The socio-economic growth of a nation depends heavily on the availability of adequate infrastructure, which relies on essential materials like river sand (RS) and cement. However, the rising demand for RS, combined with its excessive extraction causing ecological damage, and its increasing cost, has raised significant concerns. At the same time, the production of cement contributes significantly to environmental damage, especially through CO2 emissions. In this scenario geopolymer technology has emerged as a sustainable alternative to cement, offering environmental benefits and reducing the carbon footprint of construction materials. This study investigates the impact of replacing RS with copper slag (CS) and laterite soil (LS) in geopolymer mortar (GM) on key properties such as setting time, flowability, compressive strength, and microstructure. The results showed that as LS content increased, setting time and flowability decreased considerably, while increasing CS content caused a reduction in these values. Unlike the other observed parameters, the compressive strength values showed no distinct upward or downward trend. Moreover, the microstructural analysis, including SEM, EDS, XRD, FTIR, TGA and BET, provided valuable insights to support the observed results across various mix designs. Overall, the findings highlight that optimised binary blends of CS, LS and RS not only improved the compressive strength but also enhanced the microstructural characteristics of geopolymer mortar, reinforcing their potential as sustainable and high-performance alternatives to conventional fine aggregates.

In this study, the potential use of industrial waste materials, namely, copper slag (CS), iron ore tailings (IOT), and red mud (RM), as stabilizing agents for black cotton (BC) soil in pavement construction applications was evaluated. Laboratory tests were conducted to assess the performance of the stabilized BC soil, including Atterberg limits, compaction characteristics, California bearing ratio (CBR), unconfined compressive strength (UCS), permeability, and fatigue tests. Additionally, microstructural analysis was performed to further investigate the changes in the soil properties. The results indicated that BC soil mixed with CS, IOT, and RM exhibited enhanced plasticity, strength (UCS and CBR), permeability, and fatigue properties compared to untreated BC soil, regardless of the mix percentage. Notably, BC soil with 30% CS demonstrated comparable results to BC soil stabilized with 5% cement, significantly improving its properties. This study addressed a gap in pavement engineering research by evaluating the fatigue behavior of stabilized subgrade soils. It was concluded that incorporating 30% CS into BC soil not only enhanced its performance but also provided a sustainable alternative to traditional stabilizers such as cement and lime.

In the current study, the durability of a clayey-sand stabilized with copper-slag (CS)-based geopolymer and alkaline activator solution (AAS) is investigated in freezing-thawing (F-T) cycles. For this purpose, tests including Atterberg limits, pH, standard Proctor compaction, unconfined compressive strength (UCS), accumulated loss of mass (ALM), swell and shrinkage, ultrasonic P-wave velocity, the toxicity characteristic leaching procedure (TCLP), and scanning electron microscopy (SEM) analysis were conducted. Various contents of CS (i.e., 0, 10%, and 15%) and 8 and 11 M NaOH were assessed in 0, 1, 3, 6, 9, and 12 cycles. The AAS contained 70% of Na2SiO3 and 30% of NaOH. Also, the weight ratio of CS to ASS was 1 (CS/ASS = 1). According to the TCLP test, the CS-based geopolymer stabilized samples have no environmental hazards. The results illustrated that the strength and stiffness of untreated soil increased with an increase in F-T cycles until cycle 3. For samples with 11 M NaOH concentration, loss of strength and stiffness were observed due to F-T cycles. Furthermore, the sample with 8 M NaOH showed hybrid behavior (i.e., an increase in strength and stiffness until cycle 3), similar to that of untreated soil, and then declined until cycle 9, similar to soil treated with 11 M NaOH. Based on the microstructural analysis, higher microcracks were observed in the 8 M sample compared with the 11 M sample due to soft-strain behavior. Furthermore, a higher microcrack formation resulted in a higher potential for swell mass and volume change.

