Any thoughts on Sand-Cement mix for structural components? (no coarse aggregate)
Any thoughts on Sand-Cement mix for structural components? (no coarse aggregate)
(OP)
Hi all. We are working on a project which is located in an area where there is no coarse aggregate at all, only sand. We had desired to create a 4000 psi sand-cement mix to use for structural foundations, slab on grade, 8" thick 2-story high walls, CIP stairs, and infill on composite metal deck.
We are concerned about being able to achieve the 4000 psi, and about the suitability of such a mix for the intended use. Our local ready-mix supplier had no experience with such a mix, though his gut feel would be that it would be too brittle for our use.
Just wondering if anyone has any experience using a sand-cement mix for structural components. Some thoughts we had to make it more durable were adding synthetic fibers to the mix, and changing the reinforcing from a typical single layer mat (#5 @ 12" o.c.) in the walls to a double layer mat of smaller, closer spaced bars, or even heavy WWF.
Any thoughts you have are much appreciated.
Thanks.
We are concerned about being able to achieve the 4000 psi, and about the suitability of such a mix for the intended use. Our local ready-mix supplier had no experience with such a mix, though his gut feel would be that it would be too brittle for our use.
Just wondering if anyone has any experience using a sand-cement mix for structural components. Some thoughts we had to make it more durable were adding synthetic fibers to the mix, and changing the reinforcing from a typical single layer mat (#5 @ 12" o.c.) in the walls to a double layer mat of smaller, closer spaced bars, or even heavy WWF.
Any thoughts you have are much appreciated.
Thanks.






RE: Any thoughts on Sand-Cement mix for structural components? (no coarse aggregate)
Much has to do with the actual gradation of the sand AND the particle shape. I assume it may be a glacial deposit with rounded particles. A single size gradation could be very difficult.
The ASTM aggregate specs have the tradition option of saying essentially non-spec aggregate can be used if a HISTORY of performance can be shown.
I boils down to getting test reports on the aggregate and mix designs.
In a plant/manufacturing situation, that strength can be easily achieved, but that is using almost zero slump concrete and they have the advantage of having tightly controlled vibration and accelerated curing that is not available in the field.
Monitoring placement and testing will be required if you vary from the ASTM aggregate specs.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: Any thoughts on Sand-Cement mix for structural components? (no coarse aggregate)
We probably don't really need 4000 psi. I am sure anything 2500 psi or better would work just fine, compressive strength-wise. I'm just really more concerned with the behavior of the finished product. Will it behave like normal concrete structures, or will it be really brittle, and have higher shrinkage problems?
RE: Any thoughts on Sand-Cement mix for structural components? (no coarse aggregate)
Despite its size, Brazil/Brasil has some unique aggregate situations.
The floor system they use in some cities is usually referred to as a filler block system (concrete block or clay tile) that is very common for high rise (7 to 20 stories) construction. Many buildings are designed by engineers with the same floor plan and wall thicknesses for either block or poured concrete (usually 6" walls).
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.