Publications

Evaluation of the performance of high-strength geopolymer concrete prepared with recycled coarse aggregate containing eggshell powder and rice husk ash cured at different curing regimes

Incorporating geranium plant waste into ultra-high performance concrete prepared with crumb rubber as fine aggregate in the presence of polypropylene fibers

Abstract This research examines the efficiency of ultra-high-performance concrete (UHPC) when utilizing geranium plant (GP) ash, which is subjected to different curing temperatures ranging from 300 to 900°C for 3 h of burning time. The GP ash is used as a replacement for cement in varying amounts (10, 20, 30, 40, and 50 wt%). Crumb rubber powder is utilized as a substitute for fine aggregate. Polypropylene fibers have been used to improve concrete performance. The performance of UHPC is evaluated by assessing its mechanical qualities, such as flexural strength, splitting tensile strength, and compressive strength. The sorptivity test is also evaluated as a component of it. Scanning electron microscopy is used to analyze UHPC after exposure to temperatures as high as 900°C. The findings demonstrated a notable enhancement in the mechanical characteristics of all mixtures. The most favorable mixtures were achieved with proportions of 50, 40, 40, and 20% for mixtures including GP waste incinerated at temperatures ranging from 300 to 900°C. Furthermore, the optimal outcome is achieved when 40% substitution is performed at a temperature of 700°C, resulting in notable enhancements of 14% in compressive strength, 30% in flexural strength, and 17% splitting tensile strength, respectively. At a high temperature of 700°C, the decrease in strength increased to approximately 37–40% as a result of the initial removal of carbon dioxide from calcite at temperatures ranging from 600 to 900°C and reached 56% at 900°C. Great resistance to sorptivity, as well as a dense and compact microstructure with a high content of calcium and silicon, was obtained.

Identifying Causes of Traffic Crashes Associated with Driver Behavior Using Supervised Machine Learning Methods: Case of Highway 15 in Saudi Arabia

Identifying the causes of road traffic crashes (RTCs) and contributing factors is of utmost importance for developing sustainable road network plans and urban transport management. Driver-related factors are the leading causes of RTCs, and speed is claimed to be a major contributor to crash occurrences. The results reported in the literature are mixed regarding speed-crash occurrence causality on rural and urban roads. Even though recent studies shed some light on factors and the direction of effects, knowledge is still insufficient to allow for specific quantifications. Thus, this paper aimed to contribute to the analysis of speed-crash occurrence causality by identifying the road features and traffic flow parameters leading to RTCs associated with driver errors along an access-controlled major highway (761.6 km of Highway 15 between Taif and Medina) in Saudi Arabia. Binomial logistic regression (BNLOGREG) was employed to predict the probability of RTCs associated with driver errors (p < 0.001), and its results were compared with other supervised machine learning (ML) models, such as random forest (RF) and k-nearest neighbor (kNN) to search for more accurate predictions. The highest classification accuracy (CA) yielded by RF and BNLOGREG was 0.787, compared to kNN’s 0.750. Moreover, RF resulted in the largest area under the ROC (a receiver operating characteristic) curve (AUC for RF = 0.712, BLOGREG = 0.608, and kNN = 0.643). As a result, increases in the number of lanes (NL) and daily average speed of traffic flow (ASF) decreased the probability of driver error-related crashes. Conversely, an increase in annual average daily traffic (AADT) and the availability of straight and horizontal curve sections increased the probability of driver-related RTCs. The findings support previous studies in similar study contexts that looked at speed dispersion in crash occurrence and severity but disagreed with others that looked at absolute speed at individual vehicle or road segment levels. Thus, the paper contributes to insufficient knowledge of the factors in crash occurrences associated with driver errors on major roads within the context of this case study. Finally, crash prevention and mitigation strategies were recommended regarding the factors involved in RTCs and should be implemented when and where they are needed.

