Abstract
Accelerated carbonation test is performed to explain mechanism of carbonation of concrete. The depth of carbonation, the weight loss of mortar, the amount of calcium hydroxide and calcium carbonate, and pore volume and pore size distribution are measured. Water immersion test and air exposure test after accelerated carbonation test is also performed to evaluate the diffusion of calcium hydroxide. The depth of carbonation correlates the amount of evaporated water, and the amount of calcium hydroxide and calcium carbonate, pore volume and pore size distribution depend on exposure duration in the accelerated chamber. The depth of carbonation of mortar decreases due to the diffusion of calcium hydroxide from uncarbonated portion to carbonated portion under wetting condition.
Based on these test results, the diffusion equations for water, carbon dioxide and calcium hydroxide are proposed and the finite difference method is used in numerical analysis. The depth of carbonation of concrete can be predicted by analyzing these diffusion equations.
