Fresh and hardened state behaviour of aerial lime mortars with superplasticizer

Abstract

Water-reducing admixtures have the potential to minimize the disadvantages that typically discourage the use of lime in restoration works. However, the knowledge on the effect of these admixtures on the properties of lime mortars is not as consolidated as it is for cement-based materials. Therefore, this paper aims at studying the influence of two types of superplasticizer, one based on polycarboxylate ether (PCE) and the other on polynaphthalene sulfonate (PNS), on the fresh and hardened state properties of lime mortars. PCE was found to be more effective (higher dispersing ability) and efficient (less quantity needed) than PNS, leading to a lower fluidity loss over time, but to a higher tendency towards bleeding. Both admixtures led to a substantial mechanical strength increase, even at early ages, and just to small changes in the porous structure of the mortars, which suggests that lime mortars with superplasticizer have potential to be used in restoration.