CN-116234781-B - Cement-based composition comprising powdered polyurethane

Abstract

The invention relates to a cement-based composition, in particular a dry mortar, comprising a) 5 to 50 parts by mass, preferably 10 to 45 parts by mass, more preferably 15 to 29 parts by mass of a composite hydraulic binder, b) 0.1 to 4 parts by mass, preferably 0.5 to 3 parts by mass, more preferably 1 to 2 parts by mass of a powdered polyurethane, and c) optionally 50 to 90 parts by mass, preferably 60 to 85 parts by mass of an aggregate. The cement-based composition of the invention is particularly useful as a cement-based tile adhesive, plastering or part of a plastering system.

Inventors

• J. Sudia
• G. Le Sheng
• A. Ben Harat
• L. Agro

Assignees

• SIKA技术股份公司

Dates

Publication Date

20260505

Application Date

20211105

Priority Date

20201106

Claims (20)

1. 1. A method for simultaneously improving the flexibility and reducing the density of a cementitious composition, the method comprising the steps of: a) Mixing 5 to 50 parts by mass of a composite hydraulic binder, 0.1 to 4 parts by mass of powdered polyurethane, optionally 50 to 90 parts by mass of aggregate, other minerals, optionally other additives and water, B) Applying the mixture obtained in step a) onto a support or casting the mixture obtained in step a) into a mould, and C) Hardening the mixture to obtain a hardened body; Characterized in that the composite hydraulic binder comprises CEM I, CEM II, CEM III, CEM IV, CEM V or CEM VI according to EN 197-1:2018 and an auxiliary cement, which is a mixture of ground granulated blast furnace slag and basic oxygen furnace slag, and the other mineral is selected from calcium sulphate, calcium aluminate, high alumina cement, calcium sulphoaluminate cement and lime.
2. 2. The method according to claim 1, characterized in that the cement-based composition is a dry mortar.
3. 3. The method according to claim 1, characterized in that the composite hydraulic binder comprises CEM II, CEM III, CEM IV, CEM V or CEM VI according to EN 197-1:2018 and the auxiliary cement.
4. 4. Cement-based composition according to claim 1, characterized in that the weight ratio of any of CEM I, CEM II, CEM III, CEM IV, CEM V or CEM VI to auxiliary cement is 16:1-1:5.
5. 5. The method according to claim 1, characterized in that the weight ratio of any of CEM I, CEM II, CEM III, CEM IV, CEM V or CEM VI to auxiliary cement is 10:1-1:2.
6. 6. The method according to claim 1, characterized in that the weight ratio of any of CEM I, CEM II, CEM III, CEM IV, CEM V or CEM VI to auxiliary cement is 4:1-1:1.
7. 7. Process according to claim 1, characterized in that the calcium sulphate is anhydrite, alpha-or beta-hemihydrate or dihydrate form.
8. 8. Process according to claim 1, characterized in that the lime is in the form of natural hydraulic lime, formulated lime, hydraulic lime and/or air-hardening lime according to standard EN 459-1:2015.
9. 9. A process according to any one of the preceding claims 1 to 3, characterized in that the particle size of the powdered polyurethane is 0.5 μm-8mm.
10. 10. A process according to any one of the preceding claims 1 to 3, characterized in that the particle size of the powdered polyurethane is 0.8 μm-5mm.
11. 11. A process according to any one of the preceding claims 1 to 3, characterized in that the particle size of the powdered polyurethane is 10 μm-3mm.
12. 12. A process according to any one of the preceding claims 1 to 3, characterized in that the particle size of the powdered polyurethane is 50 μm-1mm.
13. 13. A process according to any one of the preceding claims 1 to 3, characterized in that the particle size of the powdered polyurethane is 1mm-3mm.
14. 14. A method according to any one of the preceding claims 1 to 3, characterized in that the volume ratio of the powdered polyurethane is 2-20% by volume relative to the total combined volume of the powdered polyurethane and the aggregate.
15. 15. A method according to any one of the preceding claims 1 to 3, characterized in that the volume ratio of the powdered polyurethane is 2-10% by volume relative to the total combined volume of the powdered polyurethane and the aggregate.
16. 16. A method according to any one of the preceding claims 1 to 3, characterized in that the volume ratio of the powdered polyurethane is 3-9% by volume relative to the total combined volume of the powdered polyurethane and the aggregate.
17. 17. A method according to any one of the preceding claims 1 to 3, characterized in that the cement-based composition is mixed with water in a water/powder weight ratio of 0.1-0.6.
18. 18. The method according to claim 17, characterized in that the cement-based composition is mixed with water in a water/powder weight ratio of 0.2-0.5.
19. 19. The method according to claim 17, characterized in that the cement-based composition is mixed with water in a water/powder weight ratio of 0.2-0.35.
20. 20. The method according to claim 1, characterized in that 10-45 parts by mass of the composite hydraulic binder are mixed in step a).

