Archives: Case Studies

Over 25,000 tonnes of asphalt were supplied by CEMEX and laid by Colas at RAF Coningsby in Lincolnshire as part of a five-month project to resurface the runway.

RAF Coningsby is one of the UK’s Quick Reaction Alert (QRA) Stations which protects UK airspace, so a key requirement of the runway resurfacing project was to ensure that the base remained operational throughout. The site is also home to two combat-ready squadrons, the permanent home of the Battle of Britain Memorial Flight and the training station for Typhoon pilots.

To ensure Typhoons could be scrambled in case of emergency, Colas resurfaced a short section of the 2,744-metre long runway each night. There was also the requirement that all plant, equipment and personnel could be removed from the runway within eight minutes, so that aircraft operations would not be compromised by runway works if a QRA situation arose.

Initially the project involved replacing the surface course material, however, once work had commenced, it became clear that the binder course layers also needed to be replaced. CEMEX provided a Porous Friction Course to meet the Ministry of Defence’s complex asphalt specifications, supplying up to 450 tonnes per shift from its nearby Lincoln coating plant, with the hardstone supplied from its Roan Edge Quarry in Kendal, Cumbria.

Cemex Area Manager for Asphalt, James Playford, said: “Meeting the requirements of this project required exceptional teamwork and coordination. Our dedicated approach paid off with the plant running day and night throughout the project, and every single order fulfilled to time.”

Colas Procurement Manager, Steve Bryant, added: “CEMEX’s collaborative approach ensured they met the intricates of this project in the constrained timeframe. The finished runaway is a quality surface that will play a key part in this site’s defence work.”

A collaborative approach and the introduction of advanced technologies enabled the completion of a complex resurfacing project at Silverstone racetrack in Northamptonshire.

Working with motorsport track experts Dromo, Tarmac undertook the challenge to resurface the circuit to the stringent requirements needed for racing: in addition to high levels of grip and durability, variations in surface profile must be kept to an absolute minimum and drainage needs to be optimised to reduce the risk of high-speed aquaplaning.

“Material selection was essential to providing the surface quality required,” said Tarmac’s Regional Technical Manager Tim Smith. “Greywacke gritstone from our Bayston Hill quarry, which has already been used at the Abu Dhabi and Bahrain Formula 1 circuits, was identified as the most suitable aggregate source due to its ability to provide optimal grip.”

The quarry manufactured the aggregates to the tight grading and shape specification. It was then washed to ensure a high level of consistency before being combined with a bespoke, highly modified bitumen manufactured by Shell.

Silverstone’s tight corners require quick camber changes over short distances. In order to deliver a seamless, smooth base on which to surface, every inch of the track was laser-scanned to create a 3D digital terrain model, allowing the difference between the existing surface and the new model design to be accurately calculated at any given position.

“The scheme necessitated a high level of logistical planning and advanced technology,” said Tim. “Ensuring continuity of supply of 350 tonnes of asphalt per hour from our Elstow and Harper Lane plants was critical. To achieve this, all the aggregates needed were moved to the plants ahead of supply and we set a maximum time limit of three hours between mixing and laying to ensure perfect quality, with delivery vehicle management being key.”

Tarmac’s logistics teams used advanced software to manage the location of each truck and its asphalt management system supported the coordination of around 70 delivery vehicles and multiple supply plants by accurately calculating the most efficient way of completing each shift.

Asphalt feeder machines were used on site so there was no break in material supply to the three paving machines that operated in echelon formation to ensure there were no longitudinal joints in the surface. Specialist oscillating rollers were then used to provide the smoothest possible finish.

“The team worked around the clock and committed over 7,000 working hours on site to get the track race ready,” added Tim. “More than 16,000 tonnes of bespoke asphalt was needed to resurface the 5.5km circuit and the result is a surface that sets a new benchmark for precision and quality using the latest innovative technology.”

Asphalt containing 50 per cent reclaimed asphalt (RA) content has been laid for the first time on a section of the M25, in what could signal a step change in approach for the Strategic Road Network (SRN).

The 50 per cent RA surface course, with high Polished Stone Value (PSV) aggregate, was designed by FM Conway in collaboration with surfacing business partner Toppesfield and Skanska UK.

