WO1992007714A1

WO1992007714A1 - Multi-component composition for system of joists and floor, and method of manufacturing such composition

Info

Publication number: WO1992007714A1
Application number: PCT/SE1991/000308
Authority: WO
Inventors: Erik Arne Kristoffer Westin; Sten Åke WESTIN
Original assignee: Erik Arne Kristoffer Westin; Westin Sten Aake
Priority date: 1990-10-25
Filing date: 1991-05-16
Publication date: 1992-05-14
Also published as: SE466498B; SE9003407D0; SE9003407L

Abstract

The invention relates to a fast-setting multi-component composition with short drying time for the manufacture of non-shrinking system of joists and floor with low weight by volume and good heat and sound insulating qualities. Up to now used concrete and mortar masses have high weight by volume and poor insulating capacity. Moreover, they set slowly and require at least a week for moisture curing besides the time needed for drying up to a moisture content which makes flooring or other treatment possible. The invented multi-component composition solves the problems mentioned and is characterized by, that it comprises 30-70 per cent by weight of grains of expanded, burnt clay, 10-70 per cent by weight of a fast-setting polymer modified, cement based mortar, and 10-70 per cent by weight of a fast-setting fibre reinforced, cement based mortar. The invention also comprise a method for the manufacture of multi-component composition, which for instance is characterized by, that the clay grains are pretreated with a PVA-based binder before being mixed with the polymer modified, cement based mortar.

Description

Multi-component composition for system of joists and floor, and method of manufacturing such composition.

Technical field

The present invention relates to a self-setting and quick drying multi-component composition with low weight by unit of volume, good heat insulating capacity and certain elasticity, which is well suited for the manufacture of system of joists and various types of floor such as floor directly on ground. The top surface of the composition can easily be made even and constitutes then an excellent bedding for all types of floor coverings. The composition is in first hand inten¬ ded to be used in dwellings, at which it without any diffi¬ culties can be adapted to those in this field for dwellings applicable building by-laws.

State of art

System of joists in dwellings and other buildings are principally manufactured in reinforced concrete, at which they are mainly cast on site in for the purpose built up and adap¬ ted moulds using reinforcing iron an concrete mass in the quality classes A and B with strength class lowest K400 respek- tively lowest K250 (Eq4.2 in Bygg AMA and the Concrete Regu¬ lations B5) . However, concrete system of joists (subfloor) cast on site have according to the regulations to be moisture cured during at least 7 days. When putting on a wearing layer on top of the subfloor in order to obtain a concrete floor, the surface of the recently spread wearing layer must, since it after 5 to 10 hours has become walkable, be moisture cured during at least 14 days. Thus early drying up is disadvan- ^* tageous for every concrete, but has an even more detrimental effect on floor concrete.

One example on the state of art concerning floor direct¬ ly on ground is to be found in the American patent publication 3 673 750, which relates to a bottom construction for buil¬ dings without basement, patented by AB Svenska Icopalfabri- ken. The construction is based upon the placing of heat and moisture insulating blocks in juxtaposition on the ground so that they form a foundation wall for the building, which shall be erected. Thereafter an equally thick bed of burnt expanded ball-shaped clay grains (prefereably such that are marketed under the trade mark "LECA") is laid out on the ground within the confines of the foundation block wall. A layer of reinforced concrete is then cast directly on top of the bed of clay grains. The obtained concrete surface is, however, to be regarded as the surface of a conventional concrete floor or subfloor, which consequently has to be moisture cured during at least 7 days. A wearing layer of concrete may be laid on the surface mentioned or it may be covered with a levelling mortar or a free-flow putty of the type described in the American patent publication 3 972 723.

In recent times one has above all in dwelling and office buildings begun to manufacture system of joists using a co¬ operation plate, type "PEVA 45", which is based upon a Finnish invention. Said plate construction functions as a re¬ maining mould for the systems of joists at the same time as its profile is modelled to constitute a lower edge reinforce¬ ment. Thus mould setting and reinforcement is done in one work operation. The concrete mass used is, however, in re¬ gard to quality and strength equal to the mass used in tradi¬ tional reinforced systems of joists and needs consequently to be moisture cured in an equal way.

The finished concrete in up to now used system of joists has a weight by unit of volume of between 2,35 and 2,45

3 kg/dm , which results in that every system of joists in a building gets a considerable dead weight and which in turn affects the construction of the building. When using co-ope¬ ration plate type "PEVA 45" the profile of the plate will, however, make a saving in concrete possible, which reduces

2 the weight of the system of joists with almost 50 kg per , but the total dead weight of each system of joists will still be considerable.

