A common issue on job sites is the decision on whether to pour an old concrete truck or send it back. In the past, concrete contractors have tried to sneak old trucks into the pour, but today we have third party testing companies that test the concrete batches. So, the question is…
When is a concrete truck considered too old to pour?
Do you have to send it back?
The answer is yes and no….
- Yes – According to ASTM C-94, concrete discharge must be complete within 90 minutes of mixing water with cement and aggregates.
- No – ASTM C-94 also states that these limitations can be waved if the slump meets mix design specifications without adding water.
What We Suggest:
- In concrete construction, planning and communication are imperative to successful projects. Before any large or unique pours are performed, there should be a pre-pour meeting between the contractor, concrete supplier, and pump operator to ensure a successful and timely pour.
- In this meeting, the parties will discuss a number of issues, but an important scenario is what to do with a concrete truck when it reaches the 90-minute mark. Every project, city, engineer, and general contractor is different. Discussing ASTM & ACI Standards will lead to positive results when problems arise.