BONDING OF CONCRETE PARTS

Abstract: A process for the bonding of a flange to at least one concrete part which comprises (a) providing an epoxy based flange having a required shape so that at least one surface can be in direct contact with one surface of the concrete part to be connected; (b) applying an epoxy based adhesive on at least one of said surfaces of the flange and the concrete part; and (c) connecting the concrete part with the flange on the surface covered with the adhesive by virtue of pressure.

Description: Bonding of concrete parts The present application relates to the bonding of concrete parts There is continuing and growing need for the bonding of concrete parts, especially of special non-standard concrete parts, in the construction industry There is a trend in the construction industry to produce special, distinct, individually styled buildings according to the needs of the purchasing client. This translates to a trend in the need for non-standard, adaptable concrete parts. More specifically, the industry prefers to produce cost efficient precast items such as pipes and beams in standard sizes. This necessitates a method to create non-standard lengths or fittings when required. High load bearing bonding of these non-standard concrete parts is therefore of considerable commercial interest. A lot of references describe the direct bonding between concrete parts using epoxy resins Fore example, US-A-5, 172,533 describes the bonding of joints to concrete using epoxy, to produce load bearing joints attached to concrete Also the bonding of plastic liners to concrete pipes is known, for example from US-A- 5,931 ,198 and US-A-5, 168,682 Load bearing characteristics are not specially required in this context Wood laminates to concrete with load bearing characteristics are described in DE-A-197 29 058, involving coating a wood surface with a 2-component adhesive paste and pouring fresh concrete on the adhesive coating, yielding thus composite boards of higher load bearing capacity Newer types of concrete mixes being used currently are described in US-A-5,643,359, and more generally in Kirk-Othmer, 'Encyclopaedia of Chemical Technology', Volume 5, 'Cement', page 163ff The subject matter of the present invention is especially suitable for such new types of concrete We have now developed a process according to which concrete parts can be easily connected with a flange and wherein the resulting product shows excellent load bearing characteristics. Accordingly, the present invention is directed to a process for the bonding of a flange to at least one concrete part which comprises a) providing an epoxy based flange having a required shape so that at least one surface can be in direct contact with one surface of the concrete part to be connected, b) applying an epoxy based adhesive on at least one of said surfaces of the flange and the concrete part, and c) connecting the concrete part with the flange on the surface covered with the adhesive by virtue of pressure. The flange is preferably moulded from a composition comprising liquid epoxy resin, hardener and a filler. Preferred epoy resins are polyglycidyl ether of a polyhydnc alcohol or phenol, phenol- formaldehyde novolak or cresol-formaldehyde novolak, preferably Bisphenol A- diglycidylether, Bisphenol F-diglycidylether, epoxy phenol-formaldehyde novolak or epoxy cresol-formaldehyde novolak. Highly preferred is Bisphenol A-diglycidylether. The viscosities of the epoxy resins as a rule range from 2000 to 50000 mPas. Epoxy resins containing low crystallisation tendency are especially useful in producing stressfree bonding. Epoxy functional reactive diluents may be added to the epoxy resin in order to reduce viscosity and modify physical properties; e.g. monofunctional materials such as the glycidyl ethers of monohydπc phenols and aliphatic alcohols, or polyfunctional materials such as the glycidyl ethers of diols, tnols and polyfunctional alcohol (e.g. butane 1-4 diol diglycidyl ether) Hardeners are generally polyammes (aliphatic, cycloa phatic). These may or may not be adducts with the epoxy. The amme value would typically range from 200 to 350 {mg KOH/g}, but could go to beyond this range to 1000 mg KOH/g for fast curing agents and/or catalytical effects. Highly preferred as a hardener is diethylenetπamine (bιs-(2-amιnoethyl)-amιne). The hardener may contain usual non-reactive diluents such as benzyl alcohol, accelerators such as bisphenol-A, nonylphenol, PTSA, etc. The composition to be used for moulding the flange preferably comprises a liquid epoxy resin which comprises polyglycidyl ether