Field assessment of the relationship between natural and accelerated concrete carbonation resistance

The relationship between natural and accelerated concrete carbonation resistance has been investigated. Cores were taken from real structures and their non-carbonated inner part was subjected to accelerated carbonation resistance testing, allowing the assessment of natural and accelerated carbonation resistance on the same specimen. The carbonation resistance was characterised by means of a coefficient given by the ratio between carbonation depth and the square root of exposure time. According to the literature on the subject a linear relationship between accelerated and natural carbonation coefficients, not influenced by cement type, was assumed. A complementary experimental study was carried out to investigate how age influences accelerated carbonation resistance. Different factors, according to exposure classes, were determined by linear regression analysis to correlate accelerated and natural carbonation coefficients. The use of these factors together with Fick’s first law enables the long term prediction of carbonation depth in structures based on accelerated carbonation resistance testing.