Glassy blocks could build sustainability into construction
Recycled glass could potentially become a staple for earth blocks.
University of Portsmouth, UK, scientists say they have identified the optimum ratio for incorporating glass waste into compressed earth blocks. The group tested the potential for using powdered recycled glass as a stabilising agent in the blocks.
Compressed earth blocks, made of soil mixed with water, and compressed at high pressure, are usually stabilised with cement. This work has shown that a reliable level of stabilisation can be achieved with a mix that includes recycled glass together with lime and a significantly reduced amount of cement.
Testing was undertaken on blocks prepared with recycled waste glass particles (RWGP) in the mix at ratios of zero to 25%.
Apart from determining the mechanical properties, the blocks were examined for microstructural characteristics using an electron microscope for 28 days.
Co-author, Dr Muhammad Ali explains, ‘At each percentage level we tested for water absorption, how resistant to breaking the blocks were when compressed, and to determine the maximum stress the block could withstand while being stretched or pulled, before breaking or becoming deformed.
‘We found that a composition of 10% lime and 10% recycled glass particles produced the strongest blocks with no cracking under intense pressure.’
This combination gave the highest compressive strength of 5.77 MPa, while the unstabilised specimens achieved 3.03 MPa at 28 days of curing. It also revealed the highest tensile strength of 0.52 MPa, while the unstabilised specimens achieved 0.40 MPa at 28 days of curing.
The team says future studies could assess the thermal and durability properties of these greener construction materials.
