Specifications on paving and repair methods

Transcription

1 PoroElastic Road SUrface: an innovation to Avoid Damages to the Environment EUROPEAN COMMISSION - DG RESEARCH Directorate 1 - Environment Seventh Framework Programme - Contract No Specifications on paving and repair methods Björn Kalman, Swedish Road and Transport Research Institute (VTI) Hans Bendtsen, Danish Road Directorate (DRD) Document type and No. Work Package WP 4 Author(s) Authors' affiliations (acronyms) Contact data for main author Report, Deliverable D4.3 Specifications on paving and repair methods B. Kalman (a), H. Bendtsen (b) (a) VTI, (b) DRD bjorn.kalman@vti.se Document status and date Final 06 December 2015 Dissemination level File Name PU = public PERSUADE-NCC-D43-WP4-V Specifications on paving and repair methods.docx Deliverables D4.3: Specifications on paving and repair methods I

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3 Foreword, acknowledgements and disclaimer The PERSUADE project aims at developing the experimental concept of a poroelastic road surfacing (PERS) into a feasible noise-abatement measure as an alternative to, for example, noise barriers. It is expected that PERS may provide substantially higher noise reductions than the best of the conventional paving materials. The specific feature of this new type of road surfacing is that it consists mainly of rubber granules from recycled car tyres bound with a synthetic resin, such as polyurethane. PERSUADE is the acronym for PoroElastic Road SUrface: an innovation to Avoid Damages to the Environment. The project programme comprises an extensive investigation in the laboratory to develop a durable mixture, the construction of seven test sections in five partner countries, a monitoring effort for the test sections (noise, rolling resistance, skid resistance, durability, winter behaviour, etc.), and a study of all conceivable environmental and economic aspects. The project has been scheduled for duration of six years. Twelve partners from seven European countries are cooperating in this project, including research institutes, universities and companies representing the involved industry sectors. See further the PERSUADE homepage at This deliverable is produced within Task 4.5 of Work Package 4 in the project. The workpackage deals with "Construction technology and test sections" and is led by Luc Goubert, Belgian Road Research Centre (BRRC). Task 4.5 Repair method is led by NCC Roads AS (NCC). Only the authors are responsible of the contents of this document. The document has been reviewed by Luc Goubert, BRRC The authors are grateful for the financial support of the major part of this project from the European Commission through its 7 th Framework Programme. Deliverables D4.3: Specifications on paving and repair methods I

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5 TABLE OF CONTENTS 1 Introduction 1 2 PURPOSE AND LIMITATIONS 1 3 The test sections The test sections 2 4 Reparations performed in Denmark Inspection of PERS-DK2 at the Kalvehave test site 3 rd of July Inspection of PERS-DK2 at the Kalvehave test site 20 th of July Reparations in Sweden Repairs of PERS-SE1-HET1 at the Landbogatan test site Repairs of PERS-SE2-HET2 and PERS-SE2-VTI at the Sjögestad test site 14 6 Conclusions 19 7 References 21 Deliverables D4.3: Specifications on paving and repair methods III

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7 SUMMARY The PERSUADE project aims to develop a poroelastic road surfacing (PERS) which allows higher noise abatement than conventional paving materials (asphalt concrete, cement concrete). These poroelastic road materials are relatively new and unexplored materials which needs to be characterized and optimized to fully exploit their potential as a tool for road traffic noise abatement, particularly in environments where noise barriers are not a viable option. The test programmes includes repair methods for PERS which could be necessary either to make a provisional restoration of a pothole or similar, or to restore PERS using new PERS mixes. During the project time we have had some defects on the tests sections which we have considered to be possible to repair using these small scale repair methods. In the report it is shown that it is possible to repair PERS provisionally during winter season using special cold asphalt repair mixes, which are normally used to fix potholes in asphalt concrete during the winter season. However if the durability of the PERS mix itself or the durability of the adhesive system is low, then the damages will continue to develop. It has also been shown that it is possible to repair PERS with the same mix using the same primer as when the PERS was constructed. Drawbacks using the latter technique is that the weather conditions during the repair has to be good and that the materials require some time to cure before traffic could be allowed on the surface. Deliverables D4.3: Specifications on paving and repair methods V

