Insulating blankets are commonly used on slabs, but may also protect formed surfaces, such as this. To be effective, insulation must be kept in close contact with the concrete or surface of the forms. Protect wet concrete against freezing, and keep it warm until it reaches the desired strength by Frank Randall Cold weather makes special problems for concrete placement, especially when temperatures are below freezing. As the temperature drops, the chemical process that hardens concrete slows down. At lower temperatures, concrete sets up more slowly and takes longer to reach a given strength level. If it freezes at an early age, strength loss, increased permeability, and reduced resistance to weathering can result. prevent damage caused by freezing at early ages protect concrete until it