Sustainable ultra-high-performance basalt fiber-reinforced geopolymer concrete incorporating carbon nanotubes and treated recycled aggregates

Machine learning models for predicting the compressive strength of cement-based mortar materials: Hyper tuning and optimization

Eco-friendly waste plastic-based mortar incorporating industrial waste powders: Interpretable models for flexural strength

Abstract Glass powder, silica fume, and marble powder (MP) were investigated for their potential as sustainable additives to enhance mechanical properties, reduce environmental impact, and improve resource utilization in mortar formulations. This study utilized gene expression programming (GEP) and multi-expression programming (MEP) with experimental data to develop flexural strength models using these materials as eco-friendly mortar cement substitutes. The models were evaluated using R ² values, statistical tests, sensitivity analysis, partial dependence plots (PDPs), Taylor’s diagram generation, and test and predicted results. The statistical measures demonstrated that MEP was the more accurate model compared to GEP. The sensitivity study revealed that plastic and sand had the most significant influence on flexural strength prediction, emphasizing the importance of their proportions in the mixture. PDPs further showed that cement, silica fume, and MP positively impact flexural strength, while sand and plastic exhibit optimal levels for enhanced performance. The study also highlighted the particle interaction sensitivity of glass powder, underlining the importance of mix design optimization to achieve improved mechanical behavior. The findings support the use of equation-based modeling and sustainable industrial byproducts to optimize mortar formulations, contributing to greener construction practices and reduced dependence on conventional cement.

Integrating micro- and nanowaste glass with waste foundry sand in ultra-high-performance concrete to enhance material performance and sustainability

Abstract The utilization of waste glass with micro- and nanoparticles in ultra-high-performance concrete (UHPC) has garnered significant interest due to its potential to enhance sustainability and material performance. This study focuses on the implications of integrating microwaste glass (MG) and nanowaste glass in the presence of waste foundry sand and its impact on the properties of UHPC. The particular emphasis of the current work is on compressive strength, tensile strength, sorptivity, and microstructure. It is found that MG enhances compressive strength, decreased tensile strength, reduced sorptivity, and a more compact microstructure. The results indicate that replacing cement with 20% microglass achieves the optimal compressive strength by increasing up to 11.6% at 7 days, 9.5% at 28 days, and 10.18% at 56 days. Nanowaste glass, owing to its increased reactivity and larger surface area, accelerates calcium silicate hydrate formation and improves compressive strength. At the same time, the effective utilization of nanowaste glass improves long-term resilience with an optimum compressive strength at 1.5% replacement ratios of 17.5, 18.9, and 16% at 7, 28, and 56 days, respectively. Splitting tensile strength increased by 16% at 20% MG and 21% at 1.5% nanowaste glass, respectively. Utilizing MG and nanowaste glass in UHPC with waste foundry sand is a promising method for boosting material performance and minimizing environmental impact.

Modeling the effects of speed limit cameras (SLCs) on air quality and traffic flow on access-controlled highways

Predictive modeling assessment of advanced concrete materials incorporating plastic waste as sand replacement

Abstract This research aims to contribute to the advancement of sustainable construction materials using a new composite of coated plastic waste as sand replacement material. This research assessed the predictive capabilities of Random Forest (RF), Particle Swarm Optimization-Support Vector Regression (PSO-SVR), and a Genetic Algorithm Optimized Artificial Neural Network (GA-ANN) that enable accurate, data-efficient prediction of compressive strength in plastic-waste foamed concrete, reducing experimental overhead and guiding sustainable mix optimization to forecast the compressive strength of foam concrete containing plastic waste. The models were evaluated using R 2 metrics, where RF scored 0.9872 and 0.9005, and GA-ANN scored 0.9979 and 0.8853 for the training and testing sets, respectively. Sensitivity analyses of the RF and GA-ANN models were conducted to evaluate the compressive strength of the foam concrete and the impact of each associated input parameter. The findings confirmed that both models accurately predicted the compressive strength of the material. The R 2 values for both models were calculated: for RF 0.9872 and 0.9005, and for GA-ANN 0.9979 and 0.8853. Sensitivity analysis indicated that the highest Permutation Importance values for cement, foam, sand, water-to-cement ratio, and plastic waste were 0.39, 0.34, 0.17, 0.11, and 0.39, respectively. In the GA-ANN case, the greatest Permutation Importance Values of 0.41, 0.31, 0.13, 0.11, and 0.05 were assigned to cement, sand, water-to-cement ratio, foam, and plastic waste, respectively, in that order concerning compressive strength. The PSO-SVR model in green maintained a good balance (AUC = 0.97 in training and AUC = 0.93) in testing. The PSO-SVR model achieved an average performance between those of the other two models. The MAE value was approximately 1.5 in training and 2.8 in testing, whereas the RMSE value was in the range of 4.5–5.0. The results showed the practicality of AI-based frameworks in the focus optimization of mix design and multi-criteria prediction of performance metrics of sustainable foam concrete containing recycled plastic waste.

