Weathered residual soil of granite (WRSG) is the predominant type of excavated soil in southern China. This study explores the high-quality utilisation potential of WRSG by mixing it with a small amount of cement and preloading it within steel tubes to create preloaded-cement-soil filled steel tubular (PCSFST) columns. The research investigates the relaxation behaviour and axial compression performance of PCSFST columns through experiments, focusing on the influence of preloading indicator, cement content ratio, and water-to-solid rat io on their axial compression behaviour. The experimental results showed that an increase in the preloading indicator significantly enhanced the axial bearing capacity of the PCSFST column. Specifically, when the preloading indicator increased from 30 % to 90 %, the axial bearing capacity increased by 22.7 %. Although the increase from 6 % to 12 % in the cement content ratio significantly improved the unconfined compressive strength (UCS) of the cement-soil core, the corresponding reduction in the confining effect only resulted in a 3.2 % increase in the axial bearing capacity, indicating a limited benefit. A moderate increase in the water-to-solid ratio significantly boosted the UCS of the cement-soil core, which in turn, enhanced the axial bearing capacity of the PCSFST column. After the preloading load was released, the cement-soil core exhibited longitudinal rebound deformation, which significantly reduced the confining effect provided by the steel tube. Nevertheless, the contribution of the confining effect to the axial bearing capacity can reach as high as 37 %, partially compensating for the relatively low UCS of the cement-soil core. Finally, based on the experimental results, a formula was proposed to predict the axial bearing capacity of PCSFST columns, which demonstrated high prediction accuracy.

Mars is increasingly considered for colonization by virtue of its Earth-like conditions and potential to harbor life. Responding to challenges of the Martian environment and the complexity of transporting resources from Earth, this study develops a novel geopolymer-based high-performance Martian concrete (HPMC) using Martian soil simulant. The optimal simulant addition, ranging from 30% to 70% of the total mass of the binders, was explored to optimize both the performance of HPMC and its cost-effectiveness. Additionally, the effects of temperature (-20 degrees C-40 degrees C) and atmospheric (ambient and carbonated) curing conditions, as well as steel fibre addition, were investigated on its long-term compressive and microstructural performance. Optimal results showed that HPMC with 50% regolith simulant achieved the best 7-day compressive strength (62.8 MPa) and the remarkable efficiency improvement, a result of ideal chemical ratios and effective geopolymerization reaction. Under various temperature conditions, sub-zero temperatures (-20 degrees C and 0 degrees C) diminished strength due to reduced aluminosilicate dissolution and gel formation. In contrast, specimens cured at 40 degrees C and 20 degrees C, respectively, showed superior early and long-term strengths, with the 40 degrees C potential for moisture loss related shrinkage cracking and reduced geopolymerization. Regarding the atmospheric environment, carbonation curing and steel fibre addition both improved the matrix compactness and compressive strength, with carbon-cured fibre-reinforced HPMC achieving 98.3 MPa after 60 days. However, long-term exposure to high levels of CO2 eventually reduced the fibres' toughening effect and caused visible damages on steel fibres.

The quest for viable construction materials for lunar bases has directed scientific inquiry towards the lunar in-situ resource utilization (ISRU), notably lunar regolith, to synthesize concrete. This study develops an innovative lunar high strength concrete (LHSC) utilizing lunar highlands simulant (LHS-1) and lunar mare simulant (LMS-1) as both precursors and aggregates within the concrete matrix. Mixtures were cured under the conditions simulating the lunar surface temperatures, enabling an evaluation of properties such as flowability, unit weight, compressive strength, modulus of elasticity, and microstructure patterns. Test results indicated that the LMS-1 mixtures exhibited a better flowability and higher unit weight as compared to LHS-1 counterparts. Moreover, the highest 28-day strength was 106.7 MPa and 98.7 MPa for LHS-1 and LMS-1 derived LHSC, respectively. Microstructure analysis revealed that under the identical simulant additions, LHS-1 mixes exhibited superior structural compactness with denser amorphous gels and fewer microcracks. In addition, it possessed a lower Si/ Al ratio and diffraction peak of calcite, along with a greater Ca/Si ratio and hump intensity of amorphous gel phases. The development of this cement-free LHSC, incorporating up to 80 % large-scale lunar materials in the total binder mass, plays a critical role in advancing ISRU on the Moon, thus boosting the viability and sustainability of future lunar construction and habitation while significantly reducing transportation and fabrication costs.