jste.6.3.13733 Healing of Micro-Cracks in Fly Ash Cement Composite using NaOH and Na2SiO3 Solution Shaswata Mukherjee Saroj Mandal U.B. Adhikari Journal on Structural Engineering 2320-2343 6 3 37 45 10.26634/jste.6.3.13733 Self Healing, FTIR, TGA, Fly Ash, EDAX, NaOH, Na2SiO3 Microstructural properties of autonomically healed 0, 20, 40, and 60% OPC replaced by fly ash in cementitious composites are reported in this paper. Artificial micro-cracks were generated on cementitious cube specimens by the applications of compressive loads. NaOH (10-M) and Na2SiO3 solution were used as healing agent. The cracked specimens were either injected or submerged in the chemical solution, followed by heat curing at 60 oC for 48 hours. Self-healing in terms of recovery of properties were observed in UPV measurement and compressive strength study. Specimens containing 40% fly ash content mortar specimens showed better recovery of UPV and compressive strength. For limitation and better control of some analytical testing like TGA (Thermogravimetric Analysis), FTIR (Fourier-Transform Infrared Spectroscopy), XRD (X-ray Diffraction), SEM-EDAX (Scanning Electron Microscope with Energy Dispersive X-ray Analysis) were done in paste mixes rather than mortar mixes. Sodium calcite and sodium aluminate phases were found at the crack zone after submerging and injection of the NaOH (10 M) and Na2SiO3 solution in 40% fly ash content paste mix. FTIR analysis shows higher degree of geo-polymerization after submerging. TGA confirms higher mass loss for mix without any fly ash for both submerged and injected specimens. SEM reveals that the microstructure is more homogeneous in submerged specimens. September - November 2017 Copyright © 2017 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=13733