摘要 发泡混凝土与CO2碳酸化反应不仅可以改善混凝土性能而且可实现CO2的矿化固定达到减排的效果。本实验分别考察了CO2反应时间对未浸、水浸和电石渣饱和液浸泡后发泡混凝土试块抗压强度的影响,并采用XRD、TGA 、SEM分析测试手段,分别对试块的矿物组成、热失重特性和微观形貌特性进行了表征。结果表明:发泡混凝土试块的抗压强度随碳酸化反应时间延长出现先增加后降低的变化趋势;碱浸碳酸化反应4 h试块强度最高为6.5 MPa,较未碳酸化反应试块强度上升80.6%。SEM分析结果显示,发泡混凝土试块孔壁结构随碳酸化反应时间延长发生较明显变化,整体上呈现“先片状致密后粒化疏松”的转化历程,这可能是导致试块抗压强度随碳酸化时间延长出现先增加后降低现象的内在原因。TGA曲线结果表明,试块达最高抗压强度时,每吨发泡混凝土可固定37 kg CO2,在不降低试块强度前提下,每吨发泡混凝土可固定61 kg CO2。
Abstract: The foaming concrete and CO2 carbonation reaction can not only improve the concrete performance but also achieve the effect of reducing the mineralization of CO2. The effects of CO2 reaction time on the compressive strength of foamed concrete blocks after immersion in unsoaked, water immersed and calcium carbide slag were investigated. XRD, TGA and SEM were used to analyze the mineral composition of the test blocks. The thermogravimetric properties and micromorphology characteristics were characterized. The results show that the compressive strength of the foamed concrete test block increases with the increase of carbonation reaction time, and the strength of the test block of alkali leaching is up to 6.5 MPa, which is lower than that of the uncarbonated reaction test. The block strength increases by 80.6%. The results of SEM analysis show that the pore wall structure of the foamed concrete test block changes significantly with the prolongation of the carbonation reaction time. The whole process shows the transformation process of “grain-like compaction and granulation looseness”, which may lead to the compressive strength of the test block. The intrinsic cause of the phenomenon of “first increase and then decrease” occurs with the prolongation of carbonation time. The TGA curve results show that when the test block reaches the highest compressive strength, the CO2 can be fixed at 37 kg per ton of foamed concrete. Under the premise of not reducing the strength of the test block, the CO2 can be fixed at 61 kg per ton of foamed concrete.
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2019, Vol. 33 
