Early Strength Traditional CIR has suffered from long curing times. The improved chemistry of the solventless ReFlex CIR-EE 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 Humbolt Stiffness Gauge. This hand portable instrument imparts a very small displacement to the newly recycled pavement at 25 steady state frequencies between 100 and 196 Hz.
Stiffness is determined at each frequency, and the average is displayed.
At the low frequencies used, the impedance at the surface is stiffness controlled and proportional to the shear modulus of the recycled material. 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.