What is the formula for calculating mixing time for concrete?

The correct answer for calculating the mixing time for concrete is based on the established standard that states it takes 1 minute for the first yard of concrete and then adds a specific number of seconds for each additional yard. In this case, the formula "1 minute for 1 yard plus 15 seconds for each additional yard" accurately reflects the widely accepted guideline for determining the appropriate mixing time, ensuring that the concrete is mixed to optimal consistency before use.

This method accounts for the fact that adding more material to the mixer will require additional time to achieve uniformity, which influences the quality and performance of the final concrete product. The choice of 15 seconds aligns with industry best practices, indicating the time needed to adequately blend the ingredients after the initial yard.

The other options suggest different increments of time for each additional yard, but the standard practice identifies 15 seconds as the correct duration. Understanding these mixing time calculations is crucial in concrete mixing operations, as improper mixing can lead to compromised strength and durability of the concrete.