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9 1 Introduction Like all road surfaces, a poroelastic road surface layer (PERS) will have to resist traffic loading and climatic conditions. As a wearing course, it will also have to exhibit adequate surface characteristics. As mentioned in the state of-the-art report D8.1 State-of-the-Art regarding poroelastic road surfaces [Sandberg et al, 2010] that the previous field experiments conducted in Japan and Sweden have articulated the many challenges to developing a road surface with both improved acoustical properties and high durability. Among the defects most frequently observed on site are weathering, cracking, poor adhesion to the underlying layer and low wet skid resistance. PERS is made of material that cannot be remoulded using heat like asphalt concrete and is thus in this respect similar to cement concrete. A crucial aspect of any repair method for such materials is the adhesion between the damaged surface and the new material. In order to be prepared for defects such as potholes, methods for repairing PERS have to be developed and tested in practice and in this report the techniques used to repair PERS in the field are reported This deliverable reports on the results of the tests performed in WP4, task PURPOSE AND LIMITATIONS This deliverable summarizes the different repair methods tested and used at the PERS test sites. It will not cover complete renovation of a damaged PERS but rather how to treat minor defects requiring a limited amount of material. It also reports on repairs where the PERS has partly or provisionally replaced with other materials, such as asphalt concrete.. Deliverables D4.3: Specifications on paving and repair methods 1

10 3 The test sections 3.1 The test sections The test sections which got moderate damages during the project and which were considered worthwhile repairing are summarized in Table 3-1..The layout, construction and details about these sections are presented in [Goubert, 2015]. Table 3-1 Overview of repaired PERS test sections. The traffic volume is the sum of the daily traffic in both lanes (AADT). Name of test section Country Street/City Length [m] Construction date Traffic volume AADT Speed limit [km/h] Heavy vehicles [%] PERS-DK2 Denmark Kalvehave PERS-SE1-HET1 Sweden Landbogatan Linkoping PERS-SE2-HET2 Sweden Sjögestad PERS-SE2-VTI Sweden Sjögestad Reparations performed in Denmark 4.1 Inspection of PERS-DK2 at the Kalvehave test site 3 rd of July 2015 An inspection of PERS-DK2 was performed on 3 rd of July 2015 when the PERS section was closed for traffic due to measurements of permeability and friction. Generally the pavement looked like it was in a reasonable condition. There was not much change since the last inspection 1 st of May 2015: The observations were: There were no marks or scars from a snow plough. See Figure 4-1. There was some tendency of raveling in the wheel tracks. See Figure 4-2 to Figure 4-4. The raveling was very low in the beginning of the test track in the driving direction but it increased down the 75 m long test track. It looked like there were losses of both stone and rubber aggregates. See Figure 4-4 None or only few loosened aggregates at the curb side were observed The soft 15 cm diameter area observed during the previous year near the video mast, could not be seen anymore The PERS material seemed firmly attached to the sublayer. 2 Deliverables D4.3: Specifications on paving and repair methods

11 Figure 4-1 Overview of the test section PERS-DK2. Figure 4-2 Close up of the right wheel track at the start of the test section. The size of the black and white squares is 10X10 mm. Deliverables D4.3: Specifications on paving and repair methods 3

12 Figure 4-3 Close up of the right wheel track at the end of the test section. The size of the black and white squares is 10X10 mm. Figure 4-4 Close up of the right wheel track at the end of the test section from an angle. The size of the black and white squares is 10X10 mm. 4 Deliverables D4.3: Specifications on paving and repair methods

