What is screed concrete, and how it is different from concrete

screed Concreting

When working on a construction project, you need to have the right kind and quantity of materials on hand to avoid any roadblocks that could cause the project to take longer than expected to complete. Even though screed concrete isn’t as well-known outside of the building business as concrete, it’s nevertheless an essential part of any project. This post will define screed concrete in detail and discuss its advantages for contractors and builders.

Types of Screed Concrete

Concrete screed comes in a variety of forms, such as:

  • Conventional screed: This is a semi-dry mixture of sand and cement that is manually levelled. It is frequently utilized in flooring applications for homes and businesses.
  • Liquid screed: Also referred to as flowing screed, this kind of screed is applied to a substrate by hand or machine and self-levels by combining cement, water, and additives. Large commercial or industrial flooring applications frequently employ it.
  • Polymer-modified screed: In order to increase the strength and longevity of this type of screed, polymer additives are added to a mixture of sand and cement. It is frequently utilized in locations subjected to high traffic or severe weather.
  • Fibre-reinforced screed: To increase the screed’s strength and endurance, fibres are mixed into the mixture. It is frequently utilized in flooring applications for businesses and industries.
  • Fast-drying screed: This kind of screed dries rapidly, usually in less than a day, which makes it perfect for tasks with short turnaround times. It is frequently utilized in flooring applications for homes and businesses.
  • Bonded screed: To achieve good adherence, this form of screed is applied straight onto a base concrete slab using a bonding agent. It is frequently utilized in remodelling projects where a fresh screed layer is applied to an existing concrete base.

Screed Concrete vs Traditional Concrete

  • The water content is the main distinction between screed concrete and regular concrete. The mix of screeded concrete is usually drier since it contains less water than regular concrete. This is significant because, when put on in thin layers, a drier mix is less prone to flow or slump before setting, making it simpler to work with.
  • The concrete mix’s composition is another significant distinction. Generally speaking, screed concrete is made with more cement than regular concrete, which gives it more strength and longevity. This is especially crucial in locations where there will be a lot of traffic, severe weather, or other wear and tear on the concrete.
  • Compared to regular concrete, screed concrete requires a different application procedure. It usually requires a competent installer with experience working with thin-layer concrete applications, and it is put in thin layers using specialized instruments including screed boards, trowels, and floats.  In order to increase its strength and resistance to cracking, screed concrete can be reinforced with wire mesh or fibers. 

Characteristics of Screed Concrete

In order for the screed to be used for floor installation, it needs to have specific performance and technical characteristics. Some qualities of screed are as follows:

Clean

The screed surface needs to be immaculate. All debris, including dust, detached parts, and other materials, must be removed before flooring can be put on top of the screed. Unclean surfaces will affect how well the floor adheres to the screed.

Dry

It is necessary to measure the residual humidity on the screed surface. This value must not go over the maximum permitted for the selected flooring and must remain constant throughout the screed’s thickness. This is especially done when laying flooring that can get damaged by moisture.

Flat

In order to guarantee uniform flatness, a straight edge of at least two meters in length is set down on the screed in all directions. The greatest deviation permitted for this straight edge is 2 mm. Until the flatness is brought inside tolerance, floor installation cannot begin. At that time, the surface needs to be levelled using the proper product.

Thickness

Numerous factors influence the thickness of the screed, such as the type of screed to be used, the floor’s thickness, and the amount of foot traffic that is anticipated.

Smoothness

The type of flooring installed significantly affects how appropriate the surface is in terms of roughness and finish grade. 

Compactness

For the entire slab, a compact and consistent concrete screed is required. If there are layers of crumbles or areas of diminished uniformity in the screed, there is a mechanical quality issue. This defect will cause the flooring to either break or come free.

Dimensions and curing of concrete screed

Make sure the screed has been spread evenly and has had enough time to dry before putting the floor in. During this curing phase, any shrinking that needs to be done could be completed. Hygrometric shrinkage occurs frequently in concrete screed during the curing cycles. This hygrometric shrinkage could be caused by the drying process or by some of the mixing water evaporating. Inevitably, this shrinking will cause the screed to curl or fracture. If these fractures occur soon after installation, the floor may separate from the subfloor or sustain damage.

