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The Quebec’s contractors experience with SMA Olivier Bouchard, ing. jr. ACRGTQ – Secteur sciences et techniques Canada User Producer Group for Asphalt CUPGA – November 16 th 2008 Saskatoon, Saskatchewan
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What is ACRGTQ ? Translation: Quebec road builders and heavy projects contractors association A private sector association of contractors who specializes in road and civil engineering infrastructures projects. More than 550 members.
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Overview Introduction Definition of SMA Types of SMA used in Quebec Contractor’s challenges Conclusion
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Introduction The Quebec Road Network –In Quebec, we have 185 000 km of road. MTQ is responsible for approximately 29 000 km of road, including national and provincial highways and regional and collector roads. To built that, one thing is sure : YOU NEED CONTRACTORS!!! When they have a new technology (like the SMA), the contractors have to modify their working methods.
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Definition of SMA The high content of crushed coarse aggregates (>5 mm) maximizes contact between aggregates. Good distribution of applied loads Excellent aggregate skeleton Good rutting resistance Good surface texture Flexible at low temperatures
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Suitable for thin courses Quieter No segregation Longer service life More expensive to produce than a conventional HMA because : –High asphalt content; –Use of asbestos fibres; –production of 0-2,5 mm granular class. Definition of SMA
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Types of SMA used in Quebec 3 types of SMA –SMA-10 (for highways and roads with high or heavy traffic) –EGM-10 (palliative interventions) –EG-10 (for highways, casual interventions, reduce noise)
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Contractor’s challenges The formulation of the SMA –Since 2008, Marshall’s method is out of use. This method has been replaced by the LC mix design. –LC mix design method is a combination of SUPERPAVE and LCPC method. –The contractors have to modify their method of formulation. –The new LC mix design method is gradually implanted in Quebec.
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Contractor’s challenges The progression is good for the contractors Source : MTQ
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Contractor’s challenges The formulation of the SMA –New granulometric characteristics
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Contractor’s challenges Placement –MTQ has identified that pavement degradations are mainly attributable to workmanship issues: Thermal and granular segregations Cyclic density differentials Truck exchanges = open texture on the mat Cold spots from asphalt spills Transverse and longitudinal joints Paver operation –Solutions : Material transfer vehicles (MTV) requirements Infrared technology in roadwork
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Contractor’s challenges Placement –The infrared technology and the MTV are used to check three points: If temperature of HMA is lower than the specification of the grade asphalt If temperature of HMA is higher than 100°C to eliminate the problem of bad compaction If we have longitudinal thermal segregation
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Contractor’s challenges Placement –Problems
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Placement –Problems Contractor’s challenges
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Placement –Solutions : Material transfer vehicles
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Contractor’s challenges Placement –Solution
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Contractor’s challenges Placement –But the MTV is not the solution for ALL the problems…
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Contractor’s challenges Placement –The longitudinal thermal segregation is a problem due to contractor's equipments. To eliminate that problem, a lot of work is made by the contractors and we hope that in few years, we have a durable solution for that problem.
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Conclusion In Quebec, we have a lot of road New technologies, like SMA, have many repercussions on contractors. But when the new formulation is gradually implanted, contractors respect the demands with a lot of work. For the placement of the HMA, new techniques are used by the contractors : infrared technology and MTV. Good construction practices ensure good pavement performances. In the future, MTQ and ACRGTQ have to work in team to ensure a good quality of asphalt road.
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Contact Olivier Bouchard, ing., jr Association des constructeurs de routes et grands travaux du Québec 435, Grande Allée Est Québec (Québec) G1R 2J5 Phone : 418 529-2949 Toll free :1 800 463-4672 Fax : 418 529-5139 www.acrgtq.qc.caobouchard@acrgtq.qc.ca
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