Waterproofing membrane

Waterproofing membrane - A Case Study on the Use of...

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Unformatted text preview: A Case Study on the Use of Waterproofing Membrane in Asphalt Pavement on Concrete Bridge CGN 6506 Bituminous Materials (Term Paper Presentation) BY: Johnny CHAN (Hong Kong) What is the purpose of asphalt pavement on concrete bridge decks for highways or expressways? Stonecutters Bridge in HK Purpose of Asphalt Pavement on Concrete Bridge Decks for Highways / Expressways Provide a smooth and safe driving surface Sustain traffic load and prevent underlying deformation Provide an impermeable layer to: a) b) c) protect concrete deck from early carbonation or chloride intrusion protect corrosion of rebars, prestressing steels and other steel elements prevent dripping or staining on deck soffits Protection Strategies for Impermeable Layer on Bridge Deck Surface Five Typical Systems (1) Thin Bonded Epoxy Concrete Overlay (2) Monolithically cast concrete Protection Strategies for Impermeable Layer on Bridge Deck Surface Five Typical Systems (3) Low permeability concrete segment (4) Thin bonded hydraulic cement concrete overlay (5) Waterproofing membrane with asphalt overlay (Liquid type – commonly used in HK, UK) Limitations and Problems of Li Liquid Waterproofing Membrane Systems (polymer based) Polymer based, e.g. polyurethane or acrylic resin system polyurethane effective adhesive to concrete, however limitations exist… Low adhesion with asphalt surfacing that causes premature deformation of asphalt surfacing Membrane easily damaged by construction plant Relatively short service life Relatively high cost Presentation Today (Literature review on use of waterproofing membrane system in HK, UK & US) 1. Causes of Premature Deformation 2. Recommendations 3. Case Study in HK with UK’s Experience 3.1 Specification on polymer waterproofing membrane system 3.2 Asphalt pavement thickness and composition 3.3 Site quality control 3.4 Sub-surface drainage 4. Situation in US (FHWA) 1. Possible Causes of Premature Deformation of Asphalt Surfacing (HyD & HKU, 1999) (a) Pavement thickness not thick enough to reduce stress bet enough to reduce stress bet’n membrane/asphalt interface (f) No quality control on tack coat to provide tack coat to provide adequate bond (e) Liquid system is weak in bond to asphalt (b) No or inadequate sub-surface drainage, esp. expansion joint drainage, esp. expansion joint Cause aggregate stripping (c) Relatively low binder content low shear shear strength at interface (d) Water retained in friction course micro-cracks Polymer Waterproofing Membrane System 2. Recommendations HyD & HKU, HK (1999) - Taking Into Account TRB,US Related Report Adopt a pavement thickness such that the resulting shear and tensile stresses at the membrane/concrete and membrane/asphalt interfaces area within the limits that can be tolerated by the waterproofing membrane system Asphalt Asphalt should have high interfacial shear to resist the traffic induced stresses HKU recommended HyD to have further laboratory tests and site trials trials to verify the findings 2. Recommendations HyD Site Trial Project : Ngong Shuen Chau Viaduct (2004 – 06) 6) Confirm HKU findings: a. a. Low adhesion bet’n membrane/ asphalt caused premature deformation (if the surfacing not thick enough and tack coat not properly applied) b. Tack coat bet’n membrane/asphalt was contaminated or damaged during construction. c. Moisture saturation in asphalt surfacing caused premature deformation if the asphalt has cracked. 