Investigation of concrete properties to support implementation of the new AASHTO pavement design guide

Abstract

This research was conducted to investigate the splitting tensile strength and coefficient of thermal expansion (CTE) of concrete to support implementation of the AASHTO Mechanistic-Empirical Pavement Design Guide in Wisconsin. Wisconsin Department of Transportation (WisDOT) Grade A-FA Class C fly ash concrete mixtures containing selected types of coarse aggregates from 15 sources were investigated: glacial gravel from six sources, dolomite from five sources, quartzite, granite, diabase, and basalt. In addition, using concrete containing dolomite, effects of cementitious materials were investigated such as the source of cement, the source of fly ash, the use of GGBFS vs. fly ash, and the use of cement alone vs. cement plus fly ash. The splitting tensile strength test results of the concrete mixtures made with glacial gravel varied when the source of the gravel was changed. The splitting tensile strength of concrete mixtures made with dolomite varied significantly depending on the source. The types and sources of cementitious materials also affected the splitting tensile strength of the concrete made with dolomite. The splitting tensile strength measured by this testing program was about 30% higher, when compared with the values estimated from compressive strength using the mechanistic-empirical design guide for Level 2 design (lower accuracy than Level 1). Concrete using quartzite had the highest CTE of 12.2 ? 10 supra -6/?C (6.8 ? 10 supra -6/?F). Concrete mixtures using diabase, basalt, and granite had the lowest CTE of 9.3 to 9.5 ? 10 supra -6/?C (5.2 to 5.3 ? 10 supra -6/?F). Concrete mixtures using glacial gravel from the six sources had CTE values of 9.7 to 10.7 ? 10 supra -6/?C (5.4 to 5.9 ? 10 supra -6/?F). Concrete mixtures using dolomite from the five sources had relatively uniform CTE values of 10.4 to 10.8 ? 10 supra -6/?C (5.8 to 6.0 ? 10 supra -6/?F). The types and sources of cementitious materials had a negligible influence, 0.0 to 0.2 ? 10 supra -6/?C (0.0 to 0.1 ? 10 supra -6/?F), on the CTE of concrete made with dolomite. It is recommended that concrete containing cementitious materials and coarse aggregates other than the ones evaluated in this project be tested for splitting tensile strength. It is also recommended that concrete containing coarse aggregates other than the ones evaluated in this project be tested for CTE. CTE testing of concrete containing other sources of dolomite does not appear to be necessary.