TH27770B - Concrete composed of organic fibers dispersed in a cement matrix, which is the cement matrix of the concrete and a premix. - Google Patents

Abstract

DC60 (28/06/42) This invention relates to concrete composed of organic fibers dispersed in a cement matrix. By combining a specific cement matrix with specific organic fibers, particularly by varying particle size and fiber length and diameter, the concrete properties are improved both in relation to the generality of microcracks and to the expansion of microcracks. Grafted forms were obtained from the four-point bending test in the cases of metallic fiber reinforced concrete and organic fiber reinforced concrete, respectively. This invention relates to concrete composed of organic fibers dispersed in a cement matrix. By combining a specific cement matrix with specific organic fibers, particularly by varying particle size and fiber length and diameter, the concrete properties are improved both in relation to the generality of microcracks and to the expansion of microcracks. Grafted forms were obtained from the four-point bending test in the cases of metallic fiber reinforced concrete and organic fiber reinforced concrete, respectively.

Claims (34)

1. Concrete is made from a hardened cement matrix containing dispersed organic fibers, which is obtained by mixing organic fiber-containing water (a), cement (b), grain material particles (c), podsolanic reactive fine components (d), and at least one dispersant, which has the following characteristics: (1) the grain component (b) has a maximum grain size D of 2 mm, with 1 mm being the most preferred; (2) the podsolanic reactive fine component has a maximum particle size of 20 µm, with 1 µm being the most preferred; and (3) the percentage by weight of water to the additional weight of cement (a) and components. Fine fibers with podsolanic reaction (c) are in the range of 8% and 25% (4) Organic fibers with individual length I of at least 2 mm and a ratio I/fi of at least 20, fi is the fiber diameter (5) Fiber content is a characteristic in which the volume of fibers represents a maximum of 8% of the volume of concrete after hardening (6) The ratio R between the average fiber length L and the maximum grain size D of the grain composition is at least 5. 2. Concrete consisting of a hardened cement matrix in which organic fibers are dispersed, obtained by mixing a mixture of (a) cement, (b) grain components, (c) podsolanic reactive aggregate, (d) at least one dispersant, which has the following characteristics: (1) the podsolanic reactive aggregate has a maximum particle size of 1 µm, the most common being 0.5 µm, and also has the following characteristics: (2) the percentage by weight of water to the additional weight of cement (a) and aggregate. (3) The organic fibers have an individual length of at least 2 µm and an I/F ratio of at least 20, where F is the fiber diameter. (4) The fiber content is characterized by the volume of fibers representing a maximum of 8% of the volume of the concrete after hardening. (5) All components (a), (b) and (c) have a maximum D75 grain size of 2 µm, a preferred maximum of 1 µm, and a maximum D50 grain size of 150 µm, a preferred maximum of 100 µm. and (6) The R ratio between the average fiber length L and the grain size D75 of all components (a), (b) and (c) is at least 5, a preferred minimum of 10. 3. Concrete that meets either claim 1 or 2, which is characterized by the concrete exhibiting ductility under direct tensile stress, as expressed by the coefficient of ductility, Delta, Delta > 1, preferably Delta > 1.5. 4. Concrete as per any of the preceding claims, which is characterized as organic fibers being polyvinyl alcohol fibers, polyacrylonitrile fibers, polyethylene fibers, high-density polyethylene fibers, polyamide or polyimide fibers, polypropylene fibers (homopolymer or copolymer), aramid fibers, charcoal fibers, or mixtures of these fibers. 5. Concrete conforming to any of the claims 1 through 4, which has the characteristic of having a maximum I/fiber ratio of 500. 6. Concrete conforming to one of the claims 1 through 5, characterized by an average bond stress of the fibers in the hardened cement matrix of at least 3 MPa, preferably at least 5 MPa. 7. Concrete conforming to any of Recollections 1 through 6, in which the cement matrix is supplemented with at least one of the following compounds which enhance the bonding of fibers in the matrix: a silica compound consisting primarily of silica, precipitated calcium carbonate, aqueous solution of polyvinyl alcohol, phosphate, latex, defoaming agent, or a mixture of such compounds. 8. Concrete pursuant to claim 7, characterized by the inclusion of silica compounds, i.e., precipitated silica, in amounts ranging from 0.1 to 5 percent by weight on a dry basis relative to the total weight of the concrete. 9. Concrete according to claim number 8, which states that precipitated silica is added to the mixture as a suspension in an aqueous medium. 10. Concrete conforming to one of the preceding claims, characterized by the organic fiber portion being replaced by metallic fibers, preferably metallic fibers of at least 2 mm length each, and an elongation ratio I/π of at least 20 (π being the fiber diameter). 11. Concrete as described in any of the preceding claims, which is characterized by the concrete being composed of a cohesive mixture of long and short organic and/or metallic fibers. 