ULTIMAT GUIDE FOR APPROVED CONTRACTORS

Transcription

1 ULTIMAT GUIDE FOR APPROVED CONTRACTORS November 2015

2 ULTIMAT GUIDE FOR APPROVED CONTRACTORS CONTENTS Introduction 1. Approval of Laying Contractors 1.1 Preparation for Approval 1.2 Initial Contract 1.3 Approval 1.4 Surveillance 2. Material Selection 2.1 Aggregate and Mixture Type 3. Site Assessment 4. Surface Preparation 5. Bond Coat 6. Transport 7. Laying Operation 7.1 Material Receipt 7.2 Placement 7.3 Joints 7.4 Thickness 7.5 Compaction 7.6 Release to Traffic 8. Inspection and Test of Laid Material

3 INTRODUCTION ULTIMAT utilises a high performance Polymer Modified Binder to give superior resistance to deformation and cracking. A range of products are available in 6mm, 10mm, 14mm and 20mm nominal sizes for use in surface course, binder course and base layers to meet site specific conditions/ requirements. ULTIMAT SAMI (Stress Absorbing Membrane Interlayer) is a 4mm nominal product designed to resist crack propagation in asphalt overlays over jointed concrete or leanmix base pavements. To achieve this it has a high content of the same Polymer Modified Binder used in all ULTIMAT products. The systems use a bond coat to impart greater adhesion to the receiving layer and help resist water ingress. Bond coats can be either applied using dedicated spray equipment or through integral pavers. The products are laid and compacted using traditional paving equipment. Customers have expectations of the highest levels of both finished appearance and performance of ULTIMAT. Compaction is the key to the performance of ULTIMAT and is influenced by the following factors: Material temperature Weather conditions Layer thickness Underlying layers Compaction plant The requirements of this guide are aimed at ensuring that proper compaction can be achieved and the correct product choice has been made to give maximum performance, along with the high levels of surface finish expected by customers. 1. APPROVAL OF LAYING CONTRACTORS ULTIMAT is supplied to approved laying contractors and its use is subject to ongoing surveillance. The approval process is explained below. 1.1 Preparation for Approval Applications for approval will be considered from experienced surfacing contractors who are established customers of Tarmac. A meeting will be held between the management of the contractor and a Tarmac Technical representative where the specific laying techniques associated with ULTIMAT shall be explained, along with the requirements detailed in this document. During the presentation, an Approved Contractor Application Form (Appendix A) shall be completed and signed by the representative of the contractor applying for approval. The application form shall be countersigned by the representative of Tarmac. Following the presentation, the contractor is given provisional approval, subject to the successful completion of their initial contract.

4 1.2 Initial Contract The initial contract will be monitored by Tarmac personnel to ensure that satisfactory performance is achieved. Where requested, assistance will be given in the planning of this contract. 1.3 Approval Subject to the successful completion of the initial contract, the contractor will be added to the list of Approved Contractors. A certificate will normally be issued at this stage. Approval is reviewed on an annual basis and may be withdrawn at any time at the discretion of Tarmac. 1.4 Surveillance Any contract where ULTIMAT is to be laid may be subject to surveillance by Tarmac Personnel. If ongoing performance is unsatisfactory, approval may be suspended or withdrawn. 2. MATERIAL SELECTION Product selection is one of the most important parts of the ULTIMAT process and needs careful consideration. Help and advice will be available to make sure the correct product is chosen for the relevant application. 2.1 Aggregate and Mixture Type The standard ULTIMAT product range comprises the following products. ULTIMAT 6mm surface course ULTIMAT AC 10mm surface course ULTIMAT 10mm surface course ULTIMAT 14mm surface course (also available as binder course) ULTIMAT 20mm Single Layer (also available as binder course) The nominal size of the material should be selected as appropriate following the site assessment. ULTIMAT SAMI is also available for more specialist applications. 3. SITE ASSESSMENT A site condition survey shall be undertaken by the contractor on each site prior to contract commencement. Particular attention should be paid to surface preparation and planning of the laying operation. a) Use / type of application b) Exact areas involved, and required thickness (see section 7.4). c) Are there any PSV or Texture Depth requirements? d) Suitability and regularity of the receiving course - are there any cracks? e) Will planing be required? f) Will the material be machine laid, hand laid, or a combination of both? g) Accessibility for delivery vehicles, and for plant.

