Density of 3500PSI 4.5% Air Entrained 5.5 Sack Concrete
Density of 3500PSI 4.5% Air Entrained 5.5 Sack Concrete
(OP)
As the title says, I'm trying to calculate the weight of the slab. I've found a standard 145lb/cf number, but I'm looking to be more specific as to the exact concrete that was used. Trying to verify proper design/construction of a 50'x10'x8" pad. Thanks! Christian





RE: Density of 3500PSI 4.5% Air Entrained 5.5 Sack Concrete
RE: Density of 3500PSI 4.5% Air Entrained 5.5 Sack Concrete
The calculations provide a good starting point since they reflect the normal aggregate densities. The consolidation of the concrete is a big factor, but eventually in the end, the voids do not usually weigh much if you are considering inplace density of cured concrete. The moisture contents can be a wild-card, but usually decrease with curing and and the exposure factors. A slab on grade, even with a vapor retarder/barrier, will have a higher actual unit pcf than an elevated slab.
If you want a higher density, use denser aggregates or use a lighter aggregates like pumice, expanded shale/slate/clay and similar premium cost materials for a lighter slab.
That is why all refernces give a range of values between 115 pcf and 150 pcf, although special materials and procedures can be used to go beyond the ranges.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: Density of 3500PSI 4.5% Air Entrained 5.5 Sack Concrete
I see you are a mechanical engineer. Advice given by Jed and CM is correct. Concrete is not a material like metals which have a known and almost constant specific gravity. There are many variables, and the type aggregates are the most important. I use 150pcf or 2400kg/m^3 for "normal" concrete in dead load calculations.
RE: Density of 3500PSI 4.5% Air Entrained 5.5 Sack Concrete
RE: Density of 3500PSI 4.5% Air Entrained 5.5 Sack Concrete
If you are using a calcareous coarse aggregate (limestone for example) then a lower unit weight is appropriate (140 pcf). For most other coarse aggregates, 150 pcf is appropriate.
Find out the coarse aggregate type, then find it's specific gravity. If the specific gravity is less than 2.50 use 140. If greater than 2.60, use 150.
RE: Density of 3500PSI 4.5% Air Entrained 5.5 Sack Concrete
RE: Density of 3500PSI 4.5% Air Entrained 5.5 Sack Concrete
RE: Density of 3500PSI 4.5% Air Entrained 5.5 Sack Concrete
RE: Density of 3500PSI 4.5% Air Entrained 5.5 Sack Concrete
RE: Density of 3500PSI 4.5% Air Entrained 5.5 Sack Concrete
RE: Density of 3500PSI 4.5% Air Entrained 5.5 Sack Concrete