American Iron and Metal Co. Inc. (AIM) needed a strong, durable platform for their new metals recycling facility in Levis, Quebec, Canada. The 70-year old company, based in Montreal, Canada, is a processor, dealer, and broker of ferrous and non-ferrous metals. The facility processes scrap metal, salvaging and recycling various metals from compressed cars, boilers, appliances, ornamental steel, etc.
This type of operation requires a large platform for storage and operations, which must also be able to stand up to the heavy loads and punishment of the operating equipment. Roller-compacted concrete (RCC) is often the material of choice for this type of application because of its high strength and durability, and large areas can be constructed with significant cost savings.
AIM needed no convincing to use RCC for this project, having used it on several projects since 1996. “Our experience with roller-compacted concrete has been excellent. It has good resistance to the abrasion caused by our operations, and we have found that we can put truck traffic back in operation in just 72 hours after construction” said Guy Monet of AIM. Another advantage was the ease of patching. If small areas needed repair, simply sawing out the area and replacing with conventional concrete eliminated the need for forms.
One aspect of this application was the requirement for very low permeability. For environmental reasons, the operating platform had to protect the groundwater underneath the pavement from any of the materials that might be involved in the recycling operation. To ensure that the RCC would provide an impermeable barrier, tests were performed by SEM Consultants in Quebec City who developed specific laboratory procedures for this evaluation. Their results found that the permeability of the RCC could be estimated at 1-by-10-11-centimeters per second, which would be very satisfactory for this application.
The pavement was built in the summer of 2006 by Carrieres St. Dominique, a contractor that has also constructed previous RCC projects for AIM. The RCC was placed on 12 inches of drainable aggregate base throughout the site. The thickness of the RCC varied from 6 to 12 inches depending on the static and dynamic loading conditions. RCC was also placed for the floors of storage bins at the facility (see pictures below).
Construction of RCC pavement with control joints.
Use of RCC for storage bin floors.
The concrete mix consisted of 2,000 lb/yd3 crushed stone, 1532 lb/yd3 sand, 175 lbs/yd3 water, and 14.75 oz/yd3 of Axim catexol 1000N water reducer. The cementitious material consisted of 480 lb/yd3 of Type I cement blended with seven percent silica fume. This blended cement, provided by Ciment Quebec Inc., is commonly used in Quebec because of its excellent resistance to freeze-thaw and deicer scaling.
The required field compaction was 98 percent of Modified Proctor, which had a value of 155 pounds/cubic foot. Concrete samples obtained in the field and tested in the lab had three-day strengths of 740 pounds per square inch (psi) in flexure and 5,380 psi in compression. Tests conducted after 28 days had an average flexural strength of 1,059 psi and compressive strength of 8,514 psi.
As part of the project, Ciment Quebec Inc. performed an evaluation of different paving equipment. This included a conventional Barber Green asphalt paver, and a Vogele Super 2100 paver with two different screeds. The two Vogele screeds were a TP2, and a TVP2. The TP2 screed incorporates a tamping bar and two pressure bars, and was used with standard procedures for roller-compacted concrete. The TVP2 screed is specifically designed for concrete, and obtains the required concrete density without additional rolling, thereby creating the term “Paver Compacted Concrete”.
Francois Marleau, vice president of Ciment Quebec, said “We were very pleased with the performance of the Vogele paver and both paving screeds. This type of new equipment improves production for the contractor and gives the owner a better final product.”
After completion of paving, the new AIM recycling facility had approximately 25 acres of roller-compacted concrete. This new operating platform was constructed at a lower cost than any comparable construction material, and will provide many years of durable service.
Evaluating the Vogele Super 2100 paver with TP2 screed
RCC provides a tough, durable, and impermeable operating platform.
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