Evaluation and Mix Design of Cement-Treated Base Materials with High Content of Reclaimed Asphalt Pavement

Reclaimed asphalt pavement (RAP) and granular base materials were collected from stockpiles throughout Texas to evaluate the feasibility of using mixes containing high RAP content for base course applications. Mixes containing 100%, 75%, and 50% RAP treated with 0%, 2%, 4%, and 6% of portland cement were evaluated in a full-factorial laboratory experiment. For mixes of 75% and 50% RAP, both virgin and salvage base materials were used. Experimental results indicated that besides the cement content, the RAP content and finer aggregate content significantly affected the properties of the RAP mixes, but the effects of RAP type and asphalt content in RAP were limited. To achieve a 300-psi unconfined compressive strength as required by the Texas Department of Transportation, the optimum cement contents were statistically about 4%, 3%, and 2% for mixes of 100%, 75%, and 50% RAP, respectively. Because the achievement of any specified strength or stiffness might not always ensure the durability of a mix, other parameters that might be relevant to performance and long-term durability were evaluated through laboratory testing. These parameters included modulus, indirect tensile strength, and moisture susceptibility as well as cement leaching.