A concrete slab is a construction material that is poured in place or placed in formwork.
Slabs are typically flat horizontal segments of reinforced concrete flooring supported on all edges by the underlying foundation or steel framework. These slabs can also be used to cover roofs. A basic slabs deck is typically formed by excavating or blasting to a depth below the top of the slab and filling it with a suitable base material such as sand, gravel or dirt. A finishing layer of waterproofing is then applied.
Concrete slabs are found in a wide variety of domestic and commercial structures. Typical residential uses include exterior porches, garages, basements, patios and a concrete slab floor inside the home. Commercial applications often involve finishing over entire new floor decks or covering expansion joints on existing slabs and floors to control cracking. Additional benefits provided to sheet metal decking is sound reduction under foot traffic which can be an advantage for a suspended slab on apartment buildings with thin walls located above retail stores, where noise may be an issue for tenants living directly overhead.
In general terms, a thick slab is better when it comes to strength and durability as more reinforcement material can be used. Slab thickness is often between 5cm and 20cm, depending on local building codes and finished concrete floors requirement. Thinner slabs are easier to work with but do not leave much room for error when mistakes are made during construction or finishing. Generally speaking, the more support that is provided to the subfloor, the better results can be expected.
Under normal conditions, most prefabricated slabs only require one worker once they have been set in place and prepared before pouring begins. Time taken will vary depending on existing site conditions such as the location of utilities, the thickness of existing foundation material and final grade level of surrounding ground surface. The majority of pours can typically be completed within one day with proper preparation time factored into the total project duration.
A foundation is a term used to describe any supporting structure constructed beneath ground slabs. This can include items such as steel beams, concrete footings or even water tanks. Slabs are designed to help distribute the weight of the finished floor directly above them over a larger area by evenly distributing their load through foundation material which in turn helps prevent sinking of the surrounding ground surface. Bearing capacity is an important factor when it comes to the thickness of flat slabs or footing materials, especially if they are required to support heavy machinery or large pieces of furniture on lower levels inside the home. Loading calculations will also be based on Occupational Health and Safety legislation which often changes with time.
Concrete has unique properties that can be manipulated to create various finishes for interior and exterior applications. When properly mixed with the correct ratios of other materials like sand, aggregate and Portland cement, concrete gains strength. It forms what is known as a chemical bond between particles. The vast majority of modern slabs poured today are reinforced with steel which helps to strengthen the mix. Waffle slabs are a good example of this. Unlike conventional slabs, they can support more weight.
For concrete to completely cover the steel, use plastic bar chairs to keep it away from touching the wooden planks on the formwork. Doing this also ensures concrete completely envelops the bars. Soil type will determine the type of slab to use. Steel reinforcement also creates hidden channels for electrical wiring or plumbing in finished interiors.Waffle raft slabs work well for lightly or moderately reactive soils. Unlike the stiffened raft slabs, a waffle slab is not lodged to the ground. But, the stiffened raft slab is still most commonly used in construction on sites with non- reactive soil.
At its most basic level, concrete has an average compressive strength ranging from around 2MPa up to 20MPa. The strength depends on early additions or admixtures added during the mixing process. Concrete is classified using grades 1 through 5 where Grade 5 has the highest compressive strength and grade 1 has the least.
In simple terms, compressive stress is a load that tends to compress an object rather than stretch or tear it as tensile forces do. This type of force is common in concrete slabs or even steel beams used for carrying significant loads. Good examples are used in building bridges or any large ground slab. Compressive stress can also be applied to columns of water, meaning that these same forces are present inside an average household hot water cylinder. It is important to note that concrete has a very low tensile strength which means it does not perform well if exposed to forces that try and stretch or tear it apart rather than compress it.
Generally speaking, there are two common concrete slab types used in residential construction projects. These include precast flat plate which is typically available as either a one-piece hollow shell or solid poured floor option and post-tensioned slabs which utilize high strength steel cables to create an ultra-strong foundation for upper floors. Precast homes can be constructed up to four storeys in height while post-tensioned structures should not exceed three without additional support framing around perimeter walls. Both are typically laid over compacted sand to gravel base, with the addition of reinforcing mesh.
Post-tensioned slabs are primarily used in areas where the ground is unsuitable for excavating due to native soils or underground services while flat plate options offer maximum design flexibility to architects and home builders alike. Both forms of the slab should only ever be installed by qualified tradespeople who have received training in proper safety procedures and steel reinforcement installation to avoid any potential collapse. Additionally, moisture testing prior to pouring both types of the slab is essential as it can cause permanent damage if left unchecked during the early stages of construction. Post-tensioning cables used inside post-tension slabs are typically pre tensioned which means they are stretched before being incorporated into the slab.
Concrete finishes vary depending on desired aesthetics. The most common finish is the smooth surface, created using a floor polisher.There is little difference between the two terms, with both referring to a foundation of reinforced concrete that often supports walls and upper floors. On the other hand, 'cement' refers to Portland cement which is one of many ingredients used within modern-day concrete mixes. Cement has been widely replaced with substitutes like fly ash or blast furnace slag for reasons including its long curing time (24 hours) compared to alternatives or improved performance when exposed to fire or impact damage. Understanding this key difference makes it easier to understand why some people refer to their slab as being made out of concrete while others say cement.