Small spheres offer a potential solution to a concrete problem The engineer

Spheres of calcium silicate the size of a micron could help create a stronger and more environmentally friendly concrete, say scientists at Rice University in Houston, Texas.

Materials scientist Rouzbeh Shahsavari and graduate student Sung Hoon Hwang formed the spheres of a solution around nanoscale seeds of a common detergent-type surfactant. According to Rice, spheres can be encouraged to self-assemble into solids that are stronger, harder, more elastic, and more durable than Portland cement.

"The cement does not have the most pleasant structure," said Shahsavari, assistant professor of materials science and nanotechnology. "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 bottom-up structure and more precisely predict how it might fracture.

In addition, Shahsavari said the spheres are suitable for bone tissue engineering, insulation, ceramics and composite applications, as well as cement. The search appears in Langmuir.

The researchers found they could control the size of spheres – ranging from 100 to 500 nanometers in diameter – by manipulating surfactants, solutions, concentrations, and temperatures during manufacturing.

"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 work uses spheres to create strong, resilient and adaptable biomimetic materials.

"Spherical shapes are important because they are much easier to synthesize, assemble automatically, and evolve from a chemical and large scale manufacturing perspective."

In the tests, the researchers used two common surfactants to make spheres and compress their products into pellets for testing. They found that DTAB-based pellets compacted better and were stronger, with a higher elastic modulus than CTAB pellets or common cement. They also showed a high electrical resistance.

Shahsavari said particle size and shape in general have a significant effect on the mechanical properties and durability of bulk materials such as concrete. "It's very beneficial to have something you can control as opposed to random material by nature," he said in a statement. "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.

According to Shahsavari, increasing the strength of cement will allow manufacturers to use less concrete, reduce weight, produce the necessary energy and emit carbon emissions associated with cement manufacturing . Since the spheres condition more efficiently than the shredded particles present in the common cement, the resulting material will be more resistant to harmful ions of water and other contaminants and should require less maintenance. and a less frequent replacement.

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