Making cement patio for a miniature garden using only Portland Cement, could I just saturate it or do I need to mix it?

I want to make a little cement and stone patio for a miniature garden with Portland Cement. Do I NEED to actively mix the cement with water to activate it or could I just use a spray bottle to spray it to the point of saturation? I would have 1/4"-1/2" of sand underneath and the cement would be at maximum 1" thick, though1/2" is more likely.
I had watched some YouTube videos of diy cement planters that only used the Portland cement and water and I thought it would be good for miniature garden patios, pathways, etc. 
Thanks for any help!

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rickharris7 months ago

1. Yes the cement will set if you just wet it in situ. When I put fence posts in I just dump dry cement/concrete mix in and wet it.

2. It will not have the strength is would have with sand & or gravel mixed into it However if this is just a model that may not matter.

3. You can minimise cracking & improve strength by embedding some fibrous material in the dry cement, bandage, fiberglass reinforcement, thread, string etc.

4. try is on an experimental area your not too worried about and see how it goes.

tseemann (author)  rickharris7 months ago

Thank you for answering my question and not just suggesting alternatives. I appreciate that.

Your welcome and good luck.

Downunder35m7 months ago

When I was too lazy to do it the correct way I attempted a similar way to yours.
There are several downsides to using cement or concrete as a dry powder.
Without sand or gravel mixed in the strength is drastically reduced, but that is no big deal for areas with noone walking on it.
Bigger problem is the curing.
Cement needs the right amount of water added so that the calcination will happen evenly and completely in the same time throughout the mix.
Doing it dry always results in different properties.

Since you don't need much try this:
Get a big rubber or plastic tub, the kind advertised in your home depot to collet garden rubbish for example.
Add your cement and then about half the volume in sand - mix the dry stuff.
Now keep mixing and add water bit by bit - you want to be able to mix without water puddles ;)
Once you see all the mix is wet or really moist without dripping you have what I call "shitty concrete".
You can check that the mix is right with an old plastic tub:
Fill with the mix and start compressing it with something like a flat stick, old piece of wood, little hammer...
If you can compress it without causing it to crumble the mix is good, if it crumbles put back in tub and add some more water.
Once satisfied you can use the mix for creating your little garden and when done with a section simply spary some water on top.
After three days the stuff should be solid enough to use.

That word, "calcination", I think that means driving water out of something by heating it, and that's kind of the opposite of what concrete does when it cures.

https://en.wikipedia.org/wiki/Calcination

Maybe the word you wanted was, "hydration"?

LOL don't ask me, I thought I got the right word.
Wahtever makes the stuff cure properly and is not evaporation LOL

tseemann (author) 7 months ago

Thank you for the quick comments everyone! I tried just the cement alone for a test. I know that using just the cement, which is just one of the ingredients in concrete, will not be as strong as mixed concrete. I figured that since I'll only be using 1/4 - 1 cup at a time and it doesn't need to be weight bearing that water alone might be enough. I tried the spraying method in a little Motts applesauce cup, it's been sitting for about a day now. I will try mixing some sand in with it for my next test.

Thanks again everyone!

Jack A Lopez7 months ago

In the vernacular, the word "cement" is kind of a misnomer for the more correct word, which is "concrete". When someone mentions a "cement sidewalk", or a "cement planter", the actual material that sidewalk or planter is made out of, is concrete.

https://en.wikipedia.org/wiki/Concrete

Concrete is typically a mixture of Portland cement, sand, gravel, and water.

The easiest way to make a small amount of concrete is too just buy a few bags of some dry, premixed stuff (containing Portland cement, sand, and gravel). The brandname, Quikrete(r), is well known, easy to find, in my home country, the former U.S. If you have a Lowes(r) or a HomeDepot(r) in your town, then that's usually the place to go to get some bags of Quikrete.

https://www.quikrete.com/

The hardware mongers will usually also sell bags of pure Portland cement, but as far as I know mixtures of pure Portand cement and water DO NOT make good, strong concrete. A lot of the strength comes from the aggregate, i.e. the sand and the gravel, or at least this is the story I have been told.

And yes, you need to some work to mix it with water. It is kind of analogous to making pancake batter. I mean, do you suppose it is possible to make good pancake batter by just spraying water on top of, or letting water slowly wick or diffuse, into the dry ingredients? The mixture needs to be well-mixed, with no little lumps of dry stuff in it anywhere.

A wheelbarrow and a shovel, are the usual, least expensive, tools used for mixing Quikrete with water. Really the wheelbarrow and shovel are just a scaled-up version of a bowl and spoon, which are the usual, least expensive, tools for making pancake batter.

Vyger7 months ago

You should look up more on cement to get a better understanding.

I am pretty sure you will get pretty poor results unless you mix everything. There is a chemical reaction that happens that causes the cement to turn hard. If it is not uniform the reaction will not occur properly. In addition you need to have something like sand mixed with the cement. This gives the cement body and gives it something to stick to which reinforces it. It also stretches the mix so it can cover more area. Sand is a lot cheaper than cement. Anyway the information is out there, you need to do more than just watch a few videos to understand it.