Modelling The Effects of Aggregate Size on Alkali Aggregate Reaction Expansion

A Asroun,N Z Sekrane

doi:10.48084/etasr.449

Abstract

This work aims at developing models to predict the potential expansion of concrete containing alkali-reactive aggregates. The paper gives measurements in order to provide experimental data concerning the effect of particle size of an alkali-reactive siliceous limestone on mortar expansion. Results show that no expansion was measured on the mortars using small particles (0.5-1.0 mm) while the particles (1.0–2.0 mm) gave the largest expansions (0.217%). Two models are proposed, the first one studies the correlations between the measured expansions and the size of aggregates, the second one calculates the thickness of the porous zone necessary to take again all the volume of the gel created.

Highlights

Alkali aggregate reaction (AAR) affects numerous civil engineering structures and causes irreversible expansion and cracking
Experiments have been performed on different types of aggregates. It seems that the highest AAR-expansion caused by the effect of the particle size of the reactive aggregate depends on the composition of the aggregate itself [6,7,8,9,10]
The expansions for bars with a single fraction of reactive aggregate were obtained by subtracting the initial length of the samples taken at the time of the demolding from the final length at time (t)

Summary

Introduction

Alkali aggregate reaction (AAR) affects numerous civil engineering structures and causes irreversible expansion and cracking. The gel volume formed by the chemical reaction can be used as input data to structural models [1]. Microscopic models [3,4,5] could be one method of doing this Such models should be able to predict the differences of expansions with the variation of all influential parameters such as the aggregate size and should be compared with experimental results. Several papers deal with the effect of particle size of reactive aggregates on the expansion due to AAR. Experiments have been performed on different types of aggregates It seems that the highest AAR-expansion caused by the effect of the particle size of the reactive aggregate depends on the composition of the aggregate itself [6,7,8,9,10]

Objectives

Results

Conclusion