مشخصات پژوهش

The high production cost of reactive powder concrete is a major challenge limiting its widespread use. The high cement content and quartz powder dosage increase manufacturing costs significantly. This study examines the effect of various aggregate amounts on compressive strength, standard water absorption, and curing time water absorption of RPC. Initially, the total aggregate amount—micronized quartz powder plus silica sand—was kept constant in all mixes, while the quartz powder ratio to the total aggregate varied at 5%, 10%, 13%, 16%, 19%, 22%, and 25%. These mixes were labeled Q1 to Q7. Then, the same mixes were tested again, replacing quartz powder with a 50%-50% blend of quartz and diatomite powders, named D1 to D7. Specimens were cured in water at 25°C without autoclaving and tested at 7, 14, and 28 days. All samples showed high strength, ranging from about 71 to 85 MPa at 28 days. Therefore, in areas where quartz powder is costly, it is feasible to reduce its content to 5–10% or replace it with the 50%-50% quartz-diatomite blend. The optimal mixes, Q5 and D5, showed the highest 28-day strength with no issues in workability or water absorption. Both have a quartz powder ratio of 19%. Their compressive strengths at 28 days were 84.2 MPa and 82.5 MPa, respectively. The differences in curing-time water absorption among the mixes in both the first and second parts of the study are very slight. Similarly, the results of 28-day standard water absorption based on ASTM C1585 show minimal variation across both series. This indicates that the capillary porosity remains nearly constant in all mixes.