Roelof
Herman
Marissen, Roelof Herman
| 1. | Products produced using a hardenable composition, in particular based on cement or a similar concrete mortar, this hardenable composition containing at least one plasticcontaining additive, characterised in that the plasticcontaining additive comprises reinforcing fibres coated with a plastic material. |
| 2. | Products according to claim 1, characterised in that the reinforcing fibres consist of organic or inorganic material. |
| 3. | Products according to claim 1 or 2, characterised in that the reinforcing fibres coated with a plastic material are glass fibres coated with epoxy, polyester, vinyl ester or phenolic resin. |
| 4. | Products according to one or more of the claims 1 to 3, characterised in that the coated glass fibres used have a length of 0.120 mm, preferably 210 and expediently about 5 mm. |
| 5. | Products according to one or more of the claims 1 to 4, characterised in that glass fibres coated with a plastic material are present in the form of bundles up to about 1 mm and preferably about 0.2 mm thick. |
| 6. | Products according to one or more of the claims 1 to 5, characterised in that the coated glass fibres are obtained from glass fibrereinforced, shaped plastic products or their byproducts. |
| 7. | Concretebased products according to one or more of the claims l to 6, characterised in that 0.10.6% by weight of glass fibres coated with a plastic material is present, based on the total weight of the hardenable composition. |
| 8. | Products according to one or more of the claims 1 to 7, characterised in that the coated glass fibres are obtained from a method in which a reinforced plastic strip is produced from glass rovings and synthetic resin. |
| 9. | Glass fibres, suitable for reinforcing a harden¬ able composition, in particular cement or a similar concrete mortar, characterised in that the glass fibres are coated with a plastic and are obtained by comminuting glass fibrereinforced plastic material. |
| 10. | Glass fibres according to claim 9, characterised in that the glass fibres are coated with epoxy, polyester, vinyl ester or phenolic resin. |
The invention relates to products produced using a hardenable composition, in particular based on cement or a similar concrete mortar, this hardenable composition containing at least one plastic-containing additive. Products of this type are known per se. In this context, the plastic-containing additive is used to improve or obtain certain characteristics.
Thus, East German Patent 247.236 discloses a method for the production of concrete slabs, in particu- lar thin slabs which seal stress cracks in concrete. Plastic particles, which are of arbitrary shape, are added to the cement concrete. The plastic particles serve to replace textile clippings which usually are added as filler. However, the correct proportions between the concrete mixture and the plastic particles must be determined empirically on the basis of the strength characteristics of the product obtained after hardening for 28 days. A product of the type mentioned in the preamble has now been found which does not have the drawbacks of the known products, associated with the fact that the correct proportions are determined afterwards, and in which, nevertheless, the formation of cracks during hardening is completely prevented.
The product according to the invention is characterised in that the plastic-containing additive comprises reinforcing fibres coated with a plastic material. Reinforcing fibres coated with a plastic material are found to be readily combinable with hardenable compo¬ sitions which in particular are based on concrete. Thus, it has proved possible to obtain a concrete product in which the formation of shrinkage cracks and shrinkage during hardening are prevented by the presence of reinforcing fibres.
The reinforcing fibres preferably consist of organic or inorganic material. Organic material which can be used is polypropene or a synthetic resin, but indus¬ trial polymer fibres, such as aramide fibres, will also fall under this type of material. An inorganic material which may be mentioned is glass. Of course, it is also possible to use other materials as the basis for the reinforcing fibres in question. After all, what is impor¬ tant is that they are coated with a plastic material. Expediently, the reinforcing fibres coated with a plastic material are glass fibres coated with epoxy, polyester, vinyl ester or phenolic resin. Plastic coating materials of this type guarantee good adhesion of the hardenable composition, as a result of which the coated glass fibres can also be incorporated well distributed in the hardenable composition.
Moreover, the specific weight of such coated glass fibres approximately corresponds to the specific weight of the concrete constituents. Consequently, no demixing occurs during the formation and hardening of the concrete mixture, and the fibres will therefore not "float" and protrude from the surface, which phenomenon has been detected when fibres consisting solely of plastic, such as, for example, polypropene, are used. Fibres of this type have a tendency to deform at the surface, since they try to return to their original shape. The surface of a concrete product according to the invention, which therefore is provided with coated glass fibres, is therefore smooth. Uncoated glass fibres can, as is known, not be used in a concrete because glass is attacked by the alkaline cement fraction in the concrete. This disadvan¬ tage is, of course completely overcome by the coating.
The coated glass fibres used preferably have a length of 0.1-20 mm, more particularly of 2-10 mm, but expediently of about 5 mm.
According to the particular embodiment, the glass fibres coated with a plastic material are present in the form of bundles which are up to about 1 mm, preferably
about 0. 2 mm, thick.
According to an embodiment which is to be par¬ ticularly preferred, the coated glass fibres are obtained from glass fibre-reinforced, shaped plastic products or their by-products.
If the hardenable plastic composition in the product according to the invention is based on concrete,
0.1-0.6% by weight of glass fibres coated with a plastic material is preferably present, based on the total weight of the hardenable composition.
Such a small amount is sufficient to prevent shrinkage and shrinkage cracks during the setting of concrete completely.
If, however, a product is desired which is able to withstand a greater load or higher stress, a larger amount of reinforcing fibres is then required, for example 1-10%. The reinforcing fibres present in this case can consist, in whole or in part, of coated glass fibres as described above. The products according to the invention prefer¬ ably contain coated glass fibres which have been obtained from a method in which a reinforced plastic strip has been made from glass rovings and synthetic resin.
According to the invention, therefore, glass fibres which are particularly suitable for reinforcing a hardenable composition, such as cement or a similar concrete mortar, are glass fibres which are coated with a plastic and have been obtained by comminution of glass fibre-reinforced plastic material. Expediently, these glass fibres are coated with epoxy, polyester, vinyl ester or phenolic resin.
The invention will be illustrated in more detail below with the aid of an illustrative embodiment.
Example Sections of glass fibre-reinforced epoxy plastic tubes are processed with a shredder and a hammer mill to form fibre bundles having a total thickness of about 0.2 mm and a fibre length of about 5 mm.
These fibres are added as filler, in an amount of
- A - about 0.2% by weight, to a concrete mixture. No shrinkage or the formation of shrinkage cracks are observed during setting of the concrete mixture.
Other glass fibre-reinforced polyester products are found to give the same favourable result, as do glass fibres which are coated with vinyl ester or phenolic resin.