Polyurea based membrane on wooden Bridges

Transcription

1 Polyurea based membrane on wooden Bridges E. Norderup Michelson 1 Polyurea based membrane on wooden Bridges Elisabet Norderup Michelson CEO Elmico AS Sagmoen 100 NO-Galterud

2 2 Polyurea based membrane on wooden Bridges E. Norderup Michelson 5. HolzBauSpezial Brückenbau 2014

3 Polyurea based membrane on wooden Bridges E. Norderup Michelson 3 Polyurea based membrane on wooden Bridges Summary Polyurea is a new type of material that is suitable for protection of steel, concrete and wooden bridges, especially in colder climate with big temperature changes. The material is spray applied with a special machine with high temperature and heated hoses and high pressure to ensure good curing conditions. One of the properties that make polyurea special for protection of bridge decks is the crack bridging in temperatures down to -30 degrees Celsius. Micorea has documented a crack opening of 20 mm in 30 degrees. The glass temperature of the product is app at -60 deg. For surfaces open for ice, salts and UV light, the material show excellent properties due to abrasion and long term stability. Keywords: Polyurea, Micorea, Elmico, waterprotection, membrane 1. Introduction Polyurea is a material with exceptional properties witch could be used for protection of building structures such as bridges, hydropower plants, parking decks, sewage plants, waste refinery plants, driving training ranges etc. The material is a fast curing reaction between an amine side and an isocyanate side. This chemical reaction is very rapid, normally only a few seconds, and for this reason a suitable machine is necessary for application and the application is executed in high temperature and pressure to ensure good mixing and end properties. The typical properties for a good formulated polyurea, is high elongation in room temperatures and in extremely low temperatures, in combination with still high tensile strength properties. The material has in addition outstanding abrasive resistance properties. This material has to be installed properly to get the right end properties. A lot of factors affect the results, and the main factor is as always good pre preparation of the surface to ensure god adhesion. 2. Polyurea 2.1 Chemistry The chemical reaction between isocyanate and amine is as follows. R-NCO + R - NH 2 R-NCO CO NH - R Urea Compared to Polyutrehane reaction Chemistry Reaktion with polyol R-NCO + R OH Reaktion with water R-NCO + H 2 O R-NH 2 CO 2 R-NH CO - R Uretan R-NCO + R-NH 2 R-NCO CO NH - R Urea

4 4 Polyurea based membrane on wooden Bridges E. Norderup Michelson 5. HolzBauSpezial Brückenbau Mixing The mixing of the two components is made after preheating to ensure low viscosity, and high pressure, through heated hoses at the very end of the nozzle in the spray gun. Below an example of a polyurea machine is shown, Gama 50H and Master II gun: Fig. 1: GAMA G50H Spray machine and Master II gun 2.3 Application To ensure a good end result, is it very important with good pre preparation of the surface and quality control during the application. The geometry of the structure, the details and the ending of the membrane has to be reviewed. Generally is good planning and experienced contractors important. 2.4 Health and safety Products based on thermosetting plastics like Epoxy and Polyurea needs to be applied with respect to the health and safety instructions. It is very important that the contractors protect themselves during the process. It is a potential risk of allergic reactions, and for spray applications it is always important to protect the respiratory. Preferably materials with low VOC content and no solvents should be used. 3. Technical properties 3.1 General information of Polyurea Polyurea could be formulated with various technical properties like good chemical resistance, outstanding abrasion resistance, high elongation at low temperature, good light stability, low water uptake etc. The problem is that it is not possible to find a formulation with the highest properties in all areas. From the formulator s point of view, right specification of the demands, is the most important stage in the development work to find the optimal solution. This is why it is so important to have good dialog with the designers to find new and more durable constructions. On the market it is a range of different brand names of Polyurea with different properties and quality. It is an advantage if the test results of the materials is tested according to European standards, (for Europe) to give the designers possibility to compare different systems. Also the applicator should be able to present documentation of a spray application course and in best case a reference list. It is actually the contractor that is the factory of the final product, and the responsibility to receive the right properties. In Europe we have an organization PDA, Polyurea Development Assosiation. Within this organisation it is possible to get more information and knowledge through webinars, practical spray application courses, conferences etc. PDA Europe:

5 Polyurea based membrane on wooden Bridges E. Norderup Michelson ETAG 033, Liquid applied bridge deck water proofing kit I will give some data s of one type of polyurea system tested and used as a bridge membrane for trafficable-, pedestrian-, and railway bridges. We made a system for steel and concrete bridges and tested this system according to the ETAG 033, Liquid applied bridge deck water proofing kit, and some additional tests especially interesting for the colder areas like Scandinavia. We have different types of build up for bridges covered with asphalt, railway bridges with ballast directly on the membrane, pedestrian bridges and wooden bridges. Elmico have applied polyuria on wooden bridges and wooden balconies in Norway with very good results. Problem could occur when wood is impregnated with an excess of creosote. 3.3 Test results Table 1: Test results of Micorea S3 system No Properties Results 1 2 Hardness Shore D Resistance against thermal ageing temperature 23 C -20 C after 1 hour: after 24 hours: hours after hot asphalt exposure temperature 23 C tensile strength: 16 MPa elongation: 258 % 3 Tensile properties temperature 23 C -20 C tensile strength 25 MPa 37 MPa elongation: 377 % 154 % 4 Flexibility at low temperatures - 20 C no cracks - 30 C: no cracks - 40 C: no cracks 5 6 Water absorption and resistance against water Chemical resistance Deicing salt, oil, alcali 7 Compatibility with bitumen 8 Water tightness 9 Adhesion to concrete 10 Adhesion to steel 11 Shear resistance < 1%, no visible changes Shore D hardness after exposure : 45 Resistant, no blisters, no deflection of hardness tensile strength / elongation / Shore D MPa / / 45 No reduction in mechanical values Resistant, no blisters, no deflection of hardness tensile strength/ elongation / Shore D 23 MPa / 405 / 46 No leakage Film thickness : 1.8 mm at minimum Adhesion strength: mean value: 2.6 MPa (failure in primer) Adhesion strength: mean value: 6.7 MPa (failure in adhesive) Shear strength 1.9 MPa failure in between waterproofing layer and asphalt