Acid Resistance of Alkali-Activated Natural Pozzolan and Limestone Powder Mortar

The development of sustainable, environmentally friendly alkali-activated binder has emerged as an alternative to ordinary Portland cement. The engineering and durability properties of alkali-activated binder using various precursor combinations have been investigated; however, no study has focused on the impact of high-volume natural pozzolan (NP) on the acid resistance of alkali-activated NP and limestone powder. Therefore, the current study assesses the impact of high-volume natural pozzolan (volcanic ash) on the durability properties of alkali-activated natural pozzolan (NP) and limestone powder (LSP) mortar by immersion in 6% H2SO4 for 365 days. The samples were prepared with different binder ratios using alkaline activators (10 M NaOH(aq) and Na2SO4) combined in a 1:1 ratio and cured at 75 °C. NP was combined with the LSP at three different combinations: NP:LSP = 40:60 (AAN40L60), 50:50 (AAN50L50), and 60:40 (AAN60L40), representing low-volume, balanced, and high-volume binder combinations. Water absorption, weight change, and compressive strength were examined. The microstructural changes were also investigated using FTIR, XRD, and SEM/EDS characterization tools. Visual examination showed insignificant deterioration in the sample with excess natural pozzolan (AAN60L40) after 1 year of acid exposure, and the maximum residual strengths were 20.8 MPa and 6.68 MPa in AAN60L40 and AAN40L60 with mass gain (1.37%) and loss (10.64%), respectively. The high sulfuric acid resistance of AAN60L40 mortar was attributed to the high Ca/Si = 10 within the C-A-S-H and N-A-S-H formed. The low residual strength recorded in AAN40L60 was a result of gypsum formation from an acid attack of calcium-dominated limestone powder. The controlling factor for the resistance of the binder to acid corrosion was the NP/LSP ratio, whose factor below 0.6 caused significant debilitating effects.

Graphene concrete: Recent advances in production methods, performance properties, environmental impact and economic viability

Concrete, foundational in modern construction, grapples with environmental concerns and performance limitations. Responding to this, this review unravels the potential of graphene-infused concrete. The techniques of integrating graphene into concrete, targeting the discovery of groundbreaking construction materials were systematically probe. Some studies highlight remarkable improvements: adding 0.03% graphene oxide (GO) bolstered concrete's flexural strength by over 40%, and a concentration of 0.05% GO optimized flexural strength by roughly 35%. Impressively, some studies showcased an elevation of up to 79.5% in flexural strength. Notably, incorporating just 0.01-0.1% graphene by weight can amplify compressive strength, flexural strength, and elastic modulus by over 100%. Parallelly, the environmental footprints of graphene's synthesis and its fusion into concrete, illuminating prospects for significant carbon emission curtailments and enhanced sustainability were scrutinized. On the economic front, while graphene concrete currently costs 5-10 times more than its conventional counterpart, its superior attributes suggest promising long-term cost benefits. Conclusively, this review findings spotlight graphene-augmented concrete as pivotal for a sustainable, economically sound, and high-caliber construction future.

Next-generation ultra high performance geopolymer concrete: Optimizing calcium aluminate cement clinker and nano rice husk ash for mechanical strength, durability and thermal resistance

