Novel Green Mortar Incorporating Crumb Rubber and Wood Fly Ash

Increased repercussions from climate change have popularized research into ways of mitigating the environmental impacts of construction processes. The production of building materials is a key concern, with the cement industry accounting for a considerable amount of global greenhouse gas emissions. Exploitative sand mining for use in infrastructure also has negative environmental impacts. The harmful effects of concrete would improve by reducing the cement and sand used in its production. Moreover, as coal plants become obsolete, coal fly ash will no longer be available and should be replaced. The purpose of this paper is to explore the behavior of mortar mixtures made with wood fly ash and crumb rubber as cement and sand replacements, respectively. The use of post-consumer waste tires as crumb rubber enhances the sustainability of these mortar mixtures by reducing the quantity of sand used. Furthermore, it eliminates the build-up of tires in landfills, which is a growing concern globally. In the samples cast, an aqueous sodium hydroxide solution-treated crumb rubber replaced 10 and 20% of the sand. Wood fly ash was used in conjunction with the crumb rubber. It substituted 15 and 30% of the cement used in the control mixture. Nine mortar mixtures were cast and tested under compression to demonstrate the effects of the combination of various materials and their failure patterns. Casting and compressive tests followed CSA standards. The microstructure of the samples was studied using scanning electron microscopy. The color of the mortar is of interest and has also been analyzed. Reducing the quantity of cement and sand used to produce mortar reduced their environmental impact. Results of the study show that incorporation of wood fly ash up to 30% can produce mortar with satisfactory strength. Although crumb rubber addition significantly reduces the mortar strength, it can still be used for constructing non-load-bearing structures. The use of wood fly ash and crumb rubber is a viable solution to the obsolescence of coal fly ash and increasing volume of tire wastes.