Preparation and characterization of autolytic mineral microsphere for self-healing cementitious materials

Abstract

Abstract This paper presents a bio-inspired autolytic mineral self-healing method for cementitious materials. The autolytic mineral microsphere (AMM) consists of porous silica microsphere adsorbed with sodium silicate as healing agent and polyvinyl pyrrolidone (PVP) as resoluble coating material which will be autolyzed gradually under alkaline solution. The porous silica microsphere and coating film were prepared by sol-gel method and solvent evaporation respectively. The microstructure of AMM were characterized by environmental scanning electron microscopy (ESEM) and specific surface & pore size analysis instrument. The PVP thickness was measured by transmission electron microscope (TEM). Autolytic behavior of AMM was studied using Ultraviolet–visible (UV-VIS) spectrophotometer under different pH values, temperature and PVP thickness. Experimental results show that autolytic behavior is mainly controlled by PVP thickness, and the dissolution rate of sodium silicate is affected by pH values and temperature. Compressive strength recovery of cementitious materials is greatly enhanced by adding AMM.