Low-carbon concrete incorporating waste materials offers significant environmental benefits while maintaining structural performance. However, designing an optimal mix of these waste materials is challenging due to their potential impact on the concrete properties. To address this challenge, this paper presents a novel meta model that introduces a non-deterministic mix design framework and simultaneously optimizes four performance metrics: environmental (global warming potential), durability (rapid chloride permeability and bulk electrical resistivity), mechanical (compressive strength and splitting tensile strength), and workability (air content and slump). The model is trained using a hybrid dataset combining literature data with response surface methodology (RSM) generated samples. To this end, a Multilayer Perceptron (MLP) neural network is trained to capture the effects of waste materials, including shredded rubber (SR), glass powder (GP), and biomass fly ash (BFA), on concrete performance and is further combined with Monte Carlo simulation to identify optimal mix designs based on specific performance targets. The results demonstrate the AI model's accuracy in predicting concrete performance, as evidenced by statistical measures such as root mean square error (RMSE), mean absolute error (MAE), and the coefficient of determination (R2). This accuracy is further validated by comparing the AI predictions with laboratory concrete mix results. The results indicated that a 23.1% increase in compressive strength and an 83% decrease in chloride ion permeability were achieved by partially substituting 30% GP for cement. The incorporation of 15% BFA consistently reduced slump by 65% and increased air content by 49%. Moreover, the control mix had the highest GWP at 325 kg CO2-eq/m3. Using 30% GP, 15% BFA, and 15% SR reduced it to 135 kg CO2-eq/m3, a 41% decrease. Additionally, the back analysis provides optimized mix designs tailored to specific performance constraints. According to the specified target for designing low-carbon, chloride-resistant, and normal strength (45-55 MPa) concrete, a mixture of waste materials with SR = 3.2%, GP = 25.8%, and BFA = 7.4% is proposed by the developed meta model.

The mining industry generates vast quantities of gold mine tailings (GMTs), which present serious environmental management challenges while simultaneously offering untapped potential as alternative construction materials. This review provides a comprehensive and critical evaluation of GMT valorization pathways in the context of sustainable concrete production and supplementary cementitious materials (SCMs). Synthesizing data from over 50 peer-reviewed studies, the paper systematically analyzes the physical, chemical, mineralogical, and microstructural characteristics of GMTs in relation to their impact on various construction materials’ performance. Four principal utilization strategies are examined: as fine aggregate replacements in concrete, in SCMs, and reactive components in both geopolymer and ultra-high-performance concrete (UHPC). The review explores the effectiveness of mechanical, thermal, chemical, and combined activation methods in enhancing the reactivity of GMTs, particularly in systems where native pozzolanic activity is limited. Particular attention is given to the environmental behavior of GMTs, especially their leaching potential, with compiled findings confirming that heavy metal mobility can be effectively mitigated through incorporation into stable cementitious matrices. Notably, most GMTs exhibit high silica content and favorable alumino-silicate ratios, supporting their integration into alkali-activated and blended binder systems. A complementary bibliometric analysis reveals a critical research gap regarding GMT-specific studies, establishing the novelty and timeliness of this work. The findings demonstrate that, when properly processed, GMTs can contribute to enhanced performance, low-carbon construction materials, aligning with circular economy goals and sustainability targets. This review offers a unified framework for GMT valorization and provides clear research directions to enable industrial-scale implementation and regulatory acceptance.

This review utilizes bibliometric analysis to examine global research trends and the chronological development of studies on the incorporation of mine wastes and tailings in concrete. A total of 345 publications were extracted from the Web of Science (WOS) database, and their analysis revealed a clear upward trajectory in scientific output since 2000. Respectively, China, India, Canada, and the USA were identified as the countries contributing the most to this research area. Among the 1139 author keywords extracted from the collected papers, 103 keywords with a minimum of three occurrences were analyzed using the VOSviewer software. VOSviewer further supports identifying research gaps and emerging trends by visualizing relationships among authors, publications, and keywords, facilitating a deeper understanding of the dynamics within the field. The analysis of keyword occurrences shows convergence towards research that focuses on the development of sustainable and high-performance materials that equate environmental responsibility with industrial economy demands. The current review also uses Biblioshiny, a web-based tool that explores topic timelines. It reflects that, in recent years, research focuses have shifted toward more sustainability, advanced materials, and performance optimization in the use of mine tailings in concrete.

