There was a strong emphasis on providing solutions to the issues and challenges the Ontario Hot Mix Producers Association (OHMPA) and its provincial and municipal partners face at the association’s recent fall seminar.
"Those challenges are not insurmountable," said executive director Vince Aurilio, in a capsulized summary of the seminar which was heavily focused on the latest technologies for improving asphalt quality and sustainability.
An update on the progress of OHMPA’s relatively new task force on the quality of asphalt was provided by Steve Smith, the association’s 2015 president (and the vice-president of paving and construction for The Miller Group).
The task force was created in response to concerns by Ontario’s Ministry of Transportation (MTO) and municipal road departments, as well as OHMPA members, over premature cracking.
"The OHMPA board decided to tackle the ongoing quality concerns head-on," said Smith, in outlining the reasons for the task force’s creation in late 2014. It held its first working meeting this past February.
Its principle mandate is to review and investigate the factors causing the cracking and to provide practical solutions to ensure long term pavement performance, he explained.
In keeping with that mandate, the task force has been issuing periodic bulletins, consulting with provincial and municipal stakeholders and conducting an internal audit of "high priority factors" such as Asphalt Cement (AC) quality and specifications, increasing AC content in Superpave mixtures, and the responsible use of recycled materials.
Possible solutions include the use of fine graded mixes, reducing the allowable acceptances for air voids and /or asphalt cement, and developing new mixing and compaction methodologies.
Some ideas were discussed and then rejected, such as reducing or banning the use of Recycling Asphalt Pavement (RAP).
"The use of RAP in HMA (hot mix asphalt) has a long and proven track record in Ontario and around North America producing quality pavements while at the same time promoting sustainability and creating environmental benefits."
Stressing the task force’s work is far from complete, Smith said it will continue to investigate the causes of premature cracking.
And the audience also learned the premature cracking problem was the catalyst for an internal MTO survey. Staff was asked for suggestions on improving the design, materials, and construction of hot mix asphalt.
"Approximately 100 ideas were generated and many were aimed at increasing the asphalt cement content in our Superpave mixes," said Pamela Marks, who heads MTO’s bituminous section.
Before going ahead with any of those ideas, MTO wanted to meet with industry representatives. In a roundtable discussion earlier the year, four Ministry and four key industry representatives "discussed in detail" 13 specific possible solutions under four groupings: Increasing Asphalt Cement, Pavement Permeability, Use of Recycled Materials, and Mixing and Compaction Temperatures.
The ministry plans to move forward with some of those ideas while keeping in mind the challenges which were identified at the roundtable, said Marks.
Other seminar speakers included Dennis Hunt, senior vice-president of Orlando Florida-based Gencor Industries Inc., who spoke on industry milestones and innovations; and Al Palmer, director of specialty products for Dallas Texas-based Safety-Kleen Systems. His presentation was on the use of Vacuum Tower Asphalt Extenders in asphalt blending.
The success the State of Louisiana has experienced over the past 20 years improving pavement by technically feasible testing and specifications was the subject of a talk by Chris Abadie, materials engineer administrator for that state’s transportation department.