STUDIES ON CARBONATION RATE OF CONCRETE : Part 1 Equation of carbonation rate and effects of constituents of concrete on carbonation rate

Accelerated carbonation tests on 46 kinds of concretes were conducted with the aim of investigating the carbonation rate of concrete. The main results are summarized as follows. 1) The carbonation rate of concrete is indicated by following equation, C=A_1t^<0.41> (where, C: depth of carbonation, A_1: constant, t: age) Constant A_1 is affected by cement and water-cement ratio. 2) In case of full hydration of cement, the carbonation rate of concrete is affected by cememt, but the influence of cement is not so large as usually mentioned by Dr. Kishitani or Dr. Shirayama. 3) The carbonation rate of concrete is remarkably affected by water-cement ratio, and the relation between the carbonation rate (R) and water-cement ratio (x) is showen by following equation, R=α・exp(βx-γ) (where, α,β,γ: constant) 4) In case of same water-cement ratio and same slump of concrete, the carbonation rate of concrete using AE agent or AE water-reducing agent is larger than that of plane concrete.