Houses made of waste
Some engineers are more ambitious than others. Two UK engineers plan to replace the 350 million concrete blocks manufactured in the UK each year by blocks made almost entirely of waste materials such as crushed glass, pulverized fuel ash, and bitumen, a by-product of the petrochemical industry. The 'Bitublocks' are about six times stronger as concrete and will not be more expensive. These eco-friendly materials should become available in about three to five years, but a house prototype should be available soon.
This new material would be beneficial to the environment for two reasons. First, there will be no need for cement which generates huge amounts of carbon dioxide. And there will be no more needs to use energy to burn millions tons of waste into incinerators.
Below is a picture of a Bitublock, a construction unit composed of recycled waste materials and bituminous binders (Credit: John Forth, University of Leeds).
This project is the brainchild of civil engineer Dr John Forth from University of Leeds and of Dr Salah Zoorob from the University of Nottingham. Their research has been funded by a £280K grant from the Engineering and Physical Sciences Research Council.
In "Building blocks from waste," published on March 2, 2007 by environmentalresearchweb.org, Nadya Anscombe provides additional details (Free registration needed).
The researchers' Bitublock uses bitumen as a binder and a variety of waste materials as aggregate, including crushed glass, pulverised fuel ash, incinerated bottom ash, incinerated sewage sludge ash and steel slag. The bitumen is first heated to make it flow, then mixed with the heated aggregate and compacted in a mould. It is then cured to oxidize the bitumen, making it hard and brittle.
The resultant blocks perform surprisingly well, says Forth. "We can make blocks that match and exceed the compressive strength of concrete blocks. Of course their properties depend on the kind of bitumen and aggregates we use as well as the compaction pressure and curing regime, but it's clear that Bitublocks can be produced with properties that are at least equivalent to current concrete block masonry units."
For more technical information about the Bitublock and its components, here is a link to the project home page, from which the above picture has been picked.
Finally, the two engineers are now thinking about building 'Vegeblocks' using waste vegetable oil. You'll find more details about the Bitublock and the Vegeblock in this short technical paper, "Non-traditional binders for construction materials" (PDF format, 6 pages), which was presented in July 2006 at the IABSE Henderson Colloquium in Cambridge.
Sources: University of Leeds news release, via EurekAlert!, April 2, 2007; and various websites
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