Influence of Hydrated Lime on the Self-Healing Capacity of Cement Mortars

¹ Ghent University, Center for Microbial Ecology and Technology (CMET), Coupure Links 653, B-9000 Ghent, Belgium
² Ghent University, Magnel-Vandepitte Laboratory, Dept. of Structural Engineering and Building Materials, Technologiepark Zwijnaarde 60, B-9052, Ghent, Belgium

^* Corresponding author: franco.grossogiordano@ugent.be

Abstract

The capacity of hydrated lime to reabsorb CO₂ as it hardens has made it a desirable replacement for cement to produce mortars with an overall lower environmental footprint. Still, research into lime-cement formulations remains limited, especially when it comes to their self-healing capacity.

Some studies show that hydrated lime can improve self-healing in cement mixes, but addition rates are low. Here we present how high lime-cement ratios influence the self-healing capacity of lime mortars. Four mixes of increasing lime-cement ratios were cracked with tensile loading and placed under 1 hour wet, 23 hours dry cycles to stimulate self-healing. The mix design of 50 % lime-50 % cement volume (L50C50) showed self-healing abilities and was tested against a pure cement mixture (L0C100). Microscopy and water flow tests were performed at a cracking age of 7 days and then again after 28 days of healing in three regimes.

Overall, submersion was the best healing regime for both L0C100 and L50C50 and crack self-healing was close to total (100 ± 1 % and 98 ± 6 %, respectively). Nevertheless, the water flow tests show that self-healing in L50C50 was in fact less efficient than that of the L0C100, achieving a 39 ± 21 % reduction in water flow versus 86 ± 11 %.