FLOOR STRUCTURE FOR INSULATING FOOTFALL SOUND AND METHOD OF PREPARING THE SAME

Abstract: The invention relates to a footfall-sound insulating floor structure which comprises a layer approx. 15-35 mm thick of a cement-based, fiber-reinforced, self-leveling, rapidly hardening, rapidly drying and shrinkage-compensated slurry screed cast on top of a footfall-sound insulating material layer, this layer combination being formed either on top of a new concrete floor having a thickness determined by the footfall-sound standards, alternately the strength standards, or as a renovation layer on top of an already existing load-bearing base. The invention also relates to a method for forming such a floor structure.

Description: Floor structure for insulating footfall sound and method of preparing the same. The present invention relates to a floor structure for insulat¬ ing footfall sound and to a method for forming such a floor structure. It is previously known to improve the footfall-sound insulating properties of concrete floors by installing on top of a con¬ crete floor a layer of a footfall-sound absorbing resilient material, such as a closed-cell plastics material, and by cast¬ ing on top of this material layer a concrete slab approx. 40-50 mm thick to form a floating floor. There are such closed-cell plastics materials on the market, one example being a 5-mm- thick foamed polyethylene mat which is supplied in rolls. With respect to a newly cast load-bearing floor, the above-mentioned technique has the disadvantage that concrete requires a very long drying period before the installation of a surface finish¬ ing material, which may be, for example, parquet, ceramic tile or a plastic mat. If the surface finishing material is in¬ stalled before the final drying of the concrete, for example fungal damage and swelling of the parquet may result. According to this technique, the surface finishing material may be in¬ stalled at the earliest a couple of months after the casting of the floor. Furthermore, the covering concrete slab must be at minimum approx. 40-50 mm thick in order to be sufficiently strong. This is a disadvantage, especially in the construction of a sound-insulating renovation floor, in which in particular maximally thin floor structures are aimed at. A further disad¬ vantage of the use of concrete in this technique is that its spreading requires auxiliary leveling tools, and therefore the making of such a floor is a slow procedure. Normally three 2 persons will make in one working day approx. 100 m of such a concrete-floor covering structure, which comprises a foamed- plastics mat and a concrete slab. It is also known to improve the footfall-sound insulation pro- perties of concrete floors by installing on top of a concrete floor a layer of a footfall-sound insulating resilient material and by spreading on top of this material layer a gypsum-based slurry screed which, upon hardening, will constitute a floating floor. There are known self-leveling gypsum-based slurry screeds the use of which speeds .up the making of a floor as compared with the use of concrete. The disadvantage of a gypsum-based material is that it is relatively brittle, and therefore it must be made thick in order to obtain sufficient strength. From FI Patent 76545 there is known a completely self-leveling slurry screed, capable of being pumped and having the following composition: by weight of the solids by weight of the solids by weight of the solids by weight of the solids by weight of the solids by weight of the solids by weight of the solids by weight of the solids This prior-art fiber-reinforced slurry screed for floors forms, upon hardening, a surfacing with excellent mechanical proper¬ ties, and it is applicable to uses which have conventionally been regarded as problem areas, for example, the leveling of weak concrete, wood, and various compound floors, such as mag- nesite floors and gypsum mix floors. This publication includes no mention that the slurry screed described in it could be used together with a resilient footfall-sound absorbing material to form for a concrete floor a thin covering structure which has excellent footfall-sound insulation properties. In most countries, requirements have been set for the highest permitted values for the footfall-sound level. In Finland the highest permitted value for the footfall-sound level (L' n w ) from one residential apartment to another is 58 dB. In order to attain this permitted value, the intermediate floors of apart¬ ment buildings must often be made thicker than required by strength standards. The highest permitted value for the footfall-sound level also sets restrictions with respect to the choice of the surface finishing material. For example, a mosaic parquet or clinker cannot in an apartment building be installed directly on top of a concrete floor, a hollow-core slab, a solid slab, or suchlike; the footfall-sound insulation proper¬ ties of the intermediate floor must first be improved, for example by the techniques described at the beginning of this specification, which for their part will considerably increase the total thickness of the floor structure. This is highly problematic in renovation building, in which doors and thres¬ holds normally allow the floor level to be raised by only approx. 