Microstructural characterization of self-healing products in cementitious systems containing crystalline admixture in the short- and long-term

This paper evaluates in the short- and long-term the healing products in cementitious systems with a crystalline admixture (CA) healing stimulator and polypropylene (PP) fibers in a thermal-activated environment at 60 °C. For this purpose, multiple microstructural characterization techniques were employed. Calorimetry tests were performed for up to 7 days to investigate the hydrate formation and a potential synergetic effect between CA and PP. Raman spectroscopy and SEM/EDS identified the healing products directly in the cracks up to 178 days. The combined use of CA and PP affected the hydration kinetics but did not change the total amount of heat released up to the investigated age. The CA inclusion promoted primary monocarboaluminate and ettringite in the short term. Otherwise, at an advanced healing age, the results revealed mainly calcium hydroxide, C–S–H, unhydrated cement grains and smaller quantities of other phases such as SiO2 and carbonaceous materials for all CA dosages.