GB2585946A

GB2585946A - Screed composition and method of use

Info

Publication number: GB2585946A
Application number: GB1910733.3A
Authority: GB
Inventors: Mccrea Brendan
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-07-26
Filing date: 2019-07-26
Publication date: 2021-01-27
Also published as: GB201910733D0; IES87239Y1; IE20200152U1

Abstract

A screed composition comprising: cement; additives including at least a surfactant and a foaming agent; expanded polystyrene beads; and water. The additives may further comprise an accelerator. The screed composition may have a density of between 80 and 300 kg/m3. The EPS beads may have a size of between 1 and 8 mm and a density of between 8 and 16 kg/m3. A method of using the screed composition is provided comprising mixing the cement, additives, EPS beads and water at or adjacent a point of use and applying the mixed screed composition to a surface to be coated at said point of use. The method may comprise: adding the additives to at least a portion of the water in a mixing device; adding the EPS beads to the water and additives in the mixing device and mixing for a period; adding the cement to the mixing device and mixing for a further period. The surface to be coated may be a subfloor. At least the cement, water and EPS beads may be separate from one another prior to mixing at or adjacent the point of use.

Description

Screed Composition and Method of Use

FIELD OF THE INVENTION

This invention relates to a screed composition having enhanced thermal insulation properties and to a method of using same.

BACKGROUND OF THE INVENTION

Screed compositions are applied to surfaces to seal the surfaces. They are used in particularly on concrete based surfaces, for example on concrete subfloors. Known screed compositions comprise cement and a fine aggregate filler, such as sand, which forms a flowable mixture when mixed with water, ideal for forming a self levelling and smooth flooring surface. However, traditional floor screeds have poor thermal insulation performance. Therefore, to meet required thermal performance standards, it is known to locate a layer of thermally insulating material, such as rigid boards of extruded or expanded polystyrene, as an intermediated layer between the subfloor and the heavy screed. However, such thermally insulating material requires careful and time consuming cutting and fitting to be effective and also compromises the load bearing capacity of the resulting floor.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a screed 25 composition comprising: (a) cement; (b) additives including at least a surfactant and a foaming agent (c) EPS beads; (d) water. 30 The additives may further comprise an accelerator.

Preferably the screed composition has a density of between 80 kg/m3 and 300 kg/m 3.

In one embodiment the screed composition has a density of approximately 250 kg/m 3.

The EPS beads may have a bead size of between 1 mm and 8 mm.

The EPS beads may have a density of between 8 and 16 kg/m3.

According to a further aspect of the present invention there is provided a method of using the screed composition of the first aspect of the invention, said method comprising the steps mixing said cement, additives, EPS beads and water at or adjacent a point of use and applying the mixed screed composition to a surface to be coated at said point of use.

In one embodiment the method may comprise the steps of adding the additives to at least a portion of the water in a mixing device, adding the EPS beads to the water and additives in the mixing device and mixing for a predetermined period, adding the cement to the mixing device and mixing for a further predetermined period and applying the mixed screed composition to said surface to be coated. The mixing device may comprise a cement mixer.

The surface to be coated may comprise a subfloor. However, it is envisaged that the surface to be coated may comprise an uneven surface to be levelled, voids in building structures to be infilled, roof and roof details or any other surface or structure to which it may be desired to apply screed to. The screed composition in accordance with the invention may also be used to form blocks or moulding products.

Preferably at least the cement, water and EPS beads are separate from one 30 another prior to mixing at or adjacent said point of use. The additives may be separate from the cement, water and EPS beads prior to mixing at or adjacent said point of use.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

A screed composition in accordance with an embodiment of the present invention will now be described, by way of example only. The screed composition comprises cement, expanded polystyrene (hereinafter abbreviated as "EPS") beads, additives, including at least a surfactant and a foaming agent, and water. The surfactant and foaming agent facilitate homogenous mixing of the EPS beads in the cement and water mixture and prevents the beads from floating to the top of the mix.

The components of the screed are mixed on site, typically in a cement mixer, and, once the screed mixture has been prepared it can be poured or pumped or delivered in hand barrows onto the subfloor or other surface or structure to be coated, as is known in the art. The screed flows easily around obstacles, such as pipes and plumbing, and is easily levelled to the desired depth. The screed sets quickly within 24 to 48 hours, allowing light foot traffic for the installation of heating pipework (where underfloor heating is used). A hard finish top coating or top surface screed may be applied to the screed, once set.

