Bi-Component Synthetic Fibres for Application in Cement-Bonded Building Materials

Abstract

The core/casing-fibre consists of plastic such as polypropylene, polyethylene or a mixture of these raw materials or other thermoplastic polymers. The fibre diameter is 0.15 to 2.0 mm and the core/casing-fibre in a continuous or intermittent manner has a structured surface. This is produced by an embossing ( 5 ) which designed in a single-sided or multi-sided manner, and its depth is at least 10% of the average fibre diameter. The embossing ( 5 ) may be designed in a transverse or diagonal manner or in another shape to the fibre course, but in any case is incorporated after a stretching of the fibre by the factor 5 to 15. The core/casing-fibre is cut in section of 10 to 80 mm and grouped together into bundles of several thousand and wrapped in a water-soluble plastic film. Such fibres are used for increasing the tensile strength, for improving the post-failure behaviour or generally for the mechanical reinforcement in cement-bonded building materials, in particular concrete. The bundles may be worked into the building material together with the plastic film without any disadvantages.

1 . A plastic fibre for the application in concrete with largest grain diameters >4 mm, with an average diameter of 0.15 to 2 mm, corresponding to approx. 160 to 28,000 dtex (Dezitex=grams per 10,000 running metres), characterised in that it is a bi-component fibre which is stretched by the factor 5 to 15 and is manufactured by way of a co-extrusion method from a central core and a casing which envelops this, of differently pure polymers or polymer mixtures, and that after the stretching has been effected, a continuously or interruptedly structured or grooved surface is embossed onto this continuously stretched bi-component fibre, wherein the depth of this structuring is more than 10% of this average fibre diameter, and the maximal distances of their structure tips within incorporated structures in the axial direction lie in the region between 0.5 mm and 3 mm. 
   
   
       2 . A plastic fibre for the application in concrete with largest grain diameters >4 mm, according to  claim 1 , characterised in that the fibre is a polyolefin fibre which means it consists of polypropylene or polyethylene or of mixtures of these raw materials, or is manufactured of other thermoplastic raw materials. 
   
   
       3 . A plastic fibre for the application in concrete with largest grain diameters >4 mm, according to  claim 1 , characterised in that its core ( 3 ) consists of polymers with a low melt flow rate (MFR) and of a narrow molecular weight distribution, and its casing ( 7 ) consists of polymer with a higher MFR and of a broader molecular weight distribution. 
   
   
       4 . A plastic fibre for the application in concrete with largest grain diameters >4 mm, according to  claim 1 , characterised in that the structured surface is a single- or multi-sided mechanical embossing ( 5 ), which is right-angled, diagonal, crossing and of any other shape. 
   
   
       5 . A plastic fibre for the application in concrete with largest grain diameters >4 mm, according to  claim 1 , characterised in that mineral, metallic or ceramic particles ( 6 ) in the form of fillers, salts, glass particles, small glass balls or fibre materials are incorporated into the core polymer ( 3 ), the casing polymer ( 7 ) or into both polymers ( 3 ,  7 ). 
   
   
       6 . A plastic fibre for the application in concrete with largest grain diameters >4 mm, according to  claim 1 , characterised in that 3% by mass to 25% by mass of fine mineral nanoparticles with a grain diameter of ≦1 μm are incorporated in the casing polymer ( 7 ). 
   
   
       7 . A plastic fibre for application into concrete with largest grain diameters >4 mm, according to  claim 1 , characterised in that functional groups are incorporated into the casing polymer ( 7 ), for increasing the surface tension and polarity of the fibres. 
   
   
       8 . A plastic fibre for the application in concrete with largest grain diameters >4 mm, according to  claim 1 , characterised in that it is packaged in bundles ( 8 ) of several thousand sections which are wrapped with a water-soluble plastic film ( 9 ) and are held together by this. 
   
   
       9 . A plastic fibre for the application in concrete with largest grain diameters >4 mm, according to  claim 1 , characterised in that it is packaged in compact bundles ( 8 ) of several thousand section, with section lengths of 10 mm to 80 mm, wherein the bundles on both sides are off in a plane manner, and are held together by a water-soluble, inert plastic film ( 9 ). 
   
   
       10 . The use of a plastic fibre for the application in concrete with largest grain diameters >4 mm, according to  claim 1 , characterised in that they are in bundles ( 8 ) of several thousand sections with section lengths of 10 mm to 80 mm, wherein these bundles ( 8 ) are wrapped with a water-soluble plastic film ( 9 ), into which cement-bonded building material is added and mixed with it.