One of the greatest advantages to pouring concrete is you can do it all year long. However, as the seasons change so does the necessary steps to ensure quality results. Summer is no exception, and as the heat indexes rise, follow the below guidelines to decrease your chances of hot weather issues for a successful finish.
Coordination between the designer, ready mix supplier, testing laboratory, and contractor are critical for successful hot weather concreting. Hot weather can be defined as any combination of high ambient temperature, high concrete temperature, low relative humidity, high wind speed, and excessive solar radiation. Hot weather conditions can produce a rapid rate of evaporation of moisture from the surface of the concrete and accelerated setting time, among other issues. Concrete that is cured at high temperatures at an early age will not be as strong at 28 days as the same concrete cured at temperatures around 70 degrees.
The key to successful hot weather concreting is:
1. Recognizing the factors that can affect concrete
2. Plan to help minimize those factors
Use of water reducing, set retarding and supplementary cementitious admixtures can aid in reducing the effects that hot weather has on concrete. Concrete temperatures can also be lowered by using ice or chilled water as part of the mixing water.
When possible, deliveries should be scheduled to avoid the hottest part of the day and delays in delivery, placing and finishing are essential. Trucks should be able to discharge immediately and adequate personnel should be ready to place and handle the concrete. When dealing with hot weather concreting, advance planning and communication can prevent concrete issues. Preventing issues before they start can result in concrete that is of greater durability and higher quality.
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