Britpave: The British In-Situ Concrete Paving Association

New Roller Compacted Concrete Guidance

Roller-compacted concrete (RCC) pavements offer a competitive and long-lasting alternative to asphalt. A new Britpave guidance document aims to encourage greater use of an approach used in the States since the 1930’s but which has yet to mainstream recognition in the UK

Roller compacted concrete or RCC, takes its name from the construction method used – it is placed by modified asphalt paving equipment, but it is stiff enough to be compacted by vibratory rollers. RCC has the same constituents as conventional concrete – cement, water and aggregates, and requires no formwork or reinforcement or finishing.

Although some early examples of RCC date back to the 1930’s and 1940’s, the first widespread use of RCC was in the 1970’s by the Canadian logging industry when new land-based log sorting methods neededa strong, fast but economic paving system that could take the massive loads and handling equipment involved. The US Army Corps of Engineers refined the use of roller compacted concrete pavements in the early 1980’s, for military facilities in the United States, and its use continued to develop in ports and container handling facilities through the 1990’s. Usage has increased steadily since 2000 in both public and private applications, including low-volume roads, commercial parking lots, container handling and military hardstands. Considerable work was carried out on the road network in Spain in the 1990’s, including experimentation with crack control systems and spacings. Reflection cracking in the asphalt surfacing, which varied in thickness between 50 and 120mm, was successfully controlled by reducing the transverse spacing to between 2.5 and 3.5m. Since its introduction into the UK in 2002, RCC has mainly been used in the construction of hardstandings for the waste industry, bulk materials handling and HGV parking.

RCC combines the strength, long-term performance and minimal maintenance of conventional concrete with the economy and simplicity of asphalt. For roads RCC offers further advantages that include minimal rutting, it can span localised soft subgrades, will not deform under heavy concentrated loads nor, as has been seen with asphalt roads this summer, will it soften due to high temperatures. Aiming to forward to benefits of RCC, the new ‘Britpave Guide to Roller Compacted Concretes’, describes the benefits, properties and applications of RCC, provides recommendations on mix design and materials selection, and discusses applicable design methods, construction methodology and techniques. Quality control recommendations are given in the context of standard UK tests and procedures.

The economy of RCC is in its simple application. Large-capacity mixers continually blend the RCC which is transported to site and discharged into an asphalt paver. This places the materials in layers up to 250mm thick and 13m wide. Compaction starts immediately after placement and continues until the pavement meets density requirements. Curing ensures a strong and durable pavement. Where appearance is important, joint can be saw cut into the RCC to control crack location. If economy outweighs appearance, then the RCC can be allowed to crack naturally.

Increasingly, RCC with induced cracking and binder/surface courses is being considered for truck lanes and motorway widening projects and as an economic alternative to fully flexible pavements. RCC has significant potential for the UK road network and this new guidance should help forward its use. It is economic and fast to lay, has long-term performance with minimum maintenance, resists rutting and potholes and can use waste materials for its construction whilst at the end-of-life it can be crushed and recycled for a new pavement.

Britpave Guide to Roller Compacted Concrete is available from www.britpave.org.uk, free for members, £10 plus p&p for non-members.

ends