FR2849064A1 - Polyolefin fiber for reinforcement of hydraulic setting products such as mortars or cement based articles which is treated with a size to promote wettability by, and adhesion to, the hydraulic binder - Google Patents

Abstract

A polyolefin fiber for the reinforcement of products based on fibers and a hydraulic setting mass is treated with a size containing functional groups, to assist fiber formation and wettability by the hydraulic setting mass, and promote adhesion to the mass. Independent claims are included for (1) a fiber and hydraulic setting mass based product comprising the claimed fiber; (2) a method of making the product by preparing a mixture of hydraulic binder, fibers and water, filtering to form primary wet sheets, superposing a number of the primary sheets and drying; (3) a composition for a hydraulic material, especially a mortar comprising a hydraulic binder and the claimed fibers.

Description

POLYOLEFIN REINFORCING FIBER, USE AND

PRODUCTS COMPRISING FIBER

  The present invention relates to the field of hydraulically setting materials, and more particularly hydraulic binder and fiber based products. These products may be in particular in the form of shaped articles in plates such as flat or corrugated plates for roofing or building elements, such as roofing or facade plates, but also in other forms such as hollow or tubular.

  Such articles can be manufactured by a filtration technique of an aqueous suspension comprising a hydraulic setting binder, reinforcing fibers and optionally fillers. A method commonly used based on this technique is known as the Hatschek process: a A very dilute aqueous suspension is contained in a tank equipped with means to ensure a homogeneous distribution of the constituents in the volume of the tank; a filtering drum partially dips into the tank, and its rotation causes the deposition on its surface of a thin film of material (fibers and hydrated binder); this film is driven by a felt to a roll format on which it winds continuously; when the film has reached the desired thickness, it is cut so as to unroll the cylinder an individual sheet of hydraulic setting material The sheet can then be shaped into a shaped product and acquires its final characteristics by hardening the binder A product of greater thickness can be obtained by superimposing an appropriate number of sheets, and pressing them to ensure cohesion of the assembly.

  As fibers used to form the reinforcement of the filtered film, asbestos has long been used whose fibers have the property of dispersing in the aqueous suspension without forming agglomerates detrimental to the regularity of the process, and are even capable of "opening" in the aqueous medium to thus form on the surface of the drum a very entangled filtering network capable of retaining the particles of hydraulic binder, including fines, with a very good filtering efficiency Asbestos fibers In addition, they have good tensile strength properties which contribute to the mechanical properties of the final product mainly stressed in bending. The asbestos fibers thus have a double function of reinforcement (in the sense of the formation of a filtering network) and reinforcement (which contributes to the final mechanical properties) Asbestos is also a very competitive material from the point of view of the cot.

  However, this material tends to be discarded from the manufacture of a wide variety of consumer products and from the field of construction for reasons of public health. This is why there is a demand for a substitute not having the disadvantages of asbestos.

  However, to date, it has not been possible to find a natural or synthetic fibrous material capable of playing the same role as asbestos, that is to say combining the ability to filter, properties mechanical and alkaline resistance of hydraulic setting masses.

  The cellulose fibers prove to be suitable for constituting a filtration armature for the inorganic binder particles, but are insufficient from the point of view of the mechanical reinforcement.

  The glass fibers have an intrinsic mechanical strength, but are generally sensitive to attack by the alkaline medium of the hydrated mineral matrix, which makes it necessary to modify the matrix by additives intended to protect the glass and / or to use alkali-resistant glasses adapted to these aggressive environments But these solutions involve a sizeable surge.

  Polyvinyl alcohol (PVA) or polyacrylonitrile PAN fibers are also considered as reinforcing fibers, in addition to any filter fibers, but they also have an economic disadvantage related to the cost of the raw material.

  Polypropylene fibers would be good candidates as reinforcing fibers because they are inexpensive and endowed with a high mechanical strength. However, they exhibit a rather poor reinforcing effect in a matrix of hydraulic setting inorganic binder. of a low affinity of the lipophilic olefinic material for hydrophilic hydrated matices.

  Many attempts have been made to improve this interaction.

  Thus, it was sought to modify the polypropylene by means of organic or inorganic additives introduced into the mass of the polymer.

  This modification inevitably results in a rise in the cost of the fibrous raw material, and has a significant influence on the intrinsic properties of the fibers, in particular a weakening of the mechanical characteristics.

  Another modification route consists of surface treatments such as texturing, sandblasting, corona effect These solutions considerably complicate the fiber manufacturing process and are generally not economically interesting.

