EP1726742A2

EP1726742A2 - Structural elements for the reinforcement of building components

Info

Publication number: EP1726742A2
Application number: EP05026444A
Authority: EP
Inventors: Maurizio Bisciotti
Original assignee: KIMIA SpA
Current assignee: KIMIA SpA
Priority date: 2005-05-23
Filing date: 2005-12-05
Publication date: 2006-11-29
Also published as: ITPG20050028A1; EP1726742A3

Abstract

Reinforcement structure for building components (Fig.1 (1)) consisting of a composite system, the components of which are:
- a material for adhesion to the building component (Fig.1 (2))
- a core of metal filaments (Fig. 1(3))
- a binding matrix (Fig.1(4))
- a material for surface protection (Fig. 1(5))
- a material for protection from fire (Fig. 1(6))
- an anchoring system (Fig.2(3))

Description

This invention concems a reinforcement structure for building components (Fig.1(1)) consisting of a composite system whose components are:

a material for adhesion to the building component (Fig. 1(2)), necessary to make the composite material adhere to the surface of the building component and to level any rough spots present;
a core of metal filaments (Fig.1(3)), arranged in a single direction, lying next to each other and bound by metal or non-metal wires to form a fabric;
a binding matrix (Fig.1(4)), which is used to impregnate the core of metal filaments in order to transmit the mechanical stress from the building component to the metal filaments, and which can be created using various types of materials;
a material for surface protection (Fig. 1 (5)), necessary to prevent the alteration of the materials making up the composite system (a component whose presence is preferable, but which may not always be necessary);
a material for protection from fire (Fig. 1(6)) (a component whose presence is preferable, but which may not always be necessary);
an anchoring system (Fig.2(3)) (a component whose presence is preferable, but which may not always be necessary).

The term "building component" concerns those construction elements made of reinforced concrete, masonry, stone, or combinations of such materials.
The metal filaments indicated in point [0001] have a diameter between 0.1 and 1 mm and are twisted together to form cords of from 3 to 21 wires.
The matrix indicated in point [0001] is selected from among the epoxy, polyurethane, polyester, and acrylic resin group or the group of cement mixtures and mixtures of lime and pozzolana materials, and may be a mixture of two or more of the materials belonging to the above-mentioned groups.
The material for adhesion to the building component indicated in point [0001] consists of a matrix selected from among the epoxy, polyurethane, polyester, and acrylic resin group with the addition of a filler, for the purpose of adjusting its viscosity, or the cement or pozzolana mortar group.
The material for the surface protection indicated in point [0001] consists of a resin belonging to the epoxy, polyurethane, polyester, or acrylic resin group.
The material for protection from fire indicated in point [0001] consists of any material with the characteristics and thickness sufficient for guaranteeing, for the building component reinforced with the method of this invention, stability for at least 180 minutes in the event of fire.
The composite system described in this invention is useful for providing guarantees of mechanical resistance to the elements stated in point [0002], which are often in a state of preservation that prevents them from continuing their original static performance, and thus require consolidation measures.
Various methods have been developed for their consolidation, but they are characterized by a series of defects as described below.
One of the methods traditionally developed for the consolidation of masonry and stone structures or combinations of the two materials is the use of electrowelded iron mesh embedded in a cement mortar. The defects of this method lie in the fact that the cement mortars used for this purpose do not prevent the oxidation of the metal components which, due to the size of the section of the metal component, cause the spalling of the mortars and jeopardize the usefulness of the method itself.
Another method developed recently involves the use of fibers of carbon, glass, or other synthetic materials with epoxy resins for impregnating the fibers according to a method that envisages the application of just two components, a mesh of synthetic fibers and a matrix belonging to the epoxy resin group. This method is characterized by a number of defects. In particular, the absence of an adhesion material as mentioned in point [0001] entails defects in the adhesion to the building component. The absence of a system of surface protection in acid or alkaline environments may cause deterioration of the matrices belonging to the epoxy resin group making up the reinforcement method. The absence of a system for protection from fire makes the structures consolidated with this reinforcement method particularly vulnerable in the event of fire. Lastly, the carbon, glass, or synthetic material fibers cannot be used to make the anchoring devices owing to their poor shearing strength.
Another method developed recently is described in EP 1 245 547 A1 ; in particular, the method concems a system for the reinforcement of existing building components by using a cement mortar and a mesh of synthetic material made up of fibers belonging to one or more of the following categories: glass, carbon, Kevlar, aramid.
The method described in the patent has, nevertheless, defects, since it has been experimentally demonstrated that cement mortar has an extremely reduced capacity for impregnating synthetic fibers, and breakage can occur from traction, thus not guaranteeing sufficient ductility of the reinforced building component.
Experimental studies conducted by A. Wiberg (2003) have also shown that the use of cement mortars as a matrix, combined with synthetic fibers, results in reinforcement factors equal to 50% of that provided by consolidation with the same quantity and type of synthetic fibers, but using epoxy resins as the matrix.
The main object of this invention is thus the creation of a simple, easily applied reinforcement method, consisting of the elements indicated in points [0002], [0003], [0004], [0005], [0006], and [0007], which does not have the defects indicated in points [0009], [0010], [0011] [0012], [0013], and [0014].
The aims of this invention are attained by means of a core consisting of metal wires of a diameter between 0.1 and 1 mm, consisting of carbon steel with or without a surface treatment to improve its adherence characteristics, and with a mechanical tensile strength between 1400 N/mm² and 4500 N/mm².
The metal wires are united to form twisted cords; each cord consists of a number of wires varying from 3 to 21. The cords are laid next to one another from 0.8 mm to 25 mm apart. The cords are tied together with metal or non-metal wires, or they can be attached to synthetic meshes by means of adhesives.
The matrix indicated in point [0004], when it belongs to the cement or pozzolana mortar group, is made with a mixture of powdered components that contain from 5 to 95% cement or natural or artificial hydraulic lime, 10% to 70% aggregate of a dimension of no more than 1000 microns and chemical additives containing 0.1 to 25% unsaturated copolymers, 0.05% to 2.5% fluidizing additives, and 0.005% to 1% thixotropic additives. All the quantities are in weight, and refer to the mass of the cement and/or lime.
The binders that can be used for the matrix indicated in point [0018] are Portland cement, composite cements, Portland-composite cements, pozzolana cements, slag cements and related subtypes and mixtures of types and subtypes, hydraulic limes and natural hydraulic limes with the possible addition of pozzolana materials, and mixtures of these. The proportions between types and subtypes vary between 5 and 95% in weight.
The mineral fillers indicated in point [0018] have dimensions of less than 1000 microns. They may be silicatic, carbonatic, calcareous, arenaceous, or granitic, or may be the by-products of other processes, such as silica fume or fly ash. It is preferable to use mixtures of these fillers.
The chemical additives used in the formulation of the mortar indicated in point [0017], when made using cement binders, and the presence of which is necessary, are as follows:

