Title:
Mechanism of Carbonation of Mortars and the Dependence of Carbonation on Pore Structure
Author(s):
Li Ying-Up and Wu Qiu-Dong
Publication:
Symposium Paper
Volume:
100
Issue:
Appears on pages(s):
1915-1944
Keywords:
blended cements; calcium carbonates; carbonation; concretes; diffusion; fly ash; kinetics; mortars (material); porosity; portland cements; portland pozzolan cements; General
DOI:
10.14359/3838
Date:
4/1/1987
Abstract:
Discusses natural and artificial carbonation of mortar and concrete. The theoretical analyses and experimental results show that in both cases the mechanism of carbonation of mortar or concrete is the same. They are comparable when CO2 diffuses in the gas phase, the carbonation coefficient equation is Q = a1(2C1 / KP)«. The experimental results also indicate that the pores with radii over 320 A have a great effect on the diffusion coefficient, and the following relation holds: ln a1 = 105.66Ec - 0.877 where Ec is the volume of these pores divided by the total volume of the system. The results point out that there are some active sites on pore walls where CaCO3 first nucleates and the Ca++ near the pore moves toward these sites as the CaCO3 crystals grow.