Accelerating Effect of Heating Treatment on the Damage of Cement Paste under Sulfate Attack

Abstract

The ettringite (AFt) formation and damage process are investigated for cement paste subjected to external sulfate attack with and without heating treatment during curing. Slice and disc specimens were exposed to 10 g/L Na2SO4 + pH of 13. The evolutions of AFt formation, pore structure, and expansion on slice specimens were characterized through 27Al NMR, MIP, and micrometer. The surface cracks on disc specimens were observed through an optical microscope. The experimental results show that: (1) heating treatment dissolves part of AFt and accelerates the ettringite formation and material expansion; and (2) heating treatment initiates the microcracks, thus promoting the material cracking.