钙矾石形成引起石灰改良土膨胀研究
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摘要
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Al3+;在本次试验条件下生成2%的钙矾石,土体的膨胀率约为5%。
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%.
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%.
引文
[1]王露,刘数华.钙矾石相的研究综述[J].混凝土,2013(8):83-90.
[2]韩宇栋,张君,高原.混凝土抗硫酸盐侵蚀研究评述[J].混凝土,2011(1):52-61.
[3]陈四利,宁宝宽.岩土材料的环境效应[M].北京:冶金工业出版社,2010.
[4]宁宝宽.环境侵蚀下水泥土的损伤破裂试验及其本构模型[D].沈阳:东北大学,2005.
[5]SIGDEL P,LIANG B H.Modelling Ettringite Induced Heaving in Cement Stabilized Soils Within a Chemo-mechanical Constitutive Framework[J]. Geotechnical Special Publiation,2015(4):125-132.
[6]CHRYSOCHOOU M,DENNIS G G,NIOHOLAS E M. Assessment of Sulfate-induced Swell in Stabilized Dredged Material:Is Ettringite Always a Problem?[J].Journal of Geotechnical and Geoenvironmental Engineering,2012,38(3):407-414.
[7]KNOPP J,MOORMANN C.Ettringite Swelling in the Treatment of Sulfate-containing Soils Used as Subgrade for Road Constructions[J].Procedia Engineering,2016,143:128-137.
[2]韩宇栋,张君,高原.混凝土抗硫酸盐侵蚀研究评述[J].混凝土,2011(1):52-61.
[3]陈四利,宁宝宽.岩土材料的环境效应[M].北京:冶金工业出版社,2010.
[4]宁宝宽.环境侵蚀下水泥土的损伤破裂试验及其本构模型[D].沈阳:东北大学,2005.
[5]SIGDEL P,LIANG B H.Modelling Ettringite Induced Heaving in Cement Stabilized Soils Within a Chemo-mechanical Constitutive Framework[J]. Geotechnical Special Publiation,2015(4):125-132.
[6]CHRYSOCHOOU M,DENNIS G G,NIOHOLAS E M. Assessment of Sulfate-induced Swell in Stabilized Dredged Material:Is Ettringite Always a Problem?[J].Journal of Geotechnical and Geoenvironmental Engineering,2012,38(3):407-414.
[7]KNOPP J,MOORMANN C.Ettringite Swelling in the Treatment of Sulfate-containing Soils Used as Subgrade for Road Constructions[J].Procedia Engineering,2016,143:128-137.