Recycling asphalt and concrete for greener construction


Buildings and roads construction/maintenance is a costly and resource-consuming process which raises concerns to the environment. Asphalt for the roads, as well as concrete for buildings wear out over time, and acquiring these materials could further deplete environment if not done properly. Luckily, today, new recycling technologies may overcome this issue.

Recycling the roads

Asphalt, consisting of gravel bounded with other materials bound by a thick petroleum, will become brittle and crack over continuous exposure to elements – hence repavement is needed to be done in a regular basis. However, when the old asphalt is pulled up, only a small fraction can be reused and the rest (majority of it) goes to waste in a landfill or gets stacked up for later use.

One possible solution for repavement is to add oil to the old asphalt to making it supple again, but it would make it too soft. Besides, the petroleum cost would cause another problem financially.

In attempt to resolve this, a group of researchers in Wilmington, Massachusetts, conceived a new plant-based compound, non-toxic molecule called Delta S. This molecule reverses oxidation in the asphalt while pulling off the old petroleum from the pieces of stone aggregate, eventually binding the whole substance together.

By restoring the binder in recycled asphalt to its original performance, 50% of the asphalt will be reusable with the same performance and lifespan of a new one.

It is not a new innovation, there are already similar technologies out there but they are toxic. And unlike them, Delta S is admittedly safe – edible, even.

This alternate product allows higher percentage of use of old asphalt, which means lower cost and reduced consumption of the heavy, toxic petroleum in fresh asphalt. I also enables asphalt to be mixed at a much lower temperature (~180 degrees compared to ~380 degrees), which means less oil evaporation, air pollution, and waster petroleum.

Recycling old buildings

On the other hand, buildings also embrace more recycled elements, which brings us to recycled concrete. The recycled concrete, sized in an inch made out of chopped-up pieces of old concrete, is found to be having much higher quality than what it was being used for.

There is also another research that reveals that the recycled concrete is just as strong as concrete with no recycled components.

Other recycled materials also make it into buildings. Coal fly ash, bottom ash, slag, and spent foundry sand, to name a few, can be used as structural fill.

At the end of the day, reusable materials aren’t really as much a question of technology as much as a question of infrastructure and economics. With global materials becoming more and more scarce, people will seek for materials closer to home.

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