The Use of Continuously Reinforced Concrete Overlays in Motorway Maintenance (A Case Study)

How do you undertake the repair of a jointed concrete carriageway on one of the busiest motorways in Europe, particularly when a large proportion of the joints have failed and the slabs are floating on a sea of Gault Clay. With differential settlements so severe that there was genuine concern for road safety, this was the problem that faced the Highways Agency and their Managing Agents, Atkins, as we approached the new millennium. Traditional wisdom in the UK would be to ‘crack ‘the carriageway into 1 metre long slabs, ‘seat’ them with a pneumatic roller and overlay the whole pavement with a minimum 150mm surfacing. Yet simple engineering judgement suggested the serviceability of the pavement would be an ongoing problem as there was no simple way of improving the foundation. Maintaining lane availability for the 120,000 vehicles using the road every day was fundamental to any option considered. The final solution adopted, was to overlay the most heavily loaded traffic lanes with a Continuously Reinforced Concrete Slab. This is the story of how and why we reached this conclusion and illustrates what can be achieved when genuine partnering relationships are developed between Clients, Consultants and Contractors, to the benefit of all stakeholders.