Concrete

[bannerd]

Anyone know the ratios to make a 4000 psi concrete?

1 part Portland cement
2 Part Sand
3 Part gravel

With some extra portland?

 

[/pine]

Anyone know the ratios to make a 4000 psi concrete?

1 part Portland cement
2 Part Sand
3 Part gravel

With some extra portland?

Do a google search for technical details...

 

[bannerd]

I suppose I would never really know the strength unless I had it tested. Depending on the water content it could increase and or decrease the concrete strength.

 

[/pine]

I suppose I would never really know the strength unless I had it tested. Depending on the water content it could increase and or decrease the concrete strength.

Yeah the slump is important...another factor is the type of large aggregate (granite is harder than limestone etc...)

if it really matters you can get test cylinders from a material testing lab and they will bust them for you for a minimal price if it's a non union shop...

 

[bannerd]

Still trying to source some large aggregate, I have mountains of clean sand. Next step will be how to put all this material in the old 1 yard gilson. Thanks for the help!

 

[Streetcar]

Your basic proportions are correct. For highest strength use as little water as possible and keep concrete damp during curing

I suppose I would never really know the strength unless I had it tested. Depending on the water content it could increase and or decrease the concrete strength.

 

[Dave M7040]

Anyone know the ratios to make a 4000 psi concrete?

1 part Portland cement
2 Part Sand
3 Part gravel

With some extra portland?

The actual weights used to make 4.5 yards of 4000 psi concrete are:

1. Cement = 2810 pounds

2. Stone = 8250 pounds

3. Sand = 5620 pounds

THIS GIVES YOU A BASIC 4000 PSI CONCRETE MIX RATIO OF:

1 PART CEMENT
2.93 PARTS STONE
2 PARTS SAND

Rounded off it's basically a 1 : 3 : 2 mix ratio

If I break the weights down per cubic yard of concrete, it comes to:

1. Cement = 624 pounds

2. Stone = 1833 pounds

3. Sand = 1249 pounds

There are 94 pounds of cement in a "sack or bag" of cement. That means 4000 psi concrete is also called a 6.5 sack or bag mix.

Dave M7040

 

[jaxs]

Any application specify's max size aggregate allowed. For max strength,aggregate should be in graduated sizes from sand to that max size. Doing that increases total surface area of aggregate that must be coated and that's why added Portland is needed. 5 bags of Portland mixed with 1.5" rock and sand is not as strong as it is with 3/4" replaceing some of the sand & 1.5". As some have stated,more water make's it easier to work but it weaken's the finished product. There's an old saying"if the finishers are not complaining,it has too much slump."

 

[Tractor Seabee]

The actual weights used to make 4.5 yards of 4000 psi concrete are:

1. Cement = 2810 pounds

2. Stone = 8250 pounds

3. Sand = 5620 pounds

THIS GIVES YOU A BASIC 4000 PSI CONCRETE MIX RATIO OF:

1 PART CEMENT
2.93 PARTS STONE
2 PARTS SAND

Rounded off it's basically a 1 : 3 : 2 mix ratio

If I break the weights down per cubic yard of concrete, it comes to:

1. Cement = 624 pounds

2. Stone = 1833 pounds

3. Sand = 1249 pounds

There are 94 pounds of cement in a "sack or bag" of cement. That means 4000 psi concrete is also called a 6.5 sack or bag mix.

Dave M7040

The missing part of this equation is the water weight. If you order 4000 PSI ready mix IAW ASTM C-94, as batched at the plant that, is the expected result if handled properly otherwise. That assumes a slump of not more than 3". Add water at the site other than water carried only to be added at the site (not from the bulk tank or a hose and it will be noted on the delivery ticket) and you can change the result as much as 1000 PSI easily. C-94 is a tested and proven standard require by building codes. Many other standard formulas are available. Consult with the batch plant for their recommendations for other conditions. Normal C-94 has max 3/4" aggregate unless specified otherwise.

Ron

 

[BrokenTrack]

Rebar goes a long ways towards strength as well. It depends on the application of course. A bridge beam has far more tensile forces acting upon the bottom of the beam then a concrete slab.

I always go by "a 5 bag mix", meaning I use (5) 94 lb bags of Portland cement when making a cubic yard of concrete from the gravel from my gravel pit. For high strength concrete, I use a "6 bag mix". But that is just knowing the aggregate source, and adding the Portland cement to it to get what I need.

I knew a guy that spent days putting rebar in his footings on his house, but then used a 2 bag mix to make weak concrete. He should have saved time and money and not used rebar, and spent more money on bags of Portland cement. In his case his footing was sitting on ledge rock; there was absolutely no tensile forces at play because the footing was under 100% compression.