Evaluation of Construction Limestone Aggregate Sourced in the Northern Part of Jordan using Superpave Tests

Abstract

SUPERPAVE is an acronym that stands for SUperior PERforming asphalt PAVEments. Superpave system is the outcome of a 5-year, $150 million research program (the Strategic Highway Research Program or SHRP) that was conducted during the time period of 1987-1992 in the United States (US) to enhance the performance of asphalt pavements. Superpave system developed and used consensus properties tests as well as source properties tests for the aggregate materials to improve the specifications and criteria used for aggregate properties. The end result will be improved performance for asphalt pavements of highways. In this study, limestone aggregate sourced in the northern part of Jordan was evaluated according to the Superpave tests. Therefore, the study aimed at evaluating the limestone aggregate material available in the northern part of Jordan for Superpave consensus aggregate properties as well as source aggregate properties to investigate the suitability of this type of aggregate for pavement construction of highways in Jordan. Limestone is considered the most common aggregate type that is used for pavement construction; all the highway pavements in Jordan are asphalt-surfaced pavements except for one highway in the southern part of the country, which has a rigid concrete pavement. The Superpave tests for consensus aggregate properties were used to evaluate the aggregate material. Those tests include: coarse aggregate angularity (CAA), flat and elongated (F&E) particles, fine aggregate angularity (FAA), and sand equivalent (SE) tests. In addition, other tests for source aggregate properties including: Los Angeles (LA) abrasion, specific gravity and absorption of coarse aggregate, specific gravity and absorption of fine aggregate, and deleterious materials tests were used in the evaluation. Basalt aggregate was also used in this study for comparison with the limestone aggregate. Basalt aggregate exists heavily in the eastern part of Jordan. Therefore, basalt aggregate sourced in the eastern part of Jordan was evaluated in this study. In the last few years, the Ministry of Public Works and Housing (MPWH) in Jordan started to search for new aggregate materials to be used for highway pavements due to the high abrasion value for the currently-used limestone aggregate that leads to polished pavement surface. As a result, skid resistance values on highway pavements are usually lower than the minimum requirement leading to lower road safety on these highways.