Bear Lake Road (Highway 36), Estes National Park
The Rocky Mountain National Park identified a section of Park Highway 36 between Bear Lake Road and Highway 34 within Estes Park, for rehabilitation by recycling, utilizing foamed bitumen as the stabilizing agent.
A study carried out by the Park shows approximately 4000 vehicles per day during peak season. Discussions with Park officials indicated that the heavy vehicle traffic is limited to tour busses and maintenance vehicles.
In order to establish the existing pavement structure and subgrade support, cores and dynamic cone penetrometer (DCP) were carried out at five locations along the section of road. The cores showed the asphalt concrete thickness to be 4” (100mm) at Bear Lake Road end and the thickness increased to 6” (150mm) towards the end of the section investigated.
Bulk samples of the HMAC, granular base and subgrade were taken. The thickness of the HMAC varies along the contract and as a safety precaution the HMAC thickness used for the mix design material blend was taken as the minimum recorded. A final mix design was determined to be 1% cement, 2.3% foamed bitumen to a depth of 6” (150mm) incorporating 2.5” (65mm) of HACP.
Due to restrictive access to the park and this route being the only access route the Park Management was particularly keen to have the recycling operation carried out in a one pas operation. A WR2500 recycler was used with pre-spreaded cement, a bitumen tanker in front of the WR and a water cart towed behind the recycler.