Description of the invention Technical problem

A great disadvantage with all known and up to now used on site cast systems of joists and concrete floor is the long time, which is required for moisture curing an drying up, before it is possible to begin covering or other treatment. A system of joists (subfloor) and one on top of that cast wearing layer of concrete require thus for example moisture curing during at least 7 days plus at least 14 days, i.e. totally at least 21 days moisture curing. If the system of joists and the wearing layer are cast consecutively, one may manage with moisture curing during at least 14 days - even that, however, a considerable time. To that must in both cases be added drying up to a moisture content, which lies below the limit value for the type of cavering in question. (Limit values for different coverings appear in Table Q2 in HusAMA) . The time required for the drying up of a certain floor surface to an acceptable moisture content varies with the conditions that prevail, i.e. with the moisture content of the surrounding air, with its tempera¬ ture and its renewal. It is usually a question of a number of days and at unfavourable conditions of weeks.

Another disadvantage with traditional floor on ground and system of joists is, that they often need to be heat insulated, at which the insulation has to be laid out under or on top of the concrete layers, alternatively between in case of several layers of concrete. This brings about in¬ creased height of the construction and additional working hours with accompanying higher cost. Moreover, when the concrete is cast in quality class A, one on top of the in¬ sulation lying concrete layer always has to be reinforced, which of course increases the cost even more.

Above all at rebuilding and repairs of water damages etc. the present-day long and often unpredictable times needed for moisture curing and drying up create many practi¬ cal problems at the planning as well as at the performance of such work, which all must be included among the disadvan¬ tages with known technique.

The purpose of the present invention os to solve the above mentioned problems and to eliminate the shortcomings and disadvantages associated with the known technique through providing a composition for the manufacture of sy¬ stem of joists and floor, which in comparison with up to now used masses has improved qualities, particularly with regard to weight by volume, setting and drying time, heat insula¬ tion, shrinkage and elasticity.

The solution

Multi-component compositions in accordance with the pre¬ sent invention solve above described problems and eliminate the shortcomings and disadvantages, which application of up to now known technique leads to. In accordance herewith the present invention concerns a fast-setting multi-component composition with short drying time for the manufacture of non-shrinking system of joists and floor with low weight by volume, good heat and sound insulating qualities and cer¬ tain elasticity. The multi-component composition is charac¬ terized of that it comprises the following components in combination: a) 30-70 per cent by weight of grains of expanded, burnt clay b) 10-70 per cent by weight of a fast-setting, polymer mo¬ dified and on hydraulic cement based mortar c) 10-70 per cent by weight of a fast-setting and on hy¬ draulic cement based, fibre reinforced mortar Preferably the graines of expanded, burnt clay consist of such grains, which are marketed under any of the trade marks "LECA" or "FIBO" and which have a grain size of 4-30 mm, preferably 12-20 mm.

Further, it has proven to be especially suitable, if the polymer modified, cement based mortar consists of such mortar, that is marketed by Svenska ICI AB under the trade

* mark "STRϋCTURITE" and if the cement based, fibre reinforced mortar consists of such mortar, that is marketed, likewise

* by Svenska ICI AB, under the trade mark "ROADPATCH" .

*) "STRϋCTURITE" as well as "ROADPATCH" are registred trade marks and belong to the group THORO-products marketed in Sweden by Svenska ICI AB. The invention also comprises a method for the manufac¬ ture of the multi-component composition in question, which is characterized by: a) that grains of expanded, burnt clay, usually ball shaped, are pre-mixed with a PVA-based binder in such a way, that the surface of each grain is given an ad¬ hering and glueing coating of the binder in question, whereafter excess of binder is allowed to drain off from the grains simultaneously as they are allowed to dry. b) that 2 parts by weight of the according to "a" pre- treated clay grains are mixed with 1 part by weight of a fast-setting polymer modified, cement based mortar, which is strengthened with about 4 per cent by volume of a PVA-based binder, and which is given a suitable mortar consistency through mixing with a liquid con¬ sisting of equal parts water and an acrylic polymer in fluid form in order to be able to be modelled and packed into a first mass layer in desired thickness and with even surface in that system of joists or floor, which is going to be manufactured, and c) that the according to "b" manufactured first mass layer is provided with a layer of a fast-setting cement based, fibre reinforced mortar mixed with water to such a con¬ sistency, that it when being spread under pressure can penetrate down between the clay grains in the first mass layer to a depth of about 10 to 15 mm, and that it can be brought to form an even surface in desired coar¬ seness through wood float rubbing or steel smoothing. The drying time for the in accordance with "b" manufac¬ tured first mass layer is about 10 hours at room temperature. If a more rapid drying and setting of this layer is wanted, this can be obtained through increasing the share of the po¬ lymer modified, cement based mortar in the mixture.

