It's summertime again! Here's a roundup of the best strategies for working concrete when the mercury is rising.
- Avoiding Hot Weather Problems "Reduce the effect of solar heat on mixers, chutes, conveyors, hoppers, pump lines, and other handling equipment by shading or covering it with wet burlap. Painting the equipment white also helps."
- What's Hot? "ACI 305 defines hot weather as any combination of conditions that impairs concrete quality by increasing the moisture loss or rate of hydration. Those conditions include high ambient temperature, high concrete temperature, low humidity, wind speed, and solar radiation ... use Fig. 2.1.5 in ACI 305 to estimate moisture loss and take precautions when the rate of evaporation is lower than 0.2 pounds per square foot per hour."
- Take the Sweat Out of Hot-Weather Concreting Generally, each 10°F rise in temperature reduces concrete slump by about 1 inch. The appropriate admixtures can help to maintain workability.
- Damage to Concrete Placed in Hot Weather Plan ahead. "Coordinate delivery and placement to avoid delays. This requires good communication between the jobsite crew and the ready mix plant."
- Keeping concrete Cool in the heat of summer "To prevent water loss, keep the slab surface moist by techniques such as fog spraying, which mists the air above the slab. Fog spraying reduces the evaporation rate and replaces evaporating bleed water."