KNOWLEDGE & SAFETY

Concrete placement in hot weather poses its own set of challenges, which some argue can be even more difficult than cold-weather placement and curing. There are several factors that contribute to the complexity of hot weather concrete placement, including the following:

1. Consistently warm, hot, and humid days that raise the concrete temperature to 90°F during batching.

2. Storage of both fine and coarse aggregates outdoors, resulting in increased heat absorption from the sun.

3. City water temperatures reaching 75°F, making it difficult to cool the aggregates effectively.

4. Heat absorption by the truck barrels during transit, further raising the concrete temperature.

Without proper precautions, the concrete is at risk of exceeding the temperature limits set by ACI, leading to premature setting. It is crucial to take necessary measures when testing and inspecting the concrete to ensure compliance with ASTM, ACI, and NYC Building Code standards.

Please read the attached guidance to ensure the correct procedures:

• Dry Shrinkage Concrete (PDF)
• Windy Day Precautions (PDF)
• Lightweight Concrete Tips (PDF)
• Crazing Concrete (PDF)

Accurate information such as slump, concrete and ambient temperatures, and the age of fresh concrete is essential for successful concrete placement in hot weather. This information is crucially reported by testing laboratories hired by the project owners.

At Gotham Ready Mix, we have made significant investments in cutting-edge technology, including the implementation of “Smarthatch.” This technology aids in concrete quality assurance by providing real-time data on air content in wet concrete and more. Many trucks in our fleet are equipped with electronic monitoring systems manufactured by Cidra, allowing our personnel to closely monitor concrete features such as temperature, air content, and slump.

Proper handling of fresh concrete data is crucial, as is the correct storage of concrete testing cylinders in ASTM-approved curing boxes, where temperature and moisture can be strictly controlled. It is essential that everyone involved in concrete placement and quality assurance is aware of accurate concrete sampling procedures and proper field sample storage.

By being vigilant and following these guidelines, we can ensure the successful placement of concrete in hot weather conditions while maintaining the highest standards of quality and compliance.

According to an NRMCA study, compressive strength is significantly lost when cylinders are not stored in accordance with ASTM. To summarize, according to ASTM and ACI, if the first 24 to 48 hours of field curing are incorrect, the resulting compressive strength is invalid.

Because it is critical to take all necessary precautions, Gotham Ready Mix would like to extend a gesture of goodwill to our loyal customers by purchasing the correct ASTM-approved curing boxes at our expense.

While our quality control team is working hard to create an appropriate environment for producing high-quality concrete, it is physically impossible to address issues on all projects. Therefore, we are asking everyone to start paying more attention to the quality of testing performed on the job site by independent testing laboratories.

Please read the attached guidance to ensure the correct procedures:

• Dry Shrinkage Concrete (PDF)
• Windy Day Precautions (PDF)
• Lightweight Concrete Tips (PDF)
• Crazing Concrete (PDF)