Concrete without Sand??? 1

[miningman]

Has anyone ever produced adequate concrete without the use of sand?? Not so hypothetically, assume local sources of sand are unavailable for environmental reasons, could a guy crush the local granite sufficiently small so as to produce not only the required aggregate but also the necessary fines?? Any special requirements , eg would all the plus say 0.25 material have to be screened out or would it be feasible to produce a spec that included ALL the minus 1 inch material??

 

[Ron]

Yes, this is possible. The workability of the concrete will be harsh; however, you can do as you propose.

Crusher run base material for roadways is very close to your thought process. If you add cement to this, you can develop a reasonably strong concrete, assuming you are not looking for strengths that are over about 4000 psi. Also, your concrete will be somewhat more pervious than typical concrete, so be aware that less protection will be afforded to any reinforcing steel within the concrete. Further, bond development of rebar will likely suffer as there might not be sufficient fines for appropriate consolidation of the concrete around the rebar.

 

[miningman]

Ron, it sounds like you might know what you are talking about. Any additional comments if I add that the prime task at hand is a 50 meter x 30 metre slab, assume 0.3 metre thick until the engineers say differently). This is heavy duty industrial construction to accommodate the big CAT 793 haultrucks ( 240 tons) and D10 dozers . Lots of rail to be embedded in the pour to accommodate the D10s etc. How would I determine the optimum gradation mix?? I have a huge crushing job going in parallel with a lot of minus 0.75 inch to be produced.

 

[cvg]

the slab is just part of the equation. you will need to pay a lot of attention to the subgrade conditions for loading like this.
normally to produce a custom mix with non-standard materials, you would need to have the lab run some mix designs with the proposed materials. Since the construction is expensive and the downtime is even more expensive, it makes sense to pay for the lab work up front.

 

[Ron]

Agree with cvg....look at the subbase and subgrade. Since it appears that you have plenty of crushed material available, you may use that to stabilize the existing soils prior to constructing the slab. Your issues with the slab will be flexural strength adequacy for heavy wheel loads and abrasion from the tracked equipment. All joints in the slab should be "armored" to prevent undue damage from the tracks. I designed a similar pavement for a large Caterpillar dealer about 30 years ago and used 3x3 steel angle with shear studs welded to the angle as edge protection for all joints. The pavements were finally removed (and recycled) about 5 years ago when the business moved and the land had a new, different use, but the pavements were still performing well.

 

[miningman]

Well for what its worth, we know the existing soils are crap (that's a highly technical mining term).. There are known ice lenses plus some organics, so all that is coming out to a depth of at least 3 metres. But what is odd is that based on test hole drilling, bedrock appears to be anywhere between 3 and 8 metres deep over the 100 x 50 area. This does not jive with my general understanding of bedrock in this area so I guess we'll have to remove the upper 3-4 metres and then plan future action on what we see. I don't want to blast to 8 metres only to find I've over excavated.

 

[TXStructural]

To your original question, many places use manufactured sand. It is not a novelty.

http://theconstructor.org/building/properties-of-manufactured-sand/8606/

 

[shazi1]

Earlier I was in a project in Mumbai, India, and natural sand was totally banned there.
We had mix with 100% replacement with crush sand and it is complying it with all requirements like water permeability and RCPT.
I think its very common and you can contact local RMC to assist you in preparing a mix with manufactured sand and compatible plasticizers.

 

[kieran1]

I have used quarry dust as a sand replacement before in a concrete pavement construction. Worked quite well.

Kieran