As we move into the cold weather, we will be using the 7 ½ bag mix for all concrete work in Ogden City. This requirement will start Monday, November 20. Please keep this in mind when ordering concrete for any work scheduled in the Ogden City Right-of-Way
C. Cold Weather Placement: ACI 306. Non-chloride accelerating admixture may be used in concrete work placed at ambient temperatures below 50 deg. F. Use of admixtures will not relax cold weather placement, curing, or protection requirements. If air temperature is forecasted to fall below 32 deg F. within 14 days of placement proceed as follows:
Provide cold weather protection (cover, insulation, heat, etc.).
Do not use chemical “anit-freeze” additives in the concrete. (NOTE: this does not apply to normal accelerators.)
Do not proceed with the placement of concrete until the temperature of all contact surfaces is 35 degrees F and ambient temperature is ascending.
Protect the concrete from freezing until a compressive strength of at least 90 percent of design strength has been achieved, determined by either:
Maturity meter. Refer to AASHTO T 324, or
Field cured cylinders.
Adequately vent combustion-type heathers that produces carbon monoxide.
When applying external heat, maintain moist conditions to avoid excessive moisture loss from concrete.
When removing heat, limit drop in temperature of concrete surfaces 20 degrees F during any 12 hour period until the surface temperature of the concrete reaches that of the atmosphere.