Alkali Silica Reaction In The Presence Of Metakaolin - The Significant Role of Calcium Hydroxide

World Multidisciplinary Civil Engineering-Architecture-Urban Planning Symposium - WMCAUS

土木建筑工程

Zapala-Slaweta, Justyna^1

Kielce University of Technology, Al. Tysiclecia Pastwa Polskiego 7, Kielce

25-314, Poland^1

关键词: Alkali-silica reaction;    Beneficial effects;    Durability property;    High-reactivity metakaolin;    Micro-structural observations;    Mineral additives;    Pozzolanic properties;    Reactive aggregate;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/245/2/022020/pdf
DOI  :  10.1088/1757-899X/245/2/022020

学科分类：土木及结构工程学

来源: IOP

【 摘 要 】

Reducing the internal corrosion, which is the result of reactions between alkalis and reactive aggregates is especially important in ensuring durability properties of concrete. One of the methods of inhibiting the reaction is using some mineral additives which have pozzolanic properties. This paper presents the efficacy of high-reactivity metakaolin in reducing expansion due to alkali-silica reaction. It was demonstrated that metakaolin in the amount from 5% to 20% by mass of Portland cement reduce linear expansion of mortar bars with opal aggregate. Nevertheless, the safe expansion level in the specimens, classified as non-destructive to concrete, was recorded for the mortars prepared with 20% addition of metakaolin. Depletion of free calcium hydroxide content was considered as one of the most beneficial effects of metakaolin in controlling alkali silica reaction. Based on thermogravimetric analysis (TGA) performed on mortar bars with and without metakaolin the differences in portlandite content were determined. Microstructural observation of the specimens containing metakaolin indicated the presence of a reaction products but fewer in number than those forming in the mortars without mineral additives.