Benchmarking UK concretes using an accelerated carbonation test

Abstract

This paper reports data on accelerated carbonation measurements. Essentially the draft European test method using the reference procedure is used but with curing and preconditioning different to the reference method. These small differences are unlikely to change the ranking of concretes with respect to carbonation resistance. The wide range of concretes tested was representative of UK ready-mix concrete production. None of the traditional specification parameters (maximum water/cement (w/c) ratio, minimum cement content and compressive strength class) on their own or in combination give a consistent accelerated carbonation resistance. When compared at a fixed w/c ratio of 0·60, there was no clear influence of cement content on carbonation resistance. The main factors influencing the accelerated carbonation depth are w/c ratio, cement type and aggregate quality. Although not the focus of the work reported, it was noted that one week of accelerated carbonation was equivalent to around 1·5 years of carbonation in outside, protected exposure.