Search Results (5)

Geopolymer-based grouting materials often have a higher early strength, better durability, and lower environmental impact than those of traditional cement-based grouts. However, existing geopolymer grouts face common challenges such as rapid setting and low compatibility with treated substrates. This study develops a new grouting material using industrial byproducts to overcome these limitations while optimizing performance for reinforcing silty mudstone slopes. The base materials used were ground granulated blast furnace slag (GGBFS) and zeolite powder, with calcium lignosulphonate (CL) serving as the retarding agent and NaOH as the alkali activator. The investigation focused on the effects of the mix ratio and water–binder ratio on the setting time, flowability, bleeding rate, concretion rate, and compressive strength of the new grouting material. Scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses were employed to examine the action mechanism of the material components in the slurry. The one-factor standard deviation method and Grey Relational Analysis (GRA) were used to assess the influence of each material component on the slurry performance indices and the correlation between each performance index and its optimal mix ratio. Subsequently, the optimal mix ratio of the new grouting material was ascertained. The results indicate that the setting time is positively correlated with the zeolite powder and CL dosages and the water–binder ratio, while it is inversely related to the NaOH dosage. The flowability is significantly enhanced with increasing zeolite powder and NaOH dosages, but decreases at a higher CL dosage and water–binder ratio. This insight is crucial for optimizing the workability of the grouting material under various conditions. The optimal ratio of the grout is zeolite powder:GGBFS:CL:NaOH = 30:70:5:7, with a water–binder ratio of 0.6. Compared to existing commercial grouting materials, the compressive strength of this new grout is comparable to that of silty mudstone. This significantly reduces the problem of stress concentration at the grout–rock interface due to strength differences, thus effectively reducing the risk of secondary cracking at the interface. These findings provide a new material solution for grouting and repairing fractured silty mudstone slopes. Full article

In this study, Ag-CaCO₃ nanocomposites were synthesized using silver nitrate as the precursor solution based on calcium carbonate nanoparticles (CaCO₃ NPs). The synthesis involved the reaction of calcium lignosulphonate and sodium bicarbonate. The properties of Ag-CaCO₃ nanocomposites were studied by various technologies, including an ultraviolet–visible spectrophotometer, a transmission electron microscope, and a Raman spectrometer. The results showed that Ag-CaCO₃ nanocomposites exhibited a maximum UV absorption peak at 430 nm, the surface-enhanced Raman spectroscopy (SERS) activity of Ag-CaCO₃ nanocomposites was evaluated using mercaptobenzoic acid (MBA) as the marker molecule, resulting in an enhancement factor of 6.5 × 10⁴. Additionally, Ag-CaCO₃ nanocomposites were utilized for the detection of forchlorfenuron. The results demonstrated a linear relationship in the concentration range of 0.01 mg/mL to 2 mg/mL, described by the equation y = 290.02x + 1598.8. The correlation coefficient was calculated to be 0.9772, and the limit of detection (LOD) was determined to be 0.001 mg/mL. These findings highlight the relatively high SERS activity of Ag-CaCO₃ nanocomposites, making them suitable for analyzing pesticide residues and detecting toxic and harmful molecules, thereby contributing to environmental protection. Full article

Soil is a composite material of great interest to civil engineers. When the quality of such composite soils is poor, ground improvement techniques must be adopted to withstand the design load of superstructure. Existing soil stabilizers include lime and cement; however, their environmental safety and sustainable use during stabilization have been receiving increasing attention in recent years. This study investigated the use of granite sand (GS) and calcium lignosulphonate (CLS) as sustainable stabilizers that could be blended with clayey soils. The considered dosages of GS were 30%, 40% and 50%, and those of the CLS were 0.25%, 0.5%, 1% and 1.5%. Direct shear and consolidation tests were performed on the GS–CLS blended soil samples that were cured for 7 and 14 days. The amended stabilizers improved the shear parameters and consolidation characteristics at an optimum dosage of 30% GS and 0.5% CLS. Maximum improvements of 84% and 163% were observed in the cohesion and angles of internal friction, respectively. A significant change was also observed in the consolidation characteristics, making them practically applicable. The soil hydraulic conductivity was reduced by 14%, and the coefficient of consolidation increased by 203% for 30% GS and 05% CLS. Carbon footprint analyses were performed on the soil composition that would be best-suited for a typical homogenous earthen dam section. The results showed that the use of GS and CLS together reduced the carbon emissions by 6.57 and 7.7 times, compared to traditional stabilizers, such as cement and lime. Full article

This paper assesses the significance of stabilizing clay soil with calcium lignosulphonate (CLS) and granite sand (GS). Unconfined compressive strength ($q_c$) and hydraulic conductivity (K) are taken as performance indicators and the effect of varying dosages of GS (30%, 40%, and 50%) and CLS (0.5%, 1%, 1.5%, and 2%) at different curing periods on $q_c$ and K are examined. The best fit regression equations have been proposed to relate $q_c$ and K of untreated clay soil and stabilized clay using GS and CLS. The proposed nonlinear regression equations provide details of experimental data and aid in estimating $q_c$ and K very efficiently and reliably for targeted geotechnical applications from a sustainable perspective. Full article

This lysimeter study investigated the effect of late-autumn application of dicyandiamide (DCD), co-poly acrylic-maleic acid (PA-MA), calcium lignosulphonate (LS), a split-application of calcium lignosulphonate (2LS), and a combination of gibberellic acid (GA) and LS (GA + LS) to reduce N leaching losses during May 2020 to December 2020 in lysimeter field sites in Manawatu (Orthic Pumice soil) and Canterbury (Pallic Orthic Brown soil), New Zealand. In a second application, urine-only, GA only and GA + LS treatments were applied during July 2020 in mid-winter on both sites. Results showed that late-autumn application of DCD, 2LS and GA + LS reduced mineral N leaching by 8%, 16%, and 35% in the Manawatu site and by 34%, 11%, and 35% in the Canterbury site, respectively when compared to urine-only. There was no significant increase in cumulative herbage N uptake and yield between urine-treated lysimeters in both sites. Mid-winter application of GA and GA + LS reduced mineral N leaching by 23% and 20%, respectively in the Manawatu site relative to urine-only treated lysimeters, but no significant reduction was observed in the Canterbury site. Our results demonstrated the potential application of these treatments in different soils under different climate and management conditions. Full article