Initiating recycling at the project level provided another challenge – finding a suitable project candidate. This proved difficult as many road sites were outside of the remediation capabilities of CIR treatment. Many roads were too complex to be used as a pilot for CIR. Some candidates had sub-base and subgrade issues that would have to be addressed during construction. Others were constructed with an existing base layer between layers of asphalt, commonly referred to as “sandwich” construction, which ARRA Award Winners would create technical issues for a CIR project. After encouraging regional branches to follow CIR selection criteria established by the MIT committee in 2007, a candidate was found between PR 282 and the Pas, on PTH 10.
Although the Pas was a good candidate, remediating this 32 kilometer (20 mile) stretch of roadway introduced further challenges. The site was located 633 kilometers (393 miles) North West of the City of Winnipeg, about a 7 ½ hour haul for the asphalt cement (AC) tankers. Keeping the AC at 302°F was crucial in order to achieve proper mix consistency and heated storage had to be specified in the contract as a requirement to ensure that this condition was achieved. Another challenge was the inclement weather in this area. The Pas is prone to experiencing frequent rain events and cooler temperatures in late summer and early fall, increasing the possibility of the CIR mat experiencing higher moisture content prior to hot mix paving. This weighed heavily in MIT’s decision to proceed with CIREAM as opposed to
CIR with emulsion, as the curing time is shorter, which allowed the contractor to lay hot mix asphalt sooner after reclamation. Specifications were modified to limit moisture content to less than 4% and tests were conducted to determine moisture increases after rain events on the exposed CIR mat. Initially, two compaction units were used on the project. A third unit was added midway through the job and testing was conducted to determine increases in compacted density. Results indicated that the addition of the third roller provided superior compaction of the mat and a third roller was specified and permanently incorporated into subsequent work in Brandon and Grand Rapids. The addition of a third roller also mitigated undue increased moisture issue by producing a tighter, better sealed mat.
Recycling of existing aggregate and asphalt cement along with reductions in fuel usage allowed for substantial financial and environmental cost savings. Specifically, there was a total financial savings of $1.9 million, or about a 15 – 20% reduction in overall project costs. The process also saved approximately 50,000 tons of raw aggregate and 2,000 tons of asphalt cement. An added benefit of the work in The Pas was the creation of an opportunity for MIT regional staff to observe and review CIREAM first-hand. In consulting with the contractor and witnessing the technical and environmental benefits of the process, the confidence level of these regional staff increased significantly, which helped foster a positive attitude towards using in-place recycling in future jobs. To date the remediated roadway at The Pas is performing well and its solid structural and aesthetic condition is yielding only minimal reflective cracking and smooth ride and surface texture.
Jointly, along with project staff, Mike and Tara reviewed and modified their initial specifications and construction techniques used at The Pas in 2012 and invested capital into essential resources. Major changes included the addition of a third compactor and the equipping of mobile lab units with a full range of testing equipment. These adjustments exemplify dedication to the CIREAM process and continuing product improvement towards process optimization. With their knowledge from 2010, they incorporated these adaptations into the Brandon and Grand Rapids projects in 2012. Through establishing working groups, teamwork, and support from neighboring Ministries, regional staff and contractors, Mike Neil and Tara Liske have helped institute recycling processes into the culture of asphalt remediation in their province.
ARRA 2013 Award for Excellence in Full Depth Reclamation