Calcium carbide residue (CCR), a calcium-rich industrial waste, shows promise in improving mechanical properties of weak soils when used alone or in combination with pozzolanic materials and alkaline activators. This study comprehensively investigated the mechanical performance and stabilisation mechanism of CCR, CCR-fly ash, and alkaline-activated CCR-fly ash on kaolin clay, aiming to clarify their differences in mechanisms, identify their limitations, and promote effective application. The contribution of CCR, fly ash, alkaline activator, and initial water content of soil on enhancing soil strength was quantitively assessed through signal-to-noise ratio and analysis of variance (ANOVA) based on the Taguchi method. The stabilisation mechanism of different CCR-based materials was investigated by assessing the morphological and mineralogical features of stabilised samples. Taguchi analysis revealed that the development of soil strength was primarily influenced by initial water content in the early curing stage, while the contribution of fly ash became larger over time. Variation in CCR content had a limited effect on soil strength across all curing periods, as indicated by low contribution values and low statistical significance in ANOVA. The microstructural analyses revealed a low degree of formation of C-S-H and CA-H gels in soil stabilised with CCR alone and CCR combined with fly ash, while alkaline activated CCR-fly ash stabilised soil exhibited the coexistence of C-A-S-H and N-A-S-H gels. Taguchi superposition model was effectively used to estimate compressive strength results and supported the determination of suitable CCR-based materials for specific strength requirements.

Graphene Oxide (GO) is widely used, but its hydrophilic properties make it difficult to remove once it enters water and soil environments. In this paper, the adsorption effect of calcium carbide residue (CCR) as adsorbent on GO was investigated through a series of adsorption tests. Adsorption thermodynamics, kinetics, isotherm models, and various characterization techniques were employed to explore the adsorption mechanism. Additionally, the study assessed CCR's ability to stabilize GO-contaminated soils through unconfined compressive strength tests. The results showed that (1) at T = 303 K, with a pH of 11 and an initial GO concentration of 80 mg/L, CCR demonstrated excellent adsorption performance. (2) The adsorption process followed the Langmuir isotherm and a quasi-second-order kinetic model, indicating chemical adsorption with spontaneous heat adsorption. (3) CCR not only acts as an effective adsorbent for removing GO from wastewater but also has the potential to strengthen GO-contaminated soils. In addition, due to its favorable environmental benefits, this study has a wide range of potential applications in industrial fields such as wastewater treatment, air purification, and energy storage and conversion. This study not only proposes an effective method for removing graphene oxide from aqueous environments, but also provides a new idea for waste resource utilization, which helps to achieve the dual goals of environmental protection and resource reuse.

To optimize the use of chlorine saline soils commonly found in many coastal areas, ground granulated blast furnace slag (GGBS) and calcium carbide residue (CCR) were used in this study to stabilize/solidify these soils. This study aims at evaluating the suitability of GGBS-CCR as industrial by-products in improving the mechanical behaviors of chlorine saline soil in comparison with the use of Portland cement (PC) as a traditional binder. The optimal proportion of the binder was determined by the unconfined compressive strength, conductivity, and leaching characteristics. Moreover, the water stability coefficients, collapse coefficients and microscopic characteristics of the solidified soil were evaluated. The results reveal that when the ratio of GGBS to CCR in the binder is 4:1, the 28-day unconfined compressive strength reaches 4.53 MPa, and the leaching of chloride ions is reduced by 94.1 %. The excellent water stability and reduced collapsibility further indicate that GGBS-CCR is a preferable binder for solidifying saline soil compared to PC. Furthermore, microscopic analysis revealed that chloride ions in the saline soil were involved in the hydration reaction to form Friedel's salt.