  The present invention proposes to provide a reinforcing fiber for hydraulically setting products, which has good reinforcing properties while remaining inexpensive.

  The invention is based on the fact that a simple modification of the exposed surface of the fibers by a size makes it possible to improve effectively and durably the interaction between the fibers and the matrix. The quantity of material brought by the size is minimal compared to the weight of fibers, this modification is done without increasing the cost of the fibrous material substantially.

  In this regard, the subject of the invention is a polyolefin fiber for reinforcing fiber-based products and a hydraulically setting composition, characterized in that it comprises a sizing bearing a function of assisting the fiberizing function, a function of wettability of the fiber by the composition of the hydraulic setting mass, and a hydraulic setting mass adhesion promoter function According to the invention the surface properties of the filaments constituting the fiber of polyolefin are modified with one or more sizing agents providing a triple function.

  In the present application, the term "fiberizing" generally refers to the manufacture of the polyolefin fiber, from spinning the melt, through drawing, to cutting cut yarns.

  The fiber assisting function consists in facilitating the constitution of the polyolefin fiber from polyolefin filaments at at least one stage of the fiberization: it is in particular to lubricate the filaments to improve their management by the transporting and assembling the yarn at different stages of fiber manufacture, minimizing the electrostatic charges carried by the filaments in order to allow them to be gathered into a yarn, or to ensure the cohesion or integrity of the yarn constituted by the gathering of filaments.

  The wettability function of the hydraulic binder composition is to facilitate the dispersion of the polyolefin fibers into the matrix, resulting from the good dispersion of the fibrous material in the initial binder and water mixture from which the product is made. This function primarily uses the surface polarity of the fibrous material to render it hydrophilic.

  The function of promoting adhesion to the hydraulically setting matrix consists in reinforcing the interaction between the fibrous reinforcement and the matrix of the cured product. The latter function also makes use of the presence of polar functional groups at the surface of the fibers.

  These functions can be provided by one or more agents selected from lubricants, antistats, surfactants, fatty-chain compounds and polar-functional polymers, in which a lubricant can be a fatty-chain compound, as well as that a surfactant may be a fatty-chain compound or that an antistatic may be a polar-functional polymer.

  It has thus been found quite unexpectedly that agents or mixtures, in particular lubricating or antistatic or surfactant, which may naturally be intended for use as spinning agents of textile materials which are not necessarily synthetic, make it possible to confer on olefinic fibers of reinforcing properties of products based on hydraulic binder 25 quite considerable.

  The size can comprise polyalkylene glycols with lubricating properties, in particular polyethylene glycol or polypropylene glycol.

  As surfactants, we consider nonionic or ionic, anionic or cationic surfactants.

  The size advantageously comprises amino or polyamino compounds, phosphoric or polyphosphoric, phosphates or polyphosphates with antistatic properties, where the amine or phosphoric function can have an adhesion promoting effect by complexing the calcium ions of the hydraulic setting mass, tending to create a strong interaction between the fiber and the matrix.

  The fatty-chain compounds are typically compounds comprising an optionally substituted hydrocarbon chain of at least 9 carbon atoms, in particular from 10 to 24 carbon atoms, which may in particular be derived from natural oils, such as oil. coconut, palm They can be based on fatty alcohols, fatty alcohol ethers, fatty acids, esters of fatty acids, amides of fatty acids, where the fatty chain is of preferably C 10 -C 24 They are optionally (poly) alkoxylated, in particular (poly) ethoxylated or (poly) propoxylated, or derived from glycerol.

  These compounds have the advantage of having a hydrocarbon portion having a good affinity with the polyolefin material of the fiber, while another part of the compound can be functionalized to provide a required function.

  Thus, the size may comprise a polyfunctional agent which is a product of combination of functional groups (in particular lubricants or antistats mentioned above) with fatty-chain residues, derived in particular from natural oil, to jointly provide several of the functions referred to in FIG. These residues may be based on fatty alcohols, fatty alcohol ethers, fatty acids, esters of fatty acids, where the fatty chain is preferably C 10 -C 24.

  Thus, polyalkylene glycols derived from fatty acids are in particular contemplated, where the fatty chain is advantageously derived from or derived from a natural oil. Fatty amines, phosphoric acid esters based on fatty chains, esters, and the like are also contemplated. The oily chain is advantageously derived from or derived from natural oil.

