Light Weight Concrete Form Blocks
Light Weight Concrete Form Blocks
(OP)
I have a builder that wants to produce his own lightweight concrete form blocks then infill the voids similar to reinforced masonry. The end result would be a wall (grid) of 5 inch thick normal concrete with voids where the webs of the block would be. The voids would be 6 inches by 6 inches at 16 inch on center horizontally and 12 inches on center vertically (with reinforcing in the solid sections). I am considering modeling this as a grid of concrete beams and columns. I do not believe that the beams and columns will fall into the technical definition in ACI, therefore I am thinking that this type of system could be designed as a wall in ACI. The blocks (forms) have 360 psi compressive strength so I do not want to use them for support nor design this system in accordance with ACI 530. Does ACI have design specifications for this type of systems yet? And if not, I would appreciate any thoughts on my design philosophy or similar specifications available for this type of design.






RE: Light Weight Concrete Form Blocks
The two different types are the molded EPS forms with formed voids and integral cross-webs in different configurations. The newer type are a system that uses parallel EPS foam exterior faces held together by a plastic truss-type with bar placement guides at different spacings to produce a wall with the reinforced concrete wall with the forms non-bearing forms left in place for future insulation. For a 6" concrete wall the outer dimension would be about 8" including the forms.
There is extensive documentation and specifications along with a massive amount of testing to achieve product approvals for the various codes.
The builder does not produce the forms - he or his sub-contractor just buy them. Find out what he is planning to use and then go from there on researching the acceptability.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: Light Weight Concrete Form Blocks
Mike McCann
MMC Engineering
RE: Light Weight Concrete Form Blocks
RE: Light Weight Concrete Form Blocks
Lightweight concrete forms would be very unpractical, too heavy and costly (materials and shipping). The bracing is critical as is the rate of pouring lifts to maintain tolerances and quality concrete (usually pumped because of access).
Most of the systems do provide good control of the rebar placement and concrete cover.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.