3. Case study in HK with UK’s experience 3.1 Specification on Polymer Waterproofing Membrane System (1) Membrane Itself : a. Tested to meet ‘Design Manual for Roads and Bridges, Vol. 2, Section 3, Pt. 4 – Waterproofing and Surfacing of Concrete Bridge Decks’ (BD 47), Highways Agency, UK (2) Concrete/Membrane Adhesion: a. Tested under BD 47 b. Average tensile adhesion strength not less than 1.0 N/mm2 c. Minimum tensile adhesion strength: 0.7 N/mm2 3. Case study in HK with UK’s experience 3.1 Specification on Polymer Waterproofing Membrane System (3) Asphalt/Membrane Adhesions: a. Tested under BD 47 b. Strength requirements: ≥ 120mm Surfacing Thickness < 120mm ≥ 90mm < 90mm ≥ 60mm (seldom used) Shear Adhesion Adhesion Strength @23 @40 0.30 N/mm2 0.30 N/mm2 N/mm N/mm 0.10 N/mm2 0.15 N/mm2 0.40 N/mm2 N/mm 0.15 N/mm2 Tensile Bond Strength @23 0.40 N/mm2 0.45 N/mm2 0.50 N/mm2 3. Case study in HK with UK’s experience 3.1 Specification on Polymer Waterproofing Membrane System (3) Asphalt/Membrane Adhesions: Shear Adhesion Test Adhesion Test Sampling for Tensile Bond Test 3. Case study in HK with UK’s experience 3.1 Specification on Polymer Waterproofing Membrane System (4) Full Size Accelerated Wheel Tracing Tracing Test: Tested at 55 - 60 (pavement service temperature in summer) Tested for first year designed traffic flow in terms of equivalent standard axle load repeatedly Recommended Criteria (1) Average rut depth along the wheel tracks not greater than tracks not greater than 13mm (2) No surface cracking will occur. 3. Case study in HK with UK’s experience 3.2 Asphalt Pavement Thickness and Composition (1) Structural Layer At Least 100mm thick : (2) Structural Layer Less Than 120mm thick : Successful trial case a. Membrane overlaid with 40mm tk effectively effectively impermeable asphalt a. 30mm tk: polymer modified layer friction course (non-structural) - No more than 4% air void content b. 40mm tk: 10mm size wearing course course - Fine aggregate used c. 60mm tk: 37.5mm size base course (e.g. Mastic asphalt / Gussasphalt) 3. Case study in HK with UK’s experience 3.2 Asphalt Pavement Thickness and Composition (2) Structural Layer Less Than Mastic asphalt is self-leveling and selfcompacting Minimize damage to membrane 120mm 120mm tk caused by compaction of loose coarse aggregates Into membrane Tack Coat 3. Case study in HK with UK’s experience 3.2 Asphalt Pavement Thickness and Composition (3) Trial Use of Special Asphalt Surfacing Stone Mastic Asphalt SMA is hot mix surface course with superior rutting resistance and more durable than wearing resistance and more durable than wearing course, esp. heavy road, R/A, uphill lane, but 80% higher in cost due to more binder and cellulose fibre used. Classification of Areas by Traffic and Stress Conditions and Recommended areas of Application of Stone Mastic Asphalt and Wearing Course 3. Case study in HK with UK’s experience 3.3 Site Quality Control (1) Protection of Membrane & Tack Coat No No construction plant/ vehicle allowed to ride on membrane and tack coat, except laying asphalt surface 3. Case study in HK with UK’s experience 3.3 Site Quality Control (1) Protection of Membrane & Tack Coat 3. Case study in HK with UK’s experience 3.3 Site Quality Control (1) Protection of Membrane & Tack Coat Damage to the tack coat by the wheels of delivery trucks during laying of mastic asphalt on mastic asphalt on a steel bridge deck 3. Case study in HK with UK’s experience 3.3 Site Quality Control (1) Protection of Membrane & Tack Coat Contractor required to give preventive proposal Paving machine mounted on rails Protective layer under wheels 3. Case study in HK with UK’s experience 3.3 Site Quality Control (2) Application of Tack Coat Uniformly applied on membrane Membrane and tack coat surfaces be cleaned immediately Minimize time gap bet’n before laying tack coat and applying membrane/tack coat asphalt respectively and that bet’n tack coat/asphalt Damaged tack coat made good immediately immediately by reapplying it. 3. Case study in HK with UK’s experience 3.4 Sub-Surface Drainage (1) Sub-surface drainage provided to drain away water that have penetrated and accumulated in asphalt surfacing (2) Edge channels or edge drains installed to collect water Buried Joint by RAB Associates (UK) ® (3) Expansion joints on bridge deck be provided with a drainage system in accordance with BA26 “Expansion Joints for use in Highway