13 Figure 4-5 Close up of the PERS in-between the wheel tracks. Basically without signs of raveling. From remote inspections from the video camera a crack had been observed on the right side of the right wheel track around 20 m from the start of the test section. The inspection on site shoved that two potholes had been developed in and around the right wheel track. Pieces of detached PERS material could be observed at the curb side. A closer inspection showed that: 2-3 new potholes had started to develop in the same area where the PERS material has started to disintegrate All PERS material had disappeared in the potholes. The intact sub layer was the bottom of the potholes Heavy raveling had occured in the wheel track at a length of 2 m and a width of cm in the pothole area. In this area at a length of 2 m and a width of cm the PERS material is loosening from the sub layer. See Figure 4-6 and Figure 4-7. Deliverables D4.3: Specifications on paving and repair methods 5

14 Figure 4-6 One of the potholes with some material starting to disintegrate at the sides of the pothole Figure 4-7 The PERS material has loosened from the sub layer 6 Deliverables D4.3: Specifications on paving and repair methods

15 DRD had prepared to repair the damages at the day of the inspection. For this purpose a two component epoxy glue was used. As aggregate material gravel at the size of 0.5 to 2 mm was used. The following was performed: The loosened area of PERS was lifted from the sub layer and epoxy glue poured and spread under the PERS, see Figure 4-8. Epoxy glue was poured and spread into the potholes, see Figure 4-9. A mix of gravel and epoxy was prepared and poured into the potholes and levelled with a wooden stick, Figure Epoxy glue was poured and spread on the areas of PERS with heavy raveling and loose gravel spread on top of the area, see Figure After minutes gravel was spread over the areas with epoxy. At the epoxy was stiff and relatively cured. The PERS section was opened for traffic at Figure 4-8 The loosened area of PERS was lifted from the sub layer and epoxy glue was poured and spread under the PERS. Deliverables D4.3: Specifications on paving and repair methods 7

16 Figure 4-9 Epoxy glue was poured and spread into the potholes. Figure 4-10 A mix of gravel and epoxy was prepared and poured into the potholed end evened out with a wooden stick. 8 Deliverables D4.3: Specifications on paving and repair methods

17 Figure 4-11 The damaged area after repair with loose gravel spread over the whole area. Based on the pictures presented in this document and from the sample collected at the PERS-DK2 test section, the relevant documented distresses can be classified in two categories: interface and mixture failures. With regard to the interface failure the following estimations can be listed: - The localized pothole seems to be related with a poor adhesion between the old pavement and the PERS. This may be a consequence of a non-homogenous distribution of the tack coat which led into a localized failure. If the same problem appears later also in other areas than a deeper investigation of the interface properties should be planned considering how these may change with aging and dynamic loading conditions. - Thin asphalt pavement usually present high deflection levels which may introduce high shear stresses at the layers interface which may fail as a consequence of load application; From the mixture point of view, the following preliminary assumptions can be made: - Poor adhesion between polyurethane and stone aggregates with worsens with the aging of the mixture; - Polyurethane seems very susceptible to aging phenomenon; For future projects the following mechanical studies are suggested: - Investigation of the interface properties using direct shear test/and or bending test both with dynamic and static loading on aged and unaged interfaces; - Can we optimize the milled surface of the old pavement in order to improve adhesion? Should one increase the level by scarfing or shot blasting? - Investigation of the adhesion properties of the polyurethane to the different stone and rubber particles; Deliverables D4.3: Specifications on paving and repair methods 9

