What is the effect of an extended duration pour, such that the first truck is batched many hours ahead of the last?
Small diameter shafts generally involve small concrete volumes (up to 4 or 5 trucks) and can be poured in a couple of hours. The time of the peak temperature for smaller diameter shafts is relatively soon after the pour (e.g. 8 to 24 hours), and the temperature differences near peak time are not generally important. Larger diameter shafts use large volumes of concrete from many trucks and can take many hours to pour. In these cases, the time of peak temperature is also much later (up to two days, or more). The longer it takes to reach peak temperature, the less important are the relative ages of the concrete.
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