  Polyethoxylated amides, based on fatty acids or not, are also contemplated. The sizing agent (s) may also be chosen from polymers with polar functions, in particular hydrodispersible or emulsion, of olefinic type modified by polar groups by copolymerization or by grafting after synthesis. By way of example, mention may be made of a polymer (In particular a halogenated polyolefin), such as chlorinated polypropylene, or a polyolefin grafted with a polar group in particular of the epoxy type, such as polypropylene grafted with glycidyl methacrylate.

  The polyolefin fibers are preferably polyethylene or polypropylene, more particularly polypropylene.

  The polyolefin does not need to be modified by organic or inorganic additives in order to make it compatible with the hydraulic setting matrix, this function being ensured by the sizing. Nevertheless, for particular applications, it may be envisaged to incorporate additives or modifying charges, especially hydrophilic additives, into the matrix. Furthermore, all the additives or fillers commonly used for drawing the polyolefin, in particular those intended to facilitate spinning, can be contained.

  A particularly advantageous reinforcing effect has been found with relatively small section polyolefin fibers, expressed by a titer of about 0.5 to 10 dtex, more preferably 0.5 to 2 dtex.

  The section of the fibers is not necessarily circular and may affect an irregular or multilobal shape.

  In a particularly advantageous embodiment, the polyolefin fiber has a high tenacity, of at least 4 c N / dtex, preferably at least 5 c N / dtex, very preferably at least 7 c N / dtex This range of toughness can be achieved by adjusting the polyolefin spinning and drawing process appropriately. A basic polyolefin material can be specifically selected with a mass distribution. Molecular fit.

  The fibers are generally in the form of cut yarn at a length of the order of 2 to 20 mm, in particular 5 to 10 mm.

  The total amount of sizing agent (s) present on the fiber is generally of the order of 0.05 to 5% by weight of dry matter relative to the weight of polyolefin, especially of the order from 0.1 to 2% by weight.

  The sizing agent (s) may be applied to the polyolefin fiber one or more times during the spinning process of the fiber, at the exit of the die, during its transport, at drawing, at cutting and / or in recovery on 30 of the unrolled fiber of a coil of polyolefin wire.

  The or each size can be applied in the form of a pure liquid or from a solution, dispersion or aqueous emulsion or from another suitable vehicle, especially aqueous based with an organic co-solvent, preferably polar , by sprinkling or bathing.

  In the case of the use of an aqueous composition or based on another vehicle, the concentration of the composition is advantageously of the order of 0.5 to 50% of dry matter relative to the total weight of the composition The concentration will be advantageously low when the size is applied by spraying. The present invention also relates to the use of a fiber as previously described as reinforcing fiber in a fiber-based product and a hydraulic setting mass, and a product thus formed.

  The hydraulic setting composition consists of a hydraulic setting binder, chosen mainly from among the various existing cements, optionally supplemented with inert or active fillers.

  Among the fillers and additives, mention may be made of rheology additives (dispersants, plasticizers, superplasticizers, flocculants), mineral fillers (silica, fly ash, slags, pozzolans, carbonates), as well as support or reinforcing fibers. for filtration or dewatering processes (natural fibers, in particular cellulose, or synthatics).

  The fibers according to the invention are effective as reinforcement in proportions which need not be increased with respect to more expensive fibers, that is to say of the order of 0.2 to 5% by weight. weight of reinforcing fibers with respect to the total dry weight of the initial mixture.

  This product may have various shapes, preferably a flat or corrugated plate form.

  The invention also relates to a method of manufacturing such a product.

  According to this method, an initial mixture based on hydraulic binder, water and fibers is prepared, the mixture is filtered on a fixed support or in motion to form a wet elementary sheet, and a plurality of elementary sheets are optionally superimposed on each other. The invention finally relates to a composition for a hydraulic setting material comprising a hydraulic binder and fibers as described above. These compositions can be cementitious preparations for suspending for dewatering process, or mortar cement preparations comprising particles including sand for other forming processes.

  The invention will now be described in a nonlimiting manner in the following examples.

  EXAMPLE 1 A 0.75 dtex polypropylene fiber of the title is produced by applying to the filaments a size containing a mixture of SILASTOL brand products sold by SCHILL & SEILACHER and which are emulsions.

  The size contains:% by weight of the product having the reference Cut 5 A and which is based on polyglycol ester derived from fatty acid 20% by weight of the product having the reference Cut 5 B and which is phosphate-based of fatty alcohol The size is applied to the spinning on the polypropylene filaments at the outlet of the die, at a rate of 0.3% by weight of dry extract relative to the dry weight of polypropylene.

