Evaluation of the Performance of Cold In-Place Recycled Base Layer Supported with Geogrid

The research presented in this study sought to determine the overall performance benefit of utilizing geogrid reinforcement in cold in-place recycled (CIR) pavement layers. A Superpave mixture with nominal maximum aggregate size of 9.5 mm was used as the control mixture while eight CIR mixtures were also evaluated. A balanced mix design approach was used to produce the eight CIR mixtures in which binder content varied (3 and 4% of CSS-1h emulsion), compaction level varied (30 and 70 gyrations) and use of geogrid reinforcement varied (with and without reinforcement). The cement and water contents of all mixtures were 1 and 3% of total mixture weight, respectively. All test specimens with and without geogrid were allowed to cure for three days at 60 °C. The approach adopted involved: performing the dynamic modulus (|E^*|) tests on all mixtures and conducting a layered elastic analysis using KenLayer. The results of the layered elastic analysis were then used to compare the relative rutting and cracking performance of the CIR mixtures (geogrid reinforced and –unreinforced). The CIR mixture that contained 3% binder, compacted at 70 gyrations with no geogrid reinforcement, was found to be the best performing CIR mixture.