Carbonation resistance of high volume fly ash concrete estimated with accelerated and natural tests

The reuse of industrial residue streams such as fly ash (FA) can be beneficial both from economic and ecological points of view but the durability properties remain the key properties to ensure sustainable application of these materials. The paper presents the results of accelerated carbonation tests carried out under CO2 concentration of 1%, 2%, 4% and 16% on high volume fly ash concrete (HVFAC) with 200 kg/m3 of cement and the same amount of fly ash. Concrete samples were also exposed to natural conditions of 0.0471% CO2 in the laboratory and after 21 months carbonation depths were measured. The effect of CO2 concentration on the kinetics of the carbonation process was analyzed. The suitability of widely used Tuutti’s model for the prediction of carbonation depth was tested on designed HVFAC. Based on collected results, modified expression derived from this model was proposed in order to secure a more accurate and reliable prediction of carbonation depth of HVFAC under natural conditions