Multi-scale analysis of carbon mineralization in lime-treated soils considering soil mineralogy  

作　　者：Dhanalakshmi Padmaraj Chinchu Cherian Dali Naidu Arnepalli 

机构地区：[1]Department of Civil Engineering,Indian Institute of Technology Madras,Chennai,600036,India [2]University of Northern British Columbia,Prince George,BC,V2N4Z9,Canada

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2024年第6期2296-2309,共14页岩石力学与岩土工程学报（英文版）

基　　金：partial financial support by the Women Leading IITM,IIT Madras,Chennai,India.

摘　　要：Mineral carbonation is emerging as a reliable CO_(2) capture technology that can mitigate climate change.In lime-treated clayey soils,mineral carbonation occurs through the carbonation of free lime and cementitious products derived from pozzolanic reactions.The kinetics of the reactions in lime-treated clayey soils are variable and depend primarily on soil mineralogy.The present study demonstrates the role of soil mineralogy in CO_(2) capture and the subsequent changes caused by carbon mineralization in terms of the unconfined compressive strength(UCS)of lime-treated soils during their service life.Three clayey soils(kaolin,bentonite,and silty clay)with different mineralogical characteristics were treated with 4%lime content,and the samples were cured in a controlled environment for 7 d,90 d,180 d,and 365 d.After the specified curing periods,the samples were exposed to CO_(2) in a carbonation cell for 7 d.The non-carbonated samples purged with N2 gas were used as a benchmark to compare the mechanical,chemical-mineralogical,and microstructure changes caused by carbonation reactions.Experimental investigations indicated that exposure to CO_(2) resulted in an average increase of 10%in the UCS of limetreated bentonite,whereas the strength of lime-treated kaolin and silty clay was reduced by an average of 35%.The chemical and microstructural analyses revealed that the precipitated carbonates effectively filled the macropores of the treated bentonite,compared to the inadequate cementation caused by pozzolanic reactions,resulting in strength enhancement.In contrast,strength loss in lime-treated kaolin and silty clay was attributed to the carbonation of cementitious phases and partly to the tensile stress induced by carbonate precipitation.In terms of carbon mineralization prospects,lime-treated kaolin exhibited maximum carbonation due to the higher availability of unreacted lime.The results suggest that,in addition to the increase in compressive strength,adequate calcium-bearing phases and macropores determine the effic

关 键 词：Clays MINERALOGY Carbon capture LIME STRENGTH Pore structure 

分 类 号：TU473.1[建筑科学—结构工程]