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https://doi.org/DOI: 10.15255/KUI.2013.025
Published: Kem. Ind. 63 (9-10) (2014) 311–316
Paper reference number: KUI-25/2013
Paper type: Original scientific paper
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Corrosion Mechanism of Cemented Soil in MgCl2 Solution

P. J. Han, W. B. Zhang, X. H. Bai and T. Tong

Abstract

Mechanical properties of the cemented soil will be reduced when cemented soils are applied in the MgCl2 corrosive environment to conduct seepage control in hydraulic engineering. The corrosive conditions will inevitably cause serious damage to the cement-soil composite, and further reduce stablity of the whole structure. Therefore, this cementation technique could be commonly used to stabilize infrastructures. More engineering practices regarding the reduction in mechanical properties of cemented soil in the MgCl2 environment are required. To simulate and study the corrosion process, a series of tests including photographing, unconfined compression tests, and measuring Mg2+ and Cl concentrations of solution were conducted on cured cemented soil blocks with different concentrations of MgCl2 solutions. Results show that the surface corrosion of the sample increases while the compression strength decreases with the increase in solution concentration given the same curing time of the concrete block. Chemical analysis of the corrosive environment indicates that the volumes of new products such as CaCl2 ⋅ 6 H2O and Mg2(OH)3Cl ⋅ 4 H2O amount to seven times that of Ca(OH)2 after reaction. The corrosion of cemented soil is a sort of crystallizing corrosion. The Mg(OH)2 takes chemical reactions with 3 CaO ⋅ 2 SiO2 ⋅ 3 H2O and forms new products such as MgO ⋅ SiO2 ⋅ H2O, which is a sort of dissolving corrosion. In addition, the authors analysed the relationships between the unconfined compressive strength of cemented soils cured for 28 days and the initial concentrations of Mg2+ and Cl. Finally, the regression equations of the strength were established.


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Keywords

cemented soil, compressive strength, modified coefficient, corrosion