Current Cold Weather Concreting specifications do not address the benefits of placing concrete in insulated concrete forms during cold weather. Cold weather conditions being defined in ACI specifications as a period when, for more than three successive days, the average daily outdoor temperature drops below 4°C. Since these conditions occur regularly throughout many parts of the globe, any system that will allow the construction season to be extended without incurring additional cost will prove extremely beneficial. The objective of this ongoing research program is to investigate the early age thermal effects of concrete cast in Blue Maxx~(TM) insulated concrete forms under sub-zero temperature conditions. Three Blue Maxx~(TM) insulated concrete units, having different sizes, were instrumented and placed for six days into a conditioned chamber at an ambient air temperature of -20°C to determine the thermal behaviour occurring after casting. This paper reports some aspects of the early age behaviour of the insulated concrete samples and will focus on the results of a finite element investigation aiming at establishing the lower boundary temperature for each of the form units as a function of cement type, cement content and concrete placing temperature.
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