Strength and Deformation Characteristics of Cement-Treated Reclaimed Pavement with a Chip Seal

Abstract

The objective of this research was to analyze the strength and deformation characteristics of a cement-treated base (CTB) constructed with full-depth reclamation, microcracked, and then surfaced with a single chip seal. In this field study, strength characteristics of the CTB layer were determined at the time of construction, and both strength and deformation characteristics were evaluated after 9 months of low-volume, heavy truck traffic. Observed distresses at 9 months included transverse cracking, rutting, and chip seal joint failure. The loss of the chip seal was caused by poor chip seal construction practices and not a deficiency in the CTB layer. The average ride qualities in and out of the wheelpath were in the fair ride category; the roughness was not likely caused by trafficking but probably resulted from construction or climatic factors. Structural testing performed after 9 months of service indicated that CTB stiffness and modulus were greater than the values measured after microcracking at the time of construction, indicating continued strength gain. However, trafficking over the 9 months had caused significantly lower stiffness in the wheelpaths than between the wheelpaths. The average unconfined compressive strength (UCS) of the cores tested at 9 months did not differ significantly from the average UCS of the field-compacted specimens tested at 6 weeks. Recommendations for improved CTB performance include the use of a thicker, stiffer, or both, CTB layer to ensure a smooth CTB surface during construction and application of a double chip seal or equivalent.