Construction Engineering

Vacuum setup

Z.022-01/02 Asphalt conditioning & MVM

General information

Determination of the maximum density

The maximum density of bituminous mixtures, in combination with the bulk density, is determined to calculate the void content of compacted bituminous samples. It is the mass per unit volume, excluding air voids, of the bituminous mixture.

Different procedures can be used to determine this parameter. In the volumetric and hydrostatic procedure the maximum density is determined from the volume of the sample (without air voids) and its dry mass. In the mathematical procedure, the maximum density is calculated from its composition.

In the volumetric procedure the volume is measured as the displacement of water by the sample in a pyknometer + head piece. Therefore a calibrated pyknometer is filled with de-aired water and a loose sample. The air included in the volume will be evacuated by a vacuum system and the maximum density will be derived by measuring different masses.

Saturating bituminous specimen for ITS-R 

For the ITS-R procedure half of the set of cylindrical bituminous test specimens needs to be saturated and stored in water. Therefor the specimens are placed on perforated shelf in the vacuum container filled with water (20 ± 5 )°C. A vacuum is slowly applied to obtain a absolute pressure of (6,7 ± 0,3) kPa and maintained for (30 ± 5)min.

Standards