|
(11) | EP 0 655 531 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
|
|
|
|
|||||||||||||||||||||||||||
| (54) | Pourable material, in particular liquid asphalt, with metal chips |
| (57) Rutting in a layer of liquid asphalt consisting of around 90 wt.-% minerals and at
least 7% bitumen can be counteracted by adding metal chips to the mixture of minerals
and bitumen. The percentage by weight of chips is at least 1, and preferably lies
between 2 and 8. The chips are a minimum length of 10 mm and a maximum length of 80
mm, and are preferably a length between 15 and 40 mm. They are a flat shape, and the
maximum breadth lies between 1 and 4 mm, while the maximum height lies between 0.15
and 0.5 mm. |
[0001] The invention relates to pourable material for the application of a waterproof covering layer which is suitable for foot and vehicular traffic, in particular liquid asphalt, consisting of around 90 wt.-% minerals with a certain granule distribution, in particular stone chippings, gravel, sand and filler, and at least 7% of a binder consisting essentially of bitumen.
[0002] Liquid asphalt is in increasingly common use as a waterproof floor finish on roof car parks and walkways. It is a bituminous mortar which is processed warm and sets by cooling. The correct granular structure of the minerals is important. The skeleton formed by the minerals must contain the lowest possible percentage of hollow space. The purpose of the filler, with a granule size of less than 63 µm, is to reduce the hollow space further, on the one hand, and to stiffen and stabilize the bitumen, on the other hand, which ensures that at higher temperatures the bitumen does not run out. The acid resistance can be increased by a suitable choice of fillers. The application temperature of mastic asphalt lies between 200 and 250°C and, since this temperature is much higher than the boiling point of water, liquid asphalt must be applied to a dry substrate. In order to avoid the risk of residual moisture in the substrate (often concrete), liquid asphalt is usually poured onto a separating layer of impregnated paper, glassfibre or impregnated felt. Any vapour tension under the liquid asphalt can then become dispersed.
[0003] It is known to apply liquid asphalt in two layers on top of one another, a mesh-type reinforcement being incorporated in the bottom layer, inter alia in order to prevent cracks forming in the top layer above the seams of the bottom layer. The seams in the top layer are replaced by a relatively broad joint filled with modified bitumen.
[0004] It has been found in practice that in the case of the abovementioned liquid asphalt covering formed from two layers and having a reinforcement mesh rutting occurs due to plastic deformation. Rutting can in turn lead to cracks. The resistance to compression and the tensile strength of the known liquid asphalt coverings leave something to be desired.
[0005] The object of the invention is to avoid these disadvantages, and to this end the pourable material mentioned in the preamble is characterized in that steel chips are incorporated in the mixture of minerals and binder in a quantity of at least 1 wt.-%, which chips are a minimum length of 10 mm and a maximum length of 80 mm, and are essentially flat in shape, the maximum breadth lying between 1 and 4 mm, and the maximum height between 0.15 and 0.5 mm.
[0006] The use of this material means that the reinforcement mesh can be dispensed with and a single liquid asphalt layer will suffice. This leads to savings in the application.
[0007] It is known per se to use steel fibres in cement concrete, in order to increase the tensile strength. It is surprising that use of the specific flat metal chips according to the invention in liquid asphalt greatly counteracts rutting through plastic deformation.
[0008] In order to achieve a substantial increase in the resistance to compression, the metal chips must be a certain minimum length and be added in a certain percentage by weight. The length of the chips is preferably 20 to 40 mm, and the percentage by weight of the chips is 2 to 8.
[0009] It is also important that the chips adhere well to the surrounding bitumen matrix. For this purpose, the chips are preferably produced by cold-milling, are a maximum height between 0.2 and 0.3 mm, and are twisted in their lengthwise direction.
[0010] Through this twisting in the chips and through the fact that the chips are preferably provided in a finishing operation with hooked or wavy end parts, the resistance to the chips being pulled out of the bitumen matrix is also increased. Besides, chips formed in this way can be mixed and homogeneously distributed without caked lumps forming.
[0011] It may be preferable to provide one of the sides of the chips with a wavy profile, in order to achieve good adhesion.
[0012] The invention also relates to a surface suitable for foot or vehicular traffic, provided with a hardened waterproof layer produced with the material according to the invention.
