为解决云母片岩强度低等难题,提出采用以水泥-石灰-粉煤灰-脱硫石膏为材料的新型粉体固化剂(Cement-Lime-Fly ash-Desulfurized gypsum,CLFD),协同尾矿渣(Tailings Slag,TS)物理改良作用加固路基土。通过开展室内力学试验,研究了不同固化剂掺量和不同养护龄期下固化土的力学与耐久性能,结合X射线衍射分析与扫描电镜试验揭示固化土的强度形成机理。结果表明:CLFD-TS固化土试样的力学性能、水稳性能、抗干湿循环性能都有了显著的改善,浸水9 d后固化剂掺入比不低于6%时,承载比与回弹模量均可满足规范要求;微观测试表明固化土中存在C-S-H、C-A-H凝胶及AFt、CaSO4晶体,这些产物通过胶结填充土颗粒,提高了土体的强度和密实度,增强土体性能;CLFD-TS固化土的早期强度主要来源于尾矿渣的物理骨架级配改良和水泥组分的水化作用,后期强度则由固化剂的火山灰作用提供。最后,建立了CLFD-TS协同固化土的微观作用机制模型,可为类似研究提供理论依据。
Abstract
To address the low strength issue of mica schist, we propose a new type of powder curing agent (CLFD) consisting of cement, lime, fly ash, and desulfurized gypsum to enhance subgrade soil in association with tailings slag (TS). Mechanical and durability properties of solidified soil with varying amount of curing agent and curing age were investigated through indoor mechanical tests. By adopting X-ray diffraction analysis and scanning electron microscope test, the mechanism of strength formation in solidified soil was revealed. Results suggest that soil samples solidified with CLFD-TS exhibit significant improvements in mechanical properties, water stability, and dry-wet cycle resistance. A mixing ratio of curing agent no less than 6% when immersed in water for 9 days meets specification requirements in terms of bearing ratio and modulus of resilience. Microscopic analysis shows the presence of C-S-H, C-A-H gel, AFt, and CaSO4 crystals in the solidified soil, which enhance soil properties by cementing and filling soil particles. Early strength of CLFD-TS-solidified soil comes from the physical skeleton gradation improvement provided by tailings slag and the hydration effect of cement components. Late strength is provided by the pozzolanic effect of the curing agent. Finally, a micro mechanism model of CLFD-TS-solidified soil is proposed to provide a theoretical basis for similar studies.
关键词
道路工程 /
云母片岩强风化土 /
CLFD固化剂 /
力学性能 /
固化机理
Key words
road engineering /
mica schist strongly weathered soil /
CLFD curing agent /
mechanical property /
curing mechanism
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基金
国家自然科学基金项目(51974146,52174078)
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