Crack-proof screed

Concrete screed fractures can have a variety of causes. One example is the impact of humidity on an object’s size. A high water content in the blend is one of the other factors. Cracking can also result from using fine materials or a combination that contains too much cement. It is advised to completely seal all openings. Epoxy resins provide extremely accurate sealing. These actions are performed prior to installing the flooring. The surface of the screed may be shielded from small cracks by using the anti-fracture membrane.

Uses of Screed Concrete

Flooring

In residential settings, screed concrete is a necessary layer for laying several types of floor coverings, such as laminate, wood, and tiles. In order to guarantee the durability and stability of the finished floor covering, it offers a flat and sturdy surface. Additionally, screed is a popular option for business facilities including warehouses, retail establishments, and offices. For a variety of flooring materials, such as carpet, vinyl, and epoxy coatings, it offers a level and long-lasting base.

Underfloor heating systems

Underfloor heating systems are frequently utilized in conjunction with screeded concrete. Because of its ability to efficiently store and transmit heat, it is a preferred material for both residential and commercial buildings.

Commercial Flooring

Screed concrete provides the strength and durability required in industrial settings, such as factories, warehouses, and manufacturing facilities, to endure heavy machinery, forklift traffic, and the possibility of chemical exposure. For increased durability, fibre-reinforced screed is frequently utilized.

Remodeling

Screed concrete is used during repairs, particularly in older buildings, to level and reinforce existing uneven or broken floors. To create a new, level surface, a bonded screed can be put directly over the existing concrete substrate.

Balconies and Terraces

For external areas such as balconies and terraces, screed concrete offers a sturdy and long-lasting foundation. Tiles or waterproofing techniques can be used to complete it and create aesthetically pleasing and useful outdoor spaces.

Sports surfaces

Sports courts and athletic venues are built using screed concrete. With an even bounce and a lower chance of damage, it provides a stable surface for a variety of sports.

Medical Facilities

Screed concrete is frequently used in hospitals and clinics because of its sanitary qualities and adaptability for flawless finishing, which are necessary to sustain a sterile environment.

Academic Establishment

Screed concrete is used in classrooms, hallways, and gymnasiums in schools and universities. Because of its adaptability and longevity, it is an affordable option for educational facilities. 

Installation Process

In order to install screed concrete, the mix is poured over a substrate that has been ready. Depending on the type of screed concrete, it is subsequently leveled and smoothed using a variety of techniques, such as human application, machine-assisted spreading, or self-leveling qualities.

Maintenance and Care

Offer tips for maintaining and caring for screed concrete, including cleaning methods, repairing cracks, and applying protective coatings.

Conclusion

In the realm of building, screed concrete is a fundamental component known for its adaptability and vital function in producing level and long-lasting surfaces. With so many different kinds of screed to choose from, its versatility in meeting the demands of any project—residential or commercial—is a big plus. Screed concrete is useful for many things, such as sustaining underfloor heating systems and making sturdy industrial flooring. It keeps created structures functional and intact for a long time.

FAQs

What is the purpose of screeding?

The main goal of the screed, which is made of one part cement to three to five parts sharp sand, is to provide a flat, smooth surface for the application of your preferred floor finish. Because of its thickness, the screed can accommodate typical changes in the levelness and flatness of the base it is laid on. 

What is the difference between screed concrete and normal concrete?

Both concrete and screeds are composed of aggregates, cement, and water; however, concrete has a rougher consistency, and fine particles are added to concrete to help it look like a finishing layer. Any construction job that calls for the laying of a floor needs screed. 

Why use screed instead of concrete?

While screed is made up of smaller bits, concrete requires larger, harder aggregates. About half as many aggregates are typically used in a screed as in a concrete mix. Concrete’s strength and durability are mostly due to the aggregates in it, however a screed isn’t really needed for this purpose. 

What is the thickness of screed concrete?

The stipulated design thickness should be at least 70mm in order to account for variations in the completed levels, as the screed thickness shouldn’t fall below 50mm.

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