A patio or a walkway made with concrete flagstones is a fun project to do and it looks great. I like to use concrete flagstones, rather than use poured concrete, because they are easy to replace if one gets a chip or begins to spall.
Safety item: always wear a face mask or at least a bandana over your nose and mouth when mixing the dry ingredients. Cement dust is very irritating to your nose, mouth and lungs. Now let’s make those concrete flagstones.
First, decide on the size and shape of your finished patio or walkway. This will determine what size and shape concrete flagstones you will be making.
Second, calculate how many concrete flagstones you will need to make and what shape they should be. Now you can make your forms. I like to make concrete flagstones in different sizes and fit them together, but you can make them all the same size for simplicity.
Your forms can be made out of anything, but I prefer wood. You can use any wood you can find – pallets, furring strips, plywood, anything you can get. As long as you can trim the wood to the proper size, you’re in great shape. Furring strips are 2 ½ inches wide and that’s a good thickness for concrete flagstones. You will also need some 2×2 for the corners.
Build your forms so they can be taken apart easily. If you wanted a flagstone 8 inches by 8 inches, then your form should be made from two 8 inch lengths and two 12 inch lengths. Attach a 2×2 to each end of the 8 inch lengths with two screws, top and bottom. Pre-drill your holes so you don’t split the wood. Now you can screw the 12 inch lengths into the 2x2s and have a clear 8 inches for your form. Use one screw and aim it into the middle of the 2×2 so you miss the other screws.
Cut some plywood larger than your form so you can have a nice flat bottom, and a moveable work surface. I like to mix the concrete and fill the forms in one place, and then move them to an out of the way place to harden.
Cover the plywood with heavy plastic, put your form on it, and spray the wood with WD-40 or something like that product. This is to keep the concrete from sticking to your forms.