12. Concrete according to one of the claims 1 through 11 which is characterized that the concrete consists of elements which improve the cohesion of the matrix, which are selected from among needle- or flake-shaped elements whose average size is the largest of 1 mm and are arranged in a volume proportion between 2.5% and 3.5% of the additional volume of the granular element (b) and the podsolanic element (c). 13. Concrete pursuant to claim 12, which has the characteristic that the toughness of the cement matrix is at least 15 J/m2. 14. Concrete conforming to one of the preceding claims, characterized by matrix cohesion achieved through the addition of anisotropic reinforcing compounds with an average particle size of up to 500 micrometers to the cementitious mix. 15. Concrete according to the prior claims, characterized by the reinforcing agent being provided in a volume proportion ranging from 5% to 25% of the additional volume of the granular component (b) and the podsolanic reactive component (c). 16. Concrete pursuant to any of the claims 12 through 15, which is characterized by the presence of needle reinforcement material selected from among wollastonite fibers, bauxite fibers, mullite fibers, potassium nitrate fibers, silicon carbide fibers, cellulose fibers or derivatives of these, charcoal fibers, calcium phosphate fibers, especially hydroxyapanite (HAP), calcium carbonate fibers, glass fibers (alkali resistant) or derivatives of such fibers and mixtures of such fibers, polyvinyl alcohol fibers, polyacrylonitrile, high-density polyethylene, polyamide, aramid or polypropylene short fibers (maximum length 2 mm, most commonly 1 mm) which may be present, as well as materials such as steel fibers. 17. Concrete according to any of the claims 12 through 15, which has the characteristic that the flakes are selected from among mica flakes, talc flakes, silicate blends (clay), vermiculite flakes, alumina flakes and aluminate flakes and mixtures of such flakes. 18. Concrete conforming to any of the claims 14 through 17 is characterized by the presence of at least one portion of the anicytropic reinforcement containing an organic polymer coating on the surface derived from at least one of the following compounds: polyvinyl alcohol, silane, silicone, silgasane resin, or polyorganosiloxane, or the product of the reaction between (i) at least one carboxylic acid with 3 to 22 carbon atoms, (ii) at least one aliphatic or aromatic polyactive amine or substituted amine with 2 to 25 carbon atoms, and (iii) a crosslinking complex of soluble metals containing at least one metal of choice from zinc, aluminum, titanium, copper, chromium, iron, zirconium, and lead. 19. Concrete according to one of the preceding claims, which has the characteristic that the size of the grain composition (b) is a maximum of 500 micrometers. 20. Concrete according to one of the preceding claims which has the characteristic that the grain composition (b) is fine sand or a mixture of fine sand that has been sieved or crushed which may be effective when combined with silicon-containing sand, especially finely crushed quartz. 21. Concrete according to one of the preceding claims, which has the characteristic that the grain component (b) is supplied in the range of 20% to 60%, preferably 25% to 50% by weight of the cement matrix. 22. Concrete according to one of the preceding claims, which is characterized that the podsonic fine composition (c) contains elements of the silica group, in particular silica soot, ash and slag from blast furnaces. 23. Concrete pursuant to one of the preceding claims, which is characterized by the percentage of water by weight of added cement (a) and podsonic reactant (c) being between 13% and 25%. 24. Concrete as per one of the preceding claims, having the characteristic that the concrete has a direct tensile strength of at least 6 MPa. 25. Concrete as per one of the preceding claims, which has the characteristic that the concrete has a 4-point bending resistance of at least 20 MPa. 26. Concrete as per one of the preceding claims, which has the characteristic that the concrete has a compressive strength of at least 120 MPa, and preferably 140 MPa. 27. Concrete as described in one of the preceding claims, which has the characteristic that the concrete has a breaking energy of at least 2000 J/m2. 28. Concrete conforming to one of the claims 1 through 27, which is characterized by the concrete being able to be set at a temperature close to ambient temperature, for example, at 20°C, for the required period to achieve the desired mechanical properties. 29. Concrete as described in any of the claims 1 through 28, which is characterized by the concrete, after hardening, being provided for heat treatment between 60°C and 100°C at normal pressure. 30. Concrete according to claim 29, which has the characteristic that the heat treatment period is between 6 hours and 4 days, generally between 6 hours and 72 hours. 31. Concrete that meets any of the claims 1 through 30, which has the characteristic of having a pre-tensile stress. 32. Which of the following concrete claims (1 through 30) exhibits the characteristic of having post-tensile prestress? 33. The use of organic fibers in concrete, as per any of Reputations 1 through 32, to improve the fire resistance of concrete. 34. Use under claim 33 where concrete contains organic fibers and/or short and long metal fibers.