AASHTO T 166-21 PDF Download

The AASHTO T 166-21 standard provides a method for determining the bulk specific gravity (Gmb) of compacted hot mix asphalt (HMA) using saturated surface-dry (SSD) specimens. This method is not suitable for samples with open or interconnecting voids or that absorb more than 2.0 percent of water by volume. In such cases, other test methods like T 275 or T 331 should be used.

The purpose of determining the bulk specific gravity of compacted HMA is to calculate the unit mass of the mixture. This information is essential for various engineering calculations and designs related to HMA. It ensures the accuracy and quality control of the asphalt mixture.

The standard specifies the procedure for preparing the SSD specimens and conducting the test. It includes details on the equipment required, such as a balance, a specific gravity refractometer, and an oven. The test involves measuring the weight of the SSD specimen in air and in water to determine its volume and ultimately calculate its bulk specific gravity.