Alternate Materials for Limestone Rock Asphalt (Revised)

摘要

The primary objective of the study is to identify cold-laid paving materials which could provide viable alternatives to Limestone Rock Asphalt (LRA) currently produced by Vulcan Materials Company at its quarry near Uvalde, Texas. The requirements were that the materials be suitable for stockpiling application in winter-wet weather, not require specialized equipment for handling, and be cost-effective. To meet the objective of the study, performance requirements for successful cold, wet-weather pothole and surface patching materials were established, using surveys of maintenance programs in Texas and other states. The study also involved the field testing and performance evaluation of a number of cold, wet-weather maintenance materials. A total of 13 different maintenance mixture designs were evaluated in seven districts. Both pothole and surface patching (blade-on) maintenance operations were incorporated into these trials. The performance of these materials was evaluated over a nine month period. All participating districts were visited at least twice during this period, and discussions relative to the handling and performance of these mixtures were held with the district maintenance personnel. A laboratory test program was performed to characterize the materials utilized in the field trials. It was found that most current mix designs for hot mix-cold laid, maintenance materials were inadequate except at temperatures above 60 F. Stockpile hardening often required that mixtures be softened with additives and reworked before they could be placed. To offset these deficiencies, a new mix design was generated using criteria gleaned from literature and field surveys.