Zahidul Q. Siddique

Effect of Quarry Production Process on Specific Gravities of Aggregates

The combined bulk specific gravity of aggregates is a basic input in the Superpave asphalt mixture volumetric design. In order to identify and quantify the factors affecting the aggregate specific gravity values, tests methods similar to AASHTO T84 and T85 were conducted on aggregate samples collected from four different quarries in Kansas. All test results were analyzed statistically to find the significance of the factors—top size and fine loss of the aggregates during replicate testing—used in the experimental program. The results show that the bed from which the aggregates are produced has a significant effect on the specific gravities. However, different aggregate products obtained from the same bed in a quarry may have dissimilar specific gravities. The analysis also shows that the aggregate production process affects the specific gravities significantly when the aggregates are softer, such as soft limestone in Kansas. Fine loss during replicate testing does not affect the results for harder aggregates.

Portland cement concrete pavement roughness and dynamic wheel loads

This paper deals with the dynamic wheel loads (DWL) generated by different trucks with varying vehicle characteristics in response to different levels of roughness for Portland Cement Concrete Pavement (PCCP) surfaces. Six newly built PCCP sections in Kansas were selected for this study. A truck simulation software package, TruckSim, was used for calculating DWL. The road roughness was represented by the statistics, International Roughness Index (IRI) and Profile Index (PI). The calculated maximum DWL was significantly affected by the roughness level, simulation speed, and pavement age. Although maximum DWL increased with higher PCCP roughness, the increase was not linear. The study shows that a PCCP with an IRI greater than 1.5 m/km will generate 4-7% higher DWL than for a PCCP with IRI less than 1.0 m/km.