Constructing infrastructure on soft soils demands the implementation of ground improvement. This study proposed an eco-friendly method of stabilizing marine soil using a calcium carbide residue (CCR)-activated coal gangue (CG) geopolymer derived from industrial waste. Laboratory experiments were conducted to investigate the mechanical properties, durability performance, and stabilization mechanisms of stabilized marine soils under multiple wetting-dry cycles. The results highlighted the effectiveness of CG-CCR geopolymer by a content of 15% to achieve satisfactory strength gain over the engineering requirements. However, the largest decrease in strength (71.89%) was observed when the initial water content was beyond 1.5 times the liquid limit (LL). The optimum solution was proposed to have a geopolymer content of 15% or an initial water content of 1.25 & sdot;LL to exhibit the highest resistance to strength decay after 12 cycles. Compared with water intrusion, mass loss had a more significant effect on soil strength deterioration. The formation of noncrystalline or amorphous-phase reaction products effectively filled intergranular pores and reduced the void space between soil particles, improving the mechanical properties. The CG-CCR geopolymer was demonstrated to offer a promising solution for soil improvement in geotechnical engineering and waste reduction in industry as a soil stabilizer.

This investigation elucidates the development of an innovative, sustainable binder derived from calcium carbide residue and silica fume, aimed at enhancing soft clay stabilization with minimal environmental impact. Various mixtures were examined, focusing on the CaO to SiO2 molar ratio (Ca/Si), which varied from 1.85 to 0.65. Comprehensive analyses of the raw materials and pastes, including chemical composition, phase evolution, and microstructure, were conducted using techniques like Energy dispersive X-ray fluorescence, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy. Results indicate a significant impact of raw material fractions on the compressive strength and cementitious properties. The mixture with a Ca/Si of 1.55 demonstrated the highest long-term strength, attributed to increased C-S-H content. A mixture of 30 wt% calcium carbide residue and silica fume was found to improve the unconfined compressive strength of soft Bangkok clay by 84% compared to 10 wt% ordinary Portland cement, demonstrating its efficacy and potential for widespread application in green construction initiatives. This research not only promotes the recycling of industrial by-products, reducing environmental impact, but also represents a significant advancement in sustainable construction materials.

Collapsible soils are located in various parts of the world. These soils are characterized by their low values of dry unit weight and natural water content. Collapse and large induced settlements at the saturation state damage the structures built on them. Therefore, measuring the collapse potential of these soils is essential for safe engineering works. This study aims to investigate the collapse index and collapse potential of clayey soil stabilized with calcium carbide residue (CCR). For this purpose, seven different contents of CCR, five curing periods, three different water contents, and two relative compactions were used. The results of tests showed that the CCR contents, relative compaction, and water content during sample preparation were the most key factors in collapsibility measurements. It was observed that CCR contents greatly reduced collapse index and collapse potential of soil and changed the degree of collapse from moderately severe to slight and non-collapsible one. Furthermore, increasing the relative compaction reduces the pore space between the soil particles, leading the denser structure. The denser the soil, the lower the initial void ratios, hence, there is less collapse upon wetting. Finally, the stabilized samples prepared with 2% less than optimum water content have a higher degree of collapse than those with optimum water content and 2% more than optimum water content. The results of this study corroborate the effectiveness of CCR as a by-product material to improve collapsible soils.

Calcium carbide residue (CCR), a by-product of the acetylene industry, is generated at a rate of 136 million tonnes per year, posing significant environmental risks. This review examines the potential utilisation of CCR in soil stabilisation, focusing on its stabilisation mechanism, performance in improving mechanical properties, environmental safety, and sustainability. The aim is to identify future research directions for CCR-based stabilisation to promote its broader application, and to provide references for managing similar Ca-rich wastes. CCRbased materials demonstrate promising benefits in enhancing various soil properties, such as uniaxial strength, swelling properties, triaxial shear behaviour, compressibility, and dynamic responses, while also reducing the mobility of contaminants. Compared to conventional stabilisers, CCR-based materials exhibit comparable performance in soil improvement, environmental impact and safety, and economic feasibility. However, further research is required to delve deeper into stabilisation mechanisms, mechanical properties, and stability of contaminants for the soil treated with CCR-based materials under diverse conditions.