Whether you are building a house or a hangar, the placement of the slab changes the course of your construction efforts. Before the slab is finished, the crew must install the underground systems, level the site and prepare the foundation, generally working in a horizontal plane. Most constructions don't really start to rise until this stage is completed, and this article tells you how to do it.
Steps
Step 1. Prepare the area where the work will be done
Heavy equipment could be used to erase the footprint of the building, unsuitable plants and materials removed, and the subsoil inspected to determine if it will provide adequate support for the slab and structure that will be built on it.
- Have a topographical survey done or design construction lines yourself. You could use pegs, or you can attach corner posts to allow construction lines to be pulled and gradients to be established for erasing and leveling.
- Uproot trees, bushes, and other plants, including their roots so they don't leave gaps in the subfloor when they decompose.
- Remove all dirt or any unsuitable material from the subsoil.
- Try the roller or use another method to compact the unbalanced subfloor soil material.
Step 2. Create and place the concrete foundation that will go under the slab
For monolithic slabs, there may simply be a "curved down edge", but for many buildings, a plinth is poured, then the CMUs (Concrete Masonry Elements, commonly called 'Blocks') are accumulated to the level of the finished floor.
Step 3. Set the shapes for your plate
Construction lines that have been laid out on the outside construction line and "level" (at the correct height), will allow you to form the edges of the slab straight and level.
Step 4. Preliminary installation of the plumbing or pipes for the electrical cables, as well as conduits for the pipes and wiring of the air conditioning
The tub drains and toilet flanges are typically "closed" so that the "siphons" can be installed when the system is then put in place.
Step 5. Fill the plate area with a material suitable for the finished layer
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Capillary filling is used where humidity could create problems.
- Pressed limestone or other aggregate base materials can be used for heavy-duty slabs, such as warehouse or hangar floors.
- Compact materials such as clay are sometimes used when the subfloor cannot be sufficiently stabilized by conventional methods.
Step 6. Compact and finish leveling the fill material
For engineering constructions, it may be required to test the fill density to meet the architect's specifications. This is normally done by a geo-technical engineering laboratory.
Step 7. Pre-treat the backfill and sub-foundation against insects using an approved and classified insecticide
This is typically done by a bonded and licensed pest control company.
Step 8. Install the required moisture protection or waterproof membrane "immediately after applying the insecticide
This will help prevent the chemicals from evaporating, and will prevent the subfloor from drying out and becoming "loose".
Step 9. Install the reinforcement wire or reinforcement required by the architect / engineer or local building codes
Make sure it is supported so that it is placed correctly after the cement is placed and fixed. Using concrete "chairs" is an effective way to do this.
Step 10. Plan the method you will use to level the concrete
For large spans, you will want to set levels or some type of guide screed to allow workers to keep the concrete flat, or at the desired angle. In the photograph image the guide tubes are used for positioning, but other techniques can also be used, including grade stakes, or using a level and laser target to position the wet plane.
Step 11. Determine the method you will use to place the concrete in the shapes
This must be done at the beginning of the process so that concrete mixers and other required appliances can enter the work area when placing the concrete.
- Aerial pumps can position the concrete in specific areas of the slab through an articulated arm and a pump reaching up to 36m from the concrete mixer. They are often used to put concrete on raised floors or in inaccessible places.
- Inline pumps also use hoses and hoses to move the concrete from the mixer to the location point, but moving the hoses while in use requires a lot of work.
- Concrete buckets can be used to put concrete in high places or inaccessible areas using a crane or forklift.
- The "Georgia Buckets" are self-propelled "Wagons" that can maneuver in tight spots to be able to lay concrete.
- Sliding or "heel" means unloading the concrete directly from the mixer to the mold.
Step 12. Check the shapes for alignment and make sure all arms are tight and well anchored so that the weight of the concrete does not cause them to bend or fall during pouring
Step 13. Calculate the amount of concrete needed to complete the slab
Measure the length, time and width and multiply it by the depth, in meters or decimal fractions, this will give you the total cubic meters of material required. Allow for an extra amount of concrete to fill all monolithic footings, depressed slabs, and base areas of the fill material.
Step 14. Order the concrete from a ready mix cement supplier, and have the delivery coincide with the target cement placement
This includes both the date and time of the deposit, and the time it takes for the various concrete mixers to arrive on site so that the team has time to unload and take care of each load, without having to wait for each other to arrive. truck.
Step 15. Coordinate the concrete test with a qualified laboratory if the construction contract requires it
Test labs often do the following test:
- Flexion. This test determines the plasticity of the concrete material. A vertical cone-shaped mold is filled with concrete and the amount of concrete that "falls" is measured, to make sure it is not too wet to meet the specifications for the job.
- Temperature. Cement suffers detrimental effects when it gets too hot, so the product temperature is monitored during placement.
- Incorporation of air. Chemicals are added to the cement to ensure that air is incorporated into the mix. These small voids will allow the concrete to expand and contract more before cracking, in cases where large variations in temperature over time are expected. A typically required air entrainment is 3-5%.
- Compressive strength. The strength of the concrete is measured in PSI (pounds per square inch), and special plastic molds are used to collect samples of the material which are then tested in laboratories to determine the strength of the concrete.
