Reprocessing C&D material with mobile plant

Is “sustainability” no longer a catchphrase? Engineering offices, construction projects and project regulations everywhere are incentivising or legislating the use of recycled materials, particularly C&D waste – materials from the construction and demolition of roads, bridges and buildings such as reinforced concrete, asphalt, gypsum and metal.

Most understand how reprocessing activities benefit communities when considering employment opportunities created, stimulated local economic activities and reduced environmental costs.

However, reprocessing C&D material is no longer just a method to pacify concerned parties. While some early opportunists modulated their quarrying and mining of virgin materials through the promotion of “green” campaigns, today’s activities aimed at conservation and minimising the impact to communities are rapidly emerging as a requirement. Many states, provinces and metropolitan areas around the globe are now banning the disposal of C&D materials, or require a waste reduction permit.

Fortunately, C&D reprocessing can present a profitable opportunity.

The late Astec Industries founder and CEO Dr J Don Brock often stated that “recycled materials are worth what they replace”. When one considers that the costs associated with reprocessing recycled materials are typically much less than virgin materials, it is easy to see how operations can become more lucrative when using recycled materials.

Also, when such activities are associated with a building project, companies frequently earn Leadership in Energy and Environmental Design (LEED) points that provide incentives such as tax rebates and zoning allowances. In these situations, the more recycled materials that are used, the higher the points total. By simultaneously utilising recycled materials while reducing waste streams (for example, using C&D as a recycled product on the same job site), additional points can be earned.

For the opportunist, this activity is driving demand for the use of reprocessed materials, which in turn has continued to fuel a rapidly growing market segment.


{{image2-A:R-w:250}}There are companies with roots dating back as early as the 1960s – some of which started out only as excavation contractors with a backhoe and a dump truck – that as the years went by noticed rubble being dumped into landfills and wondered if there was an additional use for this material. After some research, many such visionaries began to purchase equipment and a jobsite, and recycling operations were becoming prevalent in the United States by the late 1980s.

Many contractors looking for a way to diversify or carve out a niche in their local market reinvented their business model to be a producer whose primary objective is the recycling of concrete and asphalt materials. Using various crushing techniques, these companies process unwanted materials previously destined for the landfill into reusable aggregates for construction and landscaping purposes. Today, a typical recycling producer servicing a metropolitan area might operate up to four or five excavators, a couple of loaders, a couple of crushing systems and perhaps a dozen employees.

Bulk material recycling is a perfect business to supplement the local construction and dirt-moving projects, as today most of the local earthmoving and excavation contractors are just as happy to haul their material to a recycle “tipping facility” as the recycle producer is to receive it.

But it is not just nimble private companies that had the foresight to carve out a niche and reap the benefits of reprocessing C&D. Corporate giant Waste Management (WM), based in Houston, Texas, is one of the largest residential recyclers and a leading developer, operator and owner of waste-to-energy and landfill gas-to-energy facilities in North America.

WM recently established Toronto’s most advanced facility for processing construction and demolition waste materials, which company executives stated was aimed at supporting contractors and developers in measuring their C&D waste diversion performance and in applying for LEED certification. The total investment exceeded $16 million, and more than 20 new full-time jobs were initially created at the facility. The new C&D facility can process an estimated 87,000 tonnes of C&D material annually and is intended to allow WM to “mine” recycled materials for valuable recyclable content. This is part of WM’s sustainability goal of tripling the volume of recyclable materials being processed by 2020.


It is critical that the recycler understands the unique characteristics of the types of materials they will be processing. Like all recycled aggregate producers, if they are to sell reprocessed materials, they must supply non-contaminated products.

The process of separating dirt, clay, plastics, wood, steel, etc can be cost-prohibitive, if not managed properly.

For example, any pre-cast concrete materials typically must be crushed such that the rebar matrix, wire or mesh is liberated and separated from the concrete itself, to ensure quality and acceptability as a recycled material.

According to Ron Griess, product manager of crushing and screening for Kolberg-Pioneer, either jaw crushers or horizontal impact crushers – or both – can be effectively used to crush concrete.

“A jaw crusher does a good job compressing slabby material to help liberate rebar matrixes at a relatively low operating cost, but they will typically not provide enough reduction to produce a final end product without the use of a secondary crusher,” Griess said.

“An impact crusher is capable of providing a high enough reduction ratio to produce most recycled products, when used in conjunction with a screen; however, the trade-off is generally a much higher wear and maintenance cost associated with replacing consumables.”

According to Griess, often the best solution might entail combining a primary jaw crusher with a secondary impact crusher.
“This combination gives you higher capacity, enables better shaping of material, allows more wear-resistant consumables to be used to reduce operating costs and adds more application flexibility to the system,” he said.

Ron Fucinaro of ConReCo, based in Omaha, Nebraska, agreed.

“Before we purchased our primary jaw crusher, we crushed everything in our impact crusher,” he said. “It did the job but the maintenance was overwhelming. Now, by allowing the feed material to get crushed in the jaw first, we are able to save ripped belts, increase production and reduce our wear costs.”

Crushing asphalt presents a completely different set of challenges.

“The problem with asphalt is that as the ambient temperature heats up, like in the summer months, the oil in the asphalt makes the material sticky,” Griess said. “This can cause build-up and plug discharge openings. Normally we tell customers to use horizontal impact crushers if they want to crush asphalt. The asphalt can behave like chewing gum in a jaw when the hotter temperatures hit.”

As for brick and block, which is prevalent in C&D materials, these are typically less concerning in terms of ferrous material or plasticity problems as they are in terms of non-ferrous contamination.

“Typically, your C&D materials are coming from the demolition of a building or number of structures, and these will often contain glass, plastic, PVC, wood, etc,” Griess said. “When reprocessing such material for future use as a recycled product, a picking station with well trained staff to efficiently separate these materials is essential.”


The traditional method pioneered in the 1980s consisted of loads of recyclable materials being brought into a tipping yard.

Many such yards still exist today.

Once dumped, the material is generally separated according to type, which is critical for enabling recyclers to meet the stringent quality requirements for use as various recycled products.

According to Fucinaro, a careful examination of the initial incoming material is the first line of defence.

“Don’t accept anything you cannot handle,” he said. “For example, if the material is highly dirty and you cannot separate the dirt, you should reject the load. Otherwise you will be selling dirty material, and that can come back to haunt you in multiple ways.”

The same could be said for any non-ferrous materials that cannot be picked up by magnets. If there isn’t a picking station in place to separate plastics, wood, etc, it is best not to try to process such materials.


With the emergence of highly portable wheeled and track-mounted crushing and screening technologies, more producers are electing to take the equipment right to the material and process it in-situ.

This adds flexibility and reduces the need to haul the material (if being used on-site) or, through volume reduction, can reduce the number of haul loads to save fuel costs and impact to the community.

Griess said tracked machines were growing in popularity because of the rental aspect of the equipment.

“Thanks to the design of track machines, a lot of the ‘tribal knowledge’ that used to be mandatory to successfully crush has been built into the machine itself. Today, operators don’t have to know at what angle a conveyor needs to operate in order to prevent material roll-back, they just need to know how to maintain construction machinery.”

Clearly, the use of recycled materials through sustainability programs will only continue to grow. And as long as there is the need and the incentives, there will be those who will continue to emerge to fill that need.

Paul Smith is the international marketing manager for the Astec Aggregate & Mining Group.

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