Where is min concrete grade for pre-cast (no prestress) walls specified?
Where is min concrete grade for pre-cast (no prestress) walls specified?
(OP)
Friends
I can not find any recommendation on min. grade of concrete for use in pre-cast(no prestress) fences and pre-cast retaining walls, I mean walls in flexure only. It is vaguely shown in most cases and examples that high grade concrete is the usual practice for pre-cast elements
Thanks in advance.
respects
IJR
I can not find any recommendation on min. grade of concrete for use in pre-cast(no prestress) fences and pre-cast retaining walls, I mean walls in flexure only. It is vaguely shown in most cases and examples that high grade concrete is the usual practice for pre-cast elements
Thanks in advance.
respects
IJR





RE: Where is min concrete grade for pre-cast (no prestress) walls specified?
Dik
RE: Where is min concrete grade for pre-cast (no prestress) walls specified?
ACI 533 addresses precast wall panels, but that's pretty specific and they don't really require any certain strength.
Usually, precast concrete is required to have a higher strength than cast in place by the designer, but that's a function of the controlled conditions of the yard vs. field work. It's not a code requirement.
RE: Where is min concrete grade for pre-cast (no prestress) walls specified?
An extreme example is the low slump/zero slump or dry tamp concrete where the best products just happen to exceed normal specifications by large percentages. In these cases, more water would provide higher strength, but the product may not be usable. Adding cement is cheap, but the water destroys the accuracy and appearance. Fence materials and some retaining wall systems often fall into this category. In some cases, the strengths are 30% to 50% over minimums because it costs more to produce minimum strength products.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: Where is min concrete grade for pre-cast (no prestress) walls specified?
IR
RE: Where is min concrete grade for pre-cast (no prestress) walls specified?
Concrete strength of 2500 psi would be the absolute minimum, unless higher strength is recommended in Design Handbook by PCI, ACI-550: Design Recommendations for Precast Concrete Structures, or Standards directly related to Precast Concrete.
RE: Where is min concrete grade for pre-cast (no prestress) walls specified?
It is just a "boiler plate" specification inserted to provide a complete minimum specification for numerous products under ACI 318.
Normally strengths are much higher for economic purposes (production and handling).
If you need a lower strength such as 2500 psi for some reason, instead of the typical strengths of 3500-4000 psi(or 5000) it should clearly be specified and be expected to pay an additional cost. Much depends on the product and location plus shipping and erecting costs.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: Where is min concrete grade for pre-cast (no prestress) walls specified?