The Construction and Performance of Ultra-Thin Whitetopping Intersections on US-169

Status:  Complete
Report Date:  12/16/2004


The Minnesota Department of Transportation (Mn/DOT) constructed an ultra-thin whitetopping project at three intersections on US-169 at Elk River to gain more experience in both the design and performance of ultra-thin whitetopping (UTW). All concrete mixes contained either polypropylene or polyolefin fibers. The compressive strength, flexural strength, Poisson's ratio and elastic modulus were measured for these mixes and the results are provided. Distinct cracking patterns developed within each test section. The strain measurements emphasize the importance of the support provided by the hot mix asphalt (HMA) layer. A reduction in this support occurs when the temperature of the HMA is increased or when the HMA begins to ravel. Cores should be pulled from the pavement when evaluating whether UTW is a viable rehabilitation alternative to determine if the asphalt is stripping and if the asphalt layer has adequate thickness. UTW can be successfully placed on as little as 76 mm (3 in) of asphalt, if the quality of the asphalt is good. The cores should also reveal the asphalt layer is of uniform thickness and stripping/raveling has not occurred. If these conditions exist, UTW is a good option for rehabilitating asphalt pavements.

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