Influence of high contents of limestone fines on rheological behaviour and bond strength of cement-based mortars

This paper investigates the influence of cement replacement by high contents (30%vol and 60%vol) of limestone fines on rheological behaviour and mechanical properties of mortars as well as on the bond strength of mortar-ceramic interface. Mortars with 75%vol of sand and 25%vol of fines were produced using cement and two limestones having different particle size distributions and surface areas. A similar set of mortar compositions was also prepared using a polycarboxylate-based dispersing admixture. Rheological behaviour of the mortars varied depending on type and content of limestone fines, and whether the admixture was added. Elastic modulus and tensile strength of the mortars decreased with the increase of limestone content. However, for replacement rates of 30%vol, the tensile bond strength between mortar and ceramic block increased, likely because of ITZ densification. The dispersing admixture improved the tensile bond strength of all compositions without necessarily increasing their mechanical properties. The obtained results were compared to others available in the literature.