  The yarn consisting of the gathered polypropylene filaments is transported by the known means of textile fiber manufacturing processes, then stretched, before being cut into sections of 6.6 mm.

  This fiber has a tenacity greater than 9 c N / dtex.

  The adhesion of this fiber to a cementitious matrix has been qualified by a laboratory test in which a fiber is coated with a mortar leaving the ends of the fiber free, the mortar is cured and then the ends are pulled. of the fiber by measuring the tensile force and the displacement of the tensile point (s) The maximum force before loosening of the fiber makes it possible to determine the adhesion stress, whereas the slope of the curve giving the force as a function of the displacement at the point corresponding to the loosening of the fiber makes it possible to determine the sliding stress which is characteristic of the adhesion between the fibers and the matrix.

  The preparation details are as follows: A mortar containing 500 g of CPA 52 cement, 500 g of fine sand (D 50 = 254 μm according to ASTM E 11/70), 98 g of calcium carbonate and 250 g is prepared. of water. A tense fiber is put in place on a parallelepiped mold, centering the fiber well, and the mortar is molded around the fiber without breaking the fiber.

  The mold is placed in a waterproof bag.

  The cure is conducted for 48 hours at 20 ° C. and 95% relative humidity in a crushing chamber for setting the mortar. The contents of the molds are then demolded and placed with a little water in a thermosealed bag. maintained at 40 ° C. The measurements are taken on the seventh day, that is to say after five days at 40 ° C.

  The results are reported in the following Table 1.

  COMPARATIVE EXAMPLE 1 By way of comparison, the same fiber tensile test is carried out with a 2.7 dtex polypropylene fiber marketed as an anti-cracking agent for the concrete marketed under the trademark CRACKSTOP by the company SIKA Ces. The fibers do not provide structural reinforcement of the concrete, they limit shrinkage cracking and increase the impact resistance and impermeability of the hardened material.

  The results are reported in the following Table 1. EXAMPLE 2 The same tensile test is carried out on a polypropylene fiber of 1 dtex and 8 mm in length, of medium tenacity (about 5 c N / dtex), obtained by a one-stage spin-drawing process and containing a reference spinning size SYNTHESIN 7292 sold by the company Dr BOEHME, at a rate of 0.4% by weight of dry matter relative to the weight of polyolefin.

  The size comprises fatty acid polyethylene glycol ester and phosphoric acid ester compounds based on natural oil.

  The results are shown in Table 1 below Example Adhesion stress Slip load (M Pa) (M Pa) 1 0.26 0.16 2 0.44> 0.60 Comp 1 0.20 0.19

Table 1

  These results show a better adhesion to the fiber matrix of Examples 1 and 2, with, moreover, an improvement in the slip stress for the fiber of Example 2.

  Comparisons with other commercial fibers for concrete such as ISTROCHEM DIMAPOS fiber, PROIND SIRIOFIBRE fiber, ISOCRETE fiber, ETRURIA FIBERLOCK fiber, DAIWABO POLYPRO fiber from DAIWABO, MERAKLON, show results of the same order as those of Comparative Example 1.

  EXAMPLES 3 to 14 These examples illustrate the application of various polypropylene fibers according to the invention to the manufacture of a cementitious product by filtration. The products were manufactured by a laboratory method reproducing quite faithfully the main characteristics of the products obtained by industrial methods such as the Hatschek technique.

  A cementitious composition is prepared on the basis of the following cement matrix: Components Mass (in g) CPA cement (95% clinker) 79.2 calcium carbonate 15.5 cellulose Pinus Radiada 3.5 polypropylene fibers 1.8 BASF flocculant AE 70 400 ppm total 100 suspended with a large excess of water.

  It is filtered through a metal grid to form a unit layer about 1 mm thick. Six unit layers are superimposed and subjected to a pressing cycle to obtain a material containing before taking about 50% water by weight relative to to the weight of cement, and a thickness of about 6 mm.

  This laboratory material undergoes a cure of 6 days at 40 C in a sealed bag, before being cut into a test tube of 20 mm wide and longer than 200 mm, which test tubes are put in cold water for 24 hours. to be mechanically stressed in traction.

  The fibers tested have the following characteristics

EXAMPLE 3

  This example uses the same medium toughness fiber as in Example 2.

  EXAMPLE 4 This example uses the same high tenacity fiber as in Example 1, with the exception of a higher title, which is 1 dtex.

