The Assessment of Expansion Performance of Expansive Agent in Composite Cementitious Materials and its Mix Design
The expansion performance of expansive agent in cement-HCSA-fly ash cementitious materials and its coordination with strength were studied by orthogonal test. Shrinkage-compensating mortars were prepared. The results show that the restrained expansion rate (RER) of mortars cured moistly, RER residue and expansion decline rate of mortars stored drily after 7d are well consistent with each other to assess the expansion performance of expansive agent. Increase of expansive agent content and decrease of fly ash content can lead to the growth of RER. The impacts of all the factors on RER of moistly-cured mortars are becoming steady when the age is longer than 7days. The 7-day RER of 6.35×10-4 is the critical value to judge whether the shrinkage of expansive mortar occurs after it moved from moisture into dry air at 7d. The expansive agent content has no need to exceed 10% in view of compensation efficiency unless slight improvement of expansion performance is desired. 35~50%, 20~50% and 20~35% of fly ash content are recommended respectively for water-binder ratio of 0.32 0.36 and 0.40 to obtain better coordination of expansion and strength.
M. Miao et al., "The Assessment of Expansion Performance of Expansive Agent in Composite Cementitious Materials and its Mix Design", Advanced Materials Research, Vols. 168-170, pp. 2028-2032, 2011