I would imagine that adding even a little DE would be like adding *way too much* sand. The concrete will be soft and porous. That's not to say there aren't ratios of Portland Cement to DE that could produce 'ok' mortar mixes for decorative work... But a stronger product -- I don't think so.

When I was a kid, my grandfather, father, and various uncles were all working in the back yard on various 'masonry projects' (Yes, I'm Italian, we're born with concrete in our veins ^_^) -- And as the designated cement mixer, I was well schooled about the prohibitions of allowing (not good for the cement) materials to enter the process stream.

40+ New England winters later and the concrete we poured is still crack free, solid, and, yes even nostalgic.

Bad idea.

Concrete ready-mix includes air-entrainment chemical additives to acheive 3 percent air entrainment. You would be defeating this.

Air is good to allow the checical bondings during hydration to occur completely around the fine aggregate.

Don't use dirty water for the same reasons. No sub 200 sieve particles are desirable as aggregates.

That air is why ready-mix is such an inferior product to *real* concrete.

You really lost me on how air helps hydration.

Dirty water is bad *because* the components of the 'dirt' react with the high pH of the liquid, forming soluble salts that weaken the matrix.

The only things that should ever go into concrete are:

1) Reinforcing bars or wire

2) Clean aggregate (no sticks, dirt, clay, slate or other soft minerals)

3) Clean sand ( min 70% silica, no clay, fines, cat droppings, weeds, etc)

4) Fresh Portland Cement (new bags, free of lumps, never rained on)

5) Clean (potable) water (mixing is hard work, you'll want to quench your thirst)

Do not add 'lime' or 'limestone' to concrete; that's for mortar. Burnt lime, quick lime, Calcium Oxide 100% or calcined limestone is as fine as flour. White Sand, marble dust, limestone sand, etc, are not acceptable substitutes.

Once I tried to use silica sand (100% SiO2) commonly used for pool filters. The mix was fine, the set was fine, but the inertness of the material left the concrete weak, it broke with a granular fracture exposing the clean faces of the sand. It was very sparkly, clear 'white' crystalline sand in a grey matrix -- fake meteorites anyone?

Concrete should not 'foam' while mixing, there is nothing in if that should make soapy bubbles, if it does foam, there is probably organic material in the mix -- not good.

The drier you can mix, the better the resulting concrete. 7% water is a good target, freshly mixed concrete should be stiff, never soupy.

Concrete *will* burn the skin! Alkali burns are painful. Unless you have leather hands like my uncle did, *you will feel the burn/sting from even a tiny splash* Hint: if you don't feel pain from skin contact with the slurry, the Portland is *old* and the concrete will be inferior.

Sorry, my Italian is showing -- who'd a thought I'd have this much to say about concrete?

Air entrainment protects against cold weather damage from freezing!

You want the cement to completely encapsulate around the fines (which is the sand).

But if you allow silt and colloidal particles into the mix you will f**k it all up.

I'm saying that these diatoms are like silt or clay other than the may be organic (which is even worse than inorganic) fine particles.

Air entrainment makes concrete lighter. That's the only reason to allow it. All the other effects are negative. It's weaker, and has severe deleterious effects on the number of freeze-thaw cycles the concrete can endure. Water gets into the bubbles, freezes, expands, and shatters the matrix. It doesn't 'insulate' the inside of the mass.

DE (diatomaceous earth) are shells from marine organisms, they are nearly pure SiO2, nuthin organic about them except their origin. Because of their high surface to weight ratio, the DE will tend to dissolve/react with the Ca(OH)2 forming excess calcium silicate, weakening the matrix.

You got the 'eff' it up part right! ^_^

You never want to introduce any organic materials in a concrete mixture.

Also, no inorganics that are not strong and therefore subject to breakdown.