Field Investigation of Long-Pin Shear and Short-Pin Raveling Tests on Cold in-Place Recycled Layers: Wisconsin's Share for the Enhancement of Cold in-Place Recycled Sustainability

Abstract

Currently, Wisconsin, U.S., opens the cold in-place recycled (CIR) base layer to traffic 0 to 3 h after construction. The CIR layer is then paved—when the in situ moisture content drops to 2.5%—with hot mix asphalt. There is no quantitative measure for estimating the opening time to traffic, and, to determine the in situ moisture content, there is a need to obtain field samples and perform laboratory measurements. These methods are time-consuming, labor-intensive, or both. To overcome these shortcomings, the feasibility for use of quantitative and real-time evaluation techniques was investigated. Long-pin shear (LPS) and short-pin raveling (SPR) tests developed as a part of the National Corporate Highway Research Program 09-62 study were used for measuring the properties of the CIR layer (blow count and torque) over time. Regression models were developed from these tests using the in situ moisture content measured from field samples, which were then used for proposing threshold values in Wisconsin. The SPR and LPS test data enabled the establishment of correlations between the measured values. Statistical analysis revealed that the pavement temperature and curing time significantly influence the measured properties from the LPS and SPR tests.