Step 16. Plan to start placing large slabs as soon as possible to ensure that the project is completed on time
Things to consider are as follows:
- Make sure you have enough manpower to do the job.
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Check the weather conditions. These factors can contribute to the fixing times of the concrete:
- Temperature. The higher the temperature, the faster the concrete will dry, and too hot weather conditions will also hinder the work of the workers.
- Humidity. A very low percentage of humidity will evaporate the water in the concrete much faster.
- Wind. Wind can increase the rate at which the concrete surface dries.
- A cold climate can greatly increase the cement placement time. Putting the concrete in temperatures close to freezing or when freezing weather is expected for the following 48 hours is absolutely not recommended.
- Sunlight. Concrete will dry much faster when exposed to sunlight than on a cloudy day.
Place and Finish a Concrete Floor Step 17 Step 17. Arrange all equipment to be used for pouring the concrete on the designated day
- If you have to use a concrete pump, have it arrive at least an hour early to be set up and put into place, and to allow the worker to get an idea of the placement plan.
- Check the machines, that is, test the controls, the blades, and make sure they have a full tank of oil and gasoline.
- Check straight edges, screeds, strength of screeds, and screeds to make sure they are in good condition.
- Make sure the concrete vibrators are in good condition if the slab requires their use.
- Check personal safety equipment, such as gloves, rubber boots, and eye protection.
- Clean and check all hand tools to make sure they are usable.
Step 18. Begin pouring the concrete into a corner and continue to spread it along the level or screed lines as planned
The concrete can be placed in parallel sections as long as each subsequent section is placed before the previous one has started to dry, otherwise there will be cold junctions between the two.
Step 19. Make sure the wire rod mat or reinforcement is not stuck under the concrete during pouring
If necessary, have one or two workers follow the people pouring the concrete and use a hook to pull up the wire. Keeping the reinforcement in the correct position is crucial for the strength of the sheet.
Step 20. Continue pouring the concrete and pulling it level enough by accompanying and smoothing it with a straightedge or electric screed
Have trimmers work on electrical conduits and plumbing pipes with hand tools to keep the surface level.
Step 21. Have one or two finishers level the concrete, depending on what the job requires after it has been leveled
The person leveling the concrete may need a worker to add concrete to any area of elevation he notices while doing his job.
Step 22. Work the edges of the plate
This is the stage where you move around the edges to make sure the perimeter of the plate is flat and smooth. This process is particularly important if the arms are anchored above the mold, or if the molds are not flush and level.
Step 23. Remove pipe screeds or drop stakes as each area is positioned and leveled
If a hole is left in the concrete when the screed or stake is removed, add more concrete with the shovel to bring it flush with the surface of the leveled concrete.
Step 24. Continue pouring the concrete until the molds are filled to the level of the plate
Once the concrete has been completely leveled, give someone the task of cleaning the tools used to put the concrete, including pipes, spirit levels and shovels.
Step 25. Allow time for the concrete to set
If the edges have been filled properly, and the levelers have done a good job with the main areas, you will need to have the team wait until the concrete is hard enough to support the workers on the boards before continuing the refinishing process. Check the concrete by pressing with a glove until it is firm.
Step 26. Have trimmers work on boards where electric trowels cannot be used
These hard-to-reach points can require considerable effort.
Step 27. Place the trowel on the slab when the concrete is hard enough to support a worker without leaving deep imprints on the surface
If you wait too long the concrete will be too hard to achieve a good finish, but starting too early could cause the machine blades to dig into the concrete creating heat, bumps and other problems.
Step 28. Work the concrete with the blades on the flattest setting
This gives them more "surface area", so they won't risk sinking as they spin on the surface. Using a combination type blade, rather than a trimming blade, is much more useful for this step.
Step 29. Spray some water on non-trowelable areas, especially to help fill gaps and cover any aggregates left exposed during leveling
Step 30. Let the concrete continue to set after being troweled the first time
If the surface is flat and flawless, you can let it solidify until it is ready for final leveling. Since the concrete is poured in a continuous operation, the first area it is placed in will definitely set first, but beware of areas exposed to the sun or wind as they may harden before shaded or protected areas.
Step 31. Run the electric trowel over the concrete until you reach the level of finish you want
For a "hard trowel" finish, you will raise the blades as the concrete hardens, this will allow you to put more pressure on a smaller area of the blade.
Step 32. Apply a healing compound or use a maintenance technique to prevent the concrete from drying too quickly, especially in extreme weather conditions that would lead to rapid evaporation
Step 33. Saw all the joints required by the construction plans
34 Remove the molds and clean them for reuse in the next project
Be sure to remove any screws or nails that could be dangerous to the workers using these materials.
Advice
- Plan to lay concrete in moderate weather if possible.
- Clean tools immediately after use.
- Make sure the project is accessible for all equipment required for the job.
- Make sure you have enough help to properly spread and finish the concrete.
- Keep all tools in good condition.
Warnings
- Spreading concrete is a strenuous project, make sure you and your workforce are well rested and stay hydrated during the process.
- Concrete contains alkali metals and chemical additives which can be harmful. Avoid skin contact and wear eye protection when spilling.
