The Influence of the Dry Density on the Mechanical and Durability Properties of Roller Compacted Concrete Pavement Using the Response Surface Method

In the current study, the response surface methodology has been used for designing of the experiments. Considering the conventional soil-compaction method, the main factors investigated include cement and w/c contents. The upper and lower levels of the factors of cement and w/c content were 308-392 kg/m3 and 0.34-0.39, respectively. The dry specific weighs, compressive strengths, permeable voids, and capillary absorption coefficients were determined according to the ASTM D 1557, ASTM C39, ASTM C642 and ASTM C1585 at ages up to 180 days, respectively.
Using the statistical analyses, the prediction models and contours of the durability characteristic and 28 day compressive strength were derived. The analysis of variance (ANOVA) was also performed on the results to estimate the significance of the factors. It could be concluded that the terms of the cement content, w/c and their interaction significantly influenced the responses of the compressive strength, dry specific weight, water absorption and permeable voids. The results also indicated that by obtaining an optimum level of dry density one could reach the lowest level of permeable voids and water absorption into the concrete. This is achieved by adjusting the interaction of cement content and w/c content. However, no meaningful correlation was found between the dry density and capillary absorption coefficient. This indicates that the tortuously and continuously of microstructure may be independent from the dry density. However, similar contour trends were obtained for the dry density and capillary absorption coefficient.