Silica fume and carbide slag can be used to modify waste mud soil (WMS), which can not only improve the mechanical properties of WMS, but also broaden resource utilization ways of silica fume and carbide slag. For that, in this paper, WMS was modified by adopting 8 % carbide slag and silica fume with different dosages (0, 3 %, 5 %, 7 %, 9 %, and 11 %). Then the small-strain dynamic properties of modified WMS were investigated by using resonance column test, and the microscopic mechanism of modified WMS was analyzed based on Scanning electron microscopy (SEM), Energy dispersive X-ray spectrometer (EDS), Transmission electron microscopy (TEM), X-ray diffraction test (XRD) and Mercury intrusion porosimetry (MIP). It can be found from the resonance column test that the dynamic shear modulus and the damping ratio show an increasing and decreasing trend with the increase of the confining pressure respectively, and both increase with increasing silica fume dosage in the range of 0 to 11 %. A kinetic model applicable to modified WMS was established by introducing the effects of confining pressure and silica fume into the Hardin-Drnevich model. Microscopic testing experiments indicate that there is a reaction between reactive SiO2 in silica fume and Ca(OH)2 in carbide slag, and calcium hydrated silicate (CSH) was generated, which improved the specimen density.

Freeze-thaw cycles coupled with sulfate attack represent one of the most challenging service environments for concrete. This study aims to enhance the durability of concrete materials in environments characterized by sulfate attack and severe freeze-thaw conditions. Specifically, it investigates the deterioration laws and evolution models of mortar materials containing silica fume under both freeze-thaw and coupled freeze-thaw/sulfate attack conditions. Mortar specimens with varying silica fume contents (0%, 6%, 8%, and 10%) were prepared and subjected to single freeze-thaw and coupled freeze-thaw-sulfate attack tests to examine the impact of different silica fume dosages on the durability of mortar materials under these harsh conditions. Additionally, a quantitative assessment model for damage evolution was established using the entropy weight method and Wiener process model. The research findings indicate that silica fume significantly enhances the sulfate resistance and freeze-thaw durability of mortar materials, with an optimal dosage of 10%. Within the scope of this study, higher silica fume content results in a greater number of sulfate attack-freeze-thaw cycles the mortar can endure before damage and failure, thereby extending its service life. Based on the Wiener stochastic process damage model and field data, it is predicted that the service life of mortar containing 10% silica fume increases most notably to 36.6 years, representing a relative improvement of 45.8 % compared to mortar without silica fume. These results provide valuable references and guidance for the design and construction of concrete structures in regions characterized by high-cold temperatures and salt- corrosive soils.

Low-plasticity soils, characterized by low plasticity and high sand content, present challenges in engineering projects due to their inadequate strength and stability. This study evaluates the comparative effects of coal waste and silica fume as stabilizers to improve the mechanical properties of silty soils. Key parameters such as liquid limit (LL), plastic limit (PL), plasticity index (PI), maximum dry density (MDD), unconfined compressive strength (UCS), and shear strength were assessed through laboratory experiments with varying stabilizer proportions (3-12%). Results showed that silica fume increased the LL of Tarnol soil by 36% and reduced its PI, while coal waste improved the LL of Chaklala soil by 48%, also reducing its PI. Both stabilizers decreased MDD and increased optimum moisture content (OMC). Notably, UCS increased by 77% in Tarnol soil with 12% silica fume and by 83% in Chaklala soil with 12% coal waste after 28 days of curing. Coal waste improved the cohesion of Chaklala soil by a factor of 1.29 and its internal friction angle by 1.04, while silica fume enhanced Tarnol soil cohesion by 1.35 and its internal friction angle by 1.032. These findings demonstrate the potential of coal waste and silica fume as cost-effective, sustainable stabilizers for improving the geotechnical performance of low-plasticity soils. The study contributes valuable insights into using industrial by-products for soil stabilization, offering practical applications for enhancing soil strength and stability in construction and infrastructure projects.

