Retaining Walls: Can You Use Recycled Concrete Aggregate As Backfill?
As roads
are being redone and buildings are being demolished, you see an increasing
emphasis on recycling the concrete instead of filling up landfills. Most uses
involve crushing the concrete to use the product as aggregate. So the question is; can this recycled
concrete aggregate (RCA) be used as backfill material behind an Allan Block retaining
wall?
The short answer in “No”
unless you take the necessary design steps to manage the chemical properties
associated with RCA. The reason is that
the cement paste component of recycled concrete aggregate has substantial
influence on the alkalinity within the aggregate. In fact, the pH levels have often exceeded
11. Keep in mind that 7 is neutral and
anything over 11 is 10,000 times more alkaline than water. Therefore, you will need to make sure the
geogrid used can resist the elevated pH levels and maintain its integrity.
Got more questions? Give us a shout! engineering@allanblock.com
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