Tips for Pouring Concrete in Hot Weather
Concrete should cure for 7 days at temperatures between 65 - 85°F, with humidity levels under 100%. If the temperature is above 85°F, here are some tips for ensuring your concrete cures properly, creating a strong, long-lasting slab.
- Consult your ready mix producer when you order to ensure a proper mix for the current weather conditions.
- Have adequate crew, materials and equipment on hand to reduce the total time between the start of placing and the application of curing procedure.
- Plan the best time of day to place the concrete. In hot weather, the best time may be very early in the morning or late in the evening.
- Fog or sprinkle the forms, reinforcing steel and sub-grade the evening before. There should be no puddles on forms or sub-grade at placement.
- To offset effects of high temperatures, low humidity or winds, erect sun shades and wind barriers to protect concrete from stiffening or crusting to help minimize cracking, crazing, and plastic shrinkage.
- Discharge concrete as soon as possible and avoid prolonged mixing - that increases the temperature of the concrete. Doing so will make the concrete set faster and shorten the time available for placing.
- Notify your ready mix producer of any delay in placing so deliveries can be rescheduled.
- Control evaporation during and after finishing by using windbreaks, sunshade-polyethylene sheets, wet burlap, or waterproof paper.
- Hand float promptly after the water sheen disappears, or when the concrete can support a finisher.
- Moist curing is most needed during the first few hours after finishing. In hot weather, continuous moist curing for the entire period is preferred.
- Forms should be loosened as soon as possible without damage to the concrete. Then, water should be placed on exposed surfaces and allowed to run down inside the forms.
- If moist curing can't be continued beyond 24 hours, protect the surface from drying with curing paper, heat reflecting plastic sheets, or membrane forming curing compounds while the surface is still damp.
