Compressive strength, chloride-ion-penetration resistance, and crack-recovery properties of self-healing cement composites containing cementitious material capsules and blast-furnace-slag aggregates

Blast-furnace-slag aggregate (BFSA), a by-product of the steel industry, is an eco-friendly natural, aggregate substitute used in mortar and concrete. However, research on self-healing cement composites using BFSA is rare. In this study, the compressive strength, chloride-ion-penetration resistance, and crack-recovery properties of self-healing cement mortar samples prepared using cementitious material capsules (CMC) and BFSA of different ratios were examined and compared to a control sample. The test samples were: Control; C05B00 (5 % CMC and 0 % BFSA); C05B25 (5 % CMC and 25 % BFSA); C05B50 (5 % CMC and 50 % BFSA); C10B00 (10 % CMC and 0 % BFSA); C10B25 (10 % CMC and 25 % BFSA); and C10B50 (10 % CMC and 50 % BFSA). The compressive-strength recovery rate of the control stopped increasing after 28 days and was approximately 110 % on day 56 - that of C10B50 was approximately 121 %, (similar to 10 % greater than that of the control) and continued to increase even after 56 d. The chloride-ion-penetration resistance of C10B50 was excellent; the 28-day total charge was approximately 5858 C (similar to 40.2 % lower than that of the control). The crack-recovery rates, on day 28, of C05B50 and C10B25 were 71 % and 70 %, respectively (similar to 29-30 % higher than that of the control).