What is the minimum temperature at which hot mix asphalt concrete material should be accepted at the time of spreading and compaction?

The minimum temperature for accepting hot mix asphalt concrete material during the spreading and compaction phases is established to ensure optimal performance and workability of the asphalt. At 139°C, the material maintains the right viscosity and pliability necessary for proper compaction. This temperature facilitates the ease of spreading and helps achieve needed bond attributes with the underlying layers.

When the temperature is too low, the asphalt mix can become too rigid, leading to difficulties in compaction and preventing the achieving of desired density. It also affects the bond between layers, which can lead to performance issues in the finished pavement.

Thus, 139°C is the specified minimum temperature to ensure that the asphalt is workable and can be compacted effectively, leading to a durable and high-quality pavement structure.