Improving the Autogenous Self-Sealing of Mortar: Influence of Curing Condition

Abstract

With the construction of projects under severe environments, new and higher requirements are put forward for the properties of concrete, especially the autogenous self-sealing property, which is greatly affected by the curing environment and the state of the water. Herein, six types of curing conditions, including in air with a relative humidity of 30%, 60%, and 95%; flowing water; wet-dry cycles; and static water, are designed to investigate the autogenous self-sealing of mortar under different curing conditions. The results showed that the self-sealing ratios are higher than 60% and the cracks are closed for the mortar undergoing the wet-dry cycles and the static water. However, the self-sealing ratios of mortar are lower than 10% and the cracks are almost unchanged when the mortar is cured in the air with a relative humidity (RH) of 30% and 60%. The static liquid water is more conducive to the continued hydration of cement and the formation of CaCO3 than the flowing water. The research provides guidance for the design of concrete and the improvement of autogenous self-sealing when the concrete serves in different environments.

Uncovering the Mechanism of the Role of Fly Ash in the Self-Healing Ability of Mortar with Different Curing Ages

“…To improve and obtain a remarkable self-healing ability in concrete, numerous studies have been conducted based on healing conditions and alternative cementitious materials. Yuan et al [8,9] found that the self-sealing ratios in the static liquid water environment were higher than in other environments, including in air with various humidity, flowing water, and wet-dry cycles. They also noted that cement containing more 30-60 nm cement particles in mortar had a better self-healing ability in the early stage.…”

Retardation Effects of Filter Mud in Molasses on Composite Silicate Cement

“…These hydration products, depending on various gravitational forces to overlap and bind, form a cement structure with a certain strength. The added retarder can postpone the rate of cement hydration products absorbing and condensing into a continuous reticular flocculation structure, postpone the cement hydration reaction and extend the concrete setting time, and make the fresh concrete maintain not only plasticity but also other properties over a longer period [ 2 , 3 ]. Currently, the commonly used retarders include small molecule sugar, inorganic boric acid (inorganic borate), organic lignosulfonate and its derivatives, hydroxycarboxylic acid (hydroxy carboxylate), etc.…”