Tridirectional laid scrims for reinforcement purposes

Abstract

A triaxial laid scrim includes a first, second and third set of continuous fibers. The fibers of each set are regularly spaced apart and are parallel to each other. The fibers of the first set are parallel to the warp direction or to the weft direction of the scrim. The fibers of the second set and the third set are oriented symmetrically to each other, respectively at an angle of 30°-80° with respect to the fibers of the first set. Distances between the fibers of the second set and the fibers of the third set are identical. The fibers of the second set cross the fibers of the third set at the intersection thereof with the fibers of the first set, thereby defining regular openings having an isosceles triangle shape. The fibers are coated and attached to each other by a coating that does not fill-up the triangle-shaped openings.

Claims

1. A method of reinforcing a solid material, the method comprising: embedding a triaxial laid scrim into a viscous base material; and hardening the viscous base material so as to obtain a solid material comprising the triaxial laid scrim, wherein: the triaxial laid scrim comprises a first, second, and third set of continuous fibers and comprises less than 10% of simple intersections with respect to a total number of simple intersections and triple cross-points, the fibers of the first set of continuous fibers are regularly spaced apart and are parallel to each other, the fibers of the second set of continuous fibers are regularly spaced apart and are parallel to each other, and the fibers of the third set of continuous fibers are regularly spaced apart and are parallel to each other, the fibers of each of the first, second and third set of continuous fibers are mineral fibers, the fibers of the first set of fibers are parallel to the warp direction (machine direction) or to the weft direction (cross-machine direction) of the scrim, the fibers of the second set of fibers and the fibers of the third set of fibers are oriented symmetrically to each other, respectively at an angle of between 30° and 80° with respect to the fibers of the first set of fibers, a distance between the fibers of the second set of fibers is identical to a distance between the fibers of the third set of fibers, the fibers of the second set of fibers cross the fibers of the third set of fibers at an intersection of the fibers of the third set of fibers with the fibers of the first set of fibers, thereby defining regular openings having the shape of isosceles triangles, and prior to said embedding, the fibers of each of the first, second, and third sets of continuous fibers of the triaxial laid scrim are coated and attached to each other by means of a coating comprising organic polymer that does not fill-up the isosceles triangle-shaped openings, wherein the organic polymer is present in the coating in an amount of 6 wt % to 20 wt % of the triaxial laid scrim as expressed as loss-on-ignition.

2. The method according to claim 1, wherein the fibers of the second and third set of fibers are oriented respectively at an angle of about 60°, with respect to the fibers of the first set of fibers, thereby defining the openings to have the shape of equilateral triangles.

3. The method according to claim 1, wherein the fibers of the first set of fibers are divided into a first subset of fibers and a second subset of fibers, each of the first subset and the second subset of fibers forming a separate layer of fibers.

4. The method according to claim 3, the coated triaxial laid scrim comprising the following four layers of fibers, a first layer consisting of the fibers of the first subset of the first set of fibers, a second layer consisting of the fibers of the second set of fibers, a third layer consisting of the fibers of the third set of fibers, and a fourth layer of fibers consisting of the fibers of the second subset of the first set of fibers.

5. The method according to claim 1, wherein the distances between the regularly spaced apart parallel fibers of the first, second, and third set of fibers are between 3 mm and 30 mm, said distances being defined as the distance between the central axes of two adjacent fibers of the same set of fibers.

6. The method according to claim 1, the coated triaxial laid scrim having a surface weight of between 50 g/m.sup.2 and 600 g/m.sup.2.

7. The method according to claim 1, wherein the fibers of the first set of fibers are parallel to the warp direction of the scrim.

8. The method according to claim 1, the coated triaxial laid scrim having an openness, defined as a ratio of a total surface of the isosceles triangle-shaped openings to a total surface of the laid scrim, of between 50% and 80%.

9. The method according to claim 8, wherein the openness is between 60% and 75%.

10. The method according to claim 1, wherein the distances between the regularly spaced apart parallel fibers of the first, second, and third set of fibers are between 8 mm and 15 mm, said distances being defined as the distance between the central axes of two adjacent fibers of the same set of fibers.

11. The method according to claim 1, wherein the coating is an elastomer coating.

12. The method according to claim 1, the coated triaxial laid scrim having a surface weight of between 130 g/m.sup.2 and 200 g/m.sup.2.

13. The method according to claim 1, the coated triaxial laid scrim comprising less than 2% of the simple intersections.

14. The method according to claim 1, wherein the viscous base material comprises water and a hydraulic binder.

Description

(1) The present invention is now described in detail with reference to the attached drawings wherein

(2) FIG. 1 shows a first embodiment of a laid scrim of the present invention;

(3) FIG. 2 is second embodiment of a laid scrim of the present invention;

(4) FIG. 3 is a perspective view of the laid scrim of FIG. 2;

(5) FIG. 4 is a third embodiment of a laid scrim of the present invention,

(6) FIG. 5 is a forth embodiment of a laid scrim of the present invention.

(7) In the laid scrim depicted at FIG. 1, the fibers of the first set of fibers 1a,1b are weft fibers and are parallel to the cross-machine direction. A first set of bias fibers 2 is oriented at an angle +α of 60° with respect to the fibers of the first set of fibers. A second set of bias fibers 3 is oriented at an angle −α of 60° with respect to the fibers of the first set of fibers. The distance between the parallel fibers of each set of fibers is identical in all three sets of fibers. All intersections are triple cross-points, i.e. intersections of three fibers. All openings exhibit a shape of equilateral triangles.

(8) The first set of fibers comprises a first subset of fibers 1a and a second subset of fibers 1b, the fibers of the first and second subsets being located in different layers of the laid scrim.

(9) The scrim of FIG. 2 is identical to the scrim of FIG. 1 except for the fact that the fibers 1a,1b are warp fibers oriented in the machine direction.

(10) The perspective view of FIG. 3 shows the four-layer structure of the laid scrim of the present invention:

(11) an undermost first layer made of warp fibers 1b,

(12) a second layer made of bias fibers 2,

(13) a third layer made of bias fibers 3, and

(14) a uppermost forth layer made of warp fibers 1a,

(15) the warp fibers of the first and fourth layers all being parallel to each other.

(16) FIG. 4 shows an embodiment of a laid scrim of the present invention where α is about 45°. The resulting openings are right angle isosceles.

(17) FIG. 5 shows an embodiment where α is significantly higher than 60° resulting in openings having a shape of acute isosceles.