In one embodiment, to achieve a target screed density of 200kg/m3, a ratio of 150m1 of the surfactant and foaming agent containing additive is added to approximately seven litres of water in a mixing device, for example a cement mixer and approximately 50 litres (0.5kg) of EPS beads are added into the mixing device. Mixing may take place for approximately ten minutes to ensure that the EPS beads are evenly wetted and foaming has become apparent. Approximately 12.5kg of cement is then added to the mixing device and further mixing takes place, for example for a further ten minutes. Further water may be added to obtain the desired consistency.

Due to its relatively lightweight consistency, the screed can easily be easily worked to the required depth & finish required by a single person, thereby reducing labour 30 Costs.

Other target screed densities can be achieved by varying the relative proportions of EPS beads, cement, additives and water, as shown in the following table:-Screed Composition Samples -Mix Volume 0.50m3 110kg/m6 target density 150kg/m6 target density 200kg/m6 target density EPS Beads (kg) 0.5 0.5 0.5 Cement (kg) 6.9 9.4 12.5 Additive (litres) 0.125 0.125 0.150 Water (kg) 3.85 5.25 7 The screed in accordance with the present invention is very flexible in its specification, and the density and composition of the screed can be adjusted to suit 5 particular applications, giving greater scope to the building industry and architectural design. If required for lightweight or high volume specifications, low density white EPS beads or recycled EPS material can be used. If required for lightweight low Lambda (low thermal conductivity) specifications, thermally improved EPS silver beads can be used. This silver bead can also be improved by increasing its 10 density, improving its thermal performance. This may be particularly suited for use below underfloor heating systems, The screed may be improved to give improved density and strength by adding additional cement and/or additives to the mixture.

One suitable additive, containing suitable surfactants and foaming agents, comprises a blend of water, cocoamphodipropionate, lauryl sulphate and other stabilisers.

The EPS beads used may comply with Class E fire retardance properties under the European Reaction to Fire classification system, giving the finished screed good fire retardance properties The lightweight EPS beads mare preferably supplied directly to the installer along with the additives, preferably separately, to be mixed with cement and water on site following specific mixing instructions to enable preparation and mixing of the enhanced screed composition by the installer under controller conditions at the point of use.

The additive may also contain an accelerator to facilitate more rapid drying of the screed.

The EPS beads preferably have a bead size of between 1 and 8 mm. The density of the EPS beads may be between 8 and 16 kg/m3, although other densities are envisaged A screed in accordance with the present invention may be used for casting blocks, 10 bricks or other moulded products for use in lightweight and/or high thermal performance constructions.

The invention is not limited to the embodiment described herein but can be amended or modified without departing from the scope of the present invention as 15 defined by the appended claims.

Claims

CLAIMS1. A screed composition which comprises: (a) cement; (b) additives including at least a surfactant and a foaming agent (c) EPS beads; (d) water.
2. A screed composition as claimed in claim 1, wherein said additives further 10 comprise an accelerator.
3. A screed composition as claimed in any preceding claim, having a density of between 80 kg/m3 and 300 kg/m3.
4. A screed composition as claimed in claim 3, having a density of approximately 250 kg/m3.
5. A screed composition as claimed in any preceding claim, wherein said EPS beads have a bead size of between 1 mm and 8 mm.
6. A screed composition as claimed in any preceding claim, wherein said EPS beads have a density of between 8 and 16 kg/m3.
7. A method of using the screed composition of any preceding claim, comprising 25 the steps mixing said cement, additives, EPS beads and water at or adjacent a point of use and applying the mixed screed composition to a surface to be coated at said point of use.
8. A method as claimed in claim 7, comprising the steps of adding the additives to at least a portion of the water in a mixing device, adding the EPS beads to the water and additives in the mixing device and mixing for a predetermined period, adding the cement to the mixing device and mixing for a further predetermined period and applying the mixed screed composition to said surface to be coated.
9. A method as claimed in claim 8, wherein said mixing device comprises a cement mixer.
10. A method as claimed in any of claims 7 to 9, the surface to be coated 5 comprises a subfloor.
11. A method as claimed in any of claims 7 to 10, wherein at least the cement, water and EPS beads are separate from one another prior to mixing at or adjacent said point of use.
12. A method as claimed in claim 11, wherein the additives are separate from the cement, water and EPS beads prior to mixing at or adjacent said point of use.