In full-depth reclamation, what is the purpose of adding cement or lime to the pulverized material?

In full-depth reclamation (FDR), the purpose of adding cement or lime to the pulverized material is to improve the strength, stability, and durability of the reclaimed base layer. The existing asphalt pavement and a portion of the underlying base material are pulverized into a homogenous mixture. Adding cement or lime acts as a stabilizing agent, binding the pulverized material together and increasing its load-bearing capacity. Cement, when hydrated, forms strong bonds between the soil particles, creating a rigid and durable base layer. Lime reacts with the clay minerals in the soil, reducing its plasticity and increasing its strength. This makes the base layer less susceptible to deformation and cracking under traffic loads and environmental conditions. The addition of cement or lime also reduces the permeability of the base layer, preventing water from infiltrating and weakening the pavement structure. The stabilized base layer provides a strong and stable foundation for the new asphalt surface, extending the life of the pavement and reducing the need for future maintenance. The amount of cement or lime added depends on the type of soil, the desired strength, and the expected traffic loading.