huangyhg

cold joint in a foundation wall?
i have a client that wants to place a cold joint in a foundation wall. it's a residential structure and the foundation is being constructed with icf's. the builder is worried about blow-out at the bottom of the forms as some of the walls are 11' tall. his concern seems legitimate, though i need to check the icf manufacture's spec. sheets to see if this is really a concern or not. the question still remains though about having a cold joint in the foundation. i've never heard of this before in a residential structure and can not find a suitable reference in the aci pertaining to cold joints.

the wall is reinforced for the lateral soil load with the rebar in the proverbial tension zone. in theory is seems like it should work as zero tension capacity is assumed for concrete anyway and the joint in the compression zone would be in compression, so that shouldn't matter either. i have some concerns about moisture infiltration, but i would really like to be able to cite a reference one way or another on whether or not a cold joint is allowed.
can anyone help?
not familiar with icf's, i.... concrete forms? the cold joint runs vertical or horizaontal? cold joint or construction joint, you want to have some sort of shear transfer. if the joint is horizontal, it is possible, not preferable, your rienforcing should have a full tensionlap or run continiuous. a vertical joint is easier to deal with. is a water proofing going to be applied to the exterior?
icf is "insulated concrete form" basically it's a reinforced styrofoam form that is left in place after the concrete is poured. the advantage being traditional wood forms are not required to be taken down once the wall is poured and the styrofoam, being on both the interior and exterior side of the walls, offers great insulation.
the joint would be horizontal and about half the wall height. the rebar is running both vertically and horizontally. the vertical rebar is designed to resist the lateral earth loads and is continuous from the footing to the top of the wall.
being these are concrete forms from a manufacturer, check with them, see if they have any literature, if he has inadequate restraint at the bottom, sure they could blow. sounds like he is questioning the integrity of the form.
pressure at the base of the form is going to be a function of time also.
is this wall reinforced? you could not have a horizontal joint without continuous reinforcing through it.
i don't find anything against a horizontal cold joint. you could equate it to masonry construction. your vertical rebar must be in the center of the wall so that it provides strength in both directions, so you would have to re-analyze the wall with this "d" in mind. shear would have to be considered, probably with some form of shear key. leaking would probably be your biggest concern. i would use those preformed rubber key joints that are often used at the joint between stem wall and footer and use a filter fabric system, such as mirafi hc drain, to reduce the hydrostatic pressure against the foundation wall.
another alternative would be to reinforce the insulated forms part way up with traditional forms that are removed after the concrete cures.

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