, Assistant Professor, UMD-Civil Engineering
Due to increasing budget constraints, there is interest in economizing pavement structures by reducing the panel thickness or increasing the service life of the pavement. Past research has demonstrated definite limits to reducing the panel thickness of conventional, undoweled, jointed plain concrete pavement (JPCP), thus invoking interest in understanding the potential for using structural fiber-reinforced concrete (FRC) to either allow slab thickness reduction or an increase in service life. Research is needed in understanding the contribution of structural fibers in mitigating panel fatigue cracking and transverse joint faulting in thin concrete overlays and pavement on grade. There is also interest in understanding the effects of fiber-reinforced concrete on panel size, especially for much thinner slabs.
Structural fibers generally improve the performance of thin concrete pavement and overlays by: 1) holding cracks tight and 2) transferring the wheel load between adjacent slabs. Several laboratory studies are currently in progress to comprehensively quantify the above-mentioned two benefits. Performance comparison of companion pavement sections (with and without fibers) are now required to obtain a field-validated method to accurately account for the contribution of fibers for the future mechanistic-empirical design procedures of FRC-based thin concrete overlays and pavements on grade.
To achieve this, the National Road Research Alliance (NRRA) has designed and constructed seven fiber-reinforced concrete test cells and one control plain concrete cell at the MnROAD facility in summer 2017. The primary variables in these cells include panel thickness, type of support (base), panel size, and fiber dosage. All of these cells are equipped with different types of response measuring sensors. Performance of these cells is being periodically evaluated. Sensor data and periodically-collected performance data are being used to achieve the following objectives:
1) Determine contribution of fibers in reducing panel fatigue cracking
2) Determine contribution of fibers in mitigating joint faulting
3) Determine optimal panel size.