The Use of Pre-Wetting to Improve the Mechanical Behavior of Masonry Mortar Elaborated with Crushed Oyster Shell

In this research, the use of the pre-wetting technique is proposed as an ecological alternative to reduce water absorption in waste oyster shells used in the production of masonry mortar as a partial substitute for natural sand. An experimental study was conducted to assess the properties in both the fresh and hardened states of masonry mortars. Two mortar groups were prepared based on a control mixture, with natural aggregate replaced by crushed oyster shell (COS) in varying proportions. In one group, the COS was pre-wetted, while in the other group, the COS was used at its natural moisture content. The experimental results demonstrated that the pre-wetting process aided in reducing the water–cement ratio (w/c) in the mortar mixture, thereby improving its properties. In both mortar groups, favorable results were observed with respect to capillary water absorption. Although the compressive strength was affected by the incorporation of COS, pre-wetted mortars with substitutions of up to 30% achieved the reference value established in this research. The pre-wetting process proves to be a straightforward and cost-effective technique; it is environmentally friendly and will contribute to decreasing the accumulation of COS in landfills, thereby safeguarding natural material reserves.