6 6 Polyurea based membrane on wooden Bridges E. Norderup Michelson 5. HolzBauSpezial Brückenbau Crack resistance properties at low temperature 13 Adhesion to upper layer 14 Ageing properties -20 C / -30 C : no cracks, no failure final elongation at -30 C: first rupture / failure occurring in waterproofing membrane at an opening width of > 20 mm 1. without wear layer 0.5 MPa failure in the intermediate zone between waterproofing layer and asphalt 2. with wear layer 2.5 MPa failure in the asphalt layer (test at 8 C) After 5000 hours exposure no failure, only chalking, tensile properties: temperature 23 C -20 C tensile strength 22 MPa 40 MPa elongation: 323. % 136 % Fig. 2: Abration resistance test, Taber abraser, DIN EN ISO abrading wheel type H 22 Fig. 3: Tear propagation resistance Table 2: Test results of Tear propagation resistance of Micorea S3 system Properties Results at 23 C at 20 C elongation 61 N/mm 120 N/mm mm

7 Polyurea based membrane on wooden Bridges E. Norderup Michelson 7 Fig. 4: Glass transition temperature by dynamic difference calorimetry (DSC)

8 tensile strain elongation at rupture 8 Polyurea based membrane on wooden Bridges E. Norderup Michelson 5. HolzBauSpezial Brückenbau C -20 C UV 2000h 63d in water at 50 C 63d at 70 C exposure tensile strain at break [N/mm²] elongation at rupture [%] Fig. 5: Tensile properties 4. Final result 4.1 Description of the System To achieve the best final result technically and financially, the planning and solution of the details, is the most important issues. It costs a lot of money and effort to remove polyurea, if something is wrong. The build up for a bridge membrane covered with asphalt is as described in figure 6. The purpose of the tack coat is to achieve the best adhesion between membrane and asphalt. It is also very important to apply app 1 kg of mastic on top of the tack coat to wet the surface and to use asphalt with ballast of app 11 or 16 mm. The packing of the asphalt is also very important, especially in the Nordic areas, to prevent water to penetrate down to the membrane and create problems with delimitation between membrane and asphalt layer, due to freezing of water. Fig. 6: Build up of Bridge membrane with tack coat In the test results table 1, test no 13, the difference of adhesion with and without tack coat is showen. The buildup of a membrane for railway bridges is made in the same way, but the tack coat is not needed. The Swedish traffic administration requests a thickness of 5 mm for these applications.

9 Polyurea based membrane on wooden Bridges E. Norderup Michelson 9 In table 3 the test results for a ballast test is presented. This test should simulate the impact of the ballast directly on the membrane on raiwaybridges. Table 3: Test results of Ballast penetration Test resistant of Micorea S3 system Test method Ballast penetration test Load: kn number of cycles: 2x106 cycles frequency 5 Hz acc. to Railtrack company product specification RT/CE/S/041 SS-ISO 48 (Method M) Results resistant and abrasive stable in case of ballast exposure no point load or friction damage during the test procedure waterproof - no salt water passing thickness: 5.0 mm Shore D hardness before and after exposure : Quality control As always, the quality control during the application and after is very important. It is important that there is a clear demand of this documentations and that it is followed up by the producer or supplier of materials. It is possible to ask the contractor for a log from the machine during the application and also to receive a sprayed sample of the final material. 5. Final comments and Conclusion In my opinion, polyurea membrane is a fantastic material with a lot of advantages compared to other water proofing and protective membranes in the marked. It is very important to have respect for the complicated technology and the value of the knowledge and experience of the contractor. It should be optional for the contractor to have passed a PDA spray course, and a good reference list. The demands of the membrane should thoroughly be discussed and reviewed. 6. References [1] Polymer Institut, Juergen Magner, Test report P E, Test of the waterproofing system based on MICOREA S 3as bridge deck waterproofing membrane [2] Polymer Institut, Juergen Magner, Test report P 5055a-E, Test of the waterproofing system based on MICOREA S3 accoring to ETAG 033 Liquid applied water proofing kit [3] Polymer Institut, Juergen Magner, Intermediate report, Testing of the coating system Micorea S3. [4] Polymer Institut, Juergen Magner, Test report P E, Determination of the resistance to abrasion of MICOREA S 2 MICOREA S 3 MICOPUR G