Utilizing mine wastes and tailings in concrete production has been considered an environmentally friendly approach to reducing both the negative impacts of mining and the demand for natural resources for construction activities. This review aims to provide an up-to-date overview of the feasibility of mine tailings utilization in cement and aggregates, focusing on the impacts on the mechanical performance, environmental properties, durability, and sustainability of concrete. The review analyzes results from several research studies with the aim of providing a clear overview of such innovative inclusions of mine waste. According to the tests, mine tailings enhance concrete's particular performance in the application with optimum replacement percentages. Life cycle assessments have also demonstrated relevant reductions in carbon footprint and ecotoxicity in concrete, pointing out mine waste inclusions as a promising contribution to an ecological development perspective. However, optimal usage encompasses a number of challenges with regard to variability in tailing compositions, potential leachability of toxic metals, and loss of workability. This comprehensive review identifies the two ways in which mine tailings have dual advantages in concrete production: improving material performance and meeting environmental challenges associated with mining waste. The review's novelty is also demonstrated by exploring the recent research studies on using artificial intelligence (AI) for concrete mix design optimization using mine tailings, which increasingly provides a revolutionary pathway to meet sustainability goals. In addition, this review provides a bibliometric analysis that highlights the current research gaps and the trending topics related to the utilization of mine tailings in concrete.

The production process of conventional concrete has a negative impact on the environment, and it is necessary to identify innovative methods to reduce this impact. Making concrete more environmentally friendly by substituting waste materials for cement and/or aggregates is one of the practical methods. This approach not only reduces the amount of waste sent to landfills but also mitigates environmental risks and the depletion of natural resources. Waste materials such as glass powder and/or biomass ash are considered promising waste materials that can partially replace cement in concrete. In addition, the shredded rubber can also be used as a substitute for aggregates in concrete, as this would reduce the amount of naturally fine and coarse aggregates consumed. Although the use of waste material in concrete has benefits, the design of such concrete is challenging in terms of satisfying mechanical and durability standards. This study aims to evaluate the mix designs of concrete incorporating shredded rubber, biomass ash, and glass powder to satisfy the environmental, durability, and mechanical aspects. The durability of the mixes will be evaluated using various tests such as rapid chloride migration test (RCMT). Furthermore, the Global Warming Potential (GWP) of concrete production and LCA are used to evaluate its environmental impact. In addition, the slump and compressive strength of mixes are tested in order to check the acceptable workability and compressive resistance of concretes. The response surface methodology (RSM) was used to model the results, optimize them, and determine the most significant parameters. The findings of this study will contribute to the development of more sustainable and environmentally friendly concrete, which is crucial for creating a healthy built environment while being mindful of resource usage and environmental impact.

Damping ratio and dynamic shear modulus are fundamental parameters for assessing the seismic response of geotechnical structures such as retaining walls, dams, tunnels, foundations, landfill covers, and embankments. Numerous seismic wave sources can substantially impact the stability and integrity of geotechnical structures, influencing design choices and the implementation of alternative solutions. In this study, the damping ratio of sand mixed with small quantities of laponite was determined by an experimental set-up using bender elements meticulously constructed for this study. Comparative tests were conducted with pure sand (i.e., control test) and sand mixed with bentonite to evaluate the effects of two types of nanoparticles. The results revealed that the damping ratio (xi) of pure sand was approximately 7.48 %, which is generally compatible with values reported in the literature, taking into account the variations of sand and errors associated with laboratory equipment and electronic devices. Over time, the damping ratio of pure sand gradually decreased, reaching equilibrium at 0.99 % after 3-4 days of continuous shaking. The highest observed damping ratios for sand-laponite mixtures were 59 %, 69.7 %, and 98.6 % for sand+1 % laponite, sand+2 % laponite, and sand+3 % laponite, respectively. After reaching the peak, the damping ratio gradually decreased to equilibrium at 11 %, 16%, and 19.4%, respectively. The higher damping values for sand-laponite specimens reflect a viscous damping contribution from the presence of laponite at sand grain contacts, with higher laponite content resulting in increased damping. In comparison, the peak damping ratios for sand-bentonite mixtures were 21.9 %, 42.7 %, and 67.9 % for sand+1 %, +2 %, and +3 % bentonite, respectively. The findings highlight the potential of laponite to enhance the damping capacity of sands, which could be valuable for seismic design applications requiring improved energy dissipation.

