Evaluation of cement stabilization of a road base material in conjunction with full-depth reclamation in Huaquillas, Ecuador

Resumen

Evaluation of Cement Stabilization of a Road Base Material in Conjunction with Full-Depth Reclamation in Huaquillas, Ecuador Dario David Batioja Department of Civil and Environmental Engineering Master of Science The primary purposes of this research were to classify the pavement materials sampled from a failed road in Huaquillas, Ecuador, investigate the optimum cement content required to stabilize a blend of the moisture-susceptible base material and recycled asphalt pavement (RAP),and recommend a flexible pavement design adequate for the conditions at the site.The laboratory procedures consisted of material classifications, sulfate concentration tests, compaction tests, California bearing ratio (CBR) tests, unconfined compressive strength (UCS) tests, and tube suction tests (TSTs). The RAP, base, subbase, and subgrade materials tested in this research were sampled by the municipality personnel of Huaquillas, Ecuador, and shipped to the Brigham Young University Highway Materials Laboratory for evaluation. The studied road has one paved lane in each direction, and the existing pavement structure consists of 4.0 in. of asphalt on 6.0 in. of base on 15 in. of granular subbase. The sulfate concentrations for the base, subbase, and subgrade were all below the maximum threshold of 3000 ppm, indicating that the introduction of cement to these materials should not cause sulfate swelling problems. The base, subbase, and subgrade materialshad average CBR values of 31, 18, and 12, respectively. The RAP-base blend treated with 2.0, 4.0 and 6.0 percent cement had average 7-day UCS values of 233, 417, and 624 psi, respectively. Additionally, the base and subbase had average final dielectric values of 18.1 and 27.4, respectively, in the TST. On the other hand, after the 10-day soak, the RAP-base blend treated with 2.0, 4.0, and 6.0 percent cement had average final dielectric values of 5.3, 5.2, and 5.4, respectively, indicating that cement treatment helps the materials improve to a non-moisturesusceptible condition. Pavement reconstruction using full-depth reclamation (FDR) in conjunction with cement stabilization is recommended for this project. Based on the results of the UCS tests and TSTs performed in this research, a cement content of 4.0 percent is recommended for stabilizing the 50:50 ratio of RAP to base evaluated in this research. Two alternative pavement configurations were designed, both of which involve FDR. Design A specifies 4.5 in. of new HMA overlying 8.0 in. of CTB and 17 in. of granular subbase, and design B specifies 4.0 in. of new HMA over 9.0 in. of CTB and 16 in. of granular subbase. Both pavement designs provide adequate protection to each layer and should provide satisfactory performance for this site in Huaquillas, Ecuador.