What is the recommended practice for concrete temperature during placement by ACI?

The recommended practice for concrete temperature during placement, according to ACI guidelines, suggests that the ideal range is between 50°F and 90°F. This temperature range is significant because it allows for optimal hydration of the cement, thereby promoting a proper curing process and achieving desired strength and durability characteristics.

When concrete is placed within this temperature range, it helps in preventing issues such as cold jointing or inadequate hydration that can occur if temperatures are too low. Similarly, excessively high temperatures can lead to rapid evaporation of moisture, resulting in problems such as cracking or reduced workability. Maintenance of this temperature interval ensures that the chemical reactions within the concrete mix occur efficiently, leading to favorable outcomes in the final properties of the concrete.

In contrast, keeping the temperature below 32°F can lead to freezing issues and inadequate curing, while a temperature of 100°F can compromise the mix’s workability and strength development. The response that no specific temperature is required fails to consider the critical influence temperature has on the hydration and performance of concrete. Thus, adhering to the recommended temperature range is essential for ensuring the best results in concrete placement.