Description

Cement-based composition comprising powdered polyurethane Technical Field The present invention relates to a cement-based composition, in particular a dry mortar, comprising a powdered polyurethane, in particular a recycled polyurethane material. Another object of the invention is a cement-based composition and the use of the hardened cement-based composition. Background Cement-based compositions for use as plastering, tile adhesives or insulation systems are widely known. It is generally desirable for such cement-based compositions to have a low density in the fresh state, i.e. when mixed with water and before hardening. The low density then allows for particularly efficient application, which means that less weight is applied for a given geometry. Typically, lightweight fillers such as expanded clay, pumice or glass hollow spheres are used. Another desirable property of cement-based compositions is high deformability. For example, cement-based compositions for use as cement-based tile adhesives must meet specific requirements, for example, as specified in international standard EN 12004-1. To meet the performance requirements of both deformable and highly deformable cement-based tile adhesives according to this standard, a large number of soft synthetic latex polymers are typically formulated in cement-based tile adhesives. Such synthetic latex polymers are expensive and have an increased carbon footprint. Accordingly, there is a continuing need to improve the green density (FRESH DENSITY) and deformability of cement-based compositions. In view of recent efforts to more sustainable products, it is also desirable to achieve this effect using readily available materials, particularly recycled materials. Polyurethanes have shown a rapid increase in scale over the decades worldwide due to their versatility. Among the different forms of polyurethane used, polyurethane foam materials, as well as polyurethane adhesives and sealants, have been widely used. As the scale continues to grow, the recovery and reuse of such polyurethanes is increasingly important as an alternative to incineration or deposition in landfills. Recycled polyurethane materials have been considered as possible alternatives to aggregate in Cement-based compositions (see, e.g., c.junco et al, elements & Concrete Composites, 2012, 34, 1174-1179). However, it has been shown that if polyurethane materials are used instead of aggregate, strength development in particular may be negatively affected. WO 2013/062986 (Dow Global Technologies) discloses the use of blends of powdered flexible polyurethane foams with redispersible polymer powders. The use of such blends in cement-based tile adhesives can result in improved tensile bond strength after water immersion. However, the deformability of the materials described therein is significantly reduced, especially compared to compositions which do not comprise powdered polyurethane. Accordingly, it is desirable to use a cement-based composition that is a powdered polyurethane, particularly a recycled powdered polyurethane, and has improved deformability. Summary of The Invention It is an object of the present invention to provide a cement-based composition comprising a powdered polyurethane and having improved deformability. Such compositions are particularly useful as cement-based tile adhesives or in insulation systems. The object of the present invention is achieved by a cement-based composition according to the following. Wherein the cement-based composition is based on a composite hydraulic binder, a powdered polyurethane and optionally an aggregate. The composite hydraulic binder comprises CEM I, CEM II, CEM III, CEM IV, CEM V or CEM VI according to EN 197-1:2018 and at least one auxiliary cementitious material or a CEM II, CEM III, CEM IV, CEM V or CEM VI selected from according to EN 197-1:2018. One advantage of the composition of the invention is that its deformability (measured as transverse deformation after 28 days of hardening according to standard EN 12002:2009) is significantly improved compared to a composition similar but based solely on ordinary portland cement as binder. Another advantage of the present invention is that the green density of the cement-based composition can be reduced compared to the same composition without the use of powdered polyurethane. Detailed Description In a first aspect, the present invention relates to a cement-based composition, in particular a dry mortar, characterized in that it comprises A) 5 to 50 parts by mass, preferably 10 to 45 parts by mass, more preferably 15 to 29 parts by mass of a complex hydraulic binder, B) 0.1 to 4 parts by mass, preferably 0.5 to 3 parts by mass, more preferably 1 to 2 parts by mass of a powdery polyurethane, and C) Optionally 50-90 parts by mass, preferably 60-85 parts by mass of aggregate. In a preferred embodiment, the invention relates to a cement-based composition, in particular a dry mortar, characterized in that it c