The placement of quality concrete will require special measures when the outdoor ambient temperature exceeds:

• A. 60 degrees
• B. 70 degrees
• C. 80 degrees
• D. 90 degrees

Answer: (C)

Heat accelerates concrete hydration and increases evaporation, which can cause rapid loss of workability, surface cracking, and reduced early strength. When outdoor ambient temperature rises above eighty degrees Fahrenheit, these risks become significant enough that extra precautions are needed to maintain quality.

In hot weather, use measures such as cooling the mix water or incorporating ice to keep the concrete temperature down, shading the pour and using windbreaks to reduce surface evaporation, and applying retarders to slow set if placement timing is tight. After placement, implement effective curing to retain moisture—such as moist curing, curing compounds, or plastic coverings—to prevent plastic shrinkage cracks and premature drying. Monitor concrete temperature and workability closely and adjust procedures as needed.

At lower temperatures (for example, around sixty to seventy degrees), standard placement and curing practices are usually sufficient, while higher temperatures would demand even more stringent controls beyond those listed above.