Using polymers and natural stone slurry waste, researchers at UBC Okanagan are manufacturing environmentally friendly stone composites.

These new composites are made of previously discarded materials left behind during the cutting of natural structural or ornamental stone blocks for buildings, construction supplies or monuments. While reusing the waste material of natural stone production is common in cement, tile and concrete, adding the stone slurry to polymers is a new and innovative idea, explains School of Engineering Professor Abbas Milani.

A growing industrial demand for multifunctional bio-friendly raw materials is pushing researchers to develop value-added and energy-saving biocomposites and processes, he explains.

“Because the slurry is a waste material, it comes at a lower cost for recycled composite production,” says Milani, director of UBC’s Materials and Manufacturing Research Institute (MMRI)

Milani and his colleagues recently received UBC eminence funding to establish a cluster of research excellence in biocomposites. The cluster will develop novel agricultural and forestry-based bio and recycled composites to minimize the impact of conventional plastics and waste on the environment.

The powdered stone waste used in the project provides flexibility to the new particulate polymer matrix composite. It can be mixed at different ratios into the finished product through appropriate heat or pressure to meet structural requirements or aesthetic choices, defined by industry and customers.

“This green stone composite can easily be integrated into a variety of applications,” says UBC Research Associate Davoud Karimi. “These composites can be used in decorations and sanitation products ranging from aerospace to automotive applications.”

The researchers varied the amount of stone added to the composites then tested several parameters to determine strength, durability and density along with thermal conductivity. The molding and mechanical tests were conducted in the Composites Research Network Okanagan Laboratory with collaboration from the MMRI.

By adding the stone waste to the composites, researchers determined that it not only increased the virgin polymer’s strength and durability, but the composites’ conductivity increased proportionally based on the amount of stone added.

“The increased strength is important, but the increased conductivity (up to 500 per cent) opens a huge door to several new potential applications, including 3D printing with recycled composites,” explains Milani.

“Any time we can divert waste from landfills and generate a product with the potential of economic benefit is a win-win,” Milani adds. “We hope that these sorts of products, that are carefully designed with the aid of multi-disciplinary researchers focused on 3R measures (repairable, reusable, and recyclable), can significantly contribute to the economy of our region and Canada as a whole.”

The research was funded by the Natural Sciences and Engineering Research Council (NSERC) and the National Research Institute for Science Policy (NRISP). It was recently published in two prestigious journals Composite Structures and Composites Part B: Engineering.

Microorganisms growing inside aging buildings and infrastructure are more than just a health issue, according to new research from UBC Okanagan.

The research, coming from the School of Engineering and biology department, examined the impact of fungal mould growth and associated microbes within structures on university campuses. The study focuses on the observed biodeteriorative capabilities of indoor fungi upon gypsum board material (drywall) and how it affects a building’s age and room functionality.

Assistant Professor Sepideh Pakpour says fungal growth significantly affected the physical (weight loss) and mechanical (tensile strength) properties of moisture-exposed gypsum board samples. In some cases, tensile strength and weight of some boards decreased by more than 80 per cent.

And she notes the issue of fungal growth, intensified by climate change, is two-fold.

“Increasing flooding and rainfall related to climate change is aiding fungi to grow more rapidly, causing degradation of the mechanical properties of buildings and infrastructure,” she says. “Not only are the fungi breaking down the integrity of our buildings, but their proliferation is increasing health hazards for the people who live and work in these buildings.”

The researchers also looked at other factors that can impact microbial growth including temperature, humidity, dustiness and occupancy levels—the more people, the quicker it can grow

According to the study, drywall experienced a significant effect on its mechanical properties when microbes were present. If the microbes were bolstered by moisture, the drywall’s ability to withstand breakage when under tension dropped 20 per cent. Older buildings, on average, exhibited higher concentrations and types of fungi in the air, leading to higher mould coverage and biodeterioration on the drywall.

“Our findings would suggest a critical need towards multi-criteria design and optimization of next-generation healthy buildings,” explains Pakpour. “Furthermore, we hope this study will enable engineers, architects and builders to develop optimal designs for highly microbial-resistant building materials that will decrease long-term economic losses and occupant health concerns.”

The inter-disciplinary research was overseen by UBCO Biology Professor John Klironomos, Professor Abbas Milani, director of the School of Engineering’s Materials and Manufacturing Research Institute, and Pakpour, who supervised the microbial and material degradation analyses conducted by their doctoral student Negin Kazemian.

The researchers plan on turning their attention next to the exposure levels of airborne microorganisms and possible remedies.

The latest study, partially funded by a Natural Sciences and Engineering Research Council of Canada grant, was published in PLOS One, a peer-reviewed, open-access scientific journal.