The influence of simple ionic solution on consistency and strength of hydrated lime and cement mortars

Consistency which defines the workability of mortars in the freshly-mixed wet stage has been determined for hydrated lime (CL90) and cement (PC) mortars using flow table. CL90 mortar (i.e. the non-hydraulic pure lime mortar) has dramatically lower consistency than cement mortars. The work reported in this paper on hydrated lime and cement mortars has shown that the consistency of these mortars decreases as their hydraulicity. We have shown in this study that the consistency of CL90 mortars can be manipulated by the presence of cement and demonstrated that when CL90 is partially replaced cement, CL90 mortars have the same consistency as PC mortars. It is perhaps surprising that a simple compound such as sulphate has almost the same effect as PC on consistency of hydrated lime mortar. The very low consistency is one of the main barriers to the use of hydrated lime mortars in masonry construction. Therefore, the use of hydrated lime mortars may be encouraged if the simple ionic solutions as mix water can be shown to bring hydrated lime mortar up to the same consistency as PC mortar. Authors also investigated the effect of this simple ionic solution on the hardened state properties of CL90 mortars and demonstrated that the presence of sulphates as mix water significantly enhanced the hardened state properties of CL90 mortars. CL90 mortars prepared using sulphate solutions in mix water at 28, 56 and 91 days demonstrated significant increase in both flexural and compressive strength when compared to CL90 mortar alone. We clearly demonstrated in this paper that the presence of sulphate solutions as mix water in CL90 mortars both increases the consistency to release one of the main barriers of the use of hydrated lime mortars in construction and enhances the hardened state properties such as flexural and compressive strength.