预养护对二氧化碳养护混凝土过程及显微结构的影响

Effect of Pre-conditioning on Process and Microstructure of Carbon Dioxide Cured Concrete

研究了干硬性混凝土经干燥环境预养护后的剩余水灰比对其二氧化碳养护过程及显微结构发展的影响。用热重分析和Fourier红外光谱等方法对二氧化碳养护砂浆过程中形成的产物进行了定性和定量分析,并利用压汞测孔仪分别测试了二氧化碳养护3h和自然养护5h的砂浆的孔径分布。结果表明:剩余水灰比为0.16～0.20时二氧化碳养护程度及抗压强度最高;养护过程中反应物为水泥颗粒及少量水化产物,生成方解石及硅胶;养护程度较高的试件生成的碳酸钙结晶度较高;二氧化碳养护后混凝土孔隙率明显降低,50～1 000nm的毛细孔含量降低,养护程度越高的混凝土,孔结构改善程度越高。

This paper investigated the e{{ect o~ remaining water-cement ratio on the curing process and microstructure of con- crete subjected to CO2 curing. The microstructure of CO2 cured products was characterized by thermogravimetry, Fourier trans- {orm in{tared spectroscoPY and mercury Dorosimetry, resl^ectively. The result indicates that CO2 curing of cement mortar oc-curs on fresh concrete based on the reactions between cement clinker and CO2. The optimal CO2 curing degree and compressive strength can be obtained at the remaining water-cement ratio of 0. 16-0.20. The specimen with a greater CO2 curing degree produces carbonates with a better crystallinity. After COz curing, the total porosity and portion of capillary pore （50- 1 000 nm） of concrete decreases evidently.