Plastic and nonmetallic article shaping or treating: processes – With severing – removing material from preform mechanically,... – Forming continuous work followed by cutting
Patent
1996-07-29
1998-07-14
Thomas, Alexander
Plastic and nonmetallic article shaping or treating: processes
With severing, removing material from preform mechanically,...
Forming continuous work followed by cutting
264148, 26421111, 2642102, 428119, 428192, 52539, B29C 4700
Patent
active
057799571
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a shaped article of the type comprising a hydrated matrix containing cement and sand and reinforced by fibres. It is in particular applicable to covering elements for buildings, for example building roofing plates imitating slate.
BACKGROUND OF THE INVENTION
It has already been proposed, for example in document EP-A-165,388, to produce plates of the aforementioned type shaped by a plastic deformation.
However, these known plates are heavy since they are very dense (specific gravity higher than 2) and fragile and cannot be made in small thicknesses without risk of fracture or cracking.
SUMMARY OF THE INVENTION
An object of the invention is to permit, on the contrary, producing thin plates which may be conveniently used for the covering of buildings, in particular as roofing with the appearance of slate.
The invention therefore provides a shaped article of the aforementioned type, characterized in that the hydrated matrix contains 100 parts by weight of cement and about 80 to 120 parts by weight, preferably about 100 parts by weight, of sand having a grain size of less than 1 mm, and the reinforcing fibres are alkali-resistant glass fibres present in a proportion of about 3 to 4% by weight, preferably about 3.5% by weight, relative to the hydrated matrix, the article having a specific gravity of no more than 1.85.
The shaped article according to the invention may also have one or more of the following features:
the article is constituted by a plate, in particular for the covering of buildings, having a general thickness less than about 1 cm;
the hydrated matrix contains a water/cement ratio by weight between 0.30 and 0.40, and preferably of 0.35;
the glass fibres have a length/diameter ratio between about 100 and 200;
the hydrated matrix further contains ultrafine particles, in particular fumed silica or metakaolin in an amount of about 8 to 12 parts by weight and preferably about 10 parts by weight;
the hydrated matrix further contains an extrusion agent such as carboxymethylcellulose in an amount of about 1 part by weight;
the hydrated matrix further contains a colouring agent, in particular an iron oxide, in an amount of about 4 parts by weight;
the article has a roughly smooth bottom surface and a top surface imitating slate;
the plate has a thickness of no more than 6 mm;
the article comprises along an edge downwardly projecting hooking reliefs or lugs and a top surface imitating slate, optionally provided with ribs ensuring the seal between the articles disposed in overlapping relation.
The invention also provides a process for manufacturing a shaped article in the form of plate, in particular as defined hereinbefore, comprising a hydrated matrix containing cement and sand and reinforced by fibres, said process comprising the following steps:
(a) mixing the constituents until a substantially homogeneous paste is obtained;
(b) extruding the paste in the form of a strip; and, after or before the cutting of said strip;
(c) rolling the strip.
This process may also have one or more of the following features;
the process further comprises a step (d) for shaping the rolled plates by compression, preferably effecting simultaneously the final cutting of the plates to the desired dimensions,
the extruded strip has a width substantially equal to that of the plates to be obtained, and the rolling is effected between freely rotatable rolling elements,
the extruded strip has a width distinctly less than the width of the plates to be obtained, and the rolling is effected by braking the strip so as to increase the width thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
An example of carrying out the invention will now be described with reference to the accompanying drawings in which:
FIG. 1 is a perspective view of a roofing plate according to the invention;
FIG. 2 is a similar view of another embodiment of the roofing plate according to the invention;
FIGS. 3 to 5 illustrate diagrammatically respectively three successive transforming stages resulting in the p
REFERENCES:
patent: 4793861 (1988-12-01), Sohm
patent: 5108679 (1992-04-01), Rirsch et al.
patent: 5223200 (1993-06-01), Schulz et al.
Champomier Claude
Soukatchoff Pascal
Materiaux De Construction International
Thomas Alexander
LandOfFree
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