As temperatures begin to fall, special precautions must be taken when ordering, placing, finishing and curing
concrete. Placing exterior concrete in freezing temperatures is risky, even when covered with blankets. Good concrete practices and proper planning are necessary to provide a quality, long - lasting product.
Unlike most products that are completed in the factory, where the manufacturer has sole responsibility for the quality of its final product, concrete is sold before it is a finished product. A high quality, durable finished product is the responsibility of both the supplier AND the concrete contractor placing the slab.
Cold weather concrete practices should be used 30 days before temperatures fall below 40 degrees Fahrenheit. In central Iowa, this temperature drop normally occurs about October 1st. As the temperature of concrete drops, setting time and strength gain is much slower. A 20 degree drop in temperature will double the set time, and inhibit the evaporation of bleed water. Premature finishing can cause blistering, scaling, or other surface defects.
PLACING AND FINISHING
SUDAS - COLD WEATHER TEMPERATURE PROTECTION
TEMPERATURE FORECAST TYPE OF PROTECTION
One layer of burlap for concrete. Plastic top layer is required if burlap is exposed to rain or heavy winds.
31 To 25 F
Two layers of burlap or one layer of plastic on one layer of burlap
Below 25 F
Four layers of burlap between layers of four mil plastic or equivalent commercial insulating materials.
Use of straw shall not be allowed for temperature protection.
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