of a polyhydric alcohol or phenol, phenol-formaldehyde novolak or cresol-formaldehyde novolak, a hardener which comprises cycloaliphatic or aliphatic polyamine, and a filler, preferably silica. Good results are obtained if the composition comprises 5 to 30% by weight of liquid epoxy resin and hardener, and 70 to 95% by weight of filler, preferably silica. All percentages are based on the total weight of the composition. The composition the flange is moulded from may also contain coloured particles or further fillers to match the flange to the colour of the concrete parts. The flange can be prepared according to commonly known methods, for example by curing at room temperature. Highly preferred hardeners and epoxies are those given in the exemplification. The adhesive is preferably a 2-component adhesive which is based on an epoxy resin and a hardener. For these the same preferences apply as given above. Highly preferred adhesives are those given in the exemplification. Another embodiment of the present invention is directed to a process wherein two concrete parts are bonded to one flange. In such a case the epoxy based flange has a required shape so that at least two surfaces can be in direct contact with one surface of each of the the concrete parts to be connected. The concrete parts of the present invention are preferably non-standard concrete parts. This means they do not represent concrete parts which are prepared in a large number. Normally, non-standard concrete parts are prepared by modifying standard concrete parts, for example by cutting. Highly preferred as concrete parts are pipes, especially pipes which have a diameter of more than 0.5 m In addition, it is preferred that the pipes have a length of more than 1 .0 m. The load bearing capacity of the connected parts is preferably at least 400 lbs. Brief description of Figures 1 and 4: Figures 1 and 2 show views of a flange to be connected to a pipe and Figure 3 shows a concrete pipe (the dark arrow indicating the position where the flange should be connected to) Figure 4 shows an apparatus for the measurement of the load bearing capacity. Pipes 1 and 2 are connected with a polymer flange by adhesive bond. The point where the load is applied by the hydraulic ram is 20 cm from the bondlme between both pipes. The invention is illustrated by the following examples. Example 1 • This Example describes the preparation of an epoxy resin/quartz polymer concrete flange and the bonding of this flange to a non-standard (straight cut ) concrete pipe The other surface of the flange is shaped to match the bell part of another concrete pipe: the flange could be similarly bonded to the bell part of the second pipe for additional strength Normally the two standard pipes would be fashioned such that they are connected using a bell and spigot joint, with an elastomeπc sealing ring. When one of the pipes has to be cut to required size, the spigot part cannot be machined in the field easily and effectively, and therefore there is the need of a readily shaped flange which in turn needs to be therefore bonded to the end of the cut pipe and be capable of withstanding high loads. a) Preparation of the flange: A quartz matrix (silica), is dispersed in a mix of epoxy resin and hardener (the constitution is defined below) and the paste is poured into a mould to produce the composite flange shown in Figures 1 and 2. The flange is a hollow part with one side flat cut to match the non- standard concrete pipe and the other side is shaped to fit into the bellow of the second joining concrete pipe. The two part epoxy used for the part is as follows: Epoxy Resin 85% by weight liquid Bisphenol A Epoxy Resin (a reaction product of bisphenol A- (epichlorhydrin) and epoxy resin of average molecular weight <700) and, 15% by weight 1 ,4-butanediolglycidyl ether. Hardener 60.6% Diethylenetriamine (bis-(2-aminoethyl)-amine) 39.4% Bisphenol A (4,4'-isopropylidenediphenol). The castable epoxy matrix composition obtained consists of: 15% by weight of epoxy resin and hardener, and 85% by weight of Graded Quartz (or silica) fillers (where the particle size is chosen for optimal packing efficiency). The treated quartz flange is cured at 20 degrees centigrade for 48 hours. b) Preparation of non-standard concrete pipe: A standard concrete pipe (diameter 70 cm) BT45 with one end straight edge cut and the other having a bellow has the length 2.50 meters. The pipe is cut at the straight cut end to produce a pipe 1.78 meters long as required. c) bonding of the flange to the non-standard concrete pipe The straight cut pipe end and the polymer