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Can portland cement be mixed without sand or gravel?

I'm planning to switch from wood to cement because we are soon moving into a condominium where noise should be kept to a minimum. If yes, what is the ratio of water to cement? if no, can i mix it with sand only and what is the ratio. Thanks

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I'm trying to make these jigging lures using a mold and filing it with cement. How can I make the cement more rigid and heavy but less brittle?

point wilson anchovy jig.jpg

Hey Stephen, Here's some basic cement chemistry. The short answer to your question as to how to make it denser and harder is 'curing time' and by adding fly ash. The longer it 'cures', the harder it will be. I happen to live in an area where there are currently 3 volcanoes blowing off and I use the volcanic ash to 'densify' the cement. Above all, don't get in a hurry and shortcut the 'curing' time.
There are many chemical compounds in dry portland cement, but two of the most significant ones are tricalcium silicate (C3S, Ca₃SiO₅) and dicalcium silicate (C2S, Ca₂SiO₄). The first compound, C3S, reacts as soon as water comes into contact with cement, and continues reacting (hydrating) for the first 3 days or so. About 7 days after the cement has been hydrated, the C2S starts to react and continues for many months thereafter. When the cement is 28 days old, about 95% of the hydration has taken place.
The hydration of these two compounds produces the same primary reaction product-namely, calcium silicate hydrate (C-S-H). It is C-S-H that bonds everything together. When water comes into contact with cement the C3S compound releases large amounts of calcium ions and hydroxide ions. Also released are large amounts of silica, specifically SiO2. With the release of hydroxide ions the pH of the concrete rapidly increases from basically neutral to very alkaline pH of 12 to 13 (on a scale of 1 to 14). In this very alkaline environment calcium ions react with hydroxide ions to form calcium hydroxide. Calcium hydroxide then reacts with the SiO2 to form the main cementing material, C-S-H.
After curing for 28 days, 15% to 20% of the hydrated portland cement paste is calcium hydroxide. Therefore, there is large amount of calcium hydroxide normally available that can be converted to C-S-H. All that is needed to make this happen is a source of silica. Add some fly ash to your portland cement before hydration for this purpose. The silica in fly ash reacts with the calcium hydroxide in the cement paste and produces C-S-H, thereby increasing the overall strength of the cement.
I don't know how much fly ash to add. Like I said, I use volcanic ash. I hope this helps.

suzannec311 months ago

how much do you mix gravel and sand with portland cement to pour a side walk

If I was making stepping stones of a purely decorative nature, would I be able to mix just the cement & water. and if so, what is the best ratio?

Don't worry about ratios. Portland cement is anhydrous and forms a hydraulic cement when water is added. This called hydration (hardening) of the concrete

When using Portland cement alone, you only need add enough water to completely hydrate it, causing the clinker sulphates and gypsum to dissolve; producing a pourable alkaline, sulfate=rich solution. Use enough water to achieve the desired consistency for pouring.

Dry powdered pigments can be added before the water, If you are going to be walking about bear footed, choose a light colored pigment. The amount of heat gain between a white colored stone and a light grey is startling..

Decorative stones such as quartzite, small river pebbles or crushed glass are sometimes added to the surface of concrete for a decorative "exposed aggregate" finish, I live near the Pacific Coast and use crushed glass that has been submerged on the beach in a nylon bag with a little bit of sand. I wind up with polished glass pebbles.

If you are going to be using these stones where they are exposed to high levels of ultra-violet light and freezing winter temperaturs, you might consider adding an adipate-based plasticizer.

It's a wee bit more than you asked but I think fore knowledge is better than hind sight. I hope that this helps.

.

Re-design5 years ago
What are you going to do with it? Tell us what your plans are and we might be able to send you in a different direction.
lemonie5 years ago

You can, but cement on it's own is not a good material for anything really.
What is wrong with mixing in sand (which is much cheaper than cement)

L
caarntedd5 years ago
Yes.
Burf5 years ago
Not knowing what you are going to do with it makes giving you a useful answer difficult, if not impossible, so I can only give you some information.
Aggregate is added to cement to give it strength. Without aggregate, you're basically going to have grey plaster with little inherent strength for both tension and compression. Even small aggregate, sand and pea gravel, will make a significant difference in the strength.
Aggregate to cement proportions should be about 3 parts aggregate to 1 part cement by volume for field/hand mixed concrete. Only enough water should be added to afford workability and eliminate voids in the mix. The less water you use, the higher the strength of the cured concrete.
There are additives you can mix with the concrete for additional workability and strength. Check with your retailer for information on this.
Last, you can buy ready mixed, dry concrete, usually called Reddy-mix and Sackcrete. Easier to use but significantly more expensive than buying the components and preparing the mix yourself.
rickharris5 years ago
Mmmm? You can, and people do mix cement with sand (often by hand) 6:1 gives the mix generally used for mortar to hold bricks together.

Do I really understand that you can see yourself mixing cement inside your house?? Tolerant wife is all I can say.
orksecurity5 years ago
I haven't worked with cement enough to have a valid opinion, but I did want to point out that moving into an apartment/condo doesn't mean you have to give up working with wood. Hand tools, screws, and some power tools (electric drill, some sanders, ...) are much quieter than a full-scale powered woodshop, and really can do just about everything that the fancier tools will -- they may take more time and require a bit more skill, but that means you can take more pride in the result. Even unpowered woodturning is possible, with a treadle lathe.

+1

You can whittle a stick over a waste-paper bin in almost absolute silence.