5 h) Will barrowing or re-handling be necessary, and if so - over what distance? i) Laying, rolling and compaction patterns. j) Roller type (see section 7.5) and any other plant required. k) Are any performance guarantees required by the client? ULTIMAT is typically considered for difficult sites i.e. those where the pavement is particularly stressed resulting in a reduced life necessitating more frequent resurfacing. Given the demanding nature of these sites it is particularly important that a thorough investigation is carried out to determine the existing pavement construction and condition along with the traffic loadings on the pavement. The output of this investigation should be conclusions about the cause(s) of the pavement deterioration and a pavement remedial design using ULTIMAT products which address the relevant issue(s). As a minimum the following must be carried out: A detailed visual survey, noting the type(s) of pavement failure. An assessment of pavement construction and lower layer condition. This may be from historical records or a site investigation using coring and/or trial pits. An assessment of traffic loading (type, frequency, speed etc.). Relevant site assessment details shall be submitted along with the enquiry together with any site investigation data such as core logs etc. The following list of questions is included for guidance in carrying out site assessment: Is there significant debonding of asphalt layers, particularly if close to the surface? Is there evidence of water penetration between pavement layers? If there is significant deformation is it surface i.e. in the top 100mm of the asphalt or is it deeper structural rutting, potentially in the foundation layers? Is there a jointed concrete or leanmix layer in the pavement which could be the cause of reflective cracking? Is the road subject to significant movement due to shrinkage and swelling of the subgrade (this is most likely to be seasonal movement of heavy clays)? And for ULTIMAT SAMI specifically assess the condition of the joints/cracks in the underlying pavement and the likely degree of movement given the site traffic loading.

6 Table 1 ULTIMAT applications and Layer Thickness Material Application Typical Texture Depth Nominal Layer Thickness ULTIMAT SAMI Onto jointed concrete and N/A 25 strong leanmix base. ULTIMAT 6 surface course Low traffic volumes, Housing estates, car Parks ULTIMAT AC 10 Low traffic volumes, surface course rural roads and housing estates, car parks ULTIMAT 10 High traffic volumes, High surface course stress ULTIMAT 14 High traffic volumes, surface course higher speed Medium Stress ULTIMAT 20 Housing estates, deeper single layer construction, 100mm inlay alternative ULTIMAT 14 Binder course alternative binder course in deeper inlays ULTIMAT 20 Lower level construction, binder course deformation issues 0.8mm mm 0.8mm mm 1.0mm mm 1.2mm mm 1.4mm 50 75* 1.6mm n/a n/a * Thickness can be increased up to approximately 100mm but caution should be taken with regards to ride ability and compaction. 4. SURFACE PREPARATION The receiving surface should be sound and of suitable regularity to ensure satisfactory surface drainage and layer thickness of the ULTIMAT surfacing. Planing, where required, may not be necessary over the full width of the mat and care should be taken not to increase the camber to such an extent as may adversely affect the surfacing process. Existing surfaces should be cleaned and all loose material, mud, dirt and other debris must be removed. Ironwork should be raised prior to surfacing and precautions taken to ensure it is kept clean. Bituminous joint paint should be applied to the edge of ironwork which is to be subject to trafficking. The existing or planed surface shall be inspected and any unanticipated weak or deteriorated areas removed prior to overlay, which includes thin bond and structural repairs to concrete slabs. Joints in concrete bays should be resealed as should any larger cracks (>1.5mm) in exposed leanmix base. Remedies and treatments for defects should be in accordance with HD32, Maintenance of Concrete Roads in DMRB volume 7. Records of this inspection should be maintained.