Incorporating waste materials in concrete can enhance sustainability and contribute to more environmentally friendly construction practices. However, using these materials in concrete presents challenges related to durability, mechanical, and environmental performance. This study explores the effects of incorporating glass powder (GP), biomass fly ash (BFA), and shredded rubber (SR) as partial replacements for cement and aggregates in concrete. The focus is on assessing their impact on durability, mechanical properties, and the environment. To determine the most effective combination of waste materials, Response Surface Methodology (RSM) is employed to design the experimental program and optimize the mixture proportions. The research evaluates air content, freeze-thaw resistance, compressive strength, Young’s modulus of elasticity, splitting tensile strength, modulus of rupture, surface electrical resistivity, life cycle assessment (LCA), rapid chloride penetration test, and global warming potential of concrete mixtures. Results show that replacing cement with 20 % GP improves durability and strength, raising electrical resistivity by 240 % and achieving durability factors of >90 %. However, SR above 7.5 % reduces freeze-thaw resistance and stiffness. In addition, optimal mixes with a maximum of 16 % GP or 15 % BFA reach a compressive strength of 30 MPa and limit GWP to 297 kg CO₂-eq/m³.

Because of the inherent rheological property of transparent gel, laponite has been proposed for soil densification to withstand seismic events. Since the swelling behaviors of laponite could affect the soil-nanoparticle structure, one of the most important research topics is the swelling capacity of nanoparticles, particularly laponite. Hence, the objective of this study is to investigate the swelling properties of fresh laponite and sand treated with different contents of laponite. The swelling characteristics of compacted laponite hydrogel were investigated using a one-dimensional consolidation test setup. Results showed that the swelling strain of compacted laponite increased with time and as the concentration of laponite increased in specimens. The initial swelling of fresh laponite took around 4 weeks to attain equilibrium, while in the reswelling tests, laponite reached equilibrium within 60 h. The reswelling strain of laponite was higher than the initial swelling of fresh laponite, with a distinct reswelling behavior compared to other clay minerals. This swelling strain of laponite was found to be consistent with other clay minerals in which the swelling strain is caused by interlayer and double-layer forces. Scanning Electron Microscope images revealed that the structures of swollen laponite are continuous sheet-like irregular structures with pore size. Moreover, the swelling strain of the sand-laponite mixture with 3

The objectives of this study are to investigate the strength properties and permeability of soil specimens treated with microplastic at different concentrations and samples treated with both microplastic and plant roots. A clayey soil was treated with polyethylene terephthalate (PE-T) at a concentration range between 0.25 and 4

This article aims to investigate and optimise the properties of lightweight self-consolidating mortar (LSCM) by using the response surface method (RSM). Silica fume (SF), nano silica (NS), water-cement ratio (W/C) and superplasticiser (SP) were chosen as variables. Also, part of the aggregates was replaced with lightweight expanded clay aggregate (LECA). Due to the advantages of RSM in accommodating multi-response optimisation of LSCM properties, the investigation and analysis were carried out for the stability, segregation and compressive strength. The optimised results recommended acceptable ranges of the required rheological and hardened criteria for LSCM. The mixtures achieved in these ranges include an LSCM with sufficient stability and low segregation. In particular, the results showed that the ultimate segregation must be < 8% for structural concrete. In addition, the results proved that increasing the fraction of NS and SF improves the properties of the LSCM by reducing the segregation and increasing the stability and compressive strength. It was found that adding 6% of NS at a high W/C ratio decreased the segregation by at least 15%. Adding 6% NS and %SF to LSCM within 0.5 W/C increased the compressive strength up to 15.1 MPa for the former and 3.8 MPa for the latter.

In this study, heterogeneous soils contaminated with copper were remediated using solar powered electrokinetic treatment.The heterogeneous soils were composed of clay and sand with ratio 2:1.In one soil, a sand layer was sandwiched between two layers of clay while in another sand pockets made 1/3 of the soil mass.The third heterogeneous soil was a claysand mixture.An additional test was carried out with homogeneous clay to provide data for contrast.The soil samples were artificially contaminated with 150 mg of copper per kg of dry soil at water content 41% and placed inside four identical electrokinetic cells.Each cell was connected to a solar cell panel with peak voltage gradient 205 V/m.Encouraging results were obtained.Eighty-seven percent of copper was removed from specimen near the anode in the test of the clay-sand mixture compared to 86% in the homogeneous clay.

