You will need
- cement, gravel, sand, gravel, water;
- - wooden planks with a thickness of 20-50 mm, roofing sheets, plywood;
- - steel rods Ø 8-10 mm or steel reinforcing wire Ø 6-8 mm;
- - engine oil;
- - metal pin Ø 10-20 mm.
Pitch wooden formwork of the outer and inner cylindrical surfaces. To do this, we put together two wooden rings for assembling the outer cylinder and two rings for the inner cylinder. The sides of the forms can be manufactured as boards and roofing sheet, plywood, etc. make the Formwork collapsible, consisting of several parts. Secure the wall forms wooden planks. The diameters of the cylinders are interconnected with an outer Ø of 1000 mm and inner Ø 900 mm the resulting thickness of the concrete ring 100 mm. For W/b rings of sufficient thickness 50 mm.
Lubricate with engine oil turned to cement mortar the surface of the cylinder to facilitate their removal. Then the cylinder is of larger diameter set on a wooden shield and strengthen. Exactly in the center of the outer cylinder insert the cylinder interior.
Enter the lugs of the reinforcing wire (for concrete rings) or a reinforcing cage (W/W rings) into the gap between the cylinder walls. To hold the valve in a certain position to place the 4 wedge.
Prepare the cement slurry composed of cement (1 part), sand (2-3 parts), gravel, slag or gravel (4-5 pieces). Take the binder with fresh cement is not below grade "400". Good astringent properties of Portland cement or cement with no mineral admixtures. It contains up to 5% of magnesium oxide and up to 8% tricalcium aluminate. The most commonly used cement brands М500Д0 and М400Д0.
Use as filler cleaned of impurities, natural-enriched with quartz sand, the fineness modulus of which varies in the range of 2.0-2.2 mm. the Largest size of coarse filler should not exceed 20 mm. so, for the manufacture of concrete rings concrete mix of small and large fillers – sand, gravel and crushed stone, binder – cement and water.
Put the obtained cement slurry in the gap between the cylinders to a height of not more than 100 mm, metal pin, carefully tighten it. Move the wedges to a height of 150-200 mm in order to fill concrete and seal the place of their stay. Method of weaning complete the entire form. After 4 days free obtained a concrete ring from the casing.
Leave the ring on a wooden shield still day 4, periodically spraying it with water. This will give the concrete increased durability. Remove from the surface of the concrete ring engine oil. Production of concrete rings is completed.
Clayey and silty Sands significantly impair the quality of concrete, therefore are not used here.
Thoroughly mix the cement slurry as the strength of the concrete mass depends on its homogeneity. When working in cold weather use an antifreeze additive.