Researchers from the University of São Paulo have created a ceramic clay that is lighter than that typically used in civil construction by adding brown algae, otherwise known as sargassum, to the manufacturing process.

"Normally, sargassum is collected and disposed of in landfills without any practical use. That's why we decided to research a way to take advantage of this large amount of biomass on the beaches," the team explained.

The material is used to reduce the weight of concrete, improve thermal comfort in slabs. Source: João Adriano Rossignolo/FZEA-USP

The researchers included algae in the production of ceramic clays that are used in construction to reduce the weight of concrete slabs.

During trials of the sargassum infused ceramic, the team incorporated sargassum into the samples at proportions of 20% and 40%, as well as 0% for comparison. Those samples were then molded and sintered at temperatures of 800° C, 900° C and 1,000° C in conventional and microwave ovens.

Once prepared, several tests were conducted to evaluate factors such as water absorption, porosity and compressive strength. A comparison was then made between the life cycle of conventional expanded clay and the various sargassum-infused formulations via a methodology that assesses the environmental impacts of a product from raw material extraction to final disposal.

The team determined that sargassum reduced the density of lightweight ceramic clay aggregates — specifically at a concentration of 40%. Yet only materials sintered in a microwave oven achieved the strength requirements at all temperatures. Meanwhile, the iterations featuring sargassum outperformed conventional expanded clay environmentally.

An article detailing the work, “Life Cycle Assessment of Lightweight Ceramic Clay Aggregates Sintered in a Microwave Oven with the Incorporation of Sargassum spp. Particles,” appears in the Journal of Materials in Civil Engineering.