If the skeleton is double-layered, then special supports, “chairs” of reinforcement (in the photo on the left), are stacked and tied with a binding wire on the reinforcement of the first layer and the second layer is laid similarly to the first. Such coasters can even be made independently from pieces of reinforcement. The height of the “high chairs” should be such that there is at least 2.5–3 cm distance between the upper row of reinforcement laid on them and the level of concrete pouring.
Concrete for casting monolithic floors can be ordered ready (M400 brands) or prepared by hand using a concrete mixer. Ready concrete can be supplied manually, using a concrete pump or using a crane, depending on its volume and height of the floor slab.
Before pouring concrete, plywood must be treated with formwork oil, or at least working out, so that it is easier to remove formwork. A plastic film or roofing felt is spread on the planked formwork.
It is necessary to pour concrete at one time for no more than three hours.
After pouring, the concrete is stretched and leveled using a doctor blade (mop) so that it evenly covers the frame of reinforcement from the bottom and top. In this case, the concrete must fit tightly. It is best to use special vibrators to compact the concrete. If they are not available, you can use an ordinary bayonet spade or a wooden bar, piercing and sealing them with freshly cast concrete.
Depending on the air temperature, the formwork is not removed until the final hardening of the concrete, for 20-30 days. Concrete is covered on top of the film, and in sunny hot weather, it is periodically moistened with water so that the monolithic overlap gain strength gradually.
With your own hands, you can make another type of reinforced concrete floor – monolithic flooring along the corrugated flooring. At the same time the professional flooring plays the role of both fixed formwork and external working reinforcement.
This overlap has the following advantages:
- -reduction of work on the construction of the ceiling;
- -the possibility of reducing the height and mass of overlap;
- -reduction of time and cost of work.
For the device of monolithic overlapping on a professional flooring the following types of it can be used:
- -when the span of overlap is up to 5.7 meters – H75-750-0.8 decking;
- – when flying over 5.7 m – professional flooring H114-750-0.9.
Installation of formwork and frame reinforcement
Installation of formwork for the manufacture of monolithic overlap on corrugated flooring is performed almost the same way as usual, but instead of plywood or planks, sheeting is laid on transverse beams. At the same time, after solidification of the monolithic slab, decking is not removed, that is, it serves as a permanent formwork.
Such ceilings can be supported on bearing walls or columns. In brick or stone houses, monolithic overlap along corrugated flooring can be supported on walls with subsequent monolithing of the supporting part. At the same time, a “mortgage” from a metal corner is installed at the support site. Decking is attached to it with dowels.
After installation of the formwork, one layer of reinforcement (two rows in the form of a grid with cells of 20×20 cm) is laid on the plastic supports (crackers). Between themselves, the armature is connected by a soft knitting wire.
Monolithic ceiling do it yourself
In individual construction, monolithic reinforced concrete floors are increasingly used. They are characterized by a large bearing capacity and are an additional element of stiffness. The main function of the structure is to transfer the load from the floor to the load-bearing walls.
The thickness of the slab is selected depending on the size of the span and is calculated from the ratio of 1:30, but not less than 150 mm. For a span of 6 m, the overlap thickness will be 20 cm. The slab is laid on the supporting wall with the imposition on the surface equal to the slab thickness.
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Necessary tools and materials
For the manufacture of floor slabs will require the following tools and materials:
- circular saw, hacksaw;
- screws, screwdriver;
- level, tape measure;
- sawn timber (bars with a section of 150×150 mm and 50×150 mm, unedged boards with a thickness of 30 mm);
- moisture resistant laminated plywood;
- telescopic racks (as supports for formwork);
- fittings with a diameter of 10 and 8 mm, knitting wire;
- crochet hook;
- M200 concrete, crushed stone and sand;
- deep vibrator, shovel.
Features of formwork for monolithic floors
Slab formwork is a frame consisting of vertical supports, connected with each other by a longitudinal beam and perpendicular to the transverse beams nailed to it. Plywood sheets are lined on the frame, which serve as the bottom of the formwork. It is recommended to use wood with a moisture content of not more than 25%.
As supports can be used special telescopic racks with a U-shaped attachment in the upper part. They are installed in special tripods and locked with a lock. Instead of racks, the use of a wooden bar with a section of 150×150 mm is permissible.
Wooden supports are reinforced with braces made from unedged boards 30 mm thick. At the ends of the supports for connection with the longitudinal beams, a half-gap is made with a depth equal to the height of the longitudinal beam.
For the construction of the formwork, wooden or telescopic supports, boards with a section of 50×150 mm and sheets of waterproof plywood are used. The installation of the formwork is carried out in several stages:
- Racks are installed in 1 m increments (for plates up to 30 cm thick) at a distance of 20-25 cm from the wall.
