In this study, the self-healing efficiency of mortar due to “build-in” carbonation was investigated. Sodium carbonate was selected as the healing agent to be carried by porous ceramsites to carry carbonate ions in the mortar as the healing components (HCs). The coating efficiency of the HCs and its effect on the fresh and hardened properties of the mortar were investigated. To investigate the effect of carbonate and calcium ions on formation of carbonates, the healing efficiency of mortars in the presence of an external calcium source only (P), an external carbonate source only (N), and an internal carbonate source combined with an external calcium source (C), was evaluated based on the mechanical property and pore structure by characterization of water absorption, mercury intrusion porosimetry (MIP) and backscattered electron imaging (BSE) measurements. The results showed that the incorporated HCs triggered “build-in” carbonation to heal the cracks. The mechanical regains and water absorption results demonstrated that the incorporated coated HCs significantly improved the self-healing capability of the pre-cracked mortars. The specimen containing 7.5 wt% of HCs showed the maximum compressive strength recovery rate of 1.35 and the greatest value of rate of water absorption was 64%. The MIP results showed a greatest reduction of pores in 100–1800 nm for the self-healing specimens after curing. The BSE results indicated that the main healing product for specimens with HCs was CaCO3. All the results by different measurements are consistent with each other and the best healing efficiency is seen for C, followed by N and P. The availability of carbonate ions is more critical in formation of calcite than the calcium source, particularly when the carbonate ions were provided internally. The optimum HCs dosage and environment for enhancing the self-healing capability of the mortars were 7.5 wt% and a saturated Ca(OH)2 solution, respectively.
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Jul 1, 2022
A Beggas + 8
Open Access