Researchers from Newcastle University have created a mortar using silica aerogel and recycled plastic that enhances insulation and decreases plastic waste. Their findings were published in the journal Construction and Building Materials.
Thermal tests were carried out for the samples. Image Credit: Newcastle University
In addition to being environmentally sustainable, the team hopes this novel building material would lower heating and cooling costs.
By substituting silica aerogel and recycled PET plastic for sand, they created a lighter cement mortar mix that exhibits better thermal insulation. Due to their great insulating qualities, aerogels are increasingly used for thermal insulation, especially in the building and aerospace industries.
In contrast to traditional mortar, the researchers demonstrated that the novel mortar mix preserved the strength needed for masonry building while reducing heat loss by up to 55%.
Additionally, it satisfies international requirements (BS-EN 413-1:2011, ASTM C270-10, AS 1012/AS 3700), offering a sustainable and environmentally friendly substitute for energy-efficient construction.
This could enhance environmentally friendly building techniques while lowering heat loss in structures where thermal bridging occurs, such as in mortar-filled spaces between bricks in walls.
This study demonstrates that our formulation of recycled PET plastic waste can be used to produce cement-based mortars, and it is an effective way to reduce their impact on the environment. Would not be wonderful to reduce the heating bills of all our new builds and at the same time significantly reduce plastic waste in the world?
Lidija Šiller, Study Lead Author and Professor, Nanoscale Science, School of Engineering, Newcastle University
The New Mortar Mix
The most successful novel mortar mixes, which included seven distinct formulations tested alongside conventional mortar, were 3% recycled PET (polyethene terephthalate) plastic and 7% untreated silica aerogels in place of natural sand.
The PET plastic particles used in the study were coarse, irregularly shaped, and between 2.5 and 3.5 mm. They were obtained from the trash of shredded plastic bottles. After shredding the plastic, the researchers rinsed it with water and let it dry for a full day at room temperature.
The group examined important characteristics such density, strength, thermal conductivity, flowability (a metric used to assess cement mortar's workability), and setting time.
Compared to regular mortar samples, the novel formulation helped lower the mortar's heat conductivity by as much as 55%.
Improvement of the thermal performance of masonry buildings by reducing the energy required for heating and cooling in buildings to meet the users' comfort is one of the main topics considered in the modern construction sector. In our work, the modification of the surface of the silica aerogel particles was a crucial step towards successfully implementing silica aerogel particles within the cement binder and PET plastic.
Kaniaw Marof, Study Lead Author and PhD Researcher, School of Engineering, Newcastle University
The scientists want to test the new mixture in a real-world, large-scale environment.
Now it is possible to reach all British standards for this new reduced thermal heat mortar with plastic and aerogels. For the next step, we wish to find collaborators such as a construction company to apply for funding and build the house with our ‘recipe’ for mortar. This will allow us to provide direct evidence of potential energy savings and assess the economics for masonry buildings applications.
Lidija Šiller, Study Lead Author and Professor, Nanoscale Science, School of Engineering, Newcastle University
Journal Reference:
Marof, K., et al. (2025) Enhancing thermal insulation in cement mortar with silica aerogel and recycled PET plastic. Construction and Building Materials. doi.org/10.1016/j.conbuildmat.2025.140320.