In order to clarify the effects of pozzolanic reaction of fly ash on the rate of carbonation of high-volume concrete, the carbonation depth, the compressive strength, the pore structure and the amount of Ca(OH)_2 were investigated experimentally. As a result, it was found that the rate of carbonation of the concrete was not influenced by the addition of fly ash with a specific particle size and shaved a good correlation only with the water cement ratio. However, the addition of fly ash with the smaller or the larger particle size showed a positive (negative) or a negative (positive) effect on the resistance to carbonation, depending on the water cement ratio. Consequently, the resistance to carbonation of high-volume fly ash concrete is determined by both the reduced permeability of the matrix and the decreased pH due to the Pozzolanic reaction of fly ash.
