ADMIXTURES FOR SHRINK CRACK REDUCTION OF PORTLAND CEMENT-BASED MORTARS AND CONCRETES

摘要

Portland Cement-based concretes and mortars exhibit significant reduction in shrinkage cracking when combined with Magnesium Oxide (MgO), Shrinkage Reduction Admixtures (SRA) and Super Absorbent Polymers (SAP). However, MgO is a solid that reacts with water, SRA is a liquid, and SAP if not added properly could pull water out of the system and thus increase shrinkage. Unique admixture blends used as supplementary cementing materials that do not significantly affect concrete or cement strength properties of Portland cement itself address such issues. Proper ratios of MgO, SRA and/or SAP perform better against crack reduction when compared to commonly used Expansive Cements (EC).