Improvement of Khorasan mortar with fly ash for restoration of historical buildings

Abstract In this study, the effects of fly ash on Khorasan mortar composed of brick or tile powder and lime were investigated to improve its mechanical properties. In the mixtures, fly ash was used instead of 0- to 4-mm crushed tile or 0- to 1-mm tile powder as aggregate. In addition, slaked lime was used as a binder, and 0–10–20–30–40% fly ash was replaced with crushed tile or tile powder. The consistency, hardened unit weight, ultrasonic pulse velocity, compressive strength and flexural strength before and after exposure to freeze-thaw, and the microstructure and chemical composition of specimens were examined. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and thermogravimetric analysis were conducted on specimens. On the basis of the results, notable improvements were observed in the mechanical properties of specimens with addition of fly ash.