不同胶凝材料体系再生混凝土新界面微观结构与性能研究

Microstructure and performance of new interface of recycled concrete with different cementitious material systems

利用显微硬度仪、扫描电镜(SEM)等微观测试技术,系统研究了普通硅酸盐水泥(OPC)、高贝利特硫铝酸盐水泥(HBCSA)和碱激发矿渣(AAS)3种胶凝材料对于再生混凝土新界面(骨料新界面和砂浆新界面)微观结构和性能的影响。研究结果表明:强度等级为C30、C40、C50的普通硅酸盐水泥再生混凝土,砂浆新界面显微硬度均高于骨料新界面,过渡区宽度则相差不大;C30~C50强度等级的高贝利特硫铝酸盐水泥再生混凝土砂浆新界面显微硬度均高于骨料新界面;碱激发矿渣再生混凝土骨料新界面显微硬度高于基体,相同强度等级下,骨料新界面显微硬度高于砂浆新界面,且过渡区宽度较砂浆新界面明显减小;综合考虑界面过渡区(ITZ)显微硬度和宽度,相同强度等级的3种胶凝材料再生混凝土中骨料新界面性能依次为碱激发矿渣>普通硅酸盐水泥>高贝利特硫铝酸盐水泥,且砂浆新界面表现出同骨料新界面的一致性。

Using analysis methods of microhardness tester and scanning electron microscope,the effect of three cementitious materials(ordinary Portland cement,high belite sulfoaluminate cement and alkali-activated slag)on the microstructure and performance of new in terface(new aggregate interface and new mortar interface)ofrecycled concrete is studied.The results show that the microhardness ofnew mor-tar interface is higher than that of new aggregate interface for C30 and C40 ordinary Portland cement recycled concrete,and the width of ITZ has little difference.The microhardness of new mortar interface of high belite sulfoaluminate cement recycled concrete(C30,C40,C50)strength grades is all higher than that of new aggregate interface.The microhardness of new aggregate interface of alkali-activated slag recycled concrete is higher than that of paste.Alkali-activated slag recycled concrete for the same strength grade,the microhardness of new aggregate interface is higher than that of new mortar interface,and the width of new aggregate interface obviously decrease compared with that of new mortar interface.Considering the microhardness and width of the ITZ,the performance of the new aggregate interface of three cementitious materials recycled concrete for the same strength grade is as follows,alkali-activated slag>ordinary Portland ce-ment>high belite sulfoaluminate cement,and the new mortar interface is consistent with the new aggregate interface.