Development of a waste‐based eco‐friendly structural mortar without Portland cement and natural sand

Abstract

AbstractThe aim of this study is to develop a new eco‐friendly structural mortar for reducing the CO2 emissions inherent in the use of cement in concrete together with the extraction of the nonrenewable natural sand (NS). This clean production is achieved by fully replacing cement with glass powder (GP), ground granulated blast furnace slag (GGBS) and fly ash (FA) as industrial by‐products, and NS with glass sand (GS) and foundry sand (FS) as waste‐based sands. To this end, 26 mortar batches were prepared, and their compressive and direct tensile strength and flowability were studied. Scanning electron microscopy and energy dispersive x‐ray spectroscopy were employed to link the microstructure of the mortars with the obtained properties. The results show that waste‐based mortars (WBMs) with NS have a higher flowability compared with those with GS (up to 44%) and FS (up to 47%). The results also reveal that the strengths of WBMs with GS are identical to those with NS, whereas these properties of mortars containing FS are slightly lower (up to 6%). In addition, the results show that when 80% of cement is replaced with GGBS and 100% of NS is replaced with GS or FS, the strength marginally reduces (up to 7%) compared with the conventional mortar, which is attributed to their similar hydration products amounts at the interfacial transition zones of binder‐sand. At cement replacement levels of 90–100%, the strength of the WBMs degrades; however, the loss in strength is limited to ~20–30%. These promising results indicate the possibility of developing new eco‐friendly mortars for structural applications by completely replacing cement and NS with waste materials.