Concrete investigation on recycled roads

Usually made from recycled building materials like concrete, bricks and tiles, RCC can form aggregate used in the under-layers of roads, which act as the base that withstands traffic loads.

The City of Canning has already built roads designed to last 30 years by using RCC as the base and sub-base layers.

The new challenge will be using an RCC base but in conjunction with a traditionally used limestone sub-base, which is a combination that has resulted in cracks appearing within 12 months of construction.

Curtin Civil Engineering?s head of department Professor Hamid Nikraz and lecturer Colin Leek said research would test different blends, construction methods and layer thicknesses as well as exploring if the source and quality of the concrete has an effect on cracking.

?We might be able to get to what we call a perpetual pavement, where you build the base once and it?s considered something that lasts more than 100 years,? Leek said.

Research will consider methods such as inducing micro-cracking post-construction to stop ?block cracking? from occurring later when the cement rehydrates.

City of Gosnells, All Earth, Capital Recycling, Karratha Earth Moving, East Metropolitan Regional Council and the Waste Authority are all interested in the results.

?They are interested in RCC because they don?t want to bury a good resource in landfill, they want to make it something useful,? Leek explained.

Formulating a blend and process that works, using both RCC and traditional materials is important because traditional materials are often available, preferred and trusted.

?Local governments and main roads are very reluctant to move out of their comfort zones,? Leek said. ?They?ve been doing the same thing for years and they don?t want to change unless someone else takes that step first and proves that the material can be used.?

The fact that states and councils have different specifications and designs to their roads makes it tough to promote the use of RCC materials.

?Our team would like to see research findings made available to help create a uniform approach to using RCC in road construction,? Prof Nikraz said.

Source: Science Network Western Australia

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