The in accordance with "c" above manufactured surface strengthening layer is after about one hour ready for further treatment, such as fine plastering or free-flow puttying before flooring with carpet etc. If increased ad¬ hering against the bedding and/or better workability is wan¬ ted for the layer "c", this can be obtained by adding a po¬ lymer at the mixing of the mortar.

Advantages

When using multi-component compositions in accordance with the invention for the manufacture of system of joists and floor, it will through its low weight by unit of volume to a great extent aid in keeping the dead weight of the men¬ tioned constructions down. This permits in turn that founda¬ tion and load carrying construction parts, such as walls etc can be erected in smaller dimensions, which results in one in its entirety lighter and less costly building.

Multi-component composition in accordance with the in¬ vention is further through its, compared with traditional concrete constructions, low weight labour saving - a not un¬ essential advantage, when it comes to keeping the building costs as low as possible.

Another essential advantage is the short setting, cu¬ ring and drying times, which the multi-component composition in accordance with the invention has. Thus the first mass layer has a drying time at room temperature of about 10 hours. The surface strengthening layer is ready-cured after only about 15 minutes and it can be set foot on after about one hour, when it exhibits a compressive strength round

2 about lOOkp/cm . The differences against conventional con¬ crete are thus highly considerable bearing in mind that it at best requires at least 7 days of moisture curing before the drying up can be started.

The multi-component composition is further non-shrink¬ ing, which is a particularly valuable quality, not the least important when it concerns system of joists and floor in building. Moreover, the multi-component composition is not 100 per cent stiff, but has a certain elasticity.

To the advantages belong also, that the multi-component composition in itself is heat insulating and in a not insig¬ nificant extent sound insulating. Building height increasing additional insulation of system of joists and floor is therefore not normally required.

An additional advantage is, that the multi-component composition, when used for rebuilding and repairs of water damages and the like, through its low weight and its short setting an drying times makes it possible to carry out the work unusually fast and supple.

Multi-component composition in accordance with the in¬ vention has further shown itself to be very well suited for the erection of system of joists on profiled co-operation

* plate type "PEVA 45" The low weight of the composition in combination with the low weight of the moulding plate with its profiled design, which makes a mass-saving of 19 dm 3 per m 2 possible and which makes lower edge reinforcing un¬ necessary, result in this case in a finished system of joists with an unsurpassed low dead weight. The consump¬ tion of working hours from moulding to finished system of joists will also probably be as good as unbeatably small.

In order to further illustrate and explain the inven¬ tion one of the tests carried out with the present multi- component composition is accounted for below.

Example

At the manufacture of system of joists test slabs with the approximate dimensions 55x35x10 cm the following compo¬ nents were used in the below stated amounts:

Parts by weight

1. Grains of expanded, burnt clay (marke¬ ted under the trade mark LECA) grain sizes 12-20 mm 40

2. Fast-setting polymer modified cement-

^•k k based mortar STRUCTURITE 20

3. Fast-setting fibre reinforced, cementbased

^•k s mortar ROADPATCH 30 k k

4. PVA-based binder THOROBOND 2 k k

5. Acrylic polymer ACRYL 60 4

6. Water 4

*) Profiled and zincified reinforcing plate marketed under the trade mark PEVA 45 by Svenska Byggplat AB The components 1,2,4,5 and 6 were treated and mixed in accordance with the method in claims 5 a) and b) . The ob¬ tained composition was then spread and packed into test moulds to about 9 cm thick first mass layers which surfaces were levelled out.

Component 3 was then mixed with water to suitable con¬ sistency and was spread out under pressure on the first mass layers in the moulds in accordance with the method in claim 5 c) . The thereby obtained surface strengthening layers be¬ came about 2 cm thick and there surfaces were evened out through steel smoothing.

The weight of each of the 10 cm thick finished and dried slabs was approximately 15 kg, which gives a weight by

3 volume of about 0.8 kg/dm . A traditional system of joists slab of concrete with the same dimensions is thus more than

3 times heavier than the slabs manufactured in accordance with the invention.

A contributing reason to, why the first mass layer in slabs and floor manufactured according to the invention has such short drying time, is without any hesitation the drai¬ ning and ventilating interspace, which exists between the individual grains of clay in this layer. Thus, there exists a ventilating insulation layer in the slabs, which guaran¬ tees that no damp remains standing and deteriorates the in¬ sulating capacity. Apparently the low amount of mixing water, i.e. low wcr, also helps to explain why the drying time is so incomparably short.

