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PSI & Chamtech team up to meet OPSS 909 requirements
01-Jul-09 - Prestressed Systems Inc. (PSI), Windsor, ON Canada, have installed two Chamtech Rollcov-R systems to meet new, stringent standards enforced by the Ministry of Transportation of Ontario (MTO).
This spring, the MTO enforced challenging new guidlines for curing precast concrete. These new procedures stress the need to pour quickly, cover quickly and maintain a controlled and monitored environment to ensure that each precast component produced meets ministry requirements.
Some general requirements of the revised standard include (including but not limited to the following):
- Placing a moisture vapor barrier within 6 to 13ft (2 to 4m) of finishing the product.
- Provide free air circulation around the forms but not force air directly onto the form.
- Ensure that forms are no more than 86F (30C) before placing.
- Ensure no ice or snow is on the forms before placing.
- Accelerated curing shall be achieved using live steam, radiant or electric heat or forced air within an enclosure able to effect an even distribution of heat.
- Burlap or water spray must be used throughout the accelerated curing cycle to protect concrete surface from moisture loss OR ensure 100% relative humidity is present throughout the curing enclosure. The Rollcov-R protects concrete surfaces from moisture loss alleviating the need to provide these measures.
- The member shall be evenly heated.
- Accelerated curing shall continue until the specified transfer strength has been reached.
- The ambient air temperature adjacent the concrete or formwork, within the enclosure, shall not be permitted to vary by more than 14F (8C) .
- When the temperature drops below 41F (5C), protective measures (insulated tarps) are necessary unless you provide a housing and heating solution capable of ensuring the above points.
The following videos of demonstrate the systems in action:
Production form #1 - 97'-0"L x 9'-4"W (R4.5 insulated):
Please note that this video was taken before the completion of the installation. The end of the system will seal against a small shelter to provide a completely sealed enclosure. In the case that a it sealed against a building, a compressable seal is installed around the perimeter Rollcov-R™.
Production form #2 - 180'-0"L x 15'-7"W (R4.5 insulated):
These are examples of how we customise these systems to fit your requirements & current setup. PSI requested that we supply a shorter system that would ride on walls. Other precasters prefer to have the Rollcov-R™ rails installed near the ground.
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