再生骨料掺量对混凝土碳化性能的影响

Influence of recycled aggregate content on carbonation performance of concrete

为研究再生骨料掺量对混凝土碳化性能的影响,用不同再生骨料质量取代率为0、30%、50%的再生混凝土(分别记为RC0、RC30和RC50)分析不同取代率下混凝土碳化深度、抗压强度的影响规律,运用扫描电镜分析再生混凝土界面微观形貌在不同碳化时间下的变化,通过显微硬度仪对界面过渡区的显微硬度数值进行检测和分析,探讨碳化作用下再生混凝土微观结构与宏观性能的关系。结果表明:再生骨料掺量越大抗压强度越低,再生混凝土碳化深度越深;通过对比不同类型界面过渡区的抗碳化能力得出,老骨料老浆体界面>骨料新浆体界面>老浆体新浆体界面;再生骨料取代率30%的混凝土界面结构更密实;再生混凝土的微观结构与其宏观性能呈规律性变化,用界面过渡区宽度的变化表征宏观性能的规律更为准确。说明碳化对不同再生骨料掺量混凝土的界面结构优化效果不同,再生骨料掺量越大的混凝土抗碳化性能越差,且用微观结构的变化可以很好地解释宏观性能的变化。

In order to examine the impact of recycled aggregate content on the carbonation performance of concrete,the influence of different replacement rates of recycled aggregate quality on the carbonation depth and compressive strength of concrete was analyzed by using recycled concrete with different replacement rates of 0,30%and 50%(denoted as RC0,RC30 and RC50,respectively).Scanning electron microscopy was used to explore the changes of interfacial microstructure of recycled concrete under different carbonation time,and the microhardness value of interfacial transition zone was detected and analyzed by microhardness tester.The relationship between microstructure and macroscopic properties of recycled concrete under carbonation was studied.The results show that the larger the recycled aggregate content,the lower the compressive strength and the deeper the carbonation depth of recycled concrete.By comparing the anti-carbonization ability of different types of interfacial transition zones,it is concluded that the old aggregate old slurry interface>aggregate new slurry interface>old slurry new slurry interface;the interface structure of concrete with 30%replacement rate of recycled aggregate is more compact.The microstructure of recycled concrete and its macroscopic properties change regularly,and it is more accurate to characterize the macroscopic properties with the change of the width of the interface transition zone.The research indicates that carbonization has different effects on the interface structure optimization of concrete with different recycled aggregate content.The larger the recycled aggregate content,the worse the carbonation resistance of concrete,and the change of microstructure can give a clear explaination the change of macro performance.