Benchmarking UK concretes using an accelerated carbonation test

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. </jats:p

Experience of using the prTS 12390-12 accelerated carbonation test to assess the relative performance of concrete

This paper reports data on the use of the prTS 12390-12 accelerated carbonation test (reference method) over the past two decades and shows that accelerated carbonation testing is a suitable technique for ranking concretes in their carbonation resistance. Testing at 5, 7 and 10 weeks provides the optimum solution that minimises the risk of incorrect ranking of different constituent materials. Analysis of data from previous studies also shows that the reference test conditions of a partial pressure of 4% carbon dioxide are a suitable level which allows sufficient carbonation to take place for accurate depth measurement while the preconditioning period of 28 days standard followed by 2 weeks drying in laboratory air did not disadvantage pozzolanic and similar type cements. </jats:p