Knowing how to pour concrete can help you save a few dollars when you decide to do some work on your home. You can use the tools you have in the shed or garage; it is not necessary to have special tools to do small jobs. Casting the concrete requires a bit of muscle as it is quite heavy. However, with the help of these few instructions, you can easily realize your projects.
Steps
Method 1 of 2: Prepare the Flush Area
Step 1. Remove the area from any objects and materials that may interfere with your work
This includes grass, stones, trees, bushes and even old concrete. Remove everything until you see only the bare earth.
Step 2. Prepare your casting base
The term casting base refers to the material on which you will place the concrete. Gravel-type gravel fill or road bedding is usually used, although, in rare cases, bare soil is compact and stable enough to be used as a base.
- The soil under the foundation is called the subgrade and the concrete will be as strong as the subgrade is. Think about it for a moment: if the substrate is crumbly, moves or has holes, the integrity of the concrete is compromised. Make sure the subfloor is compact and stable before placing the casting base.
- Many professionals choose mixed sand gravel as a casting base. The gravel leaves spaces that allow the water to drain and at the same time is a less expensive base. As a counterpart it is not very compact and some builders choose a much finer-grained gravel to increase stability. However, this type of base is very expensive.
- Spread a 5-10cm thick base layer and compact it with a manual or electric beater. The electric one may seem oversized for small jobs or DIY, but it offers a lot more power.
Step 3. Prepare the formwork
It is usually made of wood fixed with special nails and screws and defines the perimeter around the casting area. A well-constructed formwork will help you finish your project better. Remember a couple of things when building the formwork:
- For square or rectangular perimeters, make sure the corners are 90 °. Take a tape measure and measure the diagonals of the square or rectangle: they must be equal to each other. If they are not, go back to the work table with the formwork.
- Also make sure that the formwork has a slight slope. If it were completely leveled, the water would stagnate in the middle of the concrete. To avoid this, create a small slope of 0.5 cm every 30 cm. When working with certain floors, a slope of 0.3 cm every 30 cm is also fine.
Step 4. Consider adding wire mesh or rods to the formwork (optional)
They are used to give greater stability, especially in structures that will have to bear high loads, such as traffic routes. If you want to cast concrete to create a surface that will not be excessively stressed by weight, you can avoid placing wire mesh and rods. Both have advantages and disadvantages:
- The wire mesh prevents the formation and spread of small cracks and will offer greater stability in the horizontal plane (the mesh is welded while the rods are tied together). The disadvantage of the network is that it does not contribute much to the integrity of the structure.
- Rebars give greater structural integrity and are better for surfaces that have to withstand heavy loads. The other side of the coin is that it does not reduce the formation of cracks.
Method 2 of 2: Cast the Concrete
Step 1. Prepare the concrete
It is a mixture of cement, sand and gravel in a ratio of 1: 2: 4. Water is added to mix the ingredients.
In a concrete mixer, add the water and then the mix for the concrete. You can use a wheelbarrow and mix everything up with a shovel. Use as little water as possible. Water makes the concrete malleable but weakens the final structure. Turn on the concrete mixer. The mixture should be smooth and consistent. Turn off the car
Step 2. Throw the concrete into the formwork
Sometimes you can even take a truck to lay the concrete; but you can also put it in the wheelbarrow and empty it into the formwork until it is completely filled. As you do this, find some helpers to smear the concrete with the shovel and concrete rake.
Step 3. Level the surface of the concrete
Starting at the highest point, use the rails to level and smooth the still wet concrete. Move the rods from left to right in one continuous motion to create a flat surface, even better if the rods are long enough to rest on the edges of the formwork.
Work from top to bottom, leveling gently until the surface becomes flat. The work is not finished yet but we are beginning to see the appearance of the complete work
Step 4. Refine the newly leveled surface to compact it even more
At this point you have to move as fast as possible because the concrete stabilizes quickly. Finishing involves two steps:
- Use a large tool called a trowel to press and compact the concrete and smooth the surface. Push the trowel away from you, keeping the rear edge slightly raised and then pull it towards you keeping the front edge a little raised.
- Use a smaller hand trowel to finish the surface. When a little water begins to come to the surface, use the trowel making large circular movements to smooth the concrete.
Step 5. Make control joints every 1.5m or 1.8m
Use a plank of wood to line up the edge and make regular joints. These grooves are useful for preventing the concrete from fracturing with changes in temperature. The depth of the joints must be about ¼ of that of the entire concrete.
Step 6. Create grip
Use a broom to make lines on the surface. This creates adhesion to the concrete and does not make it slippery when it gets wet. You can also use a soft brush to create a less wrinkled surface. If you want a smoother surface, but that maintains some grip, you can use a trowel and slide it in a circular motion. Make sure that the lines are not too deep, a stagnation of water would compromise the integrity of the casting.
If passing the broom creates lumps of concrete that stick to the bristles, it means that it is too early to do this job. Go over the trowel again by hand to smooth out the marks left by the broom and try again later
Step 7. Protect and seal the concrete
The cement should be left to rest for 28 days and the first few days are the most difficult. As soon as possible, professionals recommend sealing the concrete to protect it and prevent both cracking and discoloration.
Step 8. Keep the concrete in good condition
Although concrete is thought to be a problem-free surface, regular maintenance can only help. Washing it with soap and water keeps it at its best and occasional sealing (about every 5 years) protects it from damage and wear.