Over the last 20 years, the development of electrically conductive composites for removing snow and ice from transportation infrastructure has received exceptional traction. However, these composites need to exhibit stable electrical conductivity and high mechanical properties to be sustainable and cost-effective. Towards this goal, the article investigates the roles of ground granulated blast furnace slag (BFS) and copper slag (CS) content, in addition to hooked-end steel fiber length, on the electrical properties of eco-friendly ultra-high performance hybrid fiber-reinforced self-compacting concrete (HFR-SCC) for the first time in the literature. For this purpose, sixteen eco-friendly electrically conductive ultra-high-performance HFR-SCC were designed based on the variable parameters of four different BFS/total binder ratios (20, 40, 60, and 80 %), a CS/total fine aggregate ratio of 50 %, and two different hooked-end fiber lengths (30 and 60 mm), while all mixes used 1.75 % by volume fraction of steel fibers. After determining the workability properties (slump-flow and T500 values) of all mixes, compressive strength and electrical resistivity/conductivity tests of 90-day specimens were conducted. Additionally, environmental and economic evaluations of all mixes in terms of sustainability were performed in order to clarify the effects of the variable parameters. Taking into account the experimental results obtained, it was observed that all electrically conductive ultra-high performance HFR-SCC mixes demonstrated satisfactory workability properties, while the compressive strength values reached to impressive values of 127 MPa. The optimum BFS/total binder ratio was identified to be 40 % for higher compressive strength and conductivity of ultra-high performance HFR-SCC specimens. On the other hand, the addition of CS to the mixes resulted in an increase of almost 9 % in compressive strength compared to one without CS, while at the same time, a significant increase of approximately 363 % was observed in the electrical conductivity values of the specimens. As for the influence of different lengths of hooked steel fibers, the use of 30 mm length hooked-end steel fibers in HFR-SCC mixes performed better in terms of compressive strength, whereas 60 mm fibers performed better regarding electrical conductivity. In conclusion, this experimental work has evidenced that it is possible to develop an ecofriendly and sustainable electrically conductive ultra-high performance cementitious composite (the optimal mix compressive strength and electrical resistivity values were 127 MPa and 2242 Omega.cm, respectively) by using waste from different industries such as iron and copper. Thus, it will provide important insights for the design and application of future electrically conductive concretes, which can be an important alternative in efficient active deicing and snow-melting applications.

This experimental research has been conducted to improve the mechanical properties of the problematic expansive soil using copper slag. The copper slag has been utilized to improve the Talab soil in Nainwa for the first time. The swelling properties show that the collected soil has a high degree of expansive nature and low specific gravity. Therefore, the copper slag has been added to the soil from 5% to 30% at a 5% variation by its oven-dry weight. The experimental results reveal that the free swell index of soil has decreased by 69.88% with the addition of 30% copper slag. It has also been observed that the liquid and plastic limits have been decreased. The plastic limit of soil decreases, because copper slag takes place in voids. Due to this phenomenon, the maximum dry density of soil has been increased by 14.75% with the addition of 25% copper slag. The California bearing ratio (CBR) value of soil has been increased to 1.13% (soaked condition) and 3.8% (unsoaked condition) by adding 25% copper slag. This research introduces an empirical relationship between unsoaked and soaked CBR with a determination coefficient (R2) of 0.8254. Moreover, it has been observed that the unconfined compressive strength of soil has increased by 51.68% with the addition of 25% copper slag. Furthermore, the value of R2 for the experimental results obtained in this research is higher than the published experimental results, presenting the experimental study's accuracy and reliability. In addition, the analysis of variance (ANOVA) test accepts the research hypothesis for the present investigation.

The production of ferrous as well as non-ferrous metals generates slag as a byproduct material. Ferrous slags are extensively used in the construction sector as supplementary cementitious material (SCM) and aggregates. In this regard, the investigation of potential applications in similar areas for slags derived from the production of non-ferrous metals can help to address issues associated with their disposal, dumping, environmental concerns, etc. The primary aim of this research is to assess the pozzolanic activity of copper slag (CS), a type of non-ferrous slag. This investigation is conducted to replace a portion of ordinary Portland cement (OPC) incorporating CS as an SCM for sustainable construction. To assess the reactivity of the CS, comparisons were drawn with a known pozzolanic material fly ash (FA), and an inert material quartz powder (QP). The processing of raw CS (granular material) was carried out using a laboratory scale ball mill to achieve varying fineness to evaluate the effect of specific surface area (SSA) on reactivity. Initially, the investigations were conducted on paste samples of OPC-CS and suspensions of CScalcium hydroxide (CH) and were later extended to mortar studies. Mechanical characteristics such as compressive strength and open porosity of mortar specimens were determined to correlate with the paste studies results. The findings suggest that CS does exhibit pozzolanic characteristics although its reactivity is comparatively lower than that of FA. An increase in the fineness of the CS resulted in enhanced pozzolanic activity. Analysis of the hydrated suspension samples showed the formation of Fe-siliceous hydrogarnet phase indicating Fe from CS was involved in the reaction with CH. Although OPC-CS mortar samples exhibited similar open porosity compared to OPC-QP mortar samples, the interfacial transition zone (ITZ) porosity in mortar samples of OPC-CS was observed to be reduced indicating the densification of the region due to the pozzolanic reaction of CS. The permissible replacement of OPC with CS as a substitute for FA can be adjusted according to the material's fineness and the desired compressive strength.