Durability Improvement of Cement Using Amphiphilic Calcium Carbonate Nanoparticles

Abstract

The durability of cementitious materials is significant concerning long-term performance. Nanomaterials are promising candidates for deep refinement of cement durability. Hydrophobic calcium carbonate is a widely applied and easily accessible nanomaterial. However, its hydrophobicity and poor dispersity in water prohibit its direct application in cementitious materials. In this study, hydrophobic calcium carbonate nanoparticles (HbCC) were modified using a novel amphiphilic comb-shaped dispersant that is capable of laurinol release. The modification was conducted to improve the dispersity of HbCC and their compatibility with hydration products. The dispersion-improved calcium carbonate particles (AmphCC) were characterized and tested for cement durability improvement performance. According to the results, the AmphCC particles showed a pronounced effect on improving permeation resistance of cement mortars, with water absorption and chloride penetration considerably lowered. Moreover, the introduction of AmphCC in cement did not show significant adverse effects on strength development. Compared with AmphCC, a single addition of the unmodified HbCC and the dispersant cannot achieve equivalent effects. The superior effect of AmphCC is due to the synergistic effect of good particle dispersion and controlled release of the hydrophobic molecules, which is achieved by dispersion of HbCC with binding of the dispersant.