EYE ON THE ENVIRONMENT | What you need to know about concrete downcycling and recycling – VC Reporter


Pictured: Material crushers and conveyors at Santa Paula Materials Inc.

by David Goldstein

Almost all curbside recyclables can be recycled in a “closed loop”, which means that aluminum, glass, plastic and paper can be made into cans, bottles and paper. On the other hand, concrete, recycled in much higher tonnages than commonly recycled materials, can only be downcycled into a lower value product. A closely related material, asphalt, can be recycled into asphalt, but only if it is not mixed with concrete.

Rather than turning discarded concrete, or asphalt mixed with concrete, into new concrete, the best that can be expected from recyclers is to grind the material into a road foundation. The recycled road base, placed as an aggregate under a new paving material, is still ecologically important. Making a road base from urban waste generally has less of an environmental impact than mining rock from natural habitats.

Nevertheless, the energy loss due to recycling paving materials is remarkable. In an article that originally appeared in the online news publication The Hill and distributed last week on MSN, Ognjen Miljanić, professor of chemistry at the University of Houston, cited concrete manufacturing as one of the reasons why ongoing efforts to convert the US electricity grid into clean energy are not sufficient to meet national targets for reducing emissions from climate change.

Citing data from the US Energy Information Administration’s April 2021 Energy Monthly Review, Miljanić states that only about 18% of total US energy use comes from electricity and that “many consuming processes energy simply cannot be electrified ”. For example, “there are no electric planes, Christmas shopping cannot arrive from China on an electric container ship” and “the cement (from which concrete is made) produced using electricity would easily cost three times more than »current prices and would require new electrical infrastructure. Simply electrifying the country’s cars will require an increase in power generation capacity by 25%, according to Miljanić.

Little is known about the facts about concrete, but they illustrate an important environmental point. The waste management hierarchy does not put recycling at the top. The first is “reduce” and the second is “reuse”. Concrete can be reused as a road base, but the best environmental option is to reduce it. If you are thinking about paving part of your property, consider other options.

The concrete industry has been looking for ways to reduce the impact of its product. According to an Oct. 7 article by Stacy Liberatore on Dailymail.com, researchers at the University of Tokyo have found a way to turn waste concrete into new concrete while capturing carbon dioxide from industrial exhaust gases. According to researchers cited by Liberatore, concrete manufacturing currently emits 7% of the world’s carbon dioxide, so commercializing this technology could make a big difference.

While recycling concrete does not currently allow us to recover the energy invested in its manufacture, it does save money. Here are some tips for recycling concrete in Ventura County:

Concrete cannot be placed in your curbside recycling cart or commercial mixed recycling bin. Weight limits, printed on most containers, also prevent the placement of items such as concrete masonry blocks in most disposal containers. Nearly ten local inert recycling facilities offer significant discounts for the reception of the material, compensating for the inconvenience associated with the delivery of the material to them.

If you only have one piece of concrete less than a meter in diameter (resulting, for example, from removing a basketball post from an alley), some garbage collection companies will allow you to ‘Use your free annual bulky items collection allowance and will come to your home and load it into their forklift in response to your call. Second, if you have enough concrete to justify the cost, you can order a low-boy (short-sided) roller box instead of a trash can from your garbage collector.

Local landfills recycle concrete and asphalt into roads and platforms. Currently, the Toland Road landfill, which only accepts material from Fillmore, Santa Paula and Piru, does not charge to take the material, provided the rebar is cut flush and the parts are no longer than one foot on one foot.

David Goldstein, Environmental Resources Analyst with the Ventura County Public Works Agency, can be reached at 805-658-4312 or [email protected]


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