Recycled glass, a strong and sustainable building material
Recycled glass is gaining traction as an eco-friendly ingredient in the construction industry. A recent study from the University of Portsmouth investigated the use of recycled waste glass powder (RWGP) as a stabilizing agent in compressed earth blocks, paving the way for greener alternatives to conventional cement.
According to the researchers, compressed earth blocks made from a mixture of soil and water compacted under high pressure are usually stabilized with cement. By replacing it with recycled glass, a reliable level of stabilization can be achieved, which also includes lime and a significantly reduced amount of cement.
The study, published in Discover Civil Engineering, tested compressed earth blocks made with recycled glass particles in varying percentages, ranging from 0% to 25%. In addition to determining their mechanical properties, the blocks were examined for their microstructural characteristics using an electron microscope over a 28-day period.
Testing bricks made with recycled glass
The experimental phase focused on three key performance indicators:
- Water absorption, to evaluate moisture resistance
- Compressive strength, to measure how much pressure the blocks could withstand
- Tensile strength, to assess resistance to pulling or stretching forces
“After testing blocks made with various mixtures of lime and recycled glass waste, we found that a blend with 10% lime and 10% recycled glass particles produced the strongest blocks, showing no cracking under intense pressure,” one of the study authors reported.
Improved compressive strength
The tests revealed that compressed earth blocks became significantly stronger and more durable when stabilized with recycled glass powder and lime, compared to blocks made with soil alone. Notably, compressive strength, a key indicator of how much force a material can bear before breaking, showed substantial gains.
The highest compressive strength recorded was 5.77 MPa (megapascals), achieved with blocks containing 10% RWGP and 10% lime after 28 days of curing. This figure represents a 90% improvement over the unstabilized samples, which measured just 3.03 MPa.
Enhanced tensile strength
Tensile strength refers to a material’s ability to resist being pulled or stretched before breaking. The unstabilized blocks reached up to 0.40 MPa, while those containing 10% RWGP and 10% lime reached 0.52 MPa, a 30% increase. This gain means the stabilized blocks are more flexible and less prone to cracking under stress.
In summary, adding a precise amount of recycled glass and lime significantly improves the strength and stability of compressed earth blocks, under both compression and tension. The study supports scaling up their use in construction as a more reliable and sustainable alternative to traditional materials.