Current Issue : October-December Volume : 2025 Issue Number : 4 Articles : 5 Articles
Straw reinforcement improves the mechanical properties of soil matrices by uniformly incorporating dispersed straw materials, demonstrating advantages in strength enhancement, toughness improvement, and deformation control. This study aims to compare the reinforcement effects of different types of straw on soil and clarify the optimal method for straw-based soil stabilization. For wheat straw-reinforced soil using different processing methods (straw segment, straw powder, and straw ash) and mass contents, the basic geotechnical properties of each mixture were first determined. Triaxial tests were then performed under varying confining pressures and compaction conditions to assess the strength and modulus characteristics of the different reinforced soil specimens, and the microstructural characteristics of fiber-reinforced soil were investigated using scanning electron microscopy (SEM) analysis. The experimental results indicated that the strength and ductility of soils increased significantly with the addition of straw. The optimal performance of straw-reinforced soils occurred at 0.3% content. The elastic modulus increased by 85%, 64%, and 57% under confining pressures of 50 kPa, 100 kPa, and 200 kPa, respectively. At 200 kPa, straw segments provided the highest modulus increase of 57%, while straw ash achieved the greatest strength improvement of 97%. Furthermore, considering both compaction effects and cost efficiency, a compaction degree of 95% is recommended for straw-reinforced soil in engineering applications. Based on scanning electron microscopy, it was observed that the distribution characteristics of different straw types within the soil exhibit distinct patterns. This study aims to provide data to support the efficient utilization of straw materials in engineering applications....
Concerning building acoustics, the impact of sound propagation in the building structure can be considered one of the most relevant problems. Floating floors are an efficient solution, composed of a rigid walking surface above a resilient material. Functioning as a spring, the resilient layer must have adequate damping properties and compressive strength against permanent and imposed loads to guarantee its performance over time. In this context, this study aims to completely evaluate the impact sound reduction of composite lightweight floating floors formed by ceramic tiles and recycled rubber mats when subjected to prolonged loads, from material characterization to their application in a hypothetical scenario. This study was based on the dynamic stiffness (ISO 9052-1) and compressive creep (ISO 16534) of the resilient layer and the physical characterization of the ceramic tiles, predicting the present and future (15 years) impact sound reductions and their application in a hypothetical room, considering direct and indirect transmissions paths (ISO 12354-2). The results showed that the lightweight floating floor compositions lost their damping capability to a degree that can reduce their weighted reduction in the impact sound pressure level by up to 2 dB over prolonged periods (15 years). Howsoever, the compositions had considerable initial impact sound insulation capability and adequate performance maintenance over time....
Steel-fiber-reinforced geopolymer recycled-aggregate concrete (SFGRC) represents a promising low-carbon building material, yet data on its bond behavior remains scarce, limiting its structural application. To study the mechanical properties and bond strength of SFGRC, five groups of different mix proportions were designed. The main variation parameters were the content of recycled aggregate and the volume content of steel fiber. The cube compressive strength, splitting tensile strength, and flexural strength tests of SFGRC were completed. The influence law of different anchorage lengths on the bond strength between steel bars and SFGRC was studied through the central pull-out test. A multi-parameter probability prediction model of bond strength based on Bayesian method was established. The results show that with the increase of the content of recycled aggregate, the compressive strength of the specimen shows a downward trend, but the tension-compression ratio is increased by 18–22% compared to concrete with natural aggregates at equivalent strength grades. The content of steel fiber can significantly improve the mechanical properties of SFGRC. The bond strength between steel bars and SFGRC is 14.82–17.57 MPa, and the ultimate slip is 0.30–0.38 mm. A probability prediction model of ultimate bond strength is established based on 123 sets of bond test data. The mean and covariance of the ratio of the predicted value of the probability model to the test value are 1.14 and 2.61, respectively. The model has high prediction accuracy, and continuity and can reasonably calculate the bond strength between steel bars and SFGRC. The developed Bayesian model provides a highly accurate and reliable tool for predicting SFGRC bond strength, facilitating its safe and optimized design in sustainable construction projects....
Grouting is widely used in the treatment works of goaf, which can enhance the foundation bearing capacity, reduce deformation, and ensure the stability of the construction of goaf. As the goaf is located below the water table line, the mechanical properties and microscopic changes of the stone body in the water-rich environment have not been revealed, which leads to the effect of grouting treatment in water-rich goaf being difficult to achieve in terms of the expected goal. This paper used uniaxial compression, electron microscopy (SEM), and X-ray diffraction (XRD) to study the mechanical properties and microscopic changes of the nodular body under natural, pure water, and tap water curing and revealed the deterioration mechanism of the nodular body’s mechanical properties under water curing. The research results show that under identical material proportions and curing durations, compared to naturally cured specimens, the specimens cured in purified water and tap water exhibited a significant increase in the content of unreacted fly ash, a reduction in the amount of hydration products such as C-S-H gel and ettringite, and a looser microstructure, resulting in average decreases in uniaxial compressive strength of 35.7% and 49.9%, respectively. In addition, the presence of chloride ions and Friedel’s induced decalcification of the C-S-H gel under tap water curing conditions led to a significant deterioration in the physical strength of the grouted stones....
This study systematically investigates the influence of mix proportion on and the early-age properties and CO2 uptake of CO2-mixed cement paste, focusing on variations in the water-to-binder (w/b) ratio, slag content, and air-entraining agent (AEA) dosage. Mineralogical characteristics were analyzed using X-ray diffraction (XRD) and thermogravimetric analysis (TGA), while pore structures were assessed via nitrogen adsorption. CO2 uptake was quantified immediately after mixing. Results indicate that a low w/b ratio limits CO2 dissolution and transport, favors hydration over carbonation, and leads to a coarser pore structure. At moderate w/b ratios, excess free water facilitates concurrent carbonation and hydration; however, thinner water films ultimately hinder CaCO3 precipitation and C-S-H nucleation. Slag contents up to 30% slightly suppress early carbonation and hydration, while higher dosages significantly delay both reactions and increase capillary porosity. An increasing AEA dosage stabilizes CO2 bubbles, suppressing immediate CO2 dissolution and reducing the early formation of carbonation and hydration products; excessive AEAs promotes bubble coalescence and results in an interconnected pore network. An optimized mix design, moderate water content, slag below 30%, and limited AEA dosage enhance the synergy between carbonation and hydration, improving early pore refinement and reaction kinetics....
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