Blends of limestone powder and fly-ash enhance the response of self-compacting mortars

Because concrete and mortars both contain aggregate phase, it may be expected that the trend of results obtained from mortar formulations should be similar to those of concrete or vice versa. Many researchers have used either limestone powder (LSP) or fly-ash (FA) in self-compacting concrete systems. However the present study shows that using either of these secondary raw materials (SRMs) in self-compacting mortar systems does not produce an optimized response. However mixing LSP and FA in suitable proportions and then using this blended SRM enhances the response of self-compacting mortar systems as both FA and LSP seem to complement the properties of each other especially the negative ones. The formulations contain two base SRMs (limestone powder and fly-ash) and in others these two basic SRMs have been replaced at 20% of their mass by some other SRMs or their combinations. Parameters like flow, strength, microstructure, relative water absorption and early volume stability of self-compacting mortar systems have been studied. The results indicate that self-compacting mortars using blended secondary raw material of limestone powder and fly-ash had an improved overall response than those using either of them.

► Using either of LSP and FA in SCM systems does not produce an optimized response.
► Blends of LSP and FA enhance the response of SCM systems.
► Increasing LSP and decreasing FA content reduces the hardening times and strength.
► Increasing FA and decreasing LSP in SCMs the reverse may be true.