Waterproofing sheet

It comprises three layers: a first layer of plastic material that provides the whole with mechanical strength, a second intermediate layer of foam forming a union between the first and second layer, and a third layer of impermeable plastic material and is characterized in that the first layer (2) is mase on an elastomeric polyolefin of high strength and elasticity, in that the second layer (3) is of closed-cell, physically or chemically cross-linked polyethylene foam, and in that the third layer (4) is of polyolefin with high tear resistance. A light waterproofing sheet is obtained which withstands extreme meteorological conditions, is resistant to chemical agents, while it also has optimum mechanical properties at a lower thickness thanks to the material of which the first layer is comprised and unlike other sheets existing it has no ageing limit, which means that once the sheets have been fitted they do not have to be replaced.

FIELD OF THE INVENTION

This invention relates to a waterproofing sheet for tunnels, channels and underground constructions in general and for waterproofing roofs and terraces on buildings.

BACKGROUND OF THE INVENTION

In tunnels, mines and underground works in general the presence of water and excess humidity creates considerable problems, whether during the various phases of construction or throughout the life of the work or infrastructure.

The hazards that arise due to the formation of puddles or ice on traffic-bearing surfaces are well known. Similarly, in railway tunnels water is also a danger for the installations, and in regions with very low winter temperatures the formation of ice can break the track by deformation and even prevent the passage of trains.

In any underground construction work, infiltrations of water damage the complex control equipment and operating services, and the reinforced concrete structures often require special treatment to prevent them decalcifying and subsequently expanding due to oxidation of frameworks.

Conventional waterproofing systems resolve many of the aforementioned problems, but their costs are generally high. This is shown particularly when there arise difficulties such as high infiltrations of rain during application of the waterproofing, extreme climatological conditions, and even the need for waterproofing after the building work has been completed.

A type of coating is currently used which consists in sheets made of plastic material, and more specifically PVC. Said sheets have the disadvantage that their PVC content means that they are not biodegradable, while they also have low thermal gaps and low resistance to chemical agents.

Similarly, for several years now the roofs or terraces of buildings have also been waterproofed with PVC sheets or asphalt sheets to protect them from water. However, owing to the materials used in said sheets and the climatological conditions and exposure to sunlight, the sheets undergo ageing and deterioration, which means that they have to be checked and repaired.

Spanish patent no. 9600657, whose holder is the same as that of this patent application, describes a coating or waterproofing sheet, particularly for tunnels, made up of three layers: a first layer of raffia, a second intermediate layer of foam and a third layer of plastic material metallised with aluminium. This sheet has the advantage that the foam is not inflammable and its mechanical strength is higher than that of PVC sheets.

But this type of sheet has the disadvantages of only being applicable in tunnels or channels and showing rapid ageing, which means that the sheet has a short working life.

OBJECTS AND SUMMARY OF THE INVENTION

Description Of The Invention

The objective of the waterproofing sheet of this invention is to solve the disadvantages presented by the sheets known in the state of the art, while further providing a plurality of advantages which are described below.

The sheet of the invention is characterised in that the first layer is made of an elastomeric polyolefin of high strength and elasticity and flexibility, in that the second layer is of closed-cell, physically or chemically cross-linked polyethylene foam, and in that the third layer is of polyolefin with high tear resistance.

Thanks to these characteristics a flat and light waterproofing sheet is obtained which is capable of withstanding extreme meteorological conditions, including temperatures which range from 100° C. down to −60° C., is resistant to chemical agents such as concentrated acids, while it also has optimum mechanical properties at a lower thickness thanks to the material of which the first layer is comprised; unlike the sheets existing in the market it has no ageing limit, which characteristic means that once the sheets have been fitted they do not have to be replaced with new ones due to their having deteriorated. Furthermore, the sheet is cheaper than the sheets currently used, and the fact that it does not contain PVC makes it an ecological and at the same time biodegradable sheet.

