Abstract
Carbonation depths of fly ash concrete and non fly ash concrete in outside environment at 30, 65 and 100 years are predicted by 3 methods named √t law, b power law and b_0 power law, based on carbonation data collected from proceedings and journals which published from 1979 to 2005. Carbonation progress shape coefficients, b in the equation of x=At^b (x: Carbonation depth, t: Term, A: Carbonation rate coefficient) are analyzed, and the convergence values, b_0 of b are determined. The b_0 of fly ash concrete exposed outside in a long term is about 0.37, lower than that cured in accelerated condition, 0.47, and is also lower than the b_0 of non fly ash concrete exposed outside, 0.47. The relationships between predicted carbonation depths and compressive strengths of fly ash concrete and non fly ash concrete are investigated, with the result that to control carbonation depth less than 40mm, extra strength of 3N/mm^2 is required for durability design of fly ash concrete than non fly ash concrete.