The high demand for sustainable and durable construction materials has exposed the limitations of traditional Portland cement and standard geopolymer concrete, particularly in high-performance structural applications. Conventional geopolymer concrete formulations often fall short in meeting the stringent requirements for mechanical strength, thermal stability, and chemical resistance. To address these challenges, this research explores the use of calcium aluminate cement (CAC) clinker and nano rice husk ash (NRHA) in developing ultra-high-performance geopolymer concrete (UHPGC). Four groups of UHPGC mixtures were prepared by varying the CAC clinker content (0 %, 25 %, 50 %, and 75 %) as a partial sand replacement and NRHA (0 %, 1 %, 2 %, and 3 %) as a replacement for ground granulated blast furnace slag (GBFS). The physical, mechanical, and durability properties of the mixes were systematically evaluated. Results demonstrated that the incorporation of CAC clinker and NRHA significantly improved the compressive, splitting tensile, and flexural strengths. The optimal mix, designated as G3 (50 % clinker, 50 % sand, and 2 % NRHA), achieved a compressive strength of 157 MPa at 91 days, a splitting tensile strength of 11.2 MPa, and a flexural strength of 17.5 MPa at 28 days. Durability tests conducted under elevated temperatures and chemical exposures (including chloride, sulfate, and nitrate solutions) confirmed the enhanced performance of the optimized mix. G3 retained 48–53 % of its residual compressive strength at 800 °C and showed high resistance to sulfate and nitrate attack. G4 (75 % clinker, 3 % NRHA) exhibited superior resistance to chloride penetration. Microstructural analysis revealed the formation of dense C-A-S-H and N-A-S-H gels, which contributed to the improved performance. Overall, this study demonstrates the potential of CAC clinkers and NRHA to produce sustainable, high-performance geopolymer concretes suitable for demanding construction environments.

Compressive and Flexural Strengths of Bio-Recycled Concrete Incorporated with Kenaf Fibre

Kenaf fiber (KF) has been applied in concrete to compensate for the weak tensile strength. Similarly, recycled concrete aggregate (RCA) is applied to reduce problems associated with waste concrete materials. However, both KF and RCA reduce the compressive strength (fck) of concrete. This study involves addition of calcite-producing bacillus subtilis bacteria to recycled aggregate concrete (RAC) incorporated with KF. The bacteria is added to concrete with varying proportions of RCA and KF to produce bio-fibrous recycled concrete (BFRC). The proportions of RCA are 0%, 25% 50% and 75% replacement of coarse aggregate, while KF are 0.2%, 0.5% and 1% of concrete. W/C of 0.45, 0.5, and 0.6 are applied to evaluate the effects of different w/c ratios. The properties evaluated are the fck and the flexural strength (ft) of the concrete samples at 28 days. The results showed that 0.2% KF in bio-concrete (BC) increases the fck by 12%; however, increasing above 0.2% decreases fck. KF in BC increases ft by 60%. Furthermore, 0.5% KF content resulted in highest ft of BRC. Increasing RCA content in bio-recycled concrete and BFRC decreases fck by 30% and 33%, respectively, as well as ft by 13% and 18%, respectively.

Recycling Rigid Polyurethane and Aluminum Powder Waste in Sustainable Foamed Geopolymer Concrete

This study evaluates the performance of foamed geopolymer concrete (FGC) incorporating rigid polyurethane (PU) waste as a partial sand replacement and aluminum powder (AP, 1%) as a foaming agent. The mixtures were based on metakaolin, fly ash, and silica fume. Fresh and hardened properties were assessed, including workability, setting time, density, compressive strength, flexural strength, splitting tensile strength, elastic modulus, water absorption, porosity, gas permeability, and chloride ion penetration. Microstructural characteristics were examined using scanning electron microscopy (SEM). The results show that moderate PU incorporation significantly enhances mechanical performance. The optimal mixture (PU30) achieved a compressive strength of 47.25 MPa at 180 days, representing a 15.6% increase compared to the control. Flexural and splitting tensile strengths improved by 19.9% and 16.7%, respectively, while the elastic modulus increased by 33.8% to 0.95 GPa. These improvements are attributed to enhanced particle packing and more efficient stress transfer within the matrix. In contrast, higher PU contents (>30%) reduced mechanical performance due to increased total porosity and weakened interfacial bonding. Durability-related properties indicated that mixtures PU20–PU30 exhibited reduced permeability and optimized pore structure, characterized by lower pore connectivity. SEM observations confirmed a denser matrix with uniformly distributed pores at optimal PU levels. Additionally, the integration of Random Forest regression with GLCM-based texture analysis demonstrated strong capability in predicting mechanical properties from SEM images. Overall, the combined use of PU waste and AP enables the production of lightweight, structurally efficient, and sustainable FGC with improved mechanical and durability performance.

