INSULATED CURING BLANKETS
Concrete can be successfully placed, finished, and cured in cold weather or during the winter months, but it requires an understanding of the impact of cold weather on the process of creating long lasting concrete. At low temperatures, concrete sets slowly, and development of strength is delayed. Therefore, job planning for cold weather concreting should include a recognized method of protection.
In cold weather, protecting concrete against early freezing ensures the development of the proper strength. The use of insulated curing blankets can be used to maintain concrete temperatures at desired levels. The insulating blankets must keep the concrete at a temperature that will facilitate proper curing.
Curing blankets can be made from several different materials to provide an effective insulating value that minimizes rapid temperature fluctuations and wind chill effects. It is critical that none of the components absorb water or moisture. Effective curing blankets are usually constructed of an insulating layer(s) encapsulated between protective outer layers.
CLOSED CELL FOAM BLANKETS
The most common blanket used is the single or multiple layer closed cell foam blanket. Each layer is ¼” in thickness. Blankets are offered in ¼”, ½”, and ¾” thickness and can be custom made up to 1”.
They come with a high strength, lightweight, impermeable; UV stabilized outer shell made from Reinforced Polyethylene (RPE). Common sizes are 12’x20’ and 12’x24’, 6’x25’ and 12’x25’.
The outer RPE shell can come in a variety of colors and grades. Orange is an effective color selection as it is translucent allowing light to pass if the blankets are used vertically for hoarding. In addition, they are a highly visible product. White blankets offer the same light translucent properties, but they can become a slippery work place hazard after a fresh snowfall if they are undetected. Black blankets don’t allow much, if any, light transmission.
Insulated curing blankets can be custom manufactured using heavier RPE outer shells of any color the contractor desires (white, black, blue, white, orange, green). They can also be manufactured to any custom size and thickness required.
R Values are an important component to consider for each project before purchasing a product. However R Values are derived from the laboratory test method (i.e. ASTM C- 518 which is the "Standard test Method for Steady- State Thermal Transmission Properties by Means of Heat Flow Meter).
Testing does not take into account other realities of construction sites; like blankets taking on water, or the breach of an air lock (tearing of the out skin), which can greatly affect the blankets R value.