtures is proposed. Full article