  EXAMPLE 5 This example uses a high tenacity fiber similar to that of Example 4, except that it is obtained by applying a post-size, at the drawing exit before cutting. This post-size is based on a lubricant and antistatic mixture sold under the reference KB 144/2 by the company COGNIS It is applied at a rate of 0.9% by weight of dry matter relative to the weight of polypropylene.

  EXAMPLE 6 This example uses a high-tenacity fiber similar to that of the example except that the post-size is based on a chlorinated polypropylene marketed by the Eastman company. It is applied at a rate of 0.6% by weight. weight of dry matter relative to the weight of polypropylene.

  EXAMPLE 7 This example uses a fiber of high tenacity similar to that of the example except that the post-size is based on a polypropylene grafted with glycidyl methacrylate It is applied at a rate of 1% by weight of dry matter relative to the weight of polypropylene.

  EXAMPLE 8 This example uses a high tenacity fiber similar to that of Example 7 with another polypropylene grafted to glycidyl methacrylate. EXAMPLE 9 This example uses a high tenacity fiber similar to that of Example 4, except that it is obtained with a spinning size based on a polyethylene glycol ester derived from fatty acid sold under the reference STANTEX. 56077 by the company COGNIS, applied at a rate of 0.5% by weight of dry matter relative to the weight of polypropylene It also comprises a post-image is based on a chlorinated polypropylene, which is applied at a rate of 1.2% by weight of dry matter relative to the weight of polypropylene.

  EXAMPLE 10 This example uses a high tenacity fiber similar to that of Example 9 except that the post-size is based on the glycidyl methacrylate grafted polypropylene of Example 7 It is applied at 1% by weight. weight of dry matter relative to the weight of polypropylene.

  EXAMPLE 11 This example uses a high tenacity fiber similar to that of the example with a post-sizing based on the glycidyl methacrylate grafted polypropylene of Example 8.

  EXAMPLE 12 This example uses a high-tenacity fiber similar to that of Example 4, except that it is obtained with a spinning size based on nonionic surfactants and esterquats marketed under the reference STANTEX 56087/4 by the company COGNIS, applied at a rate of 0.5% by weight of dry matter relative to the weight of polypropylene It also comprises a post-sizing identical to the spin size, which is applied at a rate of 1% by weight of dry matter relative to the weight of polypropylene.

  EXAMPLE 13 This example uses a fiber of high tenacity similar to that of Example 12 except that it is obtained with application of a spin size and a post-size based on the same commercial product sold under the reference SYNTHESIN 7292 by the company Dr BOEHME previously used in

Example 2

  EXAMPLE 14 This example uses a high tenacity fiber similar to that of Example 12 except that it is obtained with application of a spin size and a post-size based on the same product under the reference KB 144/2 by the company COGNIS used previously in Example 5.

  COMPARATIVE EXAMPLE 2 For the purpose of comparison, the same mechanical tests were carried out with laboratory products where the polypropylene fibers were replaced by a PVA fiber of 2.2 dtex and 6 mm in length, with a tenacity of 12. c N / dtex, marketed by Sichuam.

  COMPARATIVE EXAMPLE 3 For comparison purposes, the PP fiber used in Comparative Example 1 was used for mechanical testing in laboratory products.

  The tensile tests were carried out by installing the test pieces between the jaws of a traction machine with a jaw distance of 200 mm. The tensile test is performed at a spreading speed of 1.2 mm / min.

  The displacement force curve is drawn which has a typical appearance of the results observed with products obtained by the Hatschek technique.

  At the beginning of the displacement the force increases rapidly, then a plateau is observed where the force evolves slowly corresponding to the multifissuration of the specimen until the appearance of a macrofissure, after which the force falls by sliding effect during the opening of the macrofissure.

  The length of the multifeeding tray reflects the effect of reinforcing the plate by all the fibers The slope of the force displacement curve in this last part of the test makes it possible to determine the slip stress which is characteristic of the adhesion between each fiber and cement matrix The slip stress was calculated by applying a fiber orientation correction factor randomly of 0.64. The results of the tests are grouped in the following Table 2.

  Example Length of the Multifissuration slip stress plate (in mm) (in M Pa) 3> 10> 1.3 4 3 0.35 6 0.6 6 11> 1.5 7 9> 1 8 9> 1.5 9 11> 1.5 10> 1.3 11 11 i> 1.2 12 12> 1.3 13 12> 1.1 14 10> 1.3 comp 2 7> 1.5 comp 3 <0.2 < 0.2

Table 2

  From these results it is obtained that with Examples 4 and 5 is much better than with the Crackstop fiber of Comparative Example 3.