18 4.2 Inspection of PERS-DK2 at the Kalvehave test site 20 th of July The potholes repaired with gravel and epoxy binder was in a fine shape and looked strong and hard. See Figure In the areas around the potholes where PERS had loosened from the sub layer the PERS was now glued fine to the sub layer again. 3. An area of 80 cm times 50 cm before the potholes (east of the potholes) is not glued to the sub layer. At a few spots of this area the PERS has a tendency to disintegrate. This area is in the shame shape as during the inspection and repair on July 3 rd. Epoxy was partly poured on this area during the repair process, but it was not easy to evaluate the effect of this operation. Figure 4-12 Close up photo of repaired pothole 20 th of July. 5 Reparations in Sweden 5.1 Repairs of PERS-SE1-HET1 at the Landbogatan test site The construction and performance of the pre-fabricated PERS plates on the Landbogatan test site is presented in a special Persuade report [Sandberg & Kalman, 2015a]. Already four weeks after laying in late November the PERS plates started to detach from the base course on some parts of the test section. This was almost certainly due to the poor drainage provided by the clogged drainage asphalt channels to the side of the road, together with the unexpected amount of large dumpers passing over the site. The poor drainage caused water to be trapped within the PERS creating very harsh conditions for the plates and the interface between PERS and the base course. Soon after a pothole had developed in the detached area. Due to the poor conditions for making repair jobs with cold and wet surfaces a regular repair with PERS was not an option. Instead cold asphalt repair mixes were placed in the pothole by the contractor (NCC) who had a contract on maintenance jobs on the city roads at the 10 Deliverables D4.3: Specifications on paving and repair methods

19 time. The cold mix asphalt worked very well with the PERS but the pothole kept growing on one side as PERS-material continued to disintegrate in the opposite direction to the driving direction. See Figure 5-1, Figure 5-2 and Figure 5-3. Figure 5-1 Pothole continued to grow on one side after it had been repaired with a cold asphalt mixture. Deliverables D4.3: Specifications on paving and repair methods 11

20 Figure 5-2 Repaired and enlarged pothole seen from the side. 12 Deliverables D4.3: Specifications on paving and repair methods

21 Figure 5-3 Repaired potholes in the asphalt concrete (in the front) and in the PERS-SE1- HET1. At the end of life of this test section, a large pothole had developed close to the end of the strip. Also this pothole grew in the opposite direction to the driving direction. See Figure 5-4. It can be speculated that in case PERS is detached from the sublayer it will be stretched in the driving direction beyond its tensile strength as heavy trucks pass over the surface. This might provide an explanation for the observations about the growing direction of the potholes. Deliverables D4.3: Specifications on paving and repair methods 13

22 Figure 5-4 Large repaired pothole at the end of the test strip. PERS has disintegrated on one side of the hole. 5.2 Repairs of PERS-SE2-HET2 and PERS-SE2-VTI at the Sjögestad test site Details regarding the construction of the two PERS sections in Sjögestad, e.g. the mix composition etc., is presented in the construction report [Sandberg & Kalman, 2015b]. The PERS-SE2-HET2 pavement was constructed of prefabricated PERS and the PERS-SE2-VTI was mixed and constructed on site. During the winter of 2014/15 snow ploughs passed over the surface approximately 100 times. The plows shaved of some PERS material and some asphalt concrete as well. At the end of the winter season a snow plough with two blades was used to push the snow barrier on the side of the road further away. At this passage the foremost end of the second blade, the wing, moved up and down and carved eight longitudinal grooves in the right hand wheel path of the PERS, beginning at the end of PERS-SE2-HET2 and all along PERS-SE2-VTI and finally also into the asphalt concrete at the end of the test section. Each groove was about one meter long. The distribution of the grooves can be seen in Figure 5-5, which was shot after damage had been repaired. 14 Deliverables D4.3: Specifications on paving and repair methods

23 Figure 5-5 Grooves created by the wing of a two blade snow plough used to push the snow barrier further away from the road. The photo was shot on 24 th of April 2015, after the groves had been repaired. Since the driving experience on the damaged PERS was not bad it was decided to wait with the repair work until the weather conditions allowed us to use PERS material for fixing the damages. It was decided to use the same PERS mix for the repair as was used for constructing the PERS-SE2-VTI. Two options for primer before applying the fresh PERS mix was considered. There were two options: to use the primer used at construction time (S100.00) to provide adhesion to the semiflexible base course, or to use the polyol/polyester mixtures (Z962) used for the PERS mix itself. After consulting experts the latter option was chosen. On the 10 th of April 2015 the grooves were repaired. The process started by brushing and blowing away any loose material from the scars using brushes and a compressed air gun. The bottom of the scars in the PERS was brushed with small amounts of the polyol/polyester mixture, see Figure 5-6. Each hole was then filled with a PERS mixture, Figure 5-7, and compacted with a roller as shown in Figure 5-8. To prevent the mixture to stick to the roller, a teflon coated paper was used on top of the PERS during the operation. Deliverables D4.3: Specifications on paving and repair methods 15