Over 250 tonnes was laid as a surface course, to a depth of 45mm, on a section of the anticlockwise inside lane between junctions 25 and 26 during an overnight closure in September.

The use of 50 per cent recycled content on this project followed permission from Highways England to depart from its standards. Previously, standard practice has been to limit the RA content of surface courses for motorways and A-roads on the SRN to around 10 per cent.

Mark Flint, Technical Manager at FM Conway, said: “Extensive core sampling and testing was imperative as we were looking for the correct grading of aggregate as well as the right PSV. Being able to carry out the research and development at our Technology Centre and engineer a bespoke Polymer Modified Bitumen (PMB) at our PMB plant was beneficial to the success of the mix.”

Skanska, contracted to carry out civil engineering and technology works for Connect Plus Services, the JV which operates and maintains the M25 for Highways England, was able to supply the recycled asphalt planings (RAP) for this high RA addition project from two Connect Plus ‘donor’ sites undergoing remedial work.

“The future uptake of 50 per cent RA could result in huge environmental benefits if adopted across the SRN,” added Mark.

Latest figures from Cycling UK[1] show that the number of cyclists killed or seriously injured on Britain’s roads has increased by 29 per cent from 2008 to 018, with cyclists being 15 times more likely to be fatally injured on the roads compared to other road users.

Local authorities are increasingly turning to coloured asphalt to create clearly-marked cycle lanes to improve safety and provide public realm benefits – a move that is supported by British Cycling’s Policy Manager, Nick Chamberlin: “Using a contrasting colour for the asphalt on bike paths alongside the main carriageway is a simple and effective way of demarcating safe space for all road users. Cities and towns could ‘own’ a colour making their cycle network both effective and a statement of civic pride and difference.”

The use of coloured road surfaces forms part of the planned £13.4 million upgrade for Chorlton in Salford, part of cycling guru Chris Boardman’s £1.5 billion Bee Network masterplan to create an integrated cycling and walking network in Greater Manchester. The proposals for Chorlton could see cyclists and pedestrians given priority in the city centre and the designs have been described as the most advanced in the UK.

Across the Pennines, Sheffield City Council recently installed a new cycle lane in Brown Street, an area of high traffic near the city centre, opting for ‘Signal Red’ asphalt, supplied by Aggregate Industries (AI), to create a lane that is easily distinguishable from the rest of the road.

AI advocates standardised colour demarcation as the way to achieve effective lane segregation and create a safe local road network.

Joanne Wilkins, Head of Business Development – Asphalt and Ready Mix Concrete said: “Cycling UK states that 1.7 million people cycle either every day or nearly every day, so having clear and coherent road markings is vital to help prevent road traffic collisions.

“We believe that joined-up planning and standardised specification should be at the heart of this strategy. Britain currently has a somewhat disjointed network of different colours and a variety of materials, which can be confusing for drivers and cyclists to navigate. Implementing a cohesive approach is needed for the construction of coloured lanes so we can build a road network that’s safe for all to use.”

[1] https://www.cyclinguk.org/statistics

High streets remain at the centre of local life in towns and villages across the country. Providing and maintaining key routes to a high standard is vital to ensuring that residents can access amenities, shops can trade and these streets can continue to define local character.

These aims were at the heart of a recent £500,000 project delivered at Heathfield high street in East Sussex, where FM Conway holds a highways surfacing partnership with Costain/Jacobs and East Sussex County Council.  As part of that wider programme, FM Conway was briefed to renew 3,600m² of road surface along the high street.

Minimising disruption for local shops and traders was crucial to the scheme’s success. FM Conway’s Senior Operational Manager, Richard Coughlin, comments: “The programme required periods of road closures so careful phasing was vital to reduce the impact on Heathfield’s shops.

“The material mix we specified was also chosen to maximise durability – driving whole life cost efficiencies for East Sussex County Council and reducing public disruption by ensuring that repairs wouldn’t be required again for many years.”

The week-long scheme was staggered across three phases along the high street, with Costain/Jacobs coordinating the project and liaising with local businesses. Each aspect of works, from initial carriageway reconstruction through to road markings, occurred continuously where possible to drive productivity. FM Conway marshals were on hand throughout to guide the public and keep them safe.

