Transport characteristics of concrete after carbonation

ABSTRACT Limited information is available on the transport behaviour of concrete after being exposed to carbon dioxide, which is one of the major reasons for the premature deterioration of reinforced concrete structures. This study investigates the changes induced in the transport characteristics of concrete after carbonation through conventional tests on concrete such as porosity, sorptivity, oxygen permeability and resistivity. A total of 10 concrete mixes were prepared using five supplementary cementitious materials (SCMs) (Class C fly ash, Class F fly ash, pumice, perlite and calcined clay) at the 30% cement replacement level and two water to binder ratios. The concrete samples were cured for 28 days in water and were subsequently placed under three different exposure conditions (2.5% CO2, oven 50°C and under water) for 60 days. In general, a reduction in porosity was observed on carbonation in all the concrete mixes. However, for SCM-incorporated concrete mixes, an inferior sorptivity, permeability and resistivity performance were observed specifically for lower compressive strength concrete mixes and clay mixes.