Reducing Sample Size for Cold In-Place Recycling Design and Testing

Abstract

Abstract Many current methods of designing and testing cold in-place recycled (CIR) asphalt are undesirable because they require large amounts of material and significant preparation. In an effort to lessen the cost and time of materials testing, this research utilizes several different methods of small scale testing of creep stiffness. These methods include using a discovery hybrid rheometer (DHR) and a three point bending test to find the creep stiffness of emulsion based CIR. The new testing methods used samples on the scale of up to a hundredth the size of what the traditional methods of testing require. The two smaller scale tests were compared to the traditional indirect tension test (IDT) testing. In order to fully evaluate the two reduced sample size test methods, this research observed the effect of gradation, temperature, emulsifier type, and recycled asphalt pavement (RAP) content on creep stiffness. If successful, the use of these new test methods could significantly decrease the damage done to roads, and reduce the cost of material management incurred through the quality control testing methods for pavement. Results showed very good correlation between DHR and IDT testing with a proportional difference between the samples. The standard deviations between the DHR and IDT testing were 18.6 % and 19.2 % of the mean values, respectively, indicating similar accuracies of tests. The tests were also able to distinguish between types of material. The proportional difference between the IDT and DHR is expected and is due to the difference of sample and loading configuration. With the proper shift factor, it is suggested that the DHR can provide similar results with significantly less material versus the traditional IDT test.