Effect of MgO Activity Index on Physicochemical, Electrical and Mechanical Properties of Carbonated MgO-admixed Silt
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The natural soil will have a significant strength improvement when admixed with reactive magnesia (MgO) and subjected to CO2 carbonation, which has been identified as an innovative and environment-friendly technique in the domain of soil treatment. MgO activity has been revealed to have a significant influence on the treatment effectiveness during the carbonation process. With this in view, the effect of MgO activity index on physicochemical, electrical and strength properties of carbonated silt was investigated. Results show that the MgO activity index and initial water-MgO ratio play crucial roles in controlling the aforementioned properties. With the initial water-MgO ratio reducing or MgO activity index increasing, the mass increment ratio, growth rate of unit weight, pH, resistivity, strength and CO2 sequestration increase to different degrees, while the volume increment ratio, water content, specific gravity, porosity and saturation degree decrease. The unconfined compressive strength shows a better linear relation with resistivity, indicating the applicability of resistivity method in the strength evaluation of carbonated MgO-admixed soil. Moreover, the thermal and microstructural analyses have explained the changing mechanism of physicochemical, electrical and strength properties. Finally, the analysis of the CO2 sequestration indicates that the carbonated MgO-admixed silt could achieve a high carbonation degree when the initial water-MgO ratio is less than 2.0, showing the feasibility of MgO carbonation in the CO2 sequestration.
Keywordscarbonation reactive magnesia activity index physicochemical properties electrical resistivity
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This work is funded by Natural Science Foundation of Jiangsu Higher Education Institutions (18KJB560012), Youth Science and Technology Innovation Fund of Nanjing Forestry University (CX2018005, GXL2018028), Science and Technology Project of Jiangsu Traffic Engineering Construction Bureau (2018T01), NSFC (41330641), Basic Research Project of Central University (2242019K30039) and Ministry of Housing and Urban-rural Development Science and Technology Project Plan (2018-K7-013).
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