A note on the comparison of crack resistance of Ca(OH)_2 crystals of unmodified and polymer-modified mortars in carbonated atmosphere

摘要

The purpose of this paper is to study morphologically the effects of carbonation on Ca(OH)_2 crystals in unmodified mortar and polymer-modified mortars (PMMs). For this purpose, unmodified mortar and PMMs with 25 mix proportions were prepared with various polymer-cement ratios (P/C) and subjected to a nonpressurizing accelerated carbonation test (NPACT). It was concluded that Ca(OH)_2 crystals formed in unmodified mortar were weak, unable to withstand stresses generated due to carbonation-related shrinkage and therefore cracked on exposure to CO_2. By contrast, Ca(OH)_2 crystals formed in PMMs were strong, withstood stresses generated due to carbonation-related shrinkage and did not crack on CO_2 exposure.