a) powdered polymer resins belonging to the unsaturated polymers class, such as styrene/butadiene, vinyl acetate/ethylene, styrene/divinylbenzene, styrene/acrylic copolymers. The proportions vary from 0.1 to 25%, Values between 0.2% and 18% are preferable.
b) plasticizing and superplasticizing additives belonging to the class of the polymers based on lignin polycondensate, beta-naphthalene, melamine, or formaldehyde sulfonates (LS, NFS, MS), or on polyacrylates (ACR). The proportion varies between 0.05 and 2.5% in weight.
c) thixotropic additives belonging to the cellulose class, such as methylcellulose, methylhydroxyethylcellulose, methylhydroxypropylcellulose, hydroethylcellulose, hydroxypropylcellulose, carboxymethylcellulose, and carboxymethylhydroxycellulose. Methylcellulose and its by-products are preferable. Proportions vary between 0.005% and 1% in weight.

The additives whose presence is preferable but not indispensable are the following:

a) air-entraining additives
b) non-shrink additives

The matrix indicated in point [0004] may, in altemative to the indications of point [0018], be made with any material belonging to the epoxy, polyurethane, polyester, or acrylic resin group.
The matrix indicated in point [0004], in altemative to the indications of points [0018] and [0023], may be made of a mixture using a material belonging to the cement matrix group described in points [0017], [0018], [0019], [0020], [0021], and [0022] and a material belonging to the epoxy, polyurethane, polyester, and acrylic resin group indicated in point [0023]. The weight proportion between the two materials may vary between 5% and 95% for each of the two.
The material for adhesion indicated in point [0005] is made with resins belonging to the class of the epoxy resins with the addition of mineral fillers to control their viscosity. The mineral fillers used to control viscosity may be made of silicatic, carbonatic, calcareous, arenaceous, or granitic, or may be the by-products of other processes.
The material for the surface protection indicated in point [0006], the presence of which is preferable but not indispensable, is made with materials belonging to the epoxy, polyurethane, polyester, or acrylic resin group.
The material for protection from fire indicated in point [0007], the presence of which is preferable but not indispensable, is made with any material in a thickness sufficient to guarantee, for the building component reinforced with the method of this invention, stability for at least 180 minutes in the event of fire.
The anchoring systems indicated in point [0001] consist of a core of metal filaments of any length, arranged in a single direction, lying next to each other and bound by non-metal wires to form a fabric. To make these anchoring devices, it is necessary to bore a hole in the building component indicated in point [0002], roll up the fabric of metal filaments, insert the roll of fabric into the hole, cut the element binding the fabric, and open the metal filaments outward like spokes.
Once the metal filaments are arranged, the adhesion can be guaranteed by using any of the matrices described in this invention.

