Water Addition After Slump Test

• A. Water addition after slump test is prohibited at temperatures above 60 F.
• B. Do not place concrete below 40 degrees Fahrenheit.
• C. Slump testing is not required in cold conditions.
• D. Do not place below 32 degrees Fahrenheit.

Answer: (B)

Cold-weather placement rules govern when concrete can be placed. The reason this matters is that hydration needs warmth to develop strength and durability, and placing concrete at too low a temperature risks freezing, slowed curing, and cracking. The standard guideline is that concrete should not be placed when the air temperature is below 40°F, unless special protective measures are in place. That threshold directly ties to whether you can place the concrete and how you handle adjustments like water additions after a slump test, since those adjustments won’t override the temperature requirement.

The other statements don’t fit the common practice: the temperature guideline isn’t about a cutoff at 60°F; slump testing is still performed in cold conditions; and 32°F is the freezing point but the typical practice uses 40°F as the placement limit with proper protections rather than a hard 32°F cutoff.