Static and Dynamic Resistance of Bio-concrete Incorporated with Kenaf Fiber

Innovative hybrid machine learning models for estimating the compressive strength of copper mine tailings concrete

Strength and Microstructural Characteristics of Flyash-Waste Glass Powders Ternary Blended Concrete

Ternary blended concrete comprising flyash powder (FA), waste glass powder (WG) and ordinary Portland cement (OPC) were prepared such that the WG to total binder varied from 0-20% (C80FA20-xGx: x = WG/(WG+FA+OPC)) at the interval of 0.05. The developed concrete was investigated for absorption, workability, 28-day compressive strength, product (binder) phases, bond characteristics, microstructural and elemental composition. The synergy of the proportion of WG and FA (5-15% and 10-10℅) together with OPC (80℅) reduced the workability, enhanced 28-day water absorption and produced moderately high compressive strength (47-48 MPa) that was about 15% lower than that recorded in pure OPC concrete (57.2 MPa). The binder with balanced proportion of FA and WG (C80FA10G10) was found to be more amorphous with better microstructural stability than pure FA blended concrete (C80FA20G0) due to pore-filling of the microcracks. Disappearance of hedenbergite phase (CaFeSi2O6) was noted in the developed ternary binder while more alumina in FA noticeably induced conversion of tobermorite (CSH to C-A-S-H in ternary binder. Besides, Si/Ca, Ca/Al and Si/Al ratios were higher in WG-FA balanced ternary binder (C80FA10WG10) than when FA preponderated WG. Finally, using WG in synergy with FA could regulate absorption, consistency, amorphorsity and microstructure characteristics of FA-WG ternary binder.

Microstructural Characteristics, Modeling of Mechanical Strength and Thermal Performance of Industrial Waste Glass Blended Concrete

The need to get rid of solid waste in the environment necessitates the incorporation of waste glass powder (WGP) in mortar and concrete. The blending of WGP (G) with ordinary Portland cement (OPC) is a valorization technique that is not only cost efficient but also environmentally friendly. The replacement level is denoted as CxG10−x, where x is 0–20 wt.% at an interval of 5 wt.% in mortar (w/b = 0.4) and 0, 10, 20 and 30 in concrete (w/b = 0.42). The study investigates the effects of glass on the setting, workability, thermal resistance, microstructure, mineral phases and bond characteristics of silicon and hydroxyl-based compounds and C-O vibrations. It also provides the model equations for strength characteristics in terms of OPC, G and ages in mortar and concrete on one hand and investigates the residual strength and density of glass blended concrete at elevated temperature (550 °C) on the other. It is found that glass enhances the workability, reduces the setting time and density and enhances the residual strength and density of concrete. The presence of glass leads to the formation of coesite and microstructural distortion and decreases the Ca/Si ratio. Besides, the bond characteristics of the binder are significantly affected, while the thermal residual strength capacity in glass blended concrete (C80G20) is 40.4% and 75.14% lower than that in OPC concrete (C100G0) because of the low thermal conduction of glass particles. The optimum glass content in mortar and concrete to produce 33 MPa (28 days) and 47 MPa (90 days) is found to be 10 wt.% and 20 wt.%, respectively.

Strength and Microstructural Characteristics of Fly Ash–Waste Glass Powder Ternary Blended Concrete

To reduce the proliferation of greenhouse gases in the construction industry, ternary blended concrete comprising fly ash (FA) powder, waste glass (WG) powder, and ordinary Portland cement (OPC) was developed such that the WG to total binder varied from 0 to 20% at intervals of 5% (C80FA20-xWGx:x = WG/(WG + FA + OPC)). The developed concrete was investigated for water absorption, workability, 28-day compressive strength, binder phases, bond characteristics, microstructure, and elemental composition of the concrete. The mixture proportions of C80FA15WG5 and C80FA10WG10 exhibited better consistency and water absorption than the OPC concrete (C100FA0WG0). Furthermore, the 28 d strength of C80FA15WG5 marginally outperformed those of C80FA10WG10 and C80FA20WG0. The sample with equal proportions of FA and WG (C80FA10G10) was more amorphous owing to the disappearance of the hedenbergite phase (CaFeSi2O6) and conversion of tobermorite (CSH) to C-A-S-H. C80FA10WG10 also exhibited better microstructural stability than FA + OPC concrete (C80FA20G0), owing to the pore-filling of the microcracks within the matrix. Finally, higher Si/Ca, Ca/Al, and Si/Al ratios were recorded in C80FA10WG10 than in the case of FA preponderating WG in ternary blending. Finally, structural concrete can be produced through the ternary blending of glass waste, fly ash, and OPC, thereby promoting the valorization of solid waste and a sustainable environment.