Properties of concrete mortar incorporating recycle pulverized sandblasting waste as additives

Sandblasting waste is a by-product obtained from the ship maintenance industry which is rich in silica content. This waste has a smaller particle size compared with typical sand and contains a high prevalence of impurities, so it is categorized as toxic and hazardous materials based on Indonesian Law. Furthermore, it also has not been efficiently harnessed, with most of it being relegated to disposal in waste landfills. To solve those problems, this research aimed to reduce the waste by reuse and recycle the sandblasting waste. In this study, the Pulverized Sandblasting Waste (PSW) used as additives in concrete mortars. Prior to use as an additive in mortar, the sandblasting waste was pretreated using chemical and mechanical processes. The mechanical pre-treatment was performed by pulverization for 8 and 12 h, later called PSW8h and PSW12h, respectively. Eleven mixture proportions were designed with constant Cement and w/c ratio. The PSW was added to the mortar specimens with a percentage of 0-5% from the weight of Cement as an additive. The test performed in this study includes compressive strength, Strength Activation Index (SAI), porosity, water absorption, and flexural test. The experimental results show that adding PSW into the mortar can enhance compressive and flexural strength. Furthermore, the results indicate that mortar with PSW has significantly lower porosity and water absorption than the control mixture. Using PSW with finer particle size shows better results in mechanical and durability properties of mortar, especially in concrete compressive and flexural strength.