home remodeling
concrete contractor
360 Construction Group
(843) 227-7660
350 Fording Island Road, Bluffton, SC 29910
home remodeling
The Basics of Concrete Laying
Concrete is a tough and long-lasting building material that serves many purposes; roads, walls, floors, footings in buildings lines pools – you name it. It is a dry mixture of cement, aggregate (sand and gravel) and water.
Use a groover to make controlled joints in the concrete at regular intervals. These will help the concrete withstand cracking due to temperature changes.
Preparation
Concrete is an incredibly versatile material that can be used for virtually anything. Roads, bridges, walls, footings in buildings, lines in pools — the list goes on and on. Before any of that can happen, though, the ground has to be prepared. This involves clearing the area, adding a subbase or gravel, and compacting to ensure a stable base for concrete laying.
Once the surface is ready for concrete laying, it must be cleaned to remove loose debris. This is usually done by scrubbing with water or using low-pressure vacuum cleaning equipment. It is also important to inspect the surface for any defects, such as voids or blowholes. Any imperfections that are discovered should be patched with the appropriate materials before continuing.
The type of surface preparation required will depend on the type of coating being applied and the substrate’s current state. For example, if the surface is in good condition, it may only need low-impact preparation methods that will not significantly alter the surface profile, such as vacuum shot blasting, grinding or vacuum cleaning. If, on the other hand, the surface is compromised to the point that it requires more aggressive preparation, methods such as scarifying, needle scaling or scabbling should be used.
The ideal surface for concrete laying is one that is clean, dry and smooth. This will help to ensure that the coating adheres properly and offers optimum performance. Every year Belzona hears of disbondment problems that are a result of poor or nonexistent surface preparation.
Mixing
Concrete requires a precise mix of Portland cement, sand and coarse aggregate to form a solid, load-bearing material. If it’s mixed wrong, it can have structural weaknesses and cost more than it should.
It’s important to start with a dry mix and mix thoroughly. Adding water is what activates the cement to bind with the sand and aggregate to make concrete. This is what gives it its strength. A good mix is the consistency of thick peanut butter.
For a basic concrete mix, it’s generally recommended to use a 1:2:4 ratio of cement:sand:coarse aggregate. This mix provides the strongest, most durable results for your construction project.
There are a number of chemicals called admixtures that can be added to the cement, water and aggregate during mixing to modify or improve its properties for a specific application. Using these doesn’t reduce the quality of your workmanship however, it just allows you to create more specialised finishes such as self-levelling or anti-slip mixes.
After the concrete is mixed, you may want to add a decorative finish for aesthetic purposes. For example, a concrete brush can be used to create traction on walkways or to add patterns to the surface. You may also choose to bullfloat the concrete, which provides a smooth finish suitable for house floors. You’ll also need to cut contraction joints, which eliminate unsightly random cracks and prevent the concrete from raveling.
Forms
Concrete forms are the structures that hold and shape the final concrete. They can be built by hand, or by using pre-manufactured forming systems designed to cast large area walls, foundations and piers. These are often made from engineered wood with a metal frame or entirely from steel. They come in a variety of sizes and are designed to attach to each other through a system of pins or latches.
Before constructing the form for your slab, stretch out strings to mark the perimeter and height of the final concrete wall or slab. This helps ensure a consistent grade of concrete, and allows you to estimate how much fill is needed. You can also use a builder’s level to ensure the form is plumb.
To prevent the concrete from pushing the form outward, wooden stakes are placed at intervals along the form boards. These need to be sufficiently tall and strong enough to withstand the weight of the wet concrete. If the stakes are too short, they may bend or even collapse under the concrete.
Before pouring the concrete, spread and tamp a layer of granular fill over the concrete forms. You should then slope the fill down towards the forms, and leave a foot-deep trench around the interior perimeter for a thickened edge. This helps to reduce cracking of the final concrete. If you used a dry mix, the concrete may need to be sprayed with water, while if it was a wet mix, the concrete must be “screeded,” or flattened, to promote crack resistance.
Pouring
Concrete is a tricky substance to work with. It dries quickly, and mistakes can become permanent. The best way to avoid such mishaps is by planning carefully. This includes establishing the correct mix, preparing forms and making sure all necessary tools are present on site. It's also worth considering adding reinforcement to the concrete for added strength and crack resistance.
Once mixed, concrete must be transported to the intended location for laying. It can be hauled in a truck, carried in a wheelbarrow or bucket, dropped free of gravity with a tremie, or poured through pipes. The type of transportation and placement depends on the distance involved, quantity required, and other factors.
Before pouring, water must be sprayed on the surface to dampen it. This helps the concrete set evenly and prevents segregation. This step is particularly important during hot conditions, when the concrete will set more rapidly and be brittle.
During a pour, all hands must be on deck to place the concrete quickly and correctly. It's also helpful to use sunshades and windbreaks to reduce the threat of harsh weather conditions. A light drizzle of chilled water can also decrease evaporation and give the concrete more time to complete the hydration process. Once poured, a screed board must be used to smooth the concrete. The ideal choice is a long piece of scrap lumber like a 2x4 or a 1x4 that can reach both ends of the form.
Screeding
Screeding is the process of smoothing out concrete and producing a uniform surface. It removes high spots and fills low ones to produce a level surface that can be finished with a variety of tools. These include smaller wood and metal hand floats for sidewalks, and larger concrete screeding tools such as a bull float for large slabs.
For a more professional finish, an engine-powered screed may be used for large projects. These are usually made of aluminum and have a long handle to reduce labor. They can also be customized to suit your project, such as adding polypropylene fibres for strength.
The primary purpose of the screed is to create a flat and even base for floor finishes, such as tiles or concrete. It can be used in wet or dry applications, depending on the type of floor being constructed.
When using wet screeding, the concrete mix must be spread evenly, and it must be kept moist while being spread. The use of excessive water will cause the concrete to slump, which can damage the surface.
The use of an appropriate type of concrete for the screed will ensure that it dries properly and that there are no cracks or fissures when it dries. It is also important to avoid low or high spots, which can occur due to improper mixing, application, or finishing. These can cause problems such as delamination or dusting.
Finishing
A few steps remain to complete concrete laying. First, compress the concrete if necessary. However, many modern concrete mixes do not need to be compressed before finishing, and tamping the wrong mix can weaken the slab. It is best to confirm with a professional before deciding whether or not to compress.
Next, bullfloat the concrete to eliminate high and low spots and embed aggregate particles below the surface. This finish is ideal for spaces that prioritize safety, such as swimming pools and walkways. After bullfloating, smooth the concrete with a magnesium float to create an even textured surface. This step is often done with a power float but can also be accomplished with a hand trowel or a long-handled tool called a fresno. This method of finishing removes the small humps and bumps left by the screed.
A broom finish is used to create a non-slip surface. Although not as attractive as other concrete finishes, this finish is preferred in areas that require traction control like driveways or sidewalks.
Before finishing, it is important to remember that wet concrete is highly alkaline and can cause chemical burns if it comes into direct contact with your skin. To minimize the risk of burning your hands, it is recommended to wear rubber gloves and safety glasses. It is also a good idea to cover the concrete surface to prevent it from drying out, and to keep it moist with water until it is ready for finishing.
concrete contractor
360 Construction Group
(843) 227-7660
350 Fording Island Road, Bluffton, SC 29910
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