Study of Autogenous Self-Healing in Different Mortar Formulations

Abstract

Autogenous self-healing of cement-based materials is a topic of current interest. This research evaluates autogenous self-healing in four types of mortars based on Portland Cement, one containing CEM II and the other 3 formulated with CEM I and different additions: fly-ashes; nanosilica and hydraulic lime. The evolution of longitudinal cracks caused by a point load has been evaluated measuring the water absorption by capillarity and studying the evolution of the crack by optical microscopy. Besides the mortar composition, it has been evaluated the effect of the environmental conditions on the crack repair. The different specimens were exposed to three different environments: water immersion, curing chamber at 20 ± 2°C and 95 ± 5% of relative humidity (RH) and the laboratory at 25 ±5°C and 65% ± 5% RH. The results obtained allow us to establish that constant hydration is an essential factor for the development of self-healing mechanism. If the samples are kept in water immersion self-healing occurs no matter the additions of the mortar formulation. Size of the crack is also an important factor to allow self-healing. The product formed during selfhealing to fill the crack is mainly calcium carbonate.