30 mm. The object of the present invention is to provide a floor structure by means of which the problems associated with the footfall-sound insulated floor structures described above are avoided and a good level of footfall-sound insulation is achieved by using structural thicknesses considerably smaller than the conventional ones. It is also an object of the invention to provide a floor covering structure which can be made very rapidly and which dries rapidly. It is a further object of the invention to provide a technique which considerably speeds up the making of a floor and enables a footfall-sound insulating covering structure which also serves as a damp course to be formed on a concrete floor only a few days after the casting of the floor. These objectives have been achieved according to the invention in a highly satisfactory manner. The characteristics of the invention are disclosed in the accompanying claims. According to the invention it has been observed surprisingly that the slurry screed for floors, known from the above- mentioned FI Patent 76545, can be used together with a resil¬ ient footfall-sound absorbing material to form a very strong and thin covering structure on a floor, thus producing a floor structure having excellent footfall-sound insulation proper¬ ties. According to the invention it has additionally been observed surprisingly that the above-mentioned covering structure can be formed on a concrete floor as early as two days after the cast¬ ing of the floor. According to the present invention, it is possible to use not only the slurry screed for floors known from FI Patent 76545 but also any other slurry screeds which are cement-based, fiber-reinforced, self-leveling, rapidly hardening, rapidly drying and shrinkage-compensated. According to the invention, there is thus provided a footfall- sound insulating floor structure which comprises a layer com¬ bination which has a resilient, footfall-sound insulating mate¬ rial layer in the form of a mat or a board and, cast on top of this material layer, a layer approx. 15-35 mm thick of a cement-based, fiber-reinforced, self-leveling, rapidly harden¬ ing, rapidly drying and shrinkage-compensated slurry screed, this layer combination being formed either on top of a new concrete floor the thickness of which is determined by the footfall-sound standards, alternatively the strength standards, or as a renovation layer on top of an existing load-bearing base, in order to provide a total structure which is thinner than conventional structures which meet the standards. According to the invention there is also provided a method for forming a footfall-sound insulating floor structure, method in which there is installed on top of a new concrete floor the thickness of which is determined by footfall-sound standards, alternatively the strength standards, or on top of an existing load-bearing base, a resilient footfall-sound absorbing layer of material in the form of a mat or a board, and on top of this material layer there is introduced a layer approx. 15-35 mm thick of a cement-based, fiber-reinforced, self-leveling, rap¬ idly hardening, rapidly drying, and shrinkage-compensated slur¬ ry screed. The said resilient footfall-sound absorbing layer of material is preferably a closed-cell plastic mat or board, or a mineral- wool mat or board, of a combination of the same. The thickness of the mineral wool mat is approx. 4-15 mm. The upper surface of the mineral wool mat is preferably equipped with a plastic membrane, such as a polyethylene membrane, in order that the slurry screed should not penetrate into the mineral wool mat. The thickness of the mineral wool board is 3 approx. 15-50 mm, and its density is at minimum 120 kg/m . When necessary, the upper surface of the mineral wool board can also be equipped with a plastic membrane. The said closed-cell plastic mat or board is preferably a mat or board of foamed polyethylene, polystyrene or styrene- butadiene copolymer. The thickness of the mat is approx. 4-15 mm " and the thickness of the board is approx. 15-50 mm. A par¬ ticularly preferred material is an approx. 5-mm-thick foamed polyethylene mat. A mat-like material has the advantage that it can easily be folded up against a wall, whereby a floating structure is obtained. According to the invention, the resilient footfall-sound ab- sorbing material layer may comprise two or more mats and/or boards one on top of the other, for example two mineral wool mats one on top of the other or a mineral wool mat and a foamed polyethylene mat fitted on top of it. When such mats one on top of the other are used, the thickness of an individual mat may be as small as 2 mm. The composition of the self-leveling, rapidly setting and rap¬ idly drying slurry screed is preferably as follows: % by weight of the solids % by weight of the solids % by weight of the solids % by weight of the solids % by weight of the solids % by weight of the solids % by weight of the solids % by weight of the solids The binder is preferably cement, the aggregate is preferably sand, and the filler is preferably fly ash. The adhesive agent used may be, for example, a polyvinyl ace¬ tate powder, and the shrinkage-compensating agent used may be, for example, gypsum. The fluidifier, i.e. the flow-promoting agent, may be, for example, Melment (trademark, manufactured by SKW) . The said fibers are preferably synthetic polymer and/or carbon fibers, particularly polyolefin, polyacrylic nitrile and/or polyvinyl alcohol fibers. Polypropylene fibers are especially preferred. The length of the fibers is preferably 1-20 mm, especially preferably 5-7 mm. The said slurry screeds may additionally contain a small amount, preferably less than 1 % by weight, of various admix¬ tures, for example anti-foaming agents and retarders, such as gypsum retarder. According to one embodiment of the invention, the said layer combination, i.e. a resilient footfall-sound absorbing material layer and a slurry screed layer, can be formed on top of a new concrete floor, such as an in situ cast concrete floor, on hollow-core slabs, on solid concrete components and on air- entrained concrete components. In this case the said new con¬ crete floor can be made considerably thinner and lighter than corresponding conventional concrete floors while producing the same or even better level of footfall-sound insulation. For example, commercial hollow-core slabs must normally be made 265 mm thick in order to achieve a sufficient level of footfall- sound insulation even when strength standards do not require so thick a structure. Instead, according to the invention, hollow- core slabs may be made 200 mm thick and be covered with the said layer combination, whereby a sufficient level of footfall- sound insulation and at the same time a light overall structure are achieved. The components constituting the intermediate floor, for example hollow-core slabs, usually have to be leveled before the installation of the surface material. Nor¬ mally the leveling is carried out by spreading on top of the components a slurry-screed layer approx. 