PRESERVATION UPDATE |
BY BARRETT REESE
THE SAFER ROAD: How Lightweight Aggregate Improves Asphalt Chip Seal Aggregates made from expanded shale, clay or slate (ESCS) enhance road safety not just when the pavement is placed, but throughout the life span of the product.
ways, asphalt chip seal made from ESCS improves paved surfaces from the day it’s placed to the day it’s replaced. The following takes a closer look at the many ways bond strength, polish resistance and consistent chip size contribute to safer and higher quality roads.
VOID IS BOND: INCREASED BOND STRENGTH IS MORE THAN JUST RETENTION ESCS’s internal network of unconnected pores increases the bond strength between it and the oil sealant. This leads to a greater percentage of chip retention when the asphalt chip seal is first placed.
S
afer roads begin with safer materials. Lightweight aggregate’s ability to improve road surfaces is due to its manufacturing process. The raw material is heated to 2000 degrees Fahrenheit in a rotary kiln. During this step, it softens and air bubbles form. The bubbles remain as unconnected pores when the aggregate cools. These voids inside ESCS particles allow the oil sealant to penetrate deep within the aggregate mix, resulting in fewer incidents of dislodged pavement. They also resist polishing to maintain a high level of skid resistance. While these qualities help contractors create safer and longer lasting roads, they are not the only ways lightweight aggregate made from ESCS can create higher quality asphalt chip seal. After the material cools, it is crushed, sifted and re-crushed to create a highly regulated particle size. This not only ensures consistent coverage but also reduces the damage large chips may cause to paving equipment. In these
44
ASPHALT CONTRACTOR DECEMBER 2022
ACON1222_44-47_Preservation_BN.indd 44
www.ForConstructionPros.com/Asphalt
11/22/22 2:11 PM