Bridge Decks” 4. Situation in US (FHWA) 4.1 National Cooperative Highway Research Program (NCHRP) TRB (NCHRP), TRB (1995) Report on “Waterproofing Membranes for Concrete Bridge Decks” Note: a. Used in not many States, and In 2006, Virginia TRC published divided over its merits under FHWA website and b. Reasons for not using: maintained similar demerits: - Inability to inspect top of deck - high risk of failure due to complex - Poor performance of trial construction - Short service life - problem of rutting and shoving of c. Asphalt surfacing thickness has asphalt asphalt surfacing major influence 4. Situation in US (FHWA) 4.2 TRB Maintenance Research Master Planning Workshop (2000) a. Research needed to define performance requirements b. But not high priority subject to available funding 4. Situation in US (FHWA) 4.3 Latest Feedback from FHWA (Dec, 2010) “ No formal comprehensive study has been initiated by the Federal Highway Administration on bridge deck membrane systems as of now. There have on bridge deck membrane systems as of now There have been a number of small studies by State DOTs and others looking at various aspects of membrane systems, and some specific products or systems being marketed by industry. ” “ We have proposed, but not been able to fund, a more comprehensive study, and continue to look for opportunities to do so. Meanwhile, the SHRP2 program (also via TRB) has a study (R-19A) which is also looking at some aspects of membrane systems, but the results of this study will not be available to the public for about another year.” By Ian M. Friedland, P.E., Assistant Director (Bridge and Structures R&D, Office of Infrastructure R&D, FHWA) Key Words Key Words Waterproofing Membrane with Asphalt Overlay Key Words Effective impermeable layer Asphalt thickness & composition Shear & tensile strengths Reduced moisture Site control Look forward to new specification (SHRP 2) ……. (SHRP References 1. 2. 3. 4. 5. 6. 7. Highways Department Technical Report RD/TR/039 – Corrosion Protection of Corrosion Concrete Bridge Deck, Highways Department, HKSAR Government, August 2002. Technical Article - Deck Protection Systems for Post-Tensioned Segmental Concrete Bridges, Michael M. Sprinkel, Virginia Transportation Research Council, USA, 2006. Highways Department Guidance Notes RD/GN/033 – The Use of Waterproofing Membranes on Concrete Bridge Deck, Highways Department, HKSAR Government, June 2008. Final Report of the Study of “Road Surface Failure on Bridges in Tropical Areas”, the University of Hong Kong in association with Sandberg Asia Ltd., October 1999. Transport and Road Research Laboratory Research Report 185, A field trial of waterproofing systems for concrete bridge decks, A R Price, 1989. Waterproofing Membranes for Concrete Bridge Decks, National Cooperative National Highway Research Program (NCHRP) Synthesis 220, Transportation Research Board, National Research Council, USA, 1995. Transportation Research E-Circular Number E-C022, ISSN 0097-8515, Maintenance Research Master Planning Workshop, Transportation Research Board, National Transportation National Research Council, USA, November 2000. References 8. 9. 10. 11. 12. Publication Number: FHWA-HRT-04-027 - Bridge System Preservation and FHWA Maintenance: Scanning for Innovation, Federal Highway Administration, USA, July 2004. BD 47/99 – Design Manual for Roads and Bridges, Vol.2, Section 3, Part 4 Waterproofing and Surfacing of Concrete Bridge Decks, the Highways Agency, UK, August 1999. Transport Research Laboratory Published Project Report PPR221 – The Performance of Surfacing Overlaying Bridge Deck Waterproofing Systems, TRL Limited, 2007. Highways Department Guidance Notes RD/GN/032 – Road Surface Requirements for Expressways and High Speed Roads, June 2008. Highways Department Guidance Notes RD/GN/030 – The Application of Stone Mastic Mastic Asphalt (SMA), Highways Department, HKSAR Government, June 2008. HKSAR June ...
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