10-20 mm thick. Ac¬ cording to the invention, the resilient footfall-sound absorb¬ ing mat or board is installed directly on top of the com¬ ponents, and then slurry screed is pumped on top of the mat or board. Thereby a floor structure with excellent footfall-sound insulation properties is produced, and a mosaic parquet or clinker can be installed directly on top of it, without- exceed¬ ing the permitted value of footfall-sound level. The total thickness of this floor structure will be thicker only by the thickness of the footfall-sound absorbing mat or board than the thickness of a conventional leveled component floor without footfall-sound insulation. According to another embodiment of the invention, the said layer combination can be formed on top of an already existing load-bearing base, which may be a concrete floor of any of the above-mentioned types or, for example, a wooden floor or a floor made of shell-structured slabs. This layer combination may be made considerably thinner than conventional systems, even as thin as 20 mm, and is thus excellent for renovation building. Normally doors and thresholds will allow the floor level to be raised by approx. 30 mm. According to the invention, the composite layer which contains a closed-cell plastics material as the footfall-sound absorbing material can be formed on top of a concrete floor which has not yet completely dried, for example 2-14 days after its casting. In this case the moisture from the base concrete will evaporate downwards. In new building this will considerably speed up construction work. Furthermore, the slurry screed used in the invention dries and hardens rapidly, and so the surface finish¬ ing material can be installed as early as a few hours after the slurry screed has been pumped on top of the closed-cell plas¬ tics material. Using the system according to the invention, three persons can in one working day make up to 1,000 m of such concrete-floor covering structure, which comprises a layer of a footfall-sound absorbing material and a slurry screed. The invention is described below in greater detail with the help of examples. Example 1 A mixture of dry materials was prepared according to FI Patent 76545 by stirring the following constituents vigorously to- gether : Water at 23 % by weight of the dry product was mixed with this dry product, whereby a completely self-leveling slurry screed was obtained. A mineral wool mat and/or a foamed polyethylene mat was in¬ stalled on top of a solid concrete slab or a hollow-core con¬ crete slab. A 20-mm-thick layer of the completely self-leveling slurry screed described above was cast on top of this mat. The footfall-sound insulation capacity of the structure thus formed was determined according to the following methods: ISO 140/6 and 8-1978 (L n ) and ISO 717/2-1982 (footfall-sound level L n w ) . The results obtained are given in Table 1. , ditions from the laboratory results It is surprisingly seen from the results that a 200-mm-thick hollow-core slab, which cannot be used in housing production because of the footfall-sound insulation standards, can be used in housing production when covered with the layer combination according to the invention. Even a total thickness of 225 mm in an intermediate floor yielded a level below the standards, i.e. below 58 dB. Respectively it is surprisingly seen from the results that a 160-mm-thick solid slab, which cannot be used in housing pro¬ duction because of the footfall-sound insulation standards, can be used in housing production when coated with the layer com¬ bination according to the invention. Even a total thickness of 190 mm in an intermediate floor yielded a level below the standards, i.e. below 58 dB. Any surface finishing material, for example hard materials such as clinker, can be used on these intermediate floors in apart¬ ment buildings. Example 2 A structure similar to that described in Example 1 was formed by using a 265-mm-thick hollow-core slab, a 5-mm-thick foamed polyethylene mat, and on top of it a slurry-screed layer as de¬ scribed in Example 1. On top of this structure, a mosaic par¬ quet or clinker was installed as a surface finish. For purposes of comparison, a similar floor structure with a mosaic parquet or clinker finish was formed, but without using the foamed polyethylene mat. The footfall-sound insulation capacities of these structures were determined in the same manner as in Example 1. The results obtained are presented in Table 2. The results show that, because of the footfall-sound insulation standards, a 265-mm-thick hollow-core slab with a 10-mm-thick layer of slurry screed cannot be surface finished with a mosaic parquet or clinker. The results surprisingly show that a 265- mm-thick hollow-core slab covered with the layer combination according to the invention can within the footfall-sound in¬ sulation standards be surface finished with a mosaic parquet or clinker.

