Laboratory Carbonation Model of Single Soil-MgO Mixing Column in Soft Ground
The carbonation of reactive MgO-treated soil are considered as an innovative treatment technology in the realm of soft ground improvement. With this in view, the indoor mixing column model tests were carried out under different initial water content and CO2 pressure through the artificial dig-hole column method. The study shows that the temperature of mixing column firstly increases and then decreases, and the temperature can reach the highest in less than 2 h. The temperature peak is the highest at the initial water content of 20%, the second at 15% and the lowest at 30%. In addition, the temperature peak increases with CO2 pressure. The strength decreases with increasing initial water content or decreasing CO2 pressure, and it decreases exponentially with the increase of water content. Nesquehonite peaks are slightly higher at water content of 30% than that at 15%. The peaks of nesquehonite and dypingite or hydromagnesite are relatively higher at 200 kPa than those at 25 kPa. At low water content of 15%, there are amounts of prismatic nesquehonite and few flake dypingite/hydromagnesite. At the high water content of 30%, there are amounts of carbonation products with loose connection. At low CO2 pressure of 25 kPa, the pores are larger, and there are lots of flocculent brucite and few nesquehonite. Based on XRD and SEM analyses, the existences of nesquehonite hydromagesite/dypingite are the main reason for strength development.
KeywordsReactive MgO Carbonation CO2 Soil-MgO mixing model
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