Designing Cold Mix Asphalt (CMA) and Cold-In-Place Recycling (CIR) Using SUPERPAVE Gyratory Compactor.

摘要

The purpose of this research was to develop a performance related mix design procedure for both cold mix asphalt (CMA) and cold-in-place Recycling (CIR) using the Superpave Gyratory compactor (SGC) and evaluate the performances of the mixes using the proposed mix design method.;Two types of aggregate gradations (coarse and fines) according to Superpave specifications and two types of emulsions (CSS-1 and engineered emulsion) were used for the mix design of CMA. The mix designs were conducted following two different methods: a modified Proctor method and a mix design method using the Superpave gyratory compactor. The modified Proctor method was useful in identifying the total fluid content required to achieve maximum dry density of the CMA, but it did not help to obtain the required amounts of water and emulsion separately. The mix design method using the Superpave gyratory compactor was successful in identifying both optimum emulsion content and water content of CMA mixes.;The designed CMA mixes using the Superpave gyratory compactor were evaluated for their moisture susceptibility and raveling performance. The mixes did not perform well in both tests. As a mitigation measure for moisture susceptibility problem, hydrated lime was added to the CMA mixes and the mix designs were conducted again. The identified mix design method for designing CMA mixes was not successful in achieving the target air void of 10.0+/-1.0% suggesting that the mix design needs to be studied further.;For the mix design of CIR, two types of RAP gradations were evaluated; a graded RAP according to Pacific Coast Conference on Asphalt Specifications (PCCAS), and a non-graded RAP passing 1 inch sieve and two types of emulsions (CMS-2s and engineered emulsion) were used. The mix designs for CIR were conducted following two different methods: a modified Proctor method and a mix design method using the Superpave gyratory compactor. The modified Proctor test method resulted in higher water content to achieve the maximum dry density of the CIR mixes, but it is not practical in the field. Therefore, the modified Proctor method was not evaluated further. The mix design method using the Superpave gyratory compactor was successful in identifying both optimum emulsion content and water content of CIR mixes.;The designed CIR mixes using the Superpave gyratory compactor were evaluated for their moisture susceptibility and raveling performance. The mixes did not perform well in both tests. As a mitigation measure for moisture susceptibility problem, hydrated lime was added to the CIR mixes and the mix designs were conducted again. The CIR mixes with lime were evaluated for their performances and they showed significant improvement. The CIR mixes were evaluated further for their rutting resistance using the repeated load triaxial (RLT) test and they performed well. The dynamic modulus of the CIR mixes were measured and the master curves were developed using a modified equation given in AASHTO PP61 and they were found to be equivalent to that of hot mix asphalt.