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New venture brings crack and seat to forefront

A joint venture is the bringing crack and seat methodology of rehabilitating concrete pavements to Australia, along with the machinery to do it.

A joint venture is the bringing crack and seat methodology of rehabilitating concrete pavements to Australia, along with the machinery to do it.The United States has introduced the electric light bulb, aeroplanes, microwaves, sunglasses and a wide array of revolutionary technology to the world. Even hotdogs have had an impact on the culinary world since the Americans introduced them in the early part of the 20th century.

The wealth of knowledge contained in one of the world’s youngest nations is extraordinary, and the things that can be learned from the ‘land of the free’ is even greater.

Australian Asphalt Pavement Association’s (AAPA) latest International Knowledge Transfer Study Tour tapped into the wealth of information that can be learned from its American counterparts.

AAPA, in association with Austroads, ARRB and industry, facilitated a study tour to the US in 2014. The delegation of individual players from the Australian flexible pavements industry included contractors, government representatives, consultants and researchers.

The purpose of the tour was to learn key pavement construction and engineering best practices as employed in the US. These included advances in pavement engineering and design, thinlays for pavement preservation, crumbed rubber asphalt and perpetual pavements.

Crack and seat is a technique the Americans are using that industry delegates Tony Wehl, Director of RPQ, and Nick Argyropoulos, Director of NA Group, saw the potential for applications in Australia.

The purpose of the methodology is to help rehabilitate a concrete pavement that is at the end of its service life prior to overlaying. This minimises the occurrence and severity of reflection cracks in the overlay. The concrete slab is cracked by a specialist machine and then seated with a roller to reestablish subgrade support.

“Anywhere where there are huge areas that need to be rehabilitated or concrete removed, that’s where it is applied,” explains Mr. Wehl.

He notes that states such as Queensland and New South Wales have large areas of concrete roads, some even dating back to when the US Army was in Australia during the Second World War. “And since then we haven’t had any options to rehabilitate them,” he adds.

Crack and seat has been explored in Australia in the early 1980s, Mr. Wehl explains, but it has never gained serious traction. The key difference is that the Americans have is a machine that can rubblise the concrete and crack and seat the pavement efficiently.

When a concrete pavement is subjected to rubblisation, it is pulverised to produce a structurally sound base, which can prevent reflective cracking by obliterating the existing pavement distresses and joints. The American crack and seat machine, however, includes an innovative multi-head apparatus and can produce what it calls “modified rubblisation”. This describes the process of rubblisation with the intent of producing larger material particle sizes, which maintain more of the existing concrete pavement’s structural support.

Seeing the potential applications for the machine here in Australia, Mr. Wehl and Mr. Argyropoulos, with the aid of AAPA, followed up with the American company Antigo after the tour.

Ultimately, Mr. Wehl and Mr. Argyropoulos’ company will look to distribute the crack and seat technology in Australia and South-East Asia.

They launched the venture to the Australian market at the 2015 AAPA International Flexible Pavements Conference at the Gold Coast in September.

Having established respective businesses with roots in road maintenance, Mr. Wehl and Mr. Argyropoulos are confident that the Australian pavements industry will see the benefits of crack and seat machinery for rehabilitating concrete pavements here. “It’s a cost-effective solution,” states Mr. Argyropoulos.

He says there are fewer limitations and more flexibility on road maintenance projects when using the crack and seat machinery. Rather than removing entire slabs of concrete or bringing in rock breaking machinery to crack the pavement and remove it, the concrete pavement can be rehabilitated quickly and easily. Mr. Argyropoulos says the machinery can do between 3000 and 4000 square metres of work a day. “It is more beneficial in an area where the pavement is less than 350 millimetres,” he adds. “It’s a really straightforward process.”

Mr. Argyropoulos says that he and Mr. Wehl are now in the process of working with AAPA to set up demonstrations of the machine for Queensland, New South Wales and Victoria.

The machinery itself is proven technology and approved for use on Australian roads. “What we’re planning to do is bring the machinery over from the US for our initial demonstrations to show the road authorities that the technology is available in Australia.”

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