The ReFlex® emulsion cold in-place recycling solution uses innovative chemistry and materials engineering principles. The result is a partial depth recycled pavement with higher early strength and more reliable performance than traditional cold in-place recycling (CIR). The design method includes performance testing of the recycled mix for raveling, rutting resistance, thermal cracking resistance and moisture susceptibility. Additionally, early strength is tested in the field, and laboratory evaluations of ReFlex® mixes show that the higher asphalt contents lead to longer durability.
Raveling
| Raveling Comparison of ReFlex® and Conventional CIR mixes | ||
|---|---|---|
| Percent Raveling Loss | ||
| Location | ReFlex® CIR | Conventional CIR |
| Blue Earth County CSAH 20 | 1.6% | 25.7% |
| WA SR 270 | 1.5% | 16.0% |
A new test method determines the resistance to raveling of recycled mixes. This procedure is a modification of the Wet Track Abrasion of Slurry Surfaces Test (ISSA TB-100). Duplicate samples of the RAP (reclaimed asphalt pavement) are adjusted to the field moisture content, treated with the design quantity of emulsion, mixed and compacted using a Superpave Gyratory Compactor (SGC). The specimens are abraded for 15 minutes. The difference in mass before and after the test is reported as the percent raveling loss. The table shows the improvement in resistance to raveling of the ReFlex® recycled mixes.
Thermal Cracking
The Indirect Tensile Test, AASHTO TP 9-96 is modified for testing the predicted thermal cracking temperature. The critical cracking temperature is the intersection of the calculated pavement thermal stress curve (derived from the tensile creep test) and the tensile strength line (derived from the results of the tensile strength test). The graphs show a sample determination of the thermal cracking temperature, and the results from two different reclaimed asphalt pavement samples, each treated with both conventional and ReFlex® emulsions. The ReFlex® emulsion treated samples showed a significant lowering of the temperature where the recycled materials are expected to crack.
Moisture (Stripping) Resistance
ReFlex® mixtures are designed using a retained Marshall Stability test adapted from AASHTO T-283. The higher asphalt content of the ReFlex® mixes and the improved chemistry of the ReFlex® emulsion result in better adhesion and cohesion. The graph shows the ReFlex® CIR sample had a significantly higher retained strength than the conventional CIR. Both samples were taken from the CSAH 20 project in Blue Earth County, Minnesota.
Early Strength
Traditional CIR has suffered from long curing times. The improved chemistry of the solventless ReFlex® emulsion was developed to set up very quickly. Normally, the ReFlex® recycled pavement is ready for compaction within minutes. The strength is determined in the field using a Humboldt GeoGauge. It takes about a minute to determine the stiffness. The graph shows the result of the stiffness testing on the project on CSAH 20 in Blue Earth County, Minnesota. The ReFlex® CIR pavement was stiffer one day after paving than the control conventional CIR pavement was a week later. The early strength means construction moves more quickly, and the road can be opened and resurfaced sooner than conventional CIR pavements. Higher Emulsion Content, Higher Film Thickness, Higher Early Strength, Stronger Mixes, Better Coating
These are just a few of the advantages of ReFlex® emulsion cold in-place recycling. For more details on these test methods, or for more information on solutions for your paving needs, contact your local Road Science™ representative.