The influence of carbonation and age on salt frost scaling of concrete with mineral additions

Paper in proceeding, 2016

Resistance to salt frost scaling is tested by accelerated methods such as CEN/TS 12390-9 which originally were developed for Portland cement concrete. However, it has been shown that ageing and coupled deterioration mechanisms, like carbonation or leaching, alter the frost resistance. An example is concrete with high amount of slag where the frost resistance is reduced when the concrete is carbonated. Hence, modifications to the test methods have been proposed to take these effects into account and often an accelerated carbonation at an early age have been used. Though, it has been found that the accelerated tests show a much more negative effect than what is experienced in field conditions. This paper presents results from a laboratory study of concrete with mineral additions at different dosages and water/binder ratios which have been exposed to accelerated carbonation at 1% CO2-concentration at different ages. The results show that exposing the specimens to accelerated carbonation at a young age will result in an increased scaling but that the carbonation depths corresponds to 10 year natural exposure. By increasing the age before the accelerated carbonation exposure the scaling is significantly reduced and the salt frost scaling resistance seems to correlate better with field observations.