混凝土中水泥浆体与骨料界面过渡区的形成和改进综述

Review on the Formation and Improvement of Interfacial Transition Zone Between Cement Paste and Aggregate in Concrete

界面过渡区是水泥浆与骨料之间的薄层部分,具有孔隙率高、氢氧化钙晶体富集和定向排列等特点。其形成机理主要包括边壁效应、微区泌水效应、离子迁移和成核效应、单边生长效应、絮凝成团效应及脱水收缩效应。各种效应协同作用,导致界面过渡区成为混凝土最薄弱的环节。提高界面过渡区的粘结性能有利于改善混凝土的力学性能和耐久性。本文综述了常用的界面过渡区改进方法,即掺加矿物掺合料和纳米材料、改性骨料、生物矿化以及二氧化碳养护等,并比较了不同改进方法的优缺点,可为界面过渡区的形成机理和改进方法的研究及其在实际工程中的应用提供参考。

The interfacial transition zone(ITZ),a thin layer formed between cement matrix and aggregate,generally has the properties of larger porosity and enrichment of the oriented calcium hydroxide crystals.The formation mechanism of ITZ mainly includes the wall effect,micro-bleeding effect,ion migration and nucleation effect,one-sided growth effect,flocculation effect and syneresis effect,and the synergistic effects of these effects makes the ITZ the weakest point of concrete.Therefore,it will be beneficial for the mechanical properties and durability of concrete if the bonding strength of ITZ can be enhanced.Commonly used methods for improvement of ITZ bonding strength,including incorporation of mineral admixtures or nanomaterials,aggregates modification,biomineralization and carbon dioxide curing,are summarized and compared in this study.This study will provide a reference for the study on formation mechanism and modification of ITZ and its application in practical engineering.