While you might assume concrete is one solid, gray material, the truth is there are many different types. Understanding these differences can help you determine the best type of concrete for your project.
Plain concrete is the simplest form, and uses the common proportions of cement, aggregates and water (typically 1:2:4). This is commonly used for pavement and buildings that don’t require high tensile strength.
Plain Concrete
Plain concrete is the type that you’ll see on a daily basis, whether you’re walking along a sidewalk or driving down a highway. It’s the most common construction material in the world and is responsible for the huge buildings, roads, bridges, sidewalks, and floors we have all around us. This is because it is incredibly durable and easy to make into whatever shape or size you need.
In its simplest form, normal concrete is a mixture of cement, sand and coarse aggregates, and a pre-specified amount of water. It doesn’t contain any reinforcement and is typically used for structures that don’t need high tensile strength. Pavements and commercial patios are common uses for this kind of concrete.
It’s important to note that although concrete is incredibly strong under compression, it can crack under tension. This is why it’s not ideal to use on curved surfaces. Additionally, it isn’t a very good choice for shear failure as it can easily crumble when faced with these types of loads.
There are a few different kinds of lightweight concrete. These include lightweight aggregate concrete, no-fines concrete and aerated concrete. These solutions have reduced weights and densities thanks to different materials like pumice, scoria, expanded shales, and clays. These also have low thermal conductivity, which makes them a great option for insulation.
High-Strength Concrete
High-strength concrete is a special form of concrete that can achieve very high compressive strengths. This is accomplished by varying the mixture proportions, using admixtures such as fly ash or silica fume to increase hydration and by adding smaller aggregate. This type of concrete is used in applications where the structural strength must be higher than normal concrete can withstand.
Because of its extreme strength, this concrete can be used to create taller and more elegant buildings. It can also be used in highway bridges where girders can span greater lengths than with ordinary-strength concrete. It is also used in culverts and other specialty structures.
Another reason to use this concrete is its speed of construction. It can set very quickly, allowing contractors to remove forms and begin construction sooner. It can even be used for repair projects, such as paving roads, where the concrete must be ready to be driven on within a few hours.
High-strength concrete also has advantages over normal concrete in that it is less porous and thus resists more damage from chemicals. This is an important factor for structures such as chemical plants, which are often exposed to harsh industrial chemicals that can deteriorate concrete over time. High-strength concrete is also lighter in weight, which means that fewer supports are needed to bear the load of the structure.
Limecrete
Limecrete is an environmentally friendly option that can be mixed with natural products, such as straw or hemp, without the risk of rotting and mould. It has a lower moisture content than concrete, so it draws out excess humidity instead of pushing it to the walls where it can climb timber and cause problems. It also works well with underfloor heating and can be painted with non-toxic materials. The material also reabsorbs carbon dioxide as it sets, which can have additional environmental benefits in terms of health and the air quality in your home.
To create limecrete, mix 2 parts aggregate to 1 part natural hydraulic lime, such as Roundtower NHL 5, and a proportion of screed fibres (we recommend adding 1 bag per tonne of aggregate). Then, use a tamper or float to make a workable surface and let it dry before covering with a suitable membrane.
The breathable nature of limecrete means that it is less prone to cracking and can withstand the movement found in older buildings that are subject to thermal expansion and contraction. This is an important consideration when planning a new build. Its high flexural strength also makes it a good material to be used underneath UFH, as it will cope with movement and reduce the need for expansion joints. This can save time and money for both you and your client.
Fiber-Reinforced Concrete
Concrete reinforced with synthetic fibers is a popular choice for homebuilding contractors and homeowners today. These fibers can improve tensile strength, durability and energy absorption in addition to other benefits. Fibers can increase bending resistance and flexural toughness in concrete, helping it resist cracking and other damage. They also have a high impact resistance, making them ideal for use in areas exposed to vehicle traffic.
The types of fibers used in concrete-reinforced materials vary by product. Steel fibers are an example of one type that can be added to concrete. They are available in a variety of lengths, diameters and slendernesses. They tend to have hook-like ends that improve the bonding with the concrete matrix. This can significantly increase the bending tensile strength of concrete, and also its ductility, flexural toughness and energy absorption capacity.
Micro synthetic fibers are another type of material often used in concrete reinforcement. They offer superior resistance to the formation of plastic shrinkage cracks versus welded wire fabric, and they can also be used to enhance toughness and improve ductility and structural capacity in certain applications.
Macro synthetic fibers, which are a recycled form of polypropylene, can be used to improve the durability of concrete. These fibers can reduce cracking due to drying shrinkage, structural load and other forms of stress, as well as improve spall protection and freeze-thaw durability. They are typically incorporated into the concrete during mixing, and they can be sized to match the size of the primary reinforcement bars.