After a rain interruption, which items should be checked when resuming the pour?

• A. Slump and air content.
• B. Ambient lighting.
• C. Color of concrete.
• D. Time of day.

Answer: (A)

When a rain interruption occurs, checking fresh concrete properties that reflect how the mix will perform in place is essential. Slump measures workability and consistency, which rain can alter by adding moisture or washing fines away, potentially making the mix too fluid or uneven. Air content checks the amount of entrained air, which rain can affect by changing the paste characteristics and how air voids are developed; too little or too much air can impact durability, especially in freeze-thaw conditions. If these two measurements stay within specified limits, you can resume placement with confidence; if not, you should pause and address the changes before continuing. Other factors like ambient lighting, color of the concrete, or time of day do not indicate whether the concrete will meet the required performance after rainfall.