Once the carriageway reconstruction works overseen by Costain were complete, FM Conway planed the road surface to a depth of 65mm, transporting all arisings to one of its depots for recycling.  It then laid a 6mm SMA Surf, followed by a CG100 geotextile membrane to ensure good adhesion with the surface course and to maximise the road’s resistance to reflective cracking, where pressure on one road layer spreads to another. After this, a 10mm Surepave Polymer Modified Bitumen (PMB) surface course was laid to a depth of 45mm. SurePol TS (Polymer Modified Binder) was added so that the road can flex and therefore last longer.

“The programme was continuously reviewed to drive efficiencies,” said Richard. “For example, we re-allocated the stretch of works outside the Co-Operative store to one night shift to avoid any impact on daytime trading.

“The carriageway reconstruction stage of the final phase was also completed quicker than anticipated so, by revising our resurfacing programme, we were able to finish the overall scheme two days early.”

Mike Egleton, service director for East Sussex Highways, said: “This was a high-profile scheme that required thorough planning, excellent communication and close cooperation by all project partners.  A fantastic team effort ensured that we kept residents and businesses’ needs in mind at all times, delivering the project ahead of schedule and safeguarding the high street’s future. It is a blueprint for how we should manage similar schemes in future.”

A skid-resistant asphalt which delivers improved safety and provides whole-life cost savings has been used to resurface a busy slip road on the A64 in Yorkshire.

Ultigrip, developed by Tarmac, was chosen for the junction with the A1237 near York, which had been highlighted by Highways England as being in urgent need of improvement following an increase in the number of recorded incidents.

The brief was to find a solution that would replace the worn high-friction surface with a more durable asphalt, while delivering improved whole-life performance, boosting safety and minimising unplanned delays.

Tarmac worked in collaboration with principal contractor AOne+ to lay 250 tonnes of Ultigrip on the slip road. Although the upfront costs were greater than a conventional solution, AOne+ quantified the whole-life savings to be £370,000 due to reduced maintenance, with 28 days of closures and 2,800 hours of labour saved over its serviceable life.

David Hardy, national product support manager at Tarmac, said: “Providing safe and secure roads is the number one priority for highways authorities. It’s especially crucial that high-risk locations such as slip roads, roundabouts, tight bends and approaches to pedestrian crossings are surfaced with the most appropriate materials available.

“Ultigrip is different to traditional high-friction surfaces as its skid resistant properties are not added at the end of the surfacing process but intrinsic to the mix. A calcined bauxite aggregate and a durable clear binder are used that, when combined, offer a durable, textured finish which reduces the dangers of skidding.

“It also lasts up to four times longer than alternative options and can be laid in a single pass meaning operatives spend less time overall on site, improving safety and reducing labour costs in both the short and long-term.”

Section 1 of Highways England’s A14 Cambridge to Huntingdon improvement scheme will see 13 miles of the road upgraded to three lanes in each direction and is expected to cut journey times by up to 20 minutes.
The works at Brampton Hut motorway services specified minimum sound level reduction requirements of -7.5db(A) compared to traditional Hot Rolled Asphalt (HRA), designed to curb noise pollution generated by the new road across built-up areas.
To meet these noise restrictions, Aggregate Industries’ 10mm SuperThin HAPAS-approved ultra-low noise asphalt is being used which, at -7.8db(A), greatly exceeds the typical sound reduction requirement of -3.5db(A).
The company is expected to lay approximately 30,000 tonnes of SuperThin across the A14 contract, which is due to be completed at the end of 2020.

Paddy Murphy, Director of Contracting at Aggregate Industries, said: “One of our key aims is to help reduce the impact of operations on the local community and the network and we’re doing this by ensuring our asphalt solutions help reduce excessive noise pollution to those living in the built-up areas of the scheme.”

A striking coloured asphalt has been used to highlight a hazardous crossroads on a new housing estate in South Yorkshire.
Aggregate Industries supplied its SuperColour red asphalt to Doncaster Council for use at crossroads along the single main road running through the 1,800-home estate. The 180 tonnes supplied replaced block paving which had deteriorated in just eight weeks and its success in achieving the safety, colour and durability requirements has seen its use extended across the town.

