Researchers create microscopic spheres that could lead to low-cost synthetic concrete

Updated Oct 10, 2018
Packed, micron-scale calcium silicate spheres developed at Rice University. Photo: Multiscale Materials Laboratory/Rice University.Packed, micron-scale calcium silicate spheres developed at Rice University. Photo: Multiscale Materials Laboratory/Rice University.

Micron-sized calcium silicate spheres developed by researchers at Rice University could be used to create a new low-cost synthetic concrete, and reduce the amount of energy required to make cement at the same time, R&D reports.

“Cement doesn’t have the nicest structure,” Rouzbeh Shahsavari, an assistant professor of materials science and nanoengineering at Rice, said in a statement, according to the news agency. “Cement particles are amorphous and disorganized, which makes it a bit vulnerable to cracks. But with this material, we know what our limits are, and we can channel polymers or other materials in between the spheres to control the structure from bottom to top and predict more accurately how it could fracture.”

The spheres, which range from 100 to 500 nanometers in diameter, can be made to self-assemble into stronger, harder, more elastic, and more durable solids around nanoscale seeds of a common detergent-like surfactant, and can be controlled by manipulating surfactants, solutions, concentrations, and temperatures during the manufacturing process.

“These are very simple but universal building blocks, two key traits of many biomaterials,” Shahsavari said, according to the news agency. “They enable advanced functionalities in synthetic materials. Previously, there were attempts to make platelet or fiber building blocks for composites, but this work uses spheres to create strong, tough, and adaptable biomimetic materials. Sphere shapes are important because they are far easier to synthesize, self-assemble, and scale up from chemistry and large-scale manufacturing standpoints.”

Two common surfactants were used to make the spheres and compress them into pellets during tests. Researchers found that the size and shape of particles have an impact on the mechanical properties and durability of the end product. DTAB-based pellets compacted better and were tougher, with a higher elastic modulus and electrical resistance, than CTAB pellets or common cement.

“It is very beneficial to have something you can control as opposed to a material that is random by nature,” Shahsavari said, according to the news agency. “Further, one can mix spheres with different diameters to fill the gaps between the self-assembled structures, leading to higher packing densities and, thus, mechanical and durability properties.”

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Stronger cement allows manufacturers to use less concrete, decreases the energy needed to make it, and reduces carbon emissions. The spheres also pack more efficiently than ragged particles found in common cement, so they will be more resistant to damage from water and other contaminants, requiring less maintenance and lasting longer.