The corrosion of concrete and environmental pollution have become major challenges for the conventional concrete used in sea beds. Comprehensive research work has been carried out to enhance the strength and effectiveness of artificial reef (AR) concrete, because of its significant benefits for the sea coastlines to enhance algae growth, fish assembly, rehabilitation, and soil erosion. An experimental investigation of the compressive strength, water absorption, flexural, split tensile strength, and sorptivity of concrete specimens used for artificial reefs concrete immersed in seawater is presented here. Natural recycled materials used in this research work includes fly ash, seashells, rice-husked ash, silica fumes, granite powder, paper pulp, and coconut fiber. To investigate the corrosion behaviors of concrete based on the M20 standard, experiments were conducted using different proportions of raw materials. Concrete strength was observed on different days (7, 14, 28, 56, and 90) and the results showed that artificial reef concrete is stronger than conventional concrete. Moreover, the strength of concrete is increased by 3% due to the addition of 5% of silica fume and granite powder. It also shows that the attack of sulfate in the concrete decreases gradually by the addition of rice husk ash and silica fume. In addition to other recycled biodegradable materials like AR2, AR3, and AR4 have flexural strengths such as 1.90%, 4.08%, and 5.07% which is higher than the conventional concrete, respectively. These approaches were eco-friendly to the ocean, because of the application of silica fumes and flyash and it does not create any type of crack in the reef. It is cost-effective and environmentally favorable. The splitting tensile strength of the traditional mixer after 28 days is measured in 2.94 MPa, which was found to be 2.11%, 4.79%, 4.68%, 23.81%, and 28.78% and it is higher than the values observed in the other specimens.

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.

To minimize the adverse impacts of cement production, introduce a natural resources as replacive cementitious material, and provide sustainable concrete, the present work identified a sub-class of zeolite soil with high SiO2 and low CaO contents, namely clinoptilolite. It is a widely spreaded soil, mechanically active, potentially ready to contribute in concrete pozzolanic reactions in a novelty manner. The mechanical activation modified the morphology and the structure of clinoptilolite to amorphous phases (e.g., hydroxyls losing bonding strength). To approach the goals, several dosages of clinoptilolite (0-20%) with and without silica fume (0-10%) contributed to the design of 567 concrete mixes, at three water-to-binder (w/b) ratios of 0.38, 0.42, and 0.45, the mixes were cured for 7, 28 and 90 days. Using the Taguchi L9 orthogonal array, 9 sets of optimum mix designs were derived out of 27 experiments and were optimized for mechanical strength tests. The experimental data and predicted results were compared and validated with a total accuracy of 90.84% (acceptable error levels). By increasing the curing age at the lowest w/b ratio, compressive strength (up to 56 MPa), Tensile strength (up to 3.9 MPa), and flexural strength (up to 7.0 MPa) were enhanced by both replacive materials (up to 30 wt%). However, long-term development (28, 90 days) is characterized by clinoptilolite, indicating a high pozzolanic reactivity in a lower w/b ratio attributable to its specific surface area and reactive SiO2 content. The experimental program and the high accuracy of the model showed that replacing OPC with clinoptilolite and SF is highly recommended in terms of sustainable concrete production, minimizing cement manufacturing impacts, and lowering the water consumption.

In the context of rapid urbanization and industrialization, subterranean engineering frequently encounters geotechnical challenges, particularly when dealing with weak soil layers, such as loose silty sand. These layers are problematic due to their poor permeability and low mechanical strength. Although cement-based solidification methods are prevalent for improving soil properties, they may prove inadequate under certain extreme conditions. This study explores the solidification efficacy of graphene oxide (GO) alone, and in conjunction with silica fume (SF), on silty sand by integrating varying proportions of GO and SF into cement-based composite materials, with a focus on assessing their influence on the impermeability and mechanical properties of the solidified soil. The findings revealed that the incorporation of GO alone markedly decreased the permeability coefficient and enhanced the early bending and compressive strength of the solidified soil. Optimal impermeability and mechanical performance were attained at a GO concentration of 0.06%, attributed to GO's high specific surface area and superior adsorption capacity, which effectively filled internal soil voids and ameliorated the microstructure. When GO and SF were added together, the solidified soil's performance improved, especially at an SF content of 10%. Notably, even with reduced GO content, a significant decrease in permeability coefficient was observed, indicating a synergistic effect between the materials. The concurrent addition of GO and SF also had a positive impact on bending and compressive strength, notably enhancing the early and intermediate mechanical performance of the solidified matrix. After a curing period of 28 days, the growth trends of bending and compressive strength decelerated. Microscopic examination indicated that GO and SF addition optimized the pore structure of the solidified soil, diminishing macropores and augmenting micropores, thereby reducing the permeability coefficient and bolstering impermeability. X-ray diffraction (XRD) analysis demonstrated that although the addition of GO and SF did not alter the primary hydration products in the solidified soil, it facilitated the cement hydration reaction, leading to increased formation of hydrated calcium silicate gels and other hydration products, thereby enhancing the compactness and mechanical strength of the solid matrix.