“Typically when people think of asphalt, they think of the standard black variety,” said Victoria Smith, General Manager for Express Asphalt at Aggregate Industries.
“But, as modern construction practices and building design has evolved, so has the choice of asphalt, with today’s market offering an explosion of colours to suit almost any application.
“Coloured asphalts combine functionality, durability and aesthetic appeal as most mixes can incorporate pigment with no effect on performance.”
In playgrounds and on sports pitches, for example, where an overriding objective is water permeability, porous asphalt mixes can be used in bold primary colours to create a striking result that offers longevity.
And, in bus lanes and cycleways, where safety is paramount, coloured asphalt enhances safety and traffic management through the creation of colour-coded demarcation areas. It can also be used to give a more natural finish that helps the hard surface blend with its surroundings.
“Colour is now increasingly playing an important role in the design of our most valued public spaces,” added Victoria Smith.
“Whether it’s parks and green spaces, or roads and football pitches, black asphalt is no longer the only option to meet the requirements of modern culture.”

A specialist durable asphalt mix design, produced entirely off-site, has been used to resurface the runway at Carlisle Lake District Airport.
It was the first time Hanson UK has supplied the hard-wearing material, which can be used in both the binder and surface courses and has been designed to meet the requirements of current BAA and Defence Estates Airfield Specifications for runways, aprons and taxi ways.
Unlike most traditional methods used for UK runways, the 15,000 tonnes of Hanson Airfields was produced at two off-site plants, saving the time and costs associated with having to establish an on-site asphalt plant, helping to meet the project’s tight delivery programme.
Hanson worked with bitumen supplier Shell on testing and approving two versions of the surface and binder course design mixes for the contract, which also included supplying 8,000 tonnes of standard heavy-duty binder course to main contractor J Hopkins (Contractors) Ltd.
“Hanson Airfields was laid with conventional equipment by the contractor,” said Hanson Technical Services Manager Jon Sharp.
“Tight technical controls at our asphalt plants and on site ensured all material was supplied and laid in line with airfield specification requirements.
“The result is a durable alternative for airfield surfacing with the added benefits of being produced off-site. The project has been quite an achievement and led to us breaking our own production record by supplying more than 900 tonnes of material on three consecutive days out of our Keepershield plant in Northumberland.”

Rochdale Borough Council has used a heavy-duty asphalt mix to improve the lifespan of a road junction servicing one of the busiest industrial estates in Europe.

On one side of the junction is the entrance to a 200-acre distribution park, while on the other is a quarry. And there are major interchanges with the M62 and M66 less than half a mile away. As a result, it is very heavily trafficked, particularly by heavy goods vehicles (HGVs).

The road was resurfaced in traditional hot rolled asphalt more than 12 years ago but was subject to regular maintenance issues within two years. In 2016, after nearly a decade of remediation, Rochdale Borough Council decided to look for a more sustainable, long-term solution that would ensure it could withstand heavy trafficking without the need for constant maintenance.

Rochdale then

Applying the solution

That solution involved planing off the existing surface and replacing it with a geotextile layer and then new binder and surface course layers incorporating Hanson’s Tufflex HD+ heavy duty asphalt mix.

“The design required a solution for slow moving HGVs negotiating the junction,” said Paul McCaffrey, Assistant Engineer at Rochdale Borough Council.

“After speaking to Hanson, Tufflex HD+ was recommended to us. The technical data indicated that the surfacing would achieve a stiffness of 7,000MPa, giving very high resistance to deformation.”

Tufflex HD+ contains Endura Z2, a premium polymer modified hot mix binder made by Nynas for heavy duty applications. It significantly enhances the toughness, rutting resistance and flexibility of the mix and provides good protection against damage caused by heavy, slow moving traffic.

Rochdale now

Hanson recommended Tufflex HD+ 20mm for the binder course and Tufflex HD+ 14mm for the surface course. A total of 1,000 tonnes was supplied from the company’s Leeds asphalt plant – and, so far, the material is performing very well.

“We hope that Tufflex HD+, combined with the geotextile layer, will give the surface a much longer lifespan,” added Paul. “So far the material is holding up well: 21 months on and we have had no maintenance issues regarding the condition of the surface.”