Road agencies and road owners are often looking for solutions to decrease their maintenance costs, and therefore their lifecycle costs. As a result, they typically look at the quality parameters that affect the lifetime of the road.
Hydrated lime is chemically active filler. It offers synergistic benefits by increasing resistance to moisture sensitivity and to rutting resistance, because it makes the mix stiffer and tougher at higher temperatures. This results in an asphalt mix that is more resistant to fatigue failure and cracking. Moreover, hydrated lime reduces the rate of asphalt pavement aging by slowing the oxidation of bitumen. As a result, the pavement remains more flexible over time, and is protected from brittle cracking for years longer than it would be without the contribution of lime.
As pavements age, cracking often begins with the formation of micro-cracks. These in turn coalesce to form pavement-damaging macro-cracks. Hydrated lime particles reduce cracking, as the lime reacts with elements within the bitumen, forming larger pieces that are better able to intercept and deflect micro-cracks. This prevents the micro-cracks from growing into the larger cracks that contribute to pavement failure.
North American State agencies estimate that hydrated lime increases the durability of asphalt mixtures from 20 to 50%. In Europe, French road managers have suggested that the beneficial effects of hydrated lime increase durability by 25%, in terms of wearing course service life expectancy. (Source: EuLA)