New method allows concrete to be recycled by adding wood
Siobhan Treacy | February 20, 2020Researchers from the Institute of Industrial Science at the University of Tokyo created a new procedure for recycling concrete by adding discarded wood.
The correct proportion of wood and concrete inputs yields an entirely new building material, with bending strength that is superior to the original concrete. This would reduce construction costs and cut carbon emissions from concrete production.
Concrete has two parts: aggregate, which is made of gravel and stone, and cement. One recycling option is to reuse the aggregate, but this is unsustainable because the problem is in new concrete production - the new method adjusts the mixture proportion, pressure, temperature, pressing duration and water content.
Wood is rigid due to lignin. In the new material, lignin fills gaps in the concrete and functions as an adhesive with waste concrete powered when heated. The material strength improved in higher temperatures and pressure during pressing. It is also likely to be biodegradable because concrete waste is attached to a wood component.
The team says that the new method could be extended to other kinds of discarded plant matter. A paper on this new procedure will be published in the Sixth International Conference on Construction Materials.
a lot seems to have been lost in translation.
A promising concept, so far...
If the added wood (particles?) make the concrete more biodegradable, then a traditional concrete structure that is typically designed for a 50-year service-life would have to be totally replaced twice if the service life if the wood-concrete service life was only, say, 25 years. Where's the economy in that?
Do they yet know how long before the wood-particles start to (chemically deteriorate) in outdoor weather conditions?
Also, if the proposed wood-concrete does provide more flexural strength, then would not there need to be added more rebar steel for the wood-concrete to keep its' original, undeformed shape?
So far, it sounds like such wood-concrete is only useable in semi-structural projects, with shorter expected life spans, where it can be better protected from direct environmental exposures.
(... and, have they done any side-by-side seismic testing yet?)
In reply to #2
The bottom-line should be to answer the question:
''Such a new wood-concrete process produces (how much) percentage less carbon emission per-cubic-(yard/metr e/other-unit-of-volu me) than the current concrete process produces?''
HardiePlank siding and similar is cement with cellulose and it is durable. Such non-structural applications may be the focus of this research.