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Researchers at Rice University have created calcium silicate spheres the size of a micron that could pave the way for a stronger, more "green" concrete.
The new spheres could be used as building blocks for a new low-cost synthetic concrete, while reducing the energy-intensive techniques currently required to make cement, the most common binder in concrete.
The researchers formed the spheres, which can be made to self-assemble into stronger, harder, more elastic, and more durable solids, in a solution around nano-sized seeds of a surfactant similar to a detergent.
"The cement does not have the most beautiful structure," said Rouzbeh Shahsavari, assistant professor of materials science and nanotechnology at Rice. "The cement particles are amorphous and disorganized, which makes them a little vulnerable to cracks.
"But with this material, we know what our limits are and we can channel polymers or other materials between the spheres to control the structure from the bottom up and predict more precisely how it could fracture," he said. -he adds.
Researchers are able to control the size of spheres, ranging in diameter from 100 to 500 nanometers, by manipulating surfactants, solutions, concentrations and temperatures during the manufacturing process.
"These are very simple but universal building blocks, two essential features of many biomaterials," Shahsavari said. "They allow advanced features in synthetic materials.
"Previously, there were attempts to manufacture platelet or fiber building blocks for composites, but this book uses spheres to create strong, resilient and adaptable biomimetic materials," he added. "Sphere shapes are important because they are much easier to synthesize, assemble and evolve from a chemistry and large scale manufacturing point of view."
During the tests, the team used two common surfactants to make the spheres and compress their products into pellets, observing that the DTAB-based granules were more compact and resistant than the CTAB granules.
Particle size and shape have a significant impact on the mechanical properties and durability of bulk materials.
"It's very beneficial to have something that you can control as opposed to a material that is random in nature," Shahsavari said. "In addition, spheres of different diameters can be mixed to fill gaps between self-assembled structures, leading to higher packaging densities and thus mechanical and durability properties.
By increasing the strength of the cement, manufacturers can use less concrete and reduce the energy required for manufacturing. They can also reduce the carbon emissions associated with cement production.
In addition, since spheres are more effective than the shredded particles currently found in ordinary cement, the new material will be more resistant to harmful ions from water and other contaminants and will require less and will last longer.
Apart from concrete, spheres could be used in a number of other applications, including bone tissue engineering, insulation, and ceramics or composite applications.
The study was published in Langmuir.
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