7 5. BOND COAT Due to the high stress applications in which ULTIMAT is used, a Polymer Modified Bitumen (PMB) bond coat is required to ensure good adhesion with the receiving course. The application rate selected shall reflect the nature and condition of the receiving course ie fresh asphalt or planed surface see BS Section Bond coat is required on freshly laid receiving course. The spread rate varies depending on the bitumen content of the bond coat. The required application rate in terms of residual bitumen is: Onto asphalt kg/m² Onto Concrete kg/m² The following PMB Bond Coats are currently approved, use of alternatives requires approval. Colas: Colbond 50 & Colbond 65 Nynas: Enduramuls 100 & Nyspec Masterbond Total: Emulsis NBC50, Emulsis NBC65 & Emulsis NTC Bituchem: Polybond 50 Ayton Asphalt: Aquagrip 60 Jobling Purser: Sprayco Armabond 6. TRANSPORT Vehicles used for the transport of ULTIMAT must be adequately cleaned prior to loading so that there is no risk of contamination. Water, an approved release agent or light applications of sealing grit may be used in the vehicle body. Excess liquid shall be drained out by raising the vehicle body and allowing it to drain through the tailgate prior to loading. Diesel must not be used as this causes binder softening and affects durability. ULTIMAT should only be transported on fully insulated vehicles. The insulation should include the vehicle floor to prevent excessive cooling of the material. 7. LAYING OPERATION 7.1 Material Receipt The delivery ticket of each load of asphalt should be checked prior to use, to confirm that the correct material has been supplied. The normal minimum temperature for discharge from the vehicle is 140 C. 7.2 Placement Material placement should be operated at such a speed as to permit continuous laying as far as supply and site conditions allow. On highways and large trafficked areas ULTIMAT should be laid by paver wherever possible. This will assist in ensuring that optimum compaction is achieved at all times. When

8 hand laying, work from the delivery vehicle as much as possible to minimise heat loss. The use of insulating duvets can also help in minimising heat loss. If the material must be deposited in heaps, use boards to insulate the base of the heap and protect the underlying surface. Heaps should be covered with an insulating duvet. The temperature should be monitored to ensure that the minimum compaction temperatures in section 7.5 can be achieved. ULTIMAT should not be laid in freezing conditions or when there is a high wind chill factor. The minimum surface temperature shall be 1 C on a rising thermometer. If the temperature falls below 0 C, laying shall be suspended. ULTIMAT should not be laid in standing water or during periods of heavy rainfall. Compactability will be affected by adverse weather conditions. Particular consideration should be given to laying ULTIMAT SAMI in adverse weather conditions as the effects of a thin layer on concrete will lead to rapid cooling of the material. ULTIMAT SAMI should not be laid when ambient temperature is below 8 C. 7.3 Joints Longitudinal joints shall be made in one of the following ways; Cold - Shall be cut to a full depth vertical face and painted prior to matching OR - Shall be formed into a chamfer during the laying process and subsequently painted prior to matching. Chamfers shall be at an angle of degrees rather than a vertical right angle. Hot - Joints may be hot matched so long as the temperature of the earlier laid mat is at least 120 C. Transverse joints shall be cut or sawn to a vertical face at least 300mm from the day joint and painted. As required joints shall be painted with either hot bitumen or an approved cold emulsion joint paint prior to matching. Care shall be taken to ensure coverage of the vertical face with a uniform coating. 7.4 Thickness The nominal compacted layer thickness shall be as shown in Table 1. The minimum thickness at any point shall be no more than 5mm below the relevant minimum nominal thickness. 7.5 Compaction Like all asphalt materials, it is essential that ULTIMAT is fully compacted to avoid fretting. Compaction of the laid material shall commence without unnecessary delay. The use of tandem rollers operated in vibrating mode shall only be permitted for a single pass over the mat width or as required on hand lay areas. A vibratory steel wheeled roller with a minimum dead weight of 6 tonnes (e.g. Bomag 161) or a 3 point dead weight roller shall be used as the lead roller. A second smaller tandem roller may be required to remove roller marks and for work in constricted areas. A sufficient number of rollers shall be provided on site to ensure that the compaction can be commenced and completed without undue delay. The minimum initial rolling temperature is 130 C. A minimum of 10 passes of the roller should

9 be used. Water sprays on the roller must be fully operational. In areas where compaction is not possible with conventional rollers, such as tight corners and immediately adjacent to walls, vibrating plate compactors or tampers may be used. This is not as effective as conventional rollers and compaction should be commenced immediately after laying to achieve the best finish possible. 7.6 Release to Traffic To avoid deformation or damage, the surface must not be trafficked until it has been allowed to cool to near ambient temperature. 8. INSPECTION AND TEST OF LAID MATERIAL The contractor shall ensure that the final laid material is visually inspected to check for defects. Where required, the laid material shall be sampled and tested in accordance with individual contract requirements.