Asphalt Compaction Tips

Once your asphalt material is laid down, follow the best practices below to ensure it is compacted properly.

• Mix Temperature – In general, the hotter the mix, the better the compaction result. However, the ideal rolling temperature varies based on a variety of factors, like mix composition, layer thickness, and the binding agent used.
• Roller Passes – The best way to complete asphalt compaction is to start at the seams and then move along the edge of the pavement. In bends or turns, the compactor operator should compact the lane that has the smallest radius first and press down the pavement on the next pass. Dynamic compaction is used for subsequent passes with the whole operation completed by a final roller pass to remove any remaining imperfections.
• Base Conditions – Base type and condition alter the level of compaction required in a new layer of asphalt. The amount of compaction needed depends on if the asphalt layer is on top of sub grade soil, aggregate base course, cold mix asphalt, cracked asphalt pavement, new asphalt concrete, or Portland cement concrete pavement. 
• Environment – The temperature of the air and base, wind speed, and cloud cover all affect the cooling rate of the mix and the level of compaction required.

3 factors that affect your screed depth

• Speed – The faster you travel the less your screed will rise up on the head of material, so you will need to increase your attachment angle. Similarly, if you are slowing down to make a turn or a tie in, the screed will ride up on the head of material more.
• Mix – The asphalt you put through your spreader changes day to day and even truck to truck. It may have more aggregate, more liquid, or it may have sat longer. With this in mind, you always need to watch your depth and match height and make fine adjustments as needed.
• Screed angle - The attachment angle on your screed controls the depth. When starting a new job for the first time, make sure you null out your screed on a flat surface. Once you set down on the mat for your first pull, then adjust your screed. It is typical for one turn of the screw to increase or decrease the material height by ½ inch.

Most common screed error: dropping the match height lower than the main screed

The match height adjusts the extension up or down in relation to the main screed. It needs to be adjusted in order to get the perfect mat. However, if you drop it lower than the main screed, you will get material starvation on your main screed. Soon after you will see shadowing or tearing behind your main screed and the screed will start to dive because it doesn't have any material to ride on.

To avoid this from happening, you should set the extension match height to the point where you start to see a small line coming off the corner of your main screed. Once you have that, you can leave it there, because this will typically roll out easily. However, if you want that perfect look, bump your match height down slightly to remove your line. Don't go too far, however, or you will have the same problem stated above.

Contact Pittman Tractor for more information on asphalt paving and asphalt compaction!