Evaluation of self-healing in concrete with limestone coarse aggregate impregnated with Na2SiO3solution

Abstract

This study investigated the self-healing process in concrete using limestone coarse aggregate impregnated with sodium silicate solution and encapsulated with polyvinyl alcohol (PVA). It discussed the self-healing mechanism by sodium silicate solution and evaluated the effect and the efficiency of this healing agent. To do this, limestone coarse aggregate was vacuum impregnated with a sodium silicate solution, encapsulated with PVA, and mixed into the concrete paste. The compressive strength was improved up to 50% in the concrete samples with sodium silicate. It also evaluated the porosity, density, and absorption ranges. It found a reduction of 4% in the range of absorption. Using x-ray diffraction (XRD), the chemical elements of the healing products were determined and the presence of the crystalline phases Etringite, Calcite, Dolomite and Minrecordite. This agreed with the chemical composition of dolomitic limestone's (CaMg (CO3)2). The self-healing process was observed in the concrete samples cured at 28 days and was attributed to the formation of calcite crystals and silica gel C-S-H. Using the Scanning Electron Microscopy (SEM), the hydration products like calcite and C-S-H were visualized. Self-healing in the concrete could be observed due to the impregnation of Sodium Silicate in the aggregates.