Claims: Claims 1. A footstep-sound insulating floor structure, charac¬ terized in that it comprises a layer combination having a ' re¬ silient, footfall-sound absorbing material layer in the form of a mat or a board and, cast on top of this material layer, a layer approx. 15-35 mm thick of a cement-based, fiber- reinforced, self-leveling, rapidly hardening, rapidly drying and.shrinkage-compensated slurry screed, and that this layer combination is formed either on top of a new concrete floor having a thickness determined by the footfall-sound standards, alternatively the strength standards, or as a renovation layer on top of an already existing load-bearing base, in order to produce a total structure which is thinner than conventional structures which meet the standards. 2. A floor structure according to Claim 1, characterized in that the footfall-sound absorbing material layer is a closed- cell plastic mat or board or a mineral wool mat or board, or a combination of these. 3. A floor structure according to Claim 2, characterized in that the upper surface of the mineral-wool mat or board is equipped with a plastic membrane. 4. A floor structure according to Claim 1 or 2, charac¬ terized in that the material layer is a mat or board of foamed polyethylene, polystyrene or styrene-butadiene copolymer. 5. A floor structure according to any of Claims 1-4, char¬ acterized in that the thickness of the footfall-sound absorbing mat is approx. 4-15 mm. 6. A floor structure according to any of Claims 1-4 char¬ acterized in that the thickness of the footfall-sound absorbing board is approx. 15-50 ram. 7. A floor structure according to any of Claims 1-6, char¬ acterized in that the composition of the slurry screed, calcu¬ lated from the solids of the slurry screed, is as follows: binder: aggregate: fillers: adhesive agent: shrinkage-compensating agent: 0.1-10 % by weight fluidifier: 0.1-1 % by weight fibers: 0.05-3 % by weight 8. A method for forming a footfall-sound insulating floor structure, characterized in that on top of a new concrete floor having a thickness determined by the footfall-sound standards, alternatively the strength standards, or on top of an already existing load-bearing base, there is installed a resilient, footfall-sound absorbing material layer in the form of a mat or a board, and on top of this material layer there is introduced a layer approx. 15-35 mm thick of a cement-based, fiber- reinforced, self-leveling, rapidly hardening, rapidly drying and shrinkage-compensated slurry screed. 9. A method according to Claim 8, characterized in that the footfall-sound absorbing material layer installed is a closed- cell plastic mat or board or a mineral-wool mat or board, or a combination of these. 10. A method according to Claim 8 or 9, characterized in that the footfall-sound absorbing material layer installed is a mineral-wool mat or board the upper surface of which is equipped with a plastic membrane. 11. A method according to Claim 8 or 9, characterized in that the footfall-sound absorbing material layer installed is a mat or board of foamed polyethylene, polystyrene or styrene- butadiene copolymer. 12. A method according to any of Claims 8-11, characterized in that the thickness of the footfall-sound absorbing mat is approx. 4-15 mm. 13. A method according to any of Claims 8-11, characterized in that the thickness of the footfall-sound absorbing board is approx. 15-50 mm. 14. A method according to any of Claims 8-13, characterized in that the footfall-sound absorbing material layer is in¬ stalled on top of a concrete floor before the floor has com¬ pletely dried. 15. A method according to Claim 14, characterized in that the footfall-sound absorbing material is installed on top of a concrete floor approx. 2-14 days after the casting of the floor. 16. A method according to any of Claims 8-13, characterized in that the footfall-sound absorbing material layer is in¬ stalled on hollow-core slabs or on other prefabricated floors. 17. A method according to any of Claims 8-16, characterized in that the composition of the slurry screed is as follows: % by weight of the solids % by weight of the solids % by weight of the solids % by weight of the solids % by weight of the solids % by weight of the solids % by weight of the solids % by weight of the solids

Inventors: AALGARS RAINER ALLAN, ETTALA VELI PEKKA, HYYTIAE TOIVO ARMAS, KOREILA ANSSI ANTERO, LAUREN STURE WILHELM, TURTO HELENA INKERI, AALGARS, RAINER, ALLAN, ETTALA, VELI, PEKKA, HYYTIAE, TOIVO, ARMAS, KOREILA, ANSSI, ANTERO, LAUREN, STURE, WILHELM, TURTO, HELENA, INKERI
Applicants: PARTEK AB, OY PARTEK AB
Application year: 1990
Main classification: E04F15
IPC codes: E04F15