Benefits Of Cold Central Plant (On-Site) Recycling Of Asphalt Concrete
SIGNIFICANTLY REDUCES COSTS
1. Experience indicates that the expense of Cold On-Site Recycling is less expensive than conventional paving methods.
2. For starters, all or a lot of the needed material is in position, so the sum total cost of new asphalt is noticeably less. Often, the only necessary new material purchase may be the hot-mix asphalt cap.
3. Because material is being recycled onsite, many fewer truck hauls are required.
4. There are no dump fees for the recycled asphalt concrete.
5. Labor costs are significantly reduced because of the shorter duration of the project.
In August of 2008 Cold On-Site Recycling was used to repave a percentage of the Vintage Faire Mall in Modesto, CA. The estimated cost to pave this mall using traditional milling and surfacing was $1.8 million. The job cost using Cold On-Site Recycling was $1.2 million, for an actual cost savings of $600,000.
POTENTIALLY SHORTER DOWNTIME
The Cold On-Site Recycling process removes only the most truly effective 2 to 4 inches of asphalt concrete. Traditional remove and replace methods take not merely the asphalt layer, but the rock and potentially some of the soil layers and replaces them. Because this isn't necessary, assuming the subgrade is in good shape, it is not required to make an effort (and spend the money) to restore the rock and prepare the soil, leading to much shorter downtimes. Another advantage to both Cold On-Site and Cold Central-Plant Recycling methods is that if you can find subgrade issues the asphalt pavement can still be stripped off and saved on site. Then, failed areas of the bottom section may be repaired prior to recycling and placing the salvaged asphalt concrete.
AS DURABLE AS TRADITIONAL SURFACING METHODS
An issue often raised with recycling is the grade of the recycled product; Cold Recycled Asphalt has different properties than "virgin" hot mix. On a structural basis, CALTRANS assigns Cold Recycled Asphalt a "Gravel Equivalency Factor'of 1.7, while for some Hot Mix Asphalts ("HMA") the Gravel Factor is 2.0. In the field this often translates into a slightly thicker section when working with cold recycled asphalt. Like, if the look calls for 4" AC section and the Owner wants to substitute cold recycled asphalt for part of the section, a typical substitution is 3" of the cold recycled asphalt over-laid by 1.5'of HMA. The resulting 4.5" section is structurally equivalent to 4" of HMA. But, as the processing of the cold recycled asphalt includes a different internal structure, and the new section is really a two-layer system, the pavement is more resistant to thermal and reflective cracking.
ENVIRONMENTAL ADVANTAGES
Energy Savings And Reduced Green House Gas Emissions
Due to the greatly reduced number of truck hauls and the utilization of recycled asphalt, the requirement for petroleum-based products is significantly reduced. Additionally, the green house gas emissions are noticeably lower. A study done by Dr. Arpad Horvath of the University of California, Berkeley for the Ministry of Transportation of Ontario discovered that green house gas emissions using Cold In-place Recycling were half to one third of traditional rehabilitation techniques (mill 100mm and 130mm hot-mix asphalt).
Society has an increasingly heightened awareness of and the need to mitigate the negative impacts of its actions on the planet. Cold recycling, when appropriate, exemplifies the strides the paving industry is making in contributing to the global effort to reduce green house gas emissions and the carbon footprint. Additionally, later on, should there be cap and trade limitations added to the paving industry, cold recycling should contribute to a company's need to limit its green house emissions.
Potential LEED Credits
Along exactly the same lines, the utilization of Cold On-Site Recycling will potentially contribute LEEDS credits for a significant renovation project, should the owner/general contractor choose to pursue LEEDS certification. Specific areas of potential credits include MR 2.1 and 2.2 (Construction Waste Management: Divert from Disposal), MR 3.1 and 3.2 (Materials Reuse), MR 4.1 and 4.2 (Recycled Content) and MR 5.1 and 5.2 (Regional Materials: Extracted, Processed and Manufactured Regionally).
Sustainability: Preserving Virgin Materials and Lowering of Land Filling
Asphalt and aggregate are not renewable resources, and as a result the ability to reuse existing asphalt concrete is good results both from the purpose of sustainability and cost savings. Additionally, a few of our best aggregates are present in place. Cold recycled asphalt is basically made up of engineered aggregates and binder already in place. Recycling in-place material preserves currently owned assets for the owner.
