Underwater surface abrasion of conventional and geopolymer concrete using the ASTM C1138 approach

This study focuses on the development of unique geopolymer-based composites made using industrial byproducts and waste materials. The first test variable was the compressive strength grade, where conventional concrete specimens with ordinary Portland cement (OPC) and GPC specimens having three target design strengths (20, 30 and 40 MPa) were prepared and tested. All specimens were tested at different ages, which is the second variable of the study, where early ages (3 and 7 days) and mature age (28 days) were adopted. It is worth mentioning that both geopolymer and concrete samples had the exact quantities of filler and binder materials. Then, the specimens were tested following the procedure of standard ASTM C1138 approach under-water abrasion tests, which were conducted at 6 intervals of 12 h each. The recorded abrasion results revealed higher abrasion losses for specimens with lower design strengths regardless of the type of concrete. Besides, the influence of the sample's age on enhancing the abrasion resistance was more apparent in conventional concrete samples than geopolymer ones since the last gained their design strength early, about three days. The GPC specimens exhibited lower abrasion losses compared to their corresponding OPC ones revealing a better abrasion resistance. The difference was the highest at the age of 3 days due to the early strength development of GPC. The abrasion resistance enhancement of GPC specimens compared to their corresponding OPC ones at 3 days was 72% for the design strength of 20 MPa and around 55% for the higher design compressive strengths.