Polymer Modified Bitumen Emulsion (PMBE) Surface Treatments in Brisbane

Transcription

1 Polymer Modified Bitumen Emulsion (PMBE) Surface Treatments in Brisbane Greg Stephenson & Nihal Palipane Asset Management Branch, Brisbane City Council

2 Brisbane City Council Formed in Local Authorities / Joint Boards 26 Electoral Wards Area = 1,367km 2 Population (2016) = 1,180,285 45km

3 BCC Road Network Sub-Network Total Length (km) Asphalt Area (million m 2 ) Bitumen Seal Concrete & Pavers Total % of Network (by area) A & B Local Street 4, % C - Collector % D - Suburban % E- Industrial Access % F & G Arterial Roads % Total 5, % 94.5% 4.3% 1.2% 100.0% 73% local roads providing direct property access 21% sub-arterial & arterial roads 6% industrial access => environmental deterioration => load induced deterioration

4 Polymer Modified Bitumen Emulsion (PMBE) Surface Treatments Bitumen oxidises on exposure to air, becoming brittle Accelerated by high temperatures and UV radiation (sunlight) Brittleness leads to cracking and ravelling of bitumen and asphalt surfaces

5 Polymer Modified Bitumen Emulsion (PMBE) Surface Treatments Contractor responsible for the mix design, manufacture, supply & placing Mix of PMBE, fibres, emulsifying agents (surfactants) and fine mineral aggregates ~ 30% residual bitumen ~ 30% fine aggregate May contain Kaolin & Bentonite clays fillers. Fine aggregate has 100% passing 2.36 mm sieve and <1% passing 150 micron sieve Sprayed application of the preblended mixture using purpose built spray equipment Protective coating, Sealing fine cracks Skid resistance (short term)

6 Polymer Modified Bitumen Emulsion (PMBE) Surface Treatments Propriety Formulations challenges for local government to ensure equitable product selection Council has used: PreserveX (Liquid Roads) Downer Seal Coat SRS Road Surfaces Jet Black Fulton Hogan Desirable for a Generic Specification similar to: AAPA Advisory Note 20 - Emulsion Primes, Rubber Latex Modified and PMB Emulsion Specifications

7 Desgrand St., Archerfield Traffic Data Northbound Southbound Date of Traffic Count 22 nd to 28 th November, 2004 Average Weekday Volume Average Daily Traffic Weekday Heavy Vehicles 11.9% 10.2% Average Daily Traffic Speed 85%-tile Daily Traffic Speed 48km/hr 57km/hr 50.5km/hr 59km/hr Liquid Roads = 12 th December 2009 Part of the road treated Remainder was left untreated

8 Desgrand St., Archerfield Skid resistance testing on treated surface by ARRB Group Ltd in 2010

9 Desgrand St., Archerfield Surface Treatment 12/12/2009

10 2015 Griffith University Industrial Affiliates Program 8 Streets in Acacia Ridge 20 to 30 years old 4 Application Rates/Street 0.5 l/m 2 to 1.5 l/m 2 Texture Depth-Sand Patch Portable Pendulum Test Permeability Melvin Ea Griffith University Student SealCoat - SRS Roads Pty Ltd

11 Application Rate Surface Texture 2015 Griffith University Industrial Affiliates Program Residential Street Mix Surface texture 0.6mm

12 Skid Resistance 2015 Griffith University Industrial Affiliates Program Minimum 45 BPN for Council s residential and collector streets BPN > 45 even if the resulting surface texture depths were less than 0.6mm

13 Permeability 2015 Griffith University Industrial Affiliates Program PMBE treatment reduces the permeability to very low or low

14 Outcomes 2015 Griffith University Industrial Affiliates Program Single coat application at 1.0l/m 2 was not adequate for the majority of streets over 20 years of age where the texture is greater than 1mm. Fine texture => 1.0 l/m 2 Coarse texture => 2.0 l/m 2 (applied in 2 coats) Overfilling texture would not reduce the skid resistance to below 45BPN Very low or low permeability. Heavier applications should maintain low permeability for longer periods Minute cracks in the surface were effectively sealed Two coat applications of PMBE were used on 59 streets in 2015/16

15 Economic Analysis Single coat PMBE which are 9 years old 15 year life for two coat PMBE appears likely 45 year NPV analysis 60 year NPV analysis Life of PMBE Treatment Seal Coat PMBE Jet Black PMBE Type 1 AC (15mm) & crack seal Type 1 AC (20mm) Type 2 AC (30mm) 15 years $13.78/m 2 $17.30/m 2 $19.07/m 2 $19.33/m 2 $23.07/m 2 12 years $16.10/m 2 $20.23/m 2 $19.07/m 2 $19.33/m 2 $23.07/m 2 Life of PMBE Treatment Seal Coat PMBE Jet Black PMBE Type 1 AC (15mm) & crack seal Type 1 AC (20mm) Type 2 AC (30mm) 15 years $26.53/m 2 $28.36/m 2 $29.13/m 2 $29.20/m 2 $34.86/m 2 12 years $27.21/m 2 $29.22/m 2 $29.13/m 2 $29.20/m 2 $34.86/m 2

16 Desktop Selection Criteria Applied to Minor Streets only (Cul-de-sacs and residential streets) Age of surface (seal age) 20 years Pavement Failure for whole street 1% Surface Failures for whole street 3% Patching for whole street 2%

17 Field Selection Criteria No excess surface stripping or ravelling Aged surface in relatively good condition minor repairs 3% of whole street. Kerb and Channel functional & does not need rehabilitation Low ride roughness no corrugations or undulations Is uninterrupted access required? Aged Care Facilities, Emergency Services access, multiple high density units Are future works planned? subdivision expansion, unit development, services

18 Spraying activities Use patrol truck - repair potholes and edge patching Poison the grass Seal cracks between 3mm and 6mm wide Suction broom to remove loose material in the joint along CKC Avoid rubbish collection day & following day Totally closed for the period of application and drying Hot, dry weather is best micro-climate around trees 2 coat applications, 2 nd coat should be sprayed on a separate day

19 Concluding Comments Where the texture is greater than 1mm single coat application at 1.0l/m 2 is not adequate Two coat applications at 1.0l/m 2 per coat used for recent programs Some single coat PMBE treatments which have lasted for 9 years Some streets have received a second application Expected 15 year life for two coat PMBE treatments. Propriety formulations present procurement challenges for local government generic specification = similar to AAPA Advisory Note 20 for Emulsion Primes, Rubber Latex Modified and PMB Emulsion Specifications?

20 Concluding Comments Applied to suitable streets Cost effective treatment Reduces surface permeability = > delay old streets in fair condition from reaching the rehabilitation intervention level Addressing ageing and oxidation of bitumen. Conducting preventive maintenance activities on a sound pavement in good condition is usually the most cost-effective alternative. PMBE Treatment is not a panacea for all pavements.

21 Polymer Modified Bitumen Emulsion (PMBE) Surface Treatments in Brisbane Greg Stephenson & Nihal Palipane Asset Management Branch, Brisbane City Council