32 SURFACE MAINTENANCE
Micro-surfacing is usually used on urban roads
è Sector schemes are competency schemes aimed at ensuring the workforce have been properly trained and qualifi ed
è Good “aftercare” is essential. This, together with the correct material design will minimise the risk of early life failure.
Environmental
considerations è These products have a relatively low carbon footprint. RSTA in association with the University of Nottingham have published a suite of carbon calculators for measuring the carbon footprint on schemes using surface treatments including slurry surfacing and micro-surfacing
è These new carbon tools are called PROTECT (Pavement Road Treatment Embodied Carbon Tool) and have been endorsed by ADEPT
è The rapid speed of the process means that disruption to road uses, local businesses and emergency services is minimised
è They are applied cold at ambient temperature so they have zero emissions and zero risk of fume installation and burns to operatives during installation.
Life expectancy
è Careful attention to material design and execution has provided in service performance of typically eight to 12 years (average 10 years life) on traffi cked sites
è Further information on service life is available in the RSTA ADEPT service life of surface treatments document published in 2011 available at
www.rsta-uk.org/publications.htm.
RSTA/ADEPT code of practice
è Published in 2011 and peer reviewed and endorsed by the Association of Directors for Environment Economy Planning and Transportation (ADEPT)
è The document is reviewed annually by the RSTA-ADEPT working party to ensure it remains rigorous, accurate and up to date to serve the needs of local authorities
è It is freely available on the RSTA website
www.rsta-uk.org/ publications.htm
è This code of practice has been written by the Road Surface Treatments Association and ADEPT to assist procurers and installers to obtain a high quality durable surface treatment. It represents best practice for the selection and application of slurry and micro surfaces to maximise their performance and durability
è To obtain the best results it is necessary to give careful consideration to a wide range of details and to plan and design the work carefully and to use experienced contractors with a good track record. All of these products comply with clause 918 of the specifi cation for highways works, part of the manual of contract documents for highway works
è The type of application in which the products are applied and the prevailing ambient conditions at the time of installation are also important to ensure long-term durability of the product
è The purpose of this code is to identify the important aspects of the process and to cross reference
other documents relating to good applications of slurry and micro surfacing and so give practical guidance on achieving high quality
è The code discusses how to determine suitable sites for treatment
è Specifi cation issues are covered in some detail and it highlights the clients’ responsibilities towards achieving a successful outcome. It goes into some detail regarding planning and coordination, health and safety aspects, planning the execution of the works, surface preparation, controlling material installation, and traffi c management. It also covers aggregates and binders used in these products, rollers, sweeping, method of working and aftercare. There is also a section on hand applied footway slurry surfacing
è Training the workforce is also a major topic covered in the document. It is imperative that local authorities ensure their contractors have properly trained and qualifi ed operatives with an NVQ level 2 in slurry surfacing and an appropriate CSCS card to ensure good workmanship which has a major impact on durability. There is also a checklist for contractors before during and after the works and a glossary of terms.
Summary
è Slurry surfacing incorporating micro-surfacing is an established, proven process with a long history of successful use
è It is an extremely cost-effective surface maintenance treatment when carefully designed, specifi ed and executed
è Developments in materials, techniques and equipment and improved operator training mean there is a very low risk of early life failure.
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