固碳轻质土制备方法与物理力学性能研究OA

To reduce carbon emissions and explore carbon dioxide(CO2)utilization technologies in geotechnical engineering,this study proposes a novel method for preparing carbon sequestration lightweight soil(C-LS)based on the magnesium oxide(MgO)carbonation mechanism.A mixture of MgO and waste soil is used as a binder instead of cement and CO2 instead of air for foaming.By mixing MgO,silty clay,water and CO2 foam in specific proportions,C-LS with a density of less than 1 g/cm3 is formed.Through unconfined compressive strength tests,scanning electron microscopy(SEM)and thermogravimetric analysis(TGA),the effects of MgO proportions,designed wet densities,water-to-solid ratios and carbonation curing conditions on the fluidity,setting time,dry density,strength,carbonation products and carbon sequestration capacity of C-LS are studied.The results show that with the increase of MgO proportion and wet density,the fluidity and setting time of C-LS decrease,while the strength and carbon sequestration efficiency improve.The optimal mix proportion of C-LS is determined,ensuring that under ambient conditions,its 28-day strength meets the requirements for highway embankment filling and other backfill applications.Under accelerated carbonation conditions,the strength of C-LS can be further improved.Based on the intrinsic relationship between the strength of C-LS,the amount of carbonation product,and the carbon sequestration rate,the study reveals the strength formation mechanism of C-LS and proposes a microscopic model.The C-LS technology can significantly consume CO2 and engineering waste soil,providing a novel technical approach for CO2 sequestration in geotechnical engineering.