Preferably, the elastomeric polyolefin of high strength and high elasticity is polyethylene.

Also preferably, the tensile strength of the sheet is between 24 Mpa and 39 Mpa.

Advantageously, the elongation at rupture lies between 550% and 900%.

According to another aspect of the invention, the layer of polyolefin of high tear resistance has channels formed in it. The running of water from the walls of constructions or excavations, such as tunnels, is thus regulated and guided.

In accordance with an alternative embodiment of the invention, the layer of polyolefin of high tear resistance is smooth and is very suitable for use on the terraces and roofs of buildings.

Advantageously, the layer of elastomeric polyolefin of high strength and high elasticity is resistant to ultraviolet light. This property allows the sheet to withstand continuous exposure to sunlight when said sheets are fitted on the roofs or terraces of buildings.

Preferably, the thickness of the sheet of the invention lies between 3 mm and 50 mm.

DETAILED DESCRIPTION OF THE INVENTION

Description of a Preferred Embodiment

AsFIG. 1shows, the waterproofing sheet1of the invention is made up of three layers: a first outer layer2of elastomeric polyolefin of high strength and high elasticity, with said polyolefin being a polyethylene, a second intermediate layer3of closed-cell, physically or chemically cross-linked polyethylene foam, and a third layer4made of polyolefin with high tear resistance. Said interior layer4is dark in hue and has a smooth profile which makes the sheet1easier to fit on roofs and/or outdoor terraces of buildings, thereby providing good thermal insulation and acoustic insulation of impact, while it also has good resistance to ultraviolet light.

FIG. 2shows another embodiment of a sheet5of the invention in which the interior layer6, unlike the previous sheet, has a channelled profile, and is suitable for interior waterproofing of tunnels and similar infrastructure by allowing the water to flow and preventing it accumulating.

Said sheets are placed between the shot concrete or rock and the reinforced concrete, which layout is more commonly known as “sandwich layout”.

The process of making the waterproofing sheet1of the invention involves a process of extrusion of the polyethylene sheet, which is later thermofused to attach it to the polyolefinic foam that has been compound-bonded to a polyolefinic base film. The final result consists in substantially flat laminar rolls.

There follow details of the tests carried out on the sheet of the invention in order to determine its technical characteristics.

Tensile strength and elongation at rupture(according to standard UNE-EN ISO 527-3 (96) /2/100):Dynamometer usedINSTROM 112Test-pieceType-2 halterioThickness (mm)4.5Test temperature (° C.)23 ± 1Jaw separation speed (mm/min)100Initial gap between jaws (mm)50Initial gap between marks (mm)20Tensile strength in longitudinal192direction (N/cm)Tensile strength in transversal183direction (N/cm)Elongation at rupture in longitudinal665direction (%)Elongation at rupture in transversal665direction (%)Resistance to perforation(according to standard UNE 104.300)Test-piece diameter (mm)65Jaw separation speed (mm/min)100Resistance to perforation (N)41.7Resistance to perforation (N/mm)41.7Resistance to chemical agentsChemicaldegradationSO4H2(30%)NoSO4H2(3%)NoNaOH (10%)NoNaOH (1%)NoC2H5OH (95%)NoC2H5OH (50%)No(CH3)2CONoCH3CCOOC2H5NoCCL4NoC6H5CH3NoC7H16NoClNa (10%)NoC6H5OH (10%)NoH2ONoNO3H (10%)NoClH (10%)NoCH3COOHNoC17H33COOHNoNH4OH (10%)NoCO3NA2(2%)NoH2O20.23OilNoPetrolNo
Independent of the object of this invention shall be the materials used in manufacturing the pieces which constitute the waterproofing sheet described, together with the shapes and dimensions of same and all accessory details that might be presented, which may be replaced by others that are technically equivalent, as long as they do not affect its essential nature nor depart from the sphere defined by the claims attached below.