Date: January 1, 2010

News - Hot Weather Concrete Placement

Hot weather poses several threats to concrete installers. Because concrete sets faster in hot weather, more water is needed to produce the desired slump. Hot weather conditions also substantially shorten the time it takes for the concrete to set, and plastic shrinkage cracking becomes a major concern because the slab is drying faster than bleed water can reach the surface. With proper planning and execution concrete can be successfully placed and finished to produce high quality durable concrete at temperatures of 95°F or more.
The contractor has several options to maintain quality during cold weather placement:
  • Keep the subgrade moist; if the subgrade is dry it will suck the water from the concrete.  Wet or sprinkle the subgrade prior to concrete placement, taking care not to leave standing water. Steel reinforcement and form work should be moistened as well.
  • Protect the concrete from evaporation by erecting wind breaks or sunshades, misting the concrete or covering with a plastic sheet.
  • Organize and execute the placement as quickly as possible, and ensure that you have adequate manpower.
  • If the concrete is approaching the upper temperature limits, cool the mix with ice or chilled water.
  • Consider fogging the area above the concrete placement to raise the relative humidity and satisfy moisture demand of the ambient air.

Hot Weather Concrete Placement

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