Title: How Does a Cold Reinforcing Bar Affect Fresh Concrete?
Author(s): Ronald L. Kozikowski, W. Calvin McCall, and Bruce A. Suprenant
Publication: Concrete International
Appears on pages(s): 49-56
Keywords: embedment, freezing, surface, temperature
This peer-reviewed article discusses the evolution of recommendations, published in several editions of “Cold Weather Concreting (ACI 306R),” regarding the minimum temperature of surfaces to be in contact with freshly placed concrete. It also provides new data on the subject, obtained using test specimens with reinforcing bars instrumented with thermocouples, showing the changes in temperature in and near cold bars after concrete placement. The cross sectional areas of the instrumented bars ranged from 0.11 to 4.00 in.2 (70 to 2580 mm2). The initial temperature of each bar was about 5°F (-21°C), and the initial concrete temperature was about 55°F (13°C).