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

by David Goldstein

Nearly all curbside recyclables can be recycled in a “closed loop,” meaning, aluminum, glass, plastic and paper can be turned back into cans, bottles and paper. In contrast, concrete, recycled in tonnages far greater than commonly recycled materials, can only be downcycled into a product of lower value. A closely related material, asphalt, can be recycled back 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 we can expect from recyclers is to crush the material into road base. Recycled road base, placed as an aggregate under new paving material, is still ecologically important. Making road base from urban waste generally has fewer environmental impacts than mining rocks from natural habitats. 

Nevertheless, energy lost through downcycling paving material is noteworthy. In an article originally appearing in the online news publication The Hill and distributed last week through MSN, Ognjen Miljanić, professor of chemistry at the University of Houston, cited concrete manufacturing as one reason why ongoing efforts to convert the American electrical grid to clean energy will not be sufficient to meet national climate change emission reduction goals. 

Citing data from the U.S. Energy Information Administration’s April 2021 Monthly Energy Review, Miljanić states that only about 18 percent of total American energy use comes from electricity, and “many energy-consuming processes simply cannot be electrified.” For example, “there are no electric airplanes, Christmas shopping cannot arrive from China on an electric container ship” and “cement (from which concrete is made) produced using electricity would easily cost three times as much as” current prices and would require massive new electricity infrastructure. Just electrifying the nation’s cars will require expanding electric generating capacity 25 percent, according to Miljanić.

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

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

While recycling concrete does not currently 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 preclude placement of items like concrete masonry blocks in most disposal containers. Nearly a dozen local facilities for inert recycling offer significant discounts to accept the material, compensating for the inconvenience of hauling material to them. 

If you have only a single chunk of concrete under three feet in diameter (resulting, for example, from removing a basketball post from a driveway), some garbage collection companies will allow you to use your free annual bulky item collection allocation and will come to your home and load it into their lift-gate truck in response to your call. Second, if you have enough concrete to justify the cost, you might order a “low-boy” (short sided) roll-off box instead of a bin from your refuse collector. 

Local landfills recycle concrete and asphalt into roads and pads. Currently, the Toland Road Landfill, which accepts material only from Fillmore, Santa Paula and Piru, is not charging to take the material, provided rebar is cut flush and pieces are no larger than one foot by one foot.

David Goldstein, Ventura County Public Works Agency Environmental Resource Analyst, can be reached as 805-658-4312 or david.goldstein@ventura.org.