Question

Ready mixed concrete should be totally discharged from the truck within how many hours after mixing?

1) 1 hour
2) 2 hours
3) 3 hours
4) 4 hours

Answer 1

Ready mixed concrete should ideally be discharged from the truck within 1.5 hours after mixing to maintain quality before initial setting time, which typically ranges from 2 to 4 hours.

Step-by-step explanation:

Ready mixed concrete should generally be totally discharged from the truck within 1.5 hours after mixing. However, this can vary based on standards such as the American Concrete Institute (ACI) or depending on specific project requirements, conditions, or as dictated by the supplier's guidelines. When considering the transportation and handling of concrete, it's essential to also consider the initial setting time, which usually occurs between 2 to 4 hours after mixing, depending on the concrete mix and environmental conditions.

To ensure the best quality and prevent the risk of the concrete beginning to set in the mixer, a safe rule is to discharge within 90 minutes, which would be the middle-ground and most commonly adhered-to timeframe within the industry standards.