huangyhg

foundation pour lengths
i've read previous posts about limitations on concrete pour lengths in concrete tanks, but i haven't found anything regarding standard foundations. i have a project under construction using concrete trench footings and standard wall footings. we require construction joints at a maximum spacing of 60'. this has been part of our standard structural notes and we've never had a problem with it before but the contractor says that this limitation throws off their schedule (even though it should've been in his bid) and asked if we could lose this limitation. we told them that we couldn't and that they should leave between 5' and 60' between adjacent pours and wait 7 days between the infill pour and to limit the shrinkage effects.
i just wanted to know if we're being too strict on these limitations and what, if any, others use for the limitations on pour lengths.

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if these are buried foundation walls, or retaining walls with earth full height or close on one side, i would agree with the contrator.
however, with no earth present to serve as a heat sink and thermal barrier, i would stick to your guns here.
mike mccann
mmc engineering
if the retaining wall (yielding) is exposed to weather on one side and not part of a heated building structure, it will need expansion/contraction joints too.
mike mccann
mmc engineering
the project is multiple buildings, so some are earth formed trench footings, and others are formed footings with stem walls. all will be buried foundations so they're not retaining soil and aren't under any flexural stresses. which part do you feel is too strict? the length or the delay in adjacent pours? we are thinking that we will stick to the 60' length, but allow them to pour adjacent pours the following day as opposed to waiting 7 days.
if there are specific places you want to read the shrinkaqe cracks, then stick to your 60 foot limit, where is where they will show.
however, as a buried trench footing and/or stem wall, and if they are not visible, what's the harm in a monopour of the entire strip footing regardless of length? variations in temperature will not be an issue here, only shrinkage, which can be limited by the amount of water in the mix.
that will be the problem though - the water added to the mix on-site by the cobntractor and truck operator to get it out of the truck quickly. that will add to the shrinkage.
mike mccann
mmc engineering
thanks, i appreciate the help.

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