  Compared to Examples 3 and 6 to 14, matrix adhesion performance of the same order or even better than with PVA is obtained with a much less expensive base material (polypropylene).

  EXAMPLES 15 and 16 These examples illustrate the application of the polypropylene fibers according to the invention to the manufacture of a cementitious product by the Hatschek process.

  Example 15 uses the same high tenacity fiber as in Example 4.

  Example 16 uses the same fiber as in Example 3 An aqueous suspension is prepared on the basis of the same matrix 10 as in Examples 3 to 14 This suspension is introduced into the tank of a Hatschek machine, for formation of a film and winding on a cylinder format of a sheet of hydrated cementitious material about 1 mm thick.

  After cutting, sheets of hydrated material are superimposed on a shape to form flat or corrugated plates having a thickness of 6 mm. The plates are subjected to mechanical tests after 28 days of curing in the ambient atmosphere.

  Test specimens of the same dimensions as in Examples 3 to 14 are subjected to tensile tests under the same conditions. The displacement force curves have a similar appearance with a multifunctional tray and a decay after removal.

  The absolute values of the measured sliding stresses are a little weaker than in the tests 3 and 4, for reasons due to the orientation of the fibers and to the stress calculation method. However, in Example 16, an improvement is observed in compared to Example 15, with a slip stress multiplied by more than 3, as observed in the laboratory tests of Examples 3 and 4.

Claims (14)

  A polyolefin fiber for reinforcing fiber-based products and a hydraulically-setting mass, characterized in that it comprises a sizing bearing a fiber-assisting function, a wetting function of the fiber by the composition of the hydraulic setting mass, and a hydraulic setting mass adhesion promoter function.   Polyolefin fiber according to claim 1, characterized in that the size comprises one or more agents selected from lubricants, antistats, surfactants, fatty-chain compounds and polar-functional polymers.   Polyolefin fiber according to Claim 2, characterized in that the size comprises a polyalkylene glycol or a derivative, in particular a polyalkylene glycol ester derived from a fatty acid.   Polyolefin fiber according to one of the preceding claims, characterized in that the size comprises an amino or polyamine, phosphoric or polyphosphoric compound, especially a phosphoric acid ester based on fatty chain.   Polyolefin fiber according to one of Claims 2 to 4, characterized in that the size comprises a halogenated polymer.   6. Polyolefin fiber according to one of claims 1 to 5, characterized in that the size comprises at least one product selected from the brand SILASTOL products Cut A and Cut 5 B SCHILL & SEILACHER, SYNTHESIN 7292 Dr BOEHME, KB 144/2 of COGNIS, STANTEX 56077 of COGNIS and STANTEX 56087/4 of COGNIS 7 Polyolefin fiber according to one of the preceding claims, characterized in that the polyolefin is polypropylene.   Polyolefin fiber according to one of the preceding claims, characterized in that the title of the polyolefin fiber is between 0 5 and 10 dtex.   9. Polyolefin fiber according to one of the preceding claims, characterized in that the polyolefin fiber has a tenacity of at least 4 c N / dtex, preferably at least 5 c N / dtex.   Polyolefin fiber according to one of the preceding claims, characterized in that the size is present on the fiber in a proportion of from 0 to 5% by weight of dry matter relative to the dry weight of fiber.   Polyolefin fiber according to one of the preceding claims, characterized in that the size is applied pure or from a solution, dispersion or aqueous emulsion or from another suitable liquid vehicle.   Use of a fiber according to one of the preceding claims as a reinforcing fiber in a fiber-based product and a hydraulic setting mass. Fiber-based product and a hydraulic setting composition, characterized in that it comprises polyolefin fibers according to one of claims 1 to 11.   14. Product according to claim 13, characterized in that it comprises from 0 to 2% by weight of reinforcing fibers relative to the total dry weight of the initial mixture.   Product according to claim 13 or 14, characterized in that it is in the form of a flat or corrugated plate.   Process for the production of a fiber-based product and a hydraulic setting compound according to one of Claims 13 to 15, characterized in that an initial mixture of hydraulic binder and water is prepared. and fibers, in that the mixture is filtered on a fixed or moving support to form a wet elemental sheet, in that a plurality of elementary sheets are superimposed to form a moist intermediate product and that the wet intermediate is dried.   17 A composition for hydraulically setting material, especially for mortar, comprising a hydraulic binder and fibers according to one of claims 1 to 11.