A lot of waste and pollution is generated every year by the construction industry. One of the best ways to make this essential industry more environmentally friendly is recycling. Recycling saves substantial amounts of energy, and generally decreases demand for new materials that are produced using natural resources. For example, if all of the asphalt and concrete waste generated in the US in one year were to be recycled, it would save about as much energy as 1 billion gallons of gasoline.
Recycling construction waste also significantly reduces the amount of waste that gets sent to landfills. Landfills are a finite resource, and they promote toxic build-up in the environment.
Here are five construction materials that are actually very recyclable!
Concrete
The first step of concrete recycling is to crush or pulverize the rubble at a location near the demolition or building site. This is done with industrial crushing equipment. After the initial phase of concrete breakup, the rubble gets run through a secondary impactor and then screen to separate small and large aggregate. Sometimes it gets further processed via water flotation, separation, or magnets to remove specific elements from the crushed concrete.
Once processed, recycled concrete can gain new life as gravel, paving material, or aggregate all of which have a variety of potential applications. Recycled crushed concrete can also be used to help control erosion along vulnerable stream banks or gullies. Recycled concrete can even be used to help rebuild coral reefs!
Slurry
Slurry is a mixture of stone and water or concrete and water. In construction, slurry usually comes from working with concrete, but it’s also a significant presence in the mining industry.
Current laws prohibit slurry from being dumped down the drain into public sewer systems because it is potentially toxic. Separating the water from the slurry with a filter press or slurry separator reduces the amount of waste and creates reusable, clean water. Remaining slurry gets solidified with nontoxic solidifying agents that encapsulate heavy metals.
Slurry waste can be reused to replace certain components in concrete. It can also be used in the manufacturing of clay bricks. Both applications are safe and do not compromise the strength of the new material.
Asphalt
Asphalt is the result of combining a binding material such as bitumen with an aggregate such as rock, stone, or sand. Bitumen is a petroleum product leftover from the crude oil refining process, although there is a more eco-friendly way to make the substance from corn stalks and other plant material.
Because asphalt is heavy and not at all biodegradable, asphalt recycling is particularly important. Fortunately, it’s also pretty easy. Asphalt recycling is much like concrete recycling. Waste asphalt gets crushed back into aggregate, then mixed in an asphalt recycler or reclaimer along with water and additives. Then it undergoes different treatments depending on the recycling method being used, before being reused elsewhere — typically to make more asphalt.
There is a lot of demand for recycled asphalt. As it turns out, mixing recycled asphalt with virgin asphalt has been shown to make the resulting product stronger than one made with entirely new materials. According to data from the U.S. Environmental Protection Agency and the Federal Highway Administration, about 90 million tons of asphalt pavement are reclaimed each year.
Lumber
Wood is more biodegradable than other construction materials, but that doesn’t mean it should be wasted. Currently wood from construction and demolition activities comprises about 28 percent of the total tonnage at landfills.
Many types of wood are recyclable, such as uprooted/felled trees, used lumber, shipping pallets, and miscellaneous wood debris from construction. The only wood that isn’t recyclable is contaminated wood that has been treated with creosote, stain, paint, or otherwise.
Recycled wood has a variety of potential applications. It can be processed into soil conditioner, pulped for paper, used as a sewage sludge bulking medium, compost additive, animal bedding, mulched, or burned as fuel to produce electricity and steam. Recycled wood can also gain new life in plywood, laminate, or particleboard.
Drywall
Drywall is essentially a sheet of gypsum (a type of rock, specifically calcium sulfate dihydrate) sandwiched between large sheets of paper. When drywall is recycled, contaminants such as nails and screws are removed, and the paper gets separated from the gypsum. The gypsum is then ground into powder or turned into pellets, which is then sold to anyone who wants it.
Gypsum has many uses outside of construction. It has many applications in fertilizing, conditioning, and amending soils, as well as in composting. It makes a good additive in animal bedding and plays a vital role in waste stabilization. It is also used as a filler/dilutant for plastics, adhesives, paint, wood filler, tile grout, body putty, textiles, and modeling clay. It can also be used as an ingredient in cement to prevent it from setting too quickly. It even plays a role in water clarification!
Conclusion
Construction recycling is an important part of making human activity more sustainable on this planet, making the most out of the resources we already have rather than depleting Earth further. We are already well on our way to making construction waste recycling more popular in the industry, but there is still more that can — and should — be done.
