I came across this idea at the home-de-pot when I found in the cement section plastic forms for making walkways. They did not have a form that I liked or one that was big enough so I decided to make my own.
Step 1: The form
I built a simple mold with 1/4" X 3" poplar stock from the local big box hardware store. Then I used 1/4"x 1/4" square stock to make a decorative pattern. The whole thing was held together with grabber screws. I used Vaseline as a release.
Step 2: The cement
It took approximately three(80 lbs) bags of cement to fill one form (3 foot x 3 foot x 3 in) so after I got the form in place and level I mixed the cement coloring with the water and then mixed the cement into a fairly workable texture. Then pour the cement into the form and work it around until all of the air pockets are worked out. It is important not to leave any aggregate from the cement on the top of the form, this will make it harder to remove later.
Step 3: Form Removal
Wait around two hours for the wet cement to harden enough to allow the form to be removed. Gently tap on the surface of the wood form to release it and slowly work the form up and off. There was some cracking but dont worry about it. The mortar will fill in any voids.
Step 4: Mortar
Finally after allowing all the cement to cure I swept in the mortar into the cracks and wet it down gently with the hose. The mortar ties the whole piece together and reinforces the cement as well as filling any voids.
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Two questions:
1. what did you use as mortar?
2. how much did this project cost?
I'm going to put in practice, however everytime I will prepare concrete, I have the same question.
Whats the best/d ratio of mixture (cement, sand, stones)?
Can someone give me ideas?
Thank you
My two cents: Vaseline may be a great way to prevent the wood for sticking but I have done the following with super results = make sure the wood is super wet before sticking it in the concrete and oil it up with motor oil.
Making it super wet will expand the wood and when it is drying it will come loose by itself. The oil prevents the cement from sticking to the wood...
I have done this about 32 times making one cover stone at a time for a brick wall.
Cement, sand and water becomes mortar. Cement and water becomes "parge" or "rough coat" ("crepi" in french. I'm not sure about the translation).
Same as with flour. Mix it with different ingredients and it becomes : bread, pancakes, cake ...
However for a nice patio I probably would reinforce the addition. You might even consider drilling holes for rebar into the edge of your existing patio. To attach the new rebar to the old patio, mix epoxy putty and put it in the holes. Then hammer the rebar into the putty inside the holes. Stuff as much putty in as you can. Once you pour the new concrete, the rebar will permanently tie the new patio to the old. I've used liquid epoxy to mount four 250 horsepower electric motors to a deep slab and it worked perfectly. For a patio I would drill the holes about four to six inches deep. Bend the end of the rebar to 90 degrees for about 4 inches.
Also for a patio I would build a dirt trench around the edge so that the outside edge of the new patio would be at least 2-3 inches deeper than the slab itself. Ten inches deeper would be much better, but you start to make much more out of the project when you get into engineering the slab. You could use rebar or cattle (or hog) panel (usually available at a feed store) to reinforce the slab and in the trench. When the trench fills with concrete, it dries to form a structural support beam around the new patio.
By the way the methods used in this Instructable can be practiced in any sand or dirt pile. Mix a gallon of redimix and make a few stepping stones to perfect your methods and timing.