Even if not mentioned above, reinforcement in the shape of wire netting or separate rods may of course be put into the first mass layer as well as into the surface strength¬ ening layer. The reinforcement may also consist of short glass fibre or steel fibre pieces, which are admixed at the preparation of respective mortar. The length of the pieces of fibre used may vary, but lies normally around 15 mm.

**) Products marketed in Sweden by Svenska ICI AB under the collection term THORO-products.

Claims

PATENT CLAIMS

1. Fast-setting multi-component composition with short drying time for the manufacture of non-shrinking system of joists and floor with low weight by volume, good heat and sound insulating qualities and certain elasticity, c h a ¬ r a c t e r i z e d by, that it comprises the following components in combination: a) 30-70 per cent by weight of grains of expanded, burnt clay b) 10-70 per cent by weight of a fast-setting, polymer modified and on hydraulic cement based mortar c) 10-70 per cent by weight of a fast-setting and on hy¬ draulic cement based, fibre reinforced mortar

2. Multi-component composition in accordance with claim 1, c h a r a c t e r i z e d by, that the grains of expanded, burnt clay consist of such grains which are marketed under any of the trade marks "LECA®" or "FIBO®" and which have a grain size of 4-30 mm, preferably 10-20 mm.

3. Multi-component composition in accordance with claim 1, c h a r a c t e r i z e d by, that the polymer modified, cement based mortar consists of such mortar that is marke¬ ted under the trade mark "STRUCTURITE®" .

4. Multi-component composition in accordance with claim 1, c h a r a c t e r i z e d by, that the cement based, fibre reinforced mortar consists of such mortar that is marketed under the trade mark "ROADPATCH®".

5. Method for the manufacture of fast-setting multi-com¬ ponent composition in accordance with claims 1-4, c h a ¬ r a c t e r i z e d by a) that the grains of expanded, burnt clay are pre-mixed with a PVA-based binder in such a way, that the sur¬ face of each grain is given a adhering and glueing coating of the binder in question, whereafter excess of binder is allowed to drain off from the grains si¬ multaneously as they are allowed to dry b) that 2 parts by weight of the according to "a" pre- treated clay grains are mixed with 1 part by weight of a fast-setting polymer modified, cement based mor¬ tar, which is strengthened with about 4 per cent by volume of a PVA-based binder, and which is given a suitable mortar consistency through mixing with a liquid consisting of equal parts water and a acrylic polymer in fluid form in order to be able to be mo¬ delled and packed into a first mass layer in desired thickness and with even surface, and c) that the according to "b" manufactured first mass layer is provided with a layer of a fast-setting cement bas¬ ed, fibre reinforced mortar mixed with water to such a consistency, that it when being spread under press¬ ure can penetrate down between the clay grains in the first mass layer to a depth of about 10 to 15 mm, and that it can be brought to form an even surface in de¬ sired coarseness through wood float rubbing or steel smoothing.

6. Method for the manufacture of fast-setting multi-com¬ ponent composition in accordance with claim 5, c h a r a c ¬ t e r i z e d by, that about 25 kg of the polymer modified, cement based mortar in dry state is mixed with about 3 lit¬ res of the liquid consisting of equal parts of water and acrylic polymer in order to obtain a suitable mortar con¬ sistency.

7. Method for the manufacture of fast-setting multi-com¬ ponent composition in accordance with claims 5-6, c h a ¬ r a c t e r i z e d by, that one as PVA-based binder uses the under the trade mark "THOROBOND®" marketed binder,and that one as acrylic polymer in fluid form uses the under the trade mark "ACRYL 60^ " marketed acrylic molymer.

8. Use of fast-setting multi-component composition with short drying time for the manufacture of system of joists and floor in buildings, c h a r a c t e r i z e d by, that multi-component composition manufactured in accor¬ dance with claim 5 a and b is spread and packed in desi¬ red thickness with an even top surface into a system of joists mould or on other bedding, whereafter the packed and levelled out top surface of the composition is sur¬ face strengthened through the putting on of another layer, which consists of a with water to suitable con¬ sistency mixed fast-setting, cement based, fibre rein¬ forced mortar, which is spread under pressure so, that it penetrates down between the clay grains in the lower lay¬ er to a depth of about 10 to 15 mm, and which finally through wood float rubbing or steel smoothing is brought to form an even top surface in desired coarseness.

9. Use of fast-setting multi-component composition with short drying time for the manufacture of system of joists in buildings in accordance with claim 8, c h a r a c t e ¬ r i z e d by, that the mould for the system of joists con¬ sists of a profiled co-operation plate of the type marketed under the trade mark "PEVA 45^", whereby the low weight by volume, the fast setting and the short drying time of the multi-component composition particularly well show to their advantages.