ULTIPAVE SINGLE LAYER
Sustainable single layer asphalt with responsible use of high PSV stone
The M67 is a key strategic route, connecting the west of Manchester with the M1 and Sheffield and South Yorkshire. A surfacing upgrade was required in anticipation of the new £228 million pound Mottram bypass, connecting the M67 in Greater Manchester to the M1 in South Yorkshire and multiple sections of the M67 between junction 2 and 4. As part of ongoing network improvements a durable and hardwearing surface had to be selected for the scheme. The identified areas were also variable depth, so would require more than just a surface course reinstatement, which would usually require multiple visits to complete the work.
Following engagement between National Highways and Tarmac’s technical team, a single layer approach was chosen, to allow the removal of the existing asphalt and the reinstatement of the carriageway sections in one operation. The material selected was ULTIPAVE SINGLE LAYER, using ULTILOW warm mix technology. ULTIPAVE SINGLE LAYER is a BBA Approved 20mm SMA designed product, which can be laid between 50mm - 100mm, negating the need for a separate binder course. It offers excellent load bearing capabilities with lower in-situ voids and the higher stiffness provides lasting durability in heavier trafficked applications.
Results and benefits
National Highways were happy with the finished surface and reduction in programme time gained using a single layer approach for the project. The extra control measures used during the installation resulted in a surface with not only comparable performance to a thin surface course, but one that will provide lasting durability for construction traffic when building the new by-pass. Based on carbon calculations undertaken for this scheme, 3.2 tonnes of CO2 emissions were saved by switching from a conventional hot mix asphalt to ULTIPAVE SINGLE LAYER as a warm mix asphalt. Reduced construction times helped to deliver additional reductions in emissions and using a 20mm aggregate meant a more responsible and sustainable choice of material.
Carbon Conscious Delivery
Warm mix asphalts are manufactured and supplied at lower temperatures than conventional hot mix asphalts. As a result, they can deliver carbon footprint savings of between 8 and 12% compared to hot equivalents. ULTILOW warm mix asphalts offer improved productivity within paving windows. Since they are supplied at lower temperatures, they need less time to cool and are quicker to reach trafficking temperatures. This allows earlier reopening to traffic or more work to be completed within a given operating window and still reopened on schedule. Less time on site and fewer lane closures also help to reduce associated emissions from stationary road users.
Sustainable Use of Hardstone Aggregates
The high PSV stone used to surface roads is a valuable resource. Hardstone quarries naturally produce a range of aggregate sizes in certain proportions. Using 14mm and 20mm asphalts, where appropriate, helps to balance out high demand for 10mm aggregate and reduce waste and losses from secondary crushing. This makes ULTIPAVE SINGLE LAYER in a 20mm aggregate, a more sustainable choice, to help achieve a long-term balance in supply and demand for high PSV stone.
7,658t of asphalt were supplied from Tarmac’s Bredbury asphalt plant over 8 day shifts and 7 nightshifts, with 1,240t of warm mix material on Hattersley Roundabout, to support earlier reopening to traffic. The material was laid at varying depths of 60mm, 65mm & 80mm across the full project. To get the best possible surface finish and ride quality when using this aggregate size, some extra paving control measures were put in place.