Success Story

US Route 89 is one the West’s most scenic highways reaching from Mexico to Canada. Known as the “National Park Highway”.  With over 1600 miles of mostly a two-lane paved highway, US 89 passes through five states, numerous cities and towns and is the gateway to seven national parks including Grand Canyon, Yellowstone and Glacier and 14 national monuments.  Over the past three years, UDOT has conducted three CIR projects on US-89 – one each year from 2019 to 2021—totaling nearly 24 miles of placement.

Prior to processing the cold in-place recycle, Coughlin Company was tasked to remove the upper 1.5 inch of the existing asphalt which primarily consisted of chip and crack seal.  This material was accepted by Sanpete County as a product they could use as patching or shouldering material.  Coughlin Company began removal of this layer a few hours ahead of the CIR process in order to facilitate a smooth ride for the public during construction operations.

The decision to use CIR was benefited by an unseasonably warm heatwave to begin the project.  Ambient temperatures surged to highs of 98°F during the week of June 14^th which led to internal windrow temperatures as high as 116°F during placement.  The compaction of the mix was benefited greatly from such high temperatures with compaction averaging nearly 95% during these processes.  The product was also benefited by roller operators that were able to catch on to the differences between CIR and HMA.  The project began with three operators typically performing three passes on the first CAT CB15 as breakdown, three passes on the CW34 as an intermediate roller, and varying between three to five static passes on the CAT CB15 roller used to finish.  During the first week of production, no supplemental rolling was required to achieve the minimum 92% average established by UDOT. 

Weather did not continue to work in favor of the project the next week with only three days of production accomplished due to rain in the area.  Cloud cover that week was as high as 100% at times with temperatures at 10am averaging 20° cooler than the week prior and daily highs about 10°F cooler.  The project added a fourth roller – a CAT CCS9 -- during the second week of production when temperatures dipped to their typical highs, reducing the passes of the second CB15 to three to four and performing two passes on its own. On the 6^th day of production, June 22^nd, the first final density results below 92% were recorded.  Those locations were able to be sufficiently rolled the next day, but similar issues presented themselves on the 7^th day of production.  These areas were not able to be supplemental rolled until two weeks after placement due to the pace of production – yet the material was able to gain 1.3% compaction during processes that much later.  Average compaction from that day increased from 90.8% to 92.1% without having the mat break over and lose compaction due to breaking up of the aggregate structure.  Supplemental rolling processes did not begin until the asphalt temperature achieved 90°F and peaked at 102°F.