[0013] The layer is usually made up of strips which abut each other by way of seams, while according to the invention a piece of roofing felt and a reinforcement mesh are applied at the bottom surface of the layer at the position of each seam.
[0016] Fig. 1 shows a section through a material according to the invention which is suitable for foot and vehicular traffic and is poured onto a concrete floor.
[0018] Fig. 3 shows a perspective view of a chip used in the liquid asphalt according to the invention.
[0019] Fig. 4 shows a graph of the relation between compression of the pourable material, chip length and percentage by weight of chips.
[0020] Fig. 1 shows a concrete surface 1 (for example, a roof car park), a layer of roofing felt 2, a layer of liquid asphalt 3 applied in strips, chips 4 mixed into said layer, the gravel 5 strewn onto the mastic asphalt, the seam 6 between two strips of liquid asphalt, a strip 7 of roofing felt at the position of the seam, and a reinforcement strip 8 at the position of the seam.
[0022] Fig. 2a shows a cross-section of a first embodiment of a chip which is obtained by cold-milling. The fibre is flat triangular and has a rough surface and a smooth surface (with breadth B). The maximum height H is 0.15 to 0.5 mm, preferably 0.25 mm, the breadth B is 1 to 4 mm, preferably around 2.0 mm, and the length is 10 to 80 mm, preferably 20 to 40 mm.
[0023] Fig. 2b shows a cross-section of a second embodiment of a chip; the only difference is that the top surface is wavy.
[0025] As can be seen from Fig. 4, the percentage by weight of steel chips and the chip length affect the resistance to compression, and thus the rutting.
[0026] The chips described, if added in the percentage by weight of 2 to 8, can be homogeneously distributed and cannot adhere to each other in caked lumps. Moreover, the adhesion to the surrounding matrix will be excellent. If the length of the chips is less than 10 mm, adhesion to the bitumen will be inadequate. A length greater than 40 mm would lead to good adhesion, but the resistance to breaking or bending can be too low.
[0027] A height of less than 0.15 mm would lead to too little improvement in the resistance to compression, and too low a breadth (less than 1.0 mm) would lead to easy bending and breaking of the chips and to inadequate adhesion with the bitumen. Too great a breadth when the percentage by weight of the chips lies between 2 and 4 can lead to inadequate uniformity in the distribution, or when there is a higher percentage by weight can lead to caked lumps forming.
1. Pourable material for the application of a waterproof covering layer which is suitable
for foot and vehicular traffic, in particular liquid asphalt, consisting of:
- around 90 wt.-% minerals with a certain granule distribution, in particular stone chippings, gravel, sand and filler, and
- at least 7% of a binder consisting essentially of bitumen,
characterized in that metal chips are incorporated in the mixture of minerals and binder in a quantity of at least 1 wt.-%, which chips are a minimum length of 10 mm and a maximum length of 80 mm, and are essentially flat in shape, the maximum breadth lying between 1 and 4 mm, and the maximum height between 0.15 and 0.5 mm.2. Pourable material according to Claim 1, characterized in that the chips are of steel.
3. Pourable material according to Claim 1 or 2, characterized in that the length of the
chips is 15 to 40 mm.
4. Pourable material according to one of the preceding claims, characterized in that
the percentage by weight of chips is 2 to 8.
5. Pourable material according to one of the preceding claims, characterized in that
the chips are produced by cold-milling.
6. Pourable material according to one of the preceding claims, characterized in that
the chips have a maximum height (thickness) between 0.2 and 0.3 mm.
7. Pourable material according to one of the preceding claims, characterized in that
the chips are twisted in their lengthwise direction.
8. Pourable material according to one of the preceding claims, characterized in that
the chips are provided in a finishing operation with hooked or wavy end parts.
9. Pourable material according to one of the preceding claims, characterized in that
one of the sides of the chips is provided with a wavy profile.
10. Surface suitable for foot or vehicular traffic, provided with a hardened waterproof
layer produced with the material according to one of the preceding claims.
11. Surface according to Claim 10, in which the layer is made of various strips which
abut each other by way of seams, characterized in that a piece of roofing felt and
a reinforcement mesh are applied at the bottom surface of the layer at the position
of each seam.
12. Surface according to Claim 10 or 11, characterized in that the layer is provided with
a layer of gravel on its top surface.