钙矾石形成引起石灰改良土膨胀研究

石灰改良土中钙矾石晶体会引起土体膨胀。本文根据钙矾石的形成机理开展了室内膨胀模拟试验,确定了试验配比与环境条件,分析了钙矾石形成引起的膨胀变形随时间的变化规律。试验结果表明:在石灰改良土中钙矾石的形成引起的膨胀变形主要分为快速期、减速期以及稳定期3个阶段;钙矾石引起改良土体膨胀主要是由于石灰中的钙、土中可供反应的铝和硫酸盐发生了化学反应;黏土矿物可提供钙矾石形成所需的Al^3+;在本次试验条件下生成2%的钙矾石,土体的膨胀率约为5%。

Research on Expansion of Lime-improved Soil Induced by Ettringite

The expansion of lime-improved soil induced by ettringite crystal is studied in this paper.According to the formation mechanism of ettringite,the indoor expansion simulation test was carried out.The mix design and the test environment were deternined,and the development of expansion induced by ettringite with time was analyzed.The test results indicate three stages of the expansion of lime-improved soil induced by ettringite including fast stage,deceleration stage and stable stage.The expansion of lime-improved soil induced by ettringite is mainly due to the chemical reaction of calcium in lime,available aluminum and sulfate in the soil.Aluminum ions in clay minerals are available for the ettringite.Under the test condition,2% ettringite is formed and the soil expansion rate is about 5 %.