24 Figure 5-6 A scar in the PERS-SE2-VTI is primed with a polyester/polyol mixture. 16 Deliverables D4.3: Specifications on paving and repair methods

25 Figure 5-7 PERS mixture mixed in a bucket is distributed in the groove. Figure 5-8 A roller is used to compact the repair mix in the grooves. A non-stick Teflon paper is used to protect the mixture from adhering to the roller. Deliverables D4.3: Specifications on paving and repair methods 17

26 One month after the repair of the groves some patches started to loosen from their positions (Figure 5-9). Apparently the choice of primer had to be reevaluated and all further repairs were done with the S primer. The repairs which were done with this primer have not failed yet, so in this case the procedure has worked well. Figure 5-9 Repair patches that has partly been lost due to poor adhesion on 15 th of May. 10 months after the construction it was observed that the part at the far end of the test section, an area of a few square decimeters in the right hand corner of the right wheel track, had loosed from the base course and had started to disintegrate. One month later the same appeared in a small patch in the left wheel track corner. It had been observed that during and after rain these particular areas had been saturated by standing water, as it is located at a lower levels compared to the rest of the test section. It was intended that the porous asphalt surrounding the PERS would drain away anywater, but the porous asphalt got clogged after only a few months, so it did not work as intended. The areas were fixed on 3 rd of July together and a groove was cut from the PERS in the lower end of the section to the side of the road. See Figure 5-10 and Figure Deliverables D4.3: Specifications on paving and repair methods

27 Figure 5-10 Removing the area at the lower end of the PERS-SE2-VTI with poor adhesion to the underlayer. Figure 5-11 Lower end of PERS-SE2-VTI repaired and a groove has been cut in order to remove water from staying in the lower end of the test section. Some gravel has been distributed on top of the PERS to prevent anything to stick to the surface while curing. 6 Conclusions Repair works have been performed on three test locations. It has been shown that it is possible to repair PERS provisionally during the winter season using special cold asphalt Deliverables D4.3: Specifications on paving and repair methods 19

28 repair mixes which is normally used to fix potholes in asphalt concrete during the winter season. However if the durability of the PERS mix itself or the durability of the adhesive system is low, then the damages will continue to grow. It has also been shown that it is possible to repair PERS with the same mix using the same primer as when the PERS was constructed. Drawbacks using the latter technique are that the weather conditions during the repair have to be good and that the materials require some time to cure before traffic could be allowed on the surface. 20 Deliverables D4.3: Specifications on paving and repair methods

29 7 References Bendtsen, H. and Stahlfest Holck Skov, R. (2015). Performance of Eight Poroelastic Test Sections. Persuade Deliverable D5.2 Goubert, L. et al. (2015). Persuade Deliverable D4.10: Report on the construction of the test sections Piérard, N, Kalman, B., Biligiri, K., Cesbron, J., Lenart, S., Kokot, D. (2013). Persuade Deliverable D2.3: Accelerated loading tests of PERS, February 2013 Sandberg, U., Goubert L., Biligiri, K. P., Kalman B. (2010). State-of-the-Art regarding poroelastic road surfaces, Report in the Persuade project, February 2010 Sandberg, U. and Kalman B. (2015 a). Performance of PERS prefabricated panels in Sweden in November 2013 April PERSUADE report, Sandberg, U. and Kalman B. (2015 b). Construction of PERS test sections in Sjögestad, Sweden, in August/September Persuade Tech Rpt 4.1 Deliverables D4.3: Specifications on paving and repair methods 21