The Newcastle Herald can reveal that authorities are grappling with expanding roads causing the emergence of dangerous speed humps, lifting median strips, cracking gutters and residential driveways being pushed into homes.

A team of engineers is investigating and maintenance crews are working overtime to reduce hazards.

The state government and most Hunter councils have suspended use of a heavily bound road base, Steelstone Mix 3, with concerns some roads may have to be ripped up.

"Last year Roads and Maritime Services suspended use of the product as it was found to expand and cause defects in some conditions," an RMS spokesman said.

"It is hoped industry investigations into expansion issues will identify possible solutions."

Supplier South Coast Equipment (SCE) declined to comment when contacted this week.

Steelstone Mix 3 is believed to have been developed in the 1990s by SCE's Steelstone at the old BHP site in Mayfield in accordance to RMS's requirements.

It had been specified for use in RMS and many council road construction projects for more than 15 years.

It is made of a mixture of steel furnace slag, blast furnace slag, bottom ash from power stations and lime.

In April last year the state government issued a directive to councils that it should no longer be used. 

At least 100 road defects have been identified across the Lake Macquarie local government area and, to date, seven claims for property damage have been lodged.

‘‘Council has been made aware of a road construction product it has used which has an inherent fault that is damaging roads and private property,’’ council documents state.

‘‘It is not possible at this stage to reliably estimate the potential financial impact on council.’’

Developers, contractors and engineers have all pointed to a moisture issue with the steel aggregate product that is causing roads to buckle, lift and dip.

At Wangi Wangi a road has expanded so much it has pushed a residential driveway into a garage, causing structural damage. Sections of guttering and driveways have been removed to relieve mounting pressure, and in some cases roads have been shaved, or milled, back to dirt to reduce bumps.

A spokeswoman for Lake Macquarie City Council said the product had been used for about 15 years. 

‘‘In recent years there have been instances of expansion of the material,’’ she said. ‘‘The problems differed from site to site, but some include the expanded material causing some damage to road surfaces, paths and driveways ... a number of sites are being surveyed and monitored. Technical advice is being obtained as part of that.’’

Newcastle City Council has also experienced problems with the material, with swelling of pavements causing ‘‘ripples in the road surface’’. The damage has mainly been identified on Woodford Street, Minmi, the off-ramp of the M1 Pacific Motorway at Blackhill Road in Black Hill and at Minmi Road and Walford Street in Wallsend.

‘‘Council has experienced some problems ... but not to the extent that has been reported by other areas in the Hunter and by the RMS,’’ a council spokeswoman said.

‘‘Due to problems that have occurred, we have stopped using Steelstone Mix 3 other than in exceptional circumstances, such as patching an existing Steelstone surface.’’

A Cessnock council spokeswoman said ‘‘some issues such as humps or push-ups’’ had been identified but could not confirm whether Steelstone Mix 3 was to blame.

Port Stephens capital works section manager Greg Kable said they had treated a ‘‘very minor number of issues’’ by milling and resealing the road surface.

‘‘Our exposure to these problems is limited as it has been used in only a handful of locations on the local road network,’’ he said.

Maitland City Council  confirmed it had used the material in the past.

Robson’s Civil general manager Kevin Rigg said his company had problems with the product on a job two years ago and ceased using it.

‘‘We only used it where it was specified for RMS projects,’’ he said. ‘‘As far as I am aware, everyone has stopped using it.’’

‘Ideal’ product poured into vital link

CASE STUDY #1

IT was often billed as one of Lake Macquarie’s worst traffic bottlenecks, resulting in a multimillion-dollar upgrade.

Yet a 1.7-kilometre stretch of Five Islands Road could need a future makeover after a material used in its construction was found to have serious defects.

More than 20,000 tonnes of Steelstone Mix 3 was used in the job.

The $30 million upgrade included widening the road from the roundabout at Speers Point and the roundabout at Booragul to four lanes and building two new bridge crossings at Cockle Creek.

It was designed to alleviate traffic congestion for the more than 30,000 vehicles that used the road each day.

Opened in January 2007, it was heralded as a vital link between Toronto and Newcastle and the booming western side of Lake Macquarie.

Yet parts of the road have been affected by road expansion,  which could be costly to fix.

In 2007, a release from the Australasian Slag Association said the superior ‘‘elastic modulus’’, ‘‘non-plasticity’’ and ‘‘relative moisture insensitivity’’ of Steelstone Mix 3 made the product ‘‘ideal’’ for the project.

The association also stated the material had been used in other major projects, including Beltana Highwall Mining’s operations in the Hunter coalfields and the development of the Wallarah peninsula interchange.

 - Janek Speight

CASE STUDY #2

UNSIGHTLY: Lifting has damaged  roads, above, as well as properties such as that of Phil O’Neill, left and right. 

TWO years ago residents of Dobell Drive, Wangi Wangi, applauded when Lake Macquarie City Council upgraded their road.

Now it is lifting and expanding so much it is pushing  driveways into homes, causing structural damage.  Some concrete slabs have risen up to 40centimetres at joins so cars can’t be driven over them.

Council workers have been forced to remove sections of driveways and replace them with flexible asphalt to allow the road to keep expanding.

Resident Phil O’Neill first noticed his driveway lifting and moving about a year ago. His garage walls and floor are cracked and twice council workers have cut strips from his concrete driveway to relieve the pressure, but the gaps keep closing.

‘‘The whole garage has been pushed back,’’ he said.

Residents told the Newcastle Herald they had been informed that a metallic component in the road base was reacting with moisture and causing expansion. Some believe part of the road will have to be pulled up.

 There are large bumps and depressions appearing every few months on it.

Graeme Sweatman contacted the council this week after noticing a section of his driveway had begun to rise. ‘‘The more you look at it, the worse it gets,’’ he said. ‘‘It seems to get worse in the heat as well.’’

Another resident, who declined to be named, said his whole driveway would need to be replaced.

STEELSTONE MIX 3

Source: Australasian Slag Association and RMS

Is a blend of steel furnace slag, blast furnace slag, bottom ash from power stations and lime

Slag is the waste product of the steel-making process

It is a dark, grey, hard, gravelly substance

Was approved as conforming to RTA Specification RN73 ‘‘Slag Based Bound Pavement’’

Originally produced from Steelstone’s operations at the former BHP site in Mayfield