HL3 or HL3A Hot Mix Asphalt. Exactly what does that mean and which one should you use on your driveway?
HL stands for Hot Load and 3 represents the size of the aggregate used. Generally speaking the majority of the aggregate and stone used in this mix would be 13.2 mm mixed with sand and other fines.
The aggregate mix of up to 13.2 mm stones and sand make up approximately 95% of the asphalt mix used to pave a driveway. The other 5% is the asphalt cement otherwise known as bitumen or liquid asphalt. Bitumen is the heavy oil or sludge leftover in the bottom of the barrel during the oil refinery process.
The bitumen component (oil basically) is to blame for the softening of our asphalt surfaces during heat waves. It is necessary to use as a binding agent for the aggregates but it will remind us that it is an oil product during a heat wave!
So, Hot Load 13.2 mm aggregate Hot Mix Asphalt or simply HL3 Hot Mix Asphalt is the most commonly used asphalt mix.
The difference between HL3 and HL3A is simply the amount of sand in the mix. The more sand in the mix, the softer and smoother the driveway will be. The more 13.2 mm aggregate used in the mix, the stronger and more durable the driveway will be.
This means that HL3 is a stronger asphalt mix than HL3A. Since more gravel is added to the mix it will be observed on the completed asphalt surface. It will also react a little less during a heatwave.
HL3A will be softer and smoother and may still hold up well under light use conditions.
Northland Paving recommends the use of HL3 Hot Mix Asphalt because we prefer to build a stronger driveway.