How to make a simple mold for casting cement blocks from boards and PVC pipe

Hollow cement-based blocks, practically without losing strength and thermal insulation, are much lighter and cheaper than solid ones. To make them, you can make a very simple but easy-to-use form from boards and PVC pipes, having basic carpentry skills.

Will need

Materials:

wooden boards of various sections;
screws and nails;
wooden blocks of different sections;
PVC pipe with a diameter of 100 mm.

Tools: drill with a 102 mm core drill, hand screwdriver, pencil, square and tape measure, metal knitting needles, hammer, etc.

Process of making a mold for cement blocks

From a board 2 cm thick and 19 cm wide, cut out two pieces of length 18 cm and 39 cm, which will serve as the outer frame of the mold for the blocks.

We connect them together using self-tapping screws so as to ensure the block dimensions are 14x19x39 cm.

At the level of the upper surface of the outer frame of the form, in the transverse direction, we fasten bars 18 cm long with self-tapping screws on both sides and in the center - two more bars of the same length, but with a larger cross-section.

We install the outer frame of the form in the center of the board, which is wider and longer than the frame and will serve as the basis for both the entire form and its inner part.

We draw the inner perimeter of the frame on the base, draw a longitudinal center line and mark on it the installation locations of three PVC pipes to form voids in the block. To ensure that the strength of the block is not affected, we retreat 2 cm from the edge and add another 5 cm (the radius of the PVC pipe). This means that the centers of the outer pipes will be at a distance of 7 cm from the inner edges of the mold.

Since the length of the block is 39 cm, the distance between the centers of the outer pipes is 25 cm, then the center of the middle pipe will be at the same distance from the outer pipes, 12.5 cm.

Using a drill, we drill holes in the three designated places and, using them for centering, use a core drill with a diameter of 102 mm to drill three through holes in the base of the mold.

We insert PVC pipes 24 cm long into these holes. We measure 19 cm from the end of each of them and drill thin diametrically opposite transverse holes. We temporarily insert metal spokes into them to prevent the pipes from falling down when installed in the holes made in the base.

We turn the base with the pipes over and trace its extension on the pipe, on which we make a system of longitudinal cuts to the mark. We bend the resulting petals outward and nail them to the base with small nails.

We return the base with the pipes to its original position and install the outer walls of the mold.To prevent them from moving in the longitudinal and transverse directions, we fasten two blocks of 18 and 39 cm in length to the base with self-tapping screws.

We also fasten one strip about 39 cm long on each side with self-tapping screws from the bottom of the base in the longitudinal direction. The mold for making blocks is ready for use.

Before filling it with cement mortar, lubricate the internal surfaces with liquid soap or any oil, for example, motor oil.

While filling the mold, compact its contents several times by shaking and tamping, let the solution set, turn the mold over and remove the base with PVC pipes.

Then we place a board on the surface of the block, the dimensions of which in plan are slightly smaller than the corresponding dimensions of the block. Holding the board with two thumbs on both sides, remove the outer frame of the mold. By repeating this simple procedure, you can make the required number of blocks.