This experimental study was carried out to investigate an innovative technique to increase the ultimate load capacities of H-pile foundation system embedded in a low plastic clay soil. Electrokinetics was utilized to treat the clay soil in the vicinity of the foundation system. The study comprised three testing categories: control, remediation, and full treatment. The control was used as a baseline load capacity of the H-pile for comparison purposes. The remediation test assessed the load capacity of the H-pile after the pile was loaded to failure and then treatment by electrokinetics. The full treatment estimated the load capacity of the H-pile after electrokinetic treatment. Two perforated steel electrodes were installed into PVC cells in the center between H-pile flanges. The H-pile and perforated electrodes were connected to a direct current power supply with the H-pile serving as the anode and electrodes as cathodes during the six-day treatment period. Intermittent current (two minutes on and two min off) was applied during the treatment. After the completion of the treatment, the H-pile was tested using tensile and compression loadings to determine the ultimate tensile and compressive load capacities. The results show that electrokinetics increases the compressive capacity of the H-pile to 227% for the remediation test and 259% on the full treatment test as compared with the capacity of the control test. For the tensile tests, the increases were equally valued at 279% for both the remediation and full treatment tests compared with the control test. The undrained shear increased in the vicinity of the H-pile after the electrokinetic treatment.

In this study, heterogeneous soils contaminated with copper were remediated using solar powered electrokinetic treatment.The heterogeneous soils were composed of clay and sand with ratio 2:1.In one soil, a sand layer was sandwiched between two layers of clay while in another sand pockets made 1/3 of the soil mass.The third heterogeneous soil was a clay-sand mixture.An additional test was carried out with homogeneous clay to provide data for contrast.The soil samples were artificially contaminated with 150 mg of copper per kg of dry soil at water content 41% and placed inside four identical electrokinetic cells.Each cell was connected to a solar cell panel with peak voltage gradient 205 V/m.Encouraging results were obtained.Eighty-seven percent of copper was removed from specimen near the anode in the test of the clay-sand mixture compared to 86% in the homogeneous clay test.

The current paper covers the literature, including the applications of nanoparticles (specifically carbon nanotubes, colloidal silica, and bentonite), on sand grain densification and future research potential. Nanoparticles can help to reinforce sand stability because pore-water pressure has such a strong influence on sand strength in geotechnical engineering. When compared with standard reinforcing fibers, carbon nanotube reinforcements can produce composites that are substantially stronger and harder. Colloidal silica and bentonite can significantly withstand sand liquefaction owing to their distinct rheological properties. Nanoparticles have advantages in geotechnical engineering applications in terms of nanomaterial manufacturing as well as soil property optimization. As a result, further research into identifying more appropriate nanomaterials for soil improvement, as well as understanding the process of improvement, is very promising.

Developing an effective phycoremediation system, especially by utilizing microalgae, could provide a valuable approach in wastewater treatment for simultaneous nutrient removal and biomass generation, which would help control environmental pollution. This research aims to study the impact of low-voltage direct current (DC) application on Chlorella vulgaris properties and the removal efficiency of nutrients (N and P) in a novel electrokinetic-assisted membrane photobioreactor (EK-MPBR) in treating synthetic municipal wastewater. Two membrane photobioreactors ran in parallel for 49 days with and without an applied electric field (current density: 0.261 A/m2). Mixed liquid suspended soils (MLSS) concentration, chemical oxygen demand (COD), floc morphology, total phosphorus (TP), and total nitrogen (TN) removals were measured during the experiments. The results showed that EK-MPBR achieved biomass production comparable to the control MPBR. In EK-MPBR, an over 97% reduction in phosphate concentration was achieved compared to 41% removal in the control MPBR. The control MPBR outperformed the nitrogen removal of EK-MPBR (68% compared to 43% removal). Induced DC electric field led to lower pH, lower zeta potential, and smaller particle sizes in the EK-MPBR as compared with MPBR. The results of this novel study investigating the incorporation of Chlorella vulgar is in an electrokinetic-assisted membrane photobioreactor indicate that this is a promising technology for wastewater treatment.

The objective of this paper is to investigate the dynamic stability of an elastic prismatic slender beam subject to axial parametric arbitrary loads by making use of a matrix method. Current research on the dynamic stability of structures are usually limited to harmonic loads, and the solution method is usually based on the Floquet’s theory. It is well known that loads on engineering structures are rarely harmonic, but arbitrary. These loads can be imposed on the structures by either human activities such as explosions and machine vibrations or natural phenomena such as earthquakes and hurricanes. This paper presents a method for the solution of second-order linear differential equations with periodic coefficients. In this approximation method, the elastic beam is considered as a continuous system with various simplifying assumptions under the sum of step functions, which is solved using a matrix method involving a set of chain of power of matrices. The governing dynamic equations of motion thus become a matrix or single differential equation being function of time only. The accuracy of the analysis is ensured by comparing the dynamic behaviour of an elastic beam obtained from this analysis with those obtained by other methods available in the previous studies of literature. Application examples are provided, and limitations of this approach are also discussed. The study provides an excellent theoretical knowledge to enhance the understanding of the dynamic stability of an elastic beam under axial arbitrary loads, which can be used to develop software and modify the relevant design codes.

