Effect of internal water content on carbonation progress in cement-treated sand and effect of carbonation on compressive strength

This study investigates the effect of internal water content in cement-treated sand on carbonation progress and the effect of carbonation on compressive strength. To alter the internal water content, specimens were cured under three conditions: sealed, drying, and water sprayed. The carbonation coefficient, which was determined by a phenolphthalein spray test, decreased as the internal water content increased because of water sprayed. However, a thermal analysis revealed that the amounts of portlandite consumed and calcium carbonate generated by carbonation exhibited dissimilar trends: the amount of generated calcium carbonate was the maximum when there was a small increase in water content by water sprayed. Further increments in water content significantly lowered the amount of generated calcium carbonate. The measured compressive strength increased linearly with the amount of calcium carbonate. This implies that the amount of calcium carbonate is a good indicator of the effect of carbonation on the strength development of cement-treated sand and that both these quantities are affected by the internal water content.