Performance of Ultra-Thin Bonded Wearing Course (UTBWC) Surface Treatment on US-169 Princeton, Minnesota

Status:  Complete
Report Date:  06/29/2007


The purpose of this report is to evaluate the performance of 1999 and 2000 ultra-thin bonded wearing course (UTBWC) surface treatment on US-169 in Princeton, Minnesota. The UTBWC consisted of gap graded course aggregate hot mix asphalt over a heavy asphalt emulsion layer and it was placed at an average thickness of inches. For comparison purposes, a control section was established to assess the performance of the overlay. This section continues to be maintained using standard sealing and patching techniques. The surface roughness and condition of these sections have been monitored on yearly basis. The overall performance of the UTBWC sections has been very good, while the control section is currently in need of major rehabilitation. The UTBWC appears to provide an economical choice for pavements in need of minor rehabilitation. In addition, UTBWC may prove beneficial as a preventive maintenance option. It should be considered for all sections with minor cracking and roughness distresses that do not stem from subgrade problems. Nationwide research has shown that UTBWC reduces deterioration caused by weathering, oxidation, traffic and provides good skid resistance, reduced rolling noise, reduction of hydroplaning, and back spray from roadway. UTBWC does not increase the structural capacity of the pavement, however, the use of UTBWC on new pavements as a wearing course could be considered.

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