A30 - Gilberts Coombe and Blowinghouse Bridge Decks

Outline In July 2003, Roadtechs were asked to survey a number of sites in the Cornwall area that were causing concern to the Managing Agent, Parsons Brinkerhoff. A combination of minor cracking and raveling of the SMA surface had produced localised rough areas that whilst these areas did not warrant resurfacing, the ride quality was poor and condition of the carriageway would lead to further more extensive damage. The site was subsequently inspected and a proposal submitted that would introduce our Techscreed system to patch the raveled areas, sealing the minor cracks, providing a durable surface arresting further deterioration. The Problem

Raveling of the hot rolled asphalt surface can clearly be seen in the photograph to the left, within the wheel-track areas. Loose chippings can be observed on the edge of the carriageway, which present a potential hazard to vehicles and cyclists.

The cost of a traditional plane and inlay to areas such as these do not warrant the cost of mobilizing the necessary plant required for such small isolated areas. Best value means that these costs must be considered when planning works and may mean that alternative solutions can provide a fast effective repair but also maximize the resources available such as traffic management and supervision.
On this occasion, the alternative treatment of Techscreed was chosen not only for the benefit and versatility that the material would provide but also, the outputs and rate of application meant that several traffic management set-ups could be erected during one shift. This was something that would be out of the question had the traditional approach been adopted, due to the traveling time required and re-establishment of plant. The Solution The product specified at this location was unique and had not been previously installed in Area 1. Keen to find a lasting solution the decision was taken to trial Techscreed which would provide all the requirements demanded of it ensuring that best value was achieved. Techscreed is a proprietary product designed and developed by Roadtechs from a blend of hydrocarbon resins, high PSV aggregate, a polymer modified bitumen binder, chopped fibres and mineral fillers. The formulation and manufacture of the product is carried out at our factory and utilises a high proportion of recycled aggregate and rubber, even the packaging is designed as part of the formulation and does not become waste. Techscreed is quick to install and providing not too much traveling is required between sites, up to 350 square metres of patching can be installed within an 8-10hour shift. If any material is left over at the end of the shift, it can be re-heated and used in the next day or bagged off and stored until required. In short, there is no waste!

The Techscreed can be seen in lane 1 as the patch in the centre of the picture. The lane joint has also been sealed using the same product on this occasion as band seal 100mm wide to incorporate all the damage preventing the further ingress of water to the structure.

Techscreed is a hot applied treatment that only requires around 30 minutes to cure before trafficking, this means that repairs to both lanes as seen on the right can be carried out in the same shift if a safe working area is available. Advantages Quick to Install Minimises Traffic Disruption Utilises Recycled Materials Requires no Excavation Can be Trafficked Usually After 30 Minutes No Waste

Economic and Effective