In this study, mixing laponite with sand to reduce the development of pore water pressure in the fully saturated conditions has been studied to evaluate the strength properties of sand. The study investigated the effect of laponite concentration and resting time in a series of triaxial tests. The results show that even a little amount of laponite can significantly decrease the pore water pressure generation in the sand–laponite specimens due to the good rheological property of transparent gel. The results show that the decrease in the pore water pressure generated in specimens with increasing laponite contents [i.e., 0.5, 1, 1.5, and 2% (mass/mass)] was 17, 22.5, 25, and 27 kPa, respectively. It was also found that the modulus of elasticity of the sand–laponite specimens is almost double than that of the pure sand. In addition, changes in the friction angle and cohesion of the sand–laponite specimens with the four laponite concentrations were examined using direct shear box tests for three different temperatures. It was found that the effect of temperature was more prominent at the lower laponite contents as compared with the higher laponite contents. Microstructural imaging with scanning electron microscope was assessed in conjunction with the pore pressure generation mechanism. This study provides an elaborate explanation of the non-homogeneity of the sand–laponite mixture and novel insight into the improvement and modification of the sand strength properties in the presence of laponite under static loading.

Laponite nanoparticles have been proposed for soil densification to reduce the negative impacts of seismic hazards. However, the effects of laponite on the aquatic ecosystem are lacking. In this study, different concentrations (0.1, 0.2, 0.3, 0.4, and 0.5%) of laponite were used to investigate the growth and total chlorophyll content of microalgae: Chlorella sp. This study examined the potential toxic effects of laponite on the growth characteristics of freshwater green algae Chlorella sp. isolated from northern Ontario. The experiments were carried out in a 500-ml glass flask with 300 ml working volume and placed under white fluorescent lights for 16 h: 8 h day-night cultivation cycle in a constant orbital shaker. The results revealed that the lower concentration of laponite can enhance microalgae growth, while the higher laponite concentration had a growth inhibitory effect. The total chlorophyll content increased by 33% at 0.1% treatment group than that of the control group. Based on the SEM images, aggregation of microalgae was significantly noticeable at the lower concentration of laponite (0.1% treatment) whereas, in the higher laponite concentration (0.4 and 0.5% treatment), algal cells were embedded in laponite gel and also noticed some physical impairment.

An experimental study was carried out to investigate the effect of electrokinetic treatment on the axial load capacity of a deep foundation model, embedded in a soft clay. Three series of tests were carried out using five identical electrokinetic treatment cells under applied voltages of 0, 5, 10, 15 and 20 V. Intermittent and continuous electric currents were implemented in the first two series with the similar energy consumptions to investigate the effect of the type of current in the improvement. In third series of tests, current intermittence was used in four tests with different applied voltages of 5, 10, 15 and 20 while the energy consumption was kept the same in the tests. The electric current and energy consumption were periodically recorded during the tests. At the end of the electrokinetic treatment, the axial load capacity of the foundation model was determined. Vane shear tests along with liquid and plastic limits tests were also conducted on the soil after the treatment. The results showed that electrokinetics had significantly increased both the shear strength of the soil and axial load capacity of the foundation model and the increases were proportional to the energy consumption. In the third series, the increases in the load capacity were found to be similar in the four tests. The maximum axial load capacity after the treatment was 336 N compared to 19 N in the control test. It was found that using the intermittent current reduces the corrosion of electrode.

Bender elements have been used as a non-destructive soil investigation technique by many researchers and have proven to be effective in predicting the shear strength of various soils. In this paper, electrokinetic treatment tests were performed with embedded bender elements to monitor the increase in the shear strength of a soft sandy clay during the treatment. The bender element system, designed and assembled for this study, was integrated into the electrokinetic treatment process in order to quell a common uncertainty associated with this form of soil improvement technique, namely: when is the treatment completed? The cross-correlation and first-peak arrival times were used to measure the shear wave velocity of a clayey soil under the treatment of electrokinetics using bender elements. To determine shear wave velocity before and during treatment, a variety of shear wave tests were performed every hour of treatment using frequencies ranging from 100 Hz to 2500 Hz via the use of bender element. The results show that monitoring the soil improvement during the treatment by bender elements can shorten the treatment time by 43% and reduce the energy consumption, which is a major expenditure in an electrokinetic treatment process, by 33% while consistently improving the shear strength and the load capacity by approximately 200% and 300%, respectively.