Developing Effective Test Methods for Evaluating Cold-Mix Asphalt Patching Materials

Cold-mix asphalt (CMA) is routinely used for temporary or emergency pothole repair to prevent further deterioration of the asphalt pavement until resurfacing can be performed. One of the difficulties encountered with CMA is that the majority of laboratory evaluations and tests were originally designed for hot-mix asphalt. There exists an incomplete understanding between viscosity gain of cold-mix binder (CMB) and strength development of CMA. The objective was to develop effective test procedures to assess the engineering properties and performance of the CMA. Results showed that the accelerated curing process with 110 degrees C for 24 h has the potential for predicting the engineering properties of the CMAs at mature state. The stability and rutting resistance of the CMAs with high CMB viscosity appear to be comparable with those of hot-mix asphalt. The CMB viscosity of 13 Pa . s (130 poise) was suggested to specify the engineering properties and performance of the CMAs. In addition, simplified wheel track testing could be useful to simulate the detrimental influence of moisture on the performance of the CMAs in the field pothole. In this study, as the workability was within the specification range, a dense-graded mix with a fast curing rate at full compaction was desired for use as a good asphalt patching material. (C) 2016 American Society of Civil Engineers.