- On the rack fit longitudinal bar at a distance of 2 m from each other. The ends of the timber are attached to the wall.
- On the longitudinal beams the cross-bar crawls with a step of 0.5 m and blends into a single grid.
- With the help of a plumb, the supports are leveled strictly vertically. Check the horizontal cross beams and, if necessary, adjust the height of the racks.
- If wooden supports are used, adjacent stands are stitched together in diameters in the longitudinal and transverse directions. The bottom of one rack connects with the top of the next.
- Sheets of plywood are laid out on the finished frame. Joints should be tight and located strictly above the bar. After plywood is laid, the horizontal bottom is checked.
- Mounted side vertical formwork shields
- The reinforcement cage is installed.
The rules of reinforcement monolithic overlap
Reinforcement of monolithic overlap is performed in two tiers. The lower part experiences tensile loads, while the upper part receives compressive loads. The framework of the frame is used reinforcement class A-III with a diameter of 8 and 10 mm. The connection of the rods is performed with wire reinforcement of class Bp-I with a diameter of 1.2-1.5 mm.
In the process of reinforcement must adhere to the following rules:
- the distance between the reinforcement cage and the vertical formwork panels must be at least 20 mm;
- reinforcement should be above and below protected by a layer of concrete with a thickness of 20-25 mm;
- the distance between reinforcement tiers is 90-100 mm;
- To install the second reinforcement layer, vertical fixers with a diameter of 8 mm are used with an upper horizontal shelf 350 mm wide and lower supporting legs;
- when building reinforcement fit with an overlap of not less than 480 mm (for a diameter of 10 mm);
- Reinforcement joints are placed in a staggered manner.
For reinforcement 1 cu. m of concrete with a slab thickness of 150 mm will require approximately 20 kg of reinforcement class A-III with a diameter of 10 mm and 7 kg of reinforcement with a diameter of 8 mm.
Installation of the metal frame is performed in the following sequence:
- Plastic clamps are placed at the bottom of the formwork with a pitch of 1-1.2 m (to provide a gap between the reinforcement and the outer surface of the slab).
- Mounted longitudinal reinforcement in increments of 20 cm. Additionally, bars are laid in the middle between the bearing supports.
- Perpendicular to the bottom row with the same step transverse rods are laid out. The intersection is tied with soft wire.
- With a pitch of 1 m in a checkerboard pattern, the detents of the lower and upper rows are set. They should be located at an angle of 10-15 degrees to the main rods.
- Similarly, the lower row is mounted the upper tier of the frame.
- At the edges, the reinforcement is reinforced by a U-shaped connection with a step of 40 cm.
How to pour concrete
Concrete of the grade not lower than M200 is used for concreting the floor. Sand and crushed stone with a fraction of not more than 20 mm are used as aggregates. Filling is carried out in one step. The solution is evenly distributed throughout the formwork, the layer thickness is controlled by beacons.
To get rid of air bubbles, concrete must be sealed with a deep vibrator. If not, then the laid solution is repeatedly pierced with a bayonet spade.
After laying the layer of concrete is covered with a film and within 2-3 days it is wetted with water so that microcracks will not appear on the surface during shrinkage. The formwork is removed in stages 20 days after concreting. First of all, the racks located near the walls are dismantled, the next day the remaining racks are removed and the entire formwork is disassembled.
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What is base waterproofing and how to use it, read here.
To create a solid monolithic overlap, you must comply with the following requirements:
- plate thickness is determined by the size of the span, the ratio of which should be 1:30 (but not less than 150 mm);
- the formwork consists of vertical supports and the base of the longitudinal and transverse bars, on which the sheets of moisture-resistant plywood are laid;
- installation step supports – 1 m, laying longitudinal bars – 2 m, transverse – 0.5 m;
- to compensate for tensile and compressive loads acting on the floor slab, the installation of a double reinforcing frame is required;
- the frame is made of reinforcement with a diameter of 10 mm and connecting elements with a diameter of 8 mm;
- the lower and upper tier consists of rods laid in the longitudinal and transverse direction and forming cells of 20×20 cm in size;
- concreting of the slab is carried out in one step with the obligatory compaction of the solution;
- the formwork is dismantled 20 days after pouring concrete.
Monolithic ceiling do it yourself. 1 comment
How to write off rebar, if you have not seen the reinforcement cage? A difficult question, but I got into this situation.
Sources: http://osnovam.ru/stroitelnye/monolitnoe-perekrytie-svoimi-rukami, http://www.postroj-dom.ru/peRkrytyia/176-monolitnoe-perekrytie-svoimi-rukami, http: // stroyergo. com / stroitelstvo / perekrytiya / monolitnoe-perekrytie-svoimi-rukami.html