Claims

A structure for the reinforcement of building components consisting of metal fibers, a matrix belonging to the epoxy, polyurethane, polyester, or acrylic resin group, or to the cement or pozzolana matrix group, or a mixture of materials belonging to one of the two groups, a material for adhesion to the support, a material for surface protection (preferable but not necessary), a material for protection from fire (preferable but not necessary), and an anchoring system (preferable but not necessary).
The reinforcement structure indicated in claim 1 is characterized by the fact that the metal fibers are arranged in such a way as to form a fabric with fibers lying next to each other between 0.8 and 25 mm apart. The metal fibers consist of carbon steel wires of a diameter between 0.1 and 1 mm twisted together to form cords of from 3 to 21 wires, and with a mechanical tensile strength between 1400 N/mm² and 4500 N/mm².
The matrix indicated in claim 1 may consist, in altemative, of: (a) a mortar whose binder may be either cement or hydraulic lime; (b) a resin belonging to the epoxy, polyurethane, polyester, or acrylic resin group; (c) a mixture of materials belonging to group (a) and group (b).
The matrix indicated in claims 1 and 3, when it consists of a cement mortar, is made using the following components: a mixture of cement binders consisting of Portland cement, composite cements, Portland-composite cements, slag cements, pozzolana cements, and related subtypes, which vary between 5% and 95% in weight; mineral fillers with a maximum diameter of 1000 microns and chemical additives belonging to the unsaturated polymers class, such as styrene/butadiene, vinyl acetate/ethylene, styrene/divinylbenzene, styrene/acrylic copolymers, with proportions varying from 0.1 to 25% in weight as compared to the cement binders and fillers mixture; plasticizing and superplasticizing additives belonging to the class of polymers based on lignin polycondensate, beta-naphthalene, melamine, or formaldehyde sulfonates (LS, NFS, MS), or on polyacrylates (ACR), with the proportion varying between 0.05 and 2.5% in weight; thixotropic additives belonging to the cellulose class, such as methylcellulose, methylhydroxyethylcellulose, methylhydroxypropylcellulose, hydroethylcellulose, hydroxypropylcellulose, carboxymethylcellulose, and carboxymethylhydroxycellulose, with proportions varying between 0.005% and 1% in weight.
The matrix indicated in claims 1 and 3, when it consists of a pozzolana mortar, is made with a mixture of the following components: hydraulic lime and natural hydraulic lime with the addition of pozzolana materials and mineral fillers.
The matrix indicated in claims 1 and 3, when it consists of a resin, is made with materials belonging to the epoxy, polyurethane, polyester, or acrylic resin group.
The matrix indicated in claim 1 may also consist of a mixture of two or more of the materials indicated in claims 3, 5 and 6, in weight proportions varying between 5% and 95% for each of the materials.
The material for adhesion indicated in claim 1 consists of a resin belonging to the epoxy resin group combined with mineral fillers.
The material for surface protection indicated in claim 1 consists of a resin belonging to the epoxy, polyurethane, polyester, or acrylic resin group.
The material for protection from fire indicated in claim 1 consists of any material capable of guaranteeing, for the building component reinforced with the method of this invention, stability for at least 180 minutes in the event of fire.
The anchoring systems indicated in claim 1 consist of a core of metal filaments of any length, arranged in a single direction, lying next to each other and bound by metal or non-metal wires to form a fabric, or attached to synthetic meshes by means of adhesives.
The structure indicated in claim 1 is formed by applying to the surface of the building component (1) a first layer consisting of the material for adhesion (2); over this layer is positioned the metal fiber fabric (3) indicated in claim 2, and over the fabric is applied the impregnation matrix (4) indicated in claims 4 and 5. Over the impregnation matrix may be applied the material for surface protection (5) indicated in claim 7. Over the impregnation matrix or surface protection material (when present) may be applied the fire protection material indicated in claim 10.
The anchoring systems indicated in claim 1 are applied (when necessary) by boring a hole in the building component, rolling up the fabric of metal filaments, inserting the roll of fabric into the hole, cutting the element binding the fabric, and opening the metal filaments outward like spokes. Once the metal filaments are arranged, the adhesion of the anchoring system to the building component can be guaranteed by using any of the matrices described in this invention.