quartz flange are treated with the following two part epoxy made up of: XW 1038 ( available from Ciba Speciality Chemicals, Germany), and XW 1015 (available from Ciba Speciality Chemicals, Germany). The weight ratio XW 1038/ XW 1015 is 2/1. The epoxy treated flange is bonded to the epoxy treated cut pipe, using a pressure of 0.1-50 Mpa and is cured at a temperature of 20 degrees centigrade for 48 hours. d) Load test The concrete pipe with the attached/bonded flange is fitted into the bell end of the second concrete pipe (BT45/ length 2 50meters) The assembly is placed in a Test Apparatus as shown in Figure 4 A load is progressively applied at a point which is 20 cm from the bond ne between the non-standard concrete pipe and the flange The point of failure is noted, as well as the fracture point Failure has been noted at above 40 tonnes Fracture failure occured in the non-standard concrete part, but not in or around the bond-line between the concrete and the flange Example 2 The procedure given in example 1 is repeated, with the exception that the bonded flange is also attached to the bell part of a second pipe This is done for the second pipe in the same way as given in example 1 for the first pipe The test shows that the load to fracture point is again >40 tonnes The fracture failure point again occurrs in the concrete parts, but not in or around the totally bonded flange Example 3 The procedure given in example 1 is repeated, with the exception that a cast polymer/ quartz flange made from silica dispersed in polyester (a polyester-polystyrene resin with a cobalt catalyst) is used The load test shows that bond failure occurrs at less than 10 tonnes, with major breakage in the bond line between the polyester/quartz flange and the epoxy adhesive/concrete pipe Examples 4 to 7 Combinations of different types of flanges with different types of adhesives are compared The preparation of the flanges is carried out according to the procedures given in examples 1 and 3 The preparation of non-standard concrete pipes, bonding of the flange to the non- standard concrete pipe and the load test are carried out according to example 1 , with the exception that in example 7 a different adhesive type is used (Polyurethane Type 2-K-PU System (RTM)Araldιte 2018) Table 1 Table 1 shows that by using epoxy based materials in the adhesive and the polymer flange/part, successful bonding of the non-standard pipes can be achieved.

Claims: Claims 1 A process for the bonding of a flange to at least one concrete part which comprises a) providing an epoxy based flange having a required shape so that at least one surface can be in direct contact with one surface of the concrete part to be connected; b) applying an epoxy based adhesive on at least one of said surfaces of the flange and the concrete part, and c) connecting the concrete part with the flange on the surface covered with the adhesive by virtue of pressure. 2. A process according to claim 1 , wherein the flange is moulded from a composition comprising a liquid epoxy resin which comprises polyglycidyl ether of a polyhydnc alcohol or phenol, phenol-formaldehyde novolak or cresol-formaldehyde novolak, a hardener which comprises cycloa phatic or aliphatic polyamme, and a filler, preferably silica. 3 A process according to claim 2, wherein the liquid epoxy resin comprises Bisphenol A- diglycidylether, Bisphenol F-diglycidylether, epoxy phenol-formaldehyde novolak or epoxy cresol-formaldehyde novolak, preferably Bisphenol A-diglycidylether. 4. A process according to claim 2 or 3, wherein the composition comprises 5 to 30% by weight of liquid epoxy resin and hardener, and 70 to 95% by weight of filler, preferably silica. 5 A process according to any of claims 2 to 4, wherein the hardener comprises bιs(2- amιnoethyl)-amιne. 6 A process according to any of claims 1 to 5, wherein two concrete parts are bonded to one flange. 7. A process according to any of claims 1 to 6, wherein at least one of the concrete parts is a non-standard concrete part. 8. A process according to any of claims 1 to 7, wherein the concrete parts are pipes. 9. A process according to claim 8, wherein the pipes have a length of more than 1.0 m and a diameter of more than 0.5 m. 10. A process according to any of claims 1 to 9, wherein the load bearing capacity of the connected parts is at least 400 lbs.

Inventors: HAUG FRANK, MOSS NOEL SYDNEY, HAUG, FRANK, MOSS, NOEL, SYDNEY
Applicants: HAUG FRANK, MOSS NOEL SYDNEY, VANTICO AG, HAUG, FRANK, MOSS, NOEL, SYDNEY
Application year: 2000
Main classification: C09J5
IPC codes: C08L63, C09J5, C09J163, E04B1, F16L23