Indirect tensile strength at high temperatures

The indirect tensile strength test at high temperatures (HT-IDT) has been found to correlate well with rut depth (Transportation Research Circular C-C068 2004) and can be used as an alternative mix design to evaluate the rut resistance of hot mix bituminous mixture (NCHRP Report 673 2011). 

The HT-IDT is carried out according to AASHTO T 283 (2011) (ASTM D 6931 2012) for unconditioned, that is, dry, specimens, but at a different test temperature. The test temperature is 10°C lower than the average 7-day maximum pavement temperature 20 mm below the surface for a given location, at 50% reliability as determined by the LTPPBind (LTPP Products Online 2013) software. 

Unlike AASHTO T 283 (2011), the specimens in this procedure are compacted by a gyratory compactor to produce an air void content of approximately 4%. 

The specimens are conditioned at the test temperature for at least 2 h, and if a water bath is used, they should be tightly sealed in plastic bags to prevent them from getting wet. 

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Note AMPT, asphalt mixture performance tester APA, asphalt pavement analyser FN, flow number HWTT, Hamburg wheel track tester IDTHT, indirect tensile strength at high-temperature test MPSS, maximum permanent shear strain SST/ RSCH, superpave shear tester/repeated shear constant height. 

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