多尺度MgO膨胀剂与SAP协同作用对UHPC力学及收缩性能的影响

摘要/Abstract

摘要： 超高性能混凝土(UHPC)水胶比较低,胶凝材料掺量较高,导致其在早龄期产生较大的自收缩,易发生收缩开裂。本文通过复掺多尺度MgO膨胀剂与高吸水树脂(SAP)内养护材料来解决此问题,探明多尺度MgO膨胀剂与内养护材料对免蒸养UHPC力学、收缩及水化特性的影响规律,并借助SEM、XRD、MIP、TG-DTG微观手段揭示复掺多尺度膨胀剂与内养护材料的协同作用机理。结果表明:与单掺MgO和纳米MgO相比,复掺多尺度MgO膨胀剂更有利于UHPC力学性能的发展,同时为UHPC体系水化过程提供稳定的膨胀源;在掺加多尺度膨胀剂的基础上继续引入SAP可以提高UHPC的工作性能,同时进一步降低UHPC早龄期的自收缩,研究结果可为解决UHPC早龄期自收缩大的难题提供数据支撑与理论指导。

关键词: 超高性能混凝土, 膨胀剂, 内养护材料, 自收缩, 强度, 协同作用

Abstract: Due to its low water-to-binder ratio and high content of cementitious materials, ultra-high performance concrete(UHPC) produces large autogenous shrinkage at early age, which easily causes shrinkage cracking of UHPC. Therefore, multi-scale MgO expansion agent and super absorbent polymer (SAP) internal curing material were mixed to solve this problem. The effects of multi-scale MgO expansion agent and internal curing material on mechanical, shrinkage and hydration characteristics of steam-free UHPC were investigated, and then the synergistic mechanism of mixing multi-scale expansion agent and internal curing material was revealed by SEM, XRD, MIP and TG-DTG microscopic methods. The results show that mixing multi-scale MgO expansion agent is more conducive to the development of mechanical properties of UHPC than single-scale MgO and nano MgO, and at the same time provides a stable expansion source for the whole process of hydration of UHPC system. On the basis of adding muti-scale expansion agent,the introduction of SAP can improve the working performance of UHPC, while further reducing the autogenous shrinkage of UHPC at early age. The research results can provide data support and theoretical guidance for solving the problem of large autogenous shrinkage in the early stage of UHPC.

Key words: ultra-high performance concrete, expansion agent, internal curing material, autogenous shrinkage, strength, synergistic effect

中图分类号:

TU528

韦亚平, 李绍成, 王有志, 田长进. 多尺度MgO膨胀剂与SAP协同作用对UHPC力学及收缩性能的影响[J]. 硅酸盐通报, 2023, 42(9): 3154-3165.

WEI Yaping, LI Shaocheng, WANG Youzhi, TIAN Changjin. Synergistic Effect of Multi-Scale MgO Expansion Agent and SAP on Mechanical and Shrinkage Properties of UHPC[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2023, 42(9): 3154-3165.

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