What is the rule of thumb temperature for hot weather concrete practices?

• A. 75
• B. 95
• C. 85
• D. 105

Answer: (C)

In hot weather concrete work, controlling the temperature of the fresh mix is crucial because temperature drives how quickly concrete hydrates, how workable it stays, and how the surface cures. A practical target is about 85 degrees Fahrenheit at placement. This mid‑80s temperature helps keep the mix workable long enough for proper placement and finishing, while not accelerating hydration so much that plastic shrinkage cracks or excessive evaporation occurs. If the concrete is much hotter, say in the upper 90s or beyond, hydration speeds up, workability can drop quickly, and surface drying can lead to cracks and weaker curing. If it’s cooler, around the low 80s or mid‑80s, you still get good finishing and a more controlled cure. To achieve this target, practices include using cooled or partially frozen aggregates, chilled mixing water or ice, placing during cooler parts of the day, shading, and employing proper curing methods to maintain moisture after placement.