Subscribe free to our newsletters via your
. 24/7 Space News .




Subscribe free to our newsletters via your




















TECH SPACE
Decoding cement's shape promises greener concrete
by Staff Writers
Houston TX (SPX) Dec 12, 2016


Rice University scientists created microscopic cubes and other shapes of cement and crushed them to test their mechanical properties. The shapes may serve as 'seeds' for the bottom-up manufacture of stronger, more durable concrete. Image courtesy Multiscale Materials Laboratory/Rice University. For a larger version of this image please go here.

Bringing order to disorder is key to making stronger and greener cement, the paste that binds concrete. Scientists at Rice University have decoded the kinetic properties of cement and developed a way to "program" the microscopic, semicrystalline particles within. The process turns particles from disordered clumps into regimented cubes, spheres and other forms that combine to make the material less porous and more durable.

Their study appears in the Royal Society of Chemistry's Journal of Materials Chemistry A.

The technique may lead to stronger structures that require less concrete - and less is better, said Rice materials scientist and lead author Rouzbeh Shahsavari. Worldwide production of more than 3 billion tons of concrete a year now emits as much as 10 percent of the carbon dioxide, a greenhouse gas, released to the atmosphere.

Through extensive experiments, Shahsavari and his colleagues decoded the nanoscale reactions - or "morphogenesis" - of the crystallization within calcium-silicate hydrate (C-S-H) cement that holds concrete together.

For the first time, they synthesized C-S-H particles in a variety of shapes, including cubes, rectangular prisms, dendrites, core-shells and rhombohedra and mapped them into a unified morphology diagram for manufacturers and builders who wish to engineer concrete from the bottom up.

"We call it programmable cement," he said. "The great advance of this work is that it's the first step in controlling the kinetics of cement to get desired shapes. We show how one can control the morphology and size of the basic building blocks of C-S-H so that they can self-assemble into microstructures with far greater packing density compared with conventional amorphous C-S-H microstructures."

He said the idea is akin to the self-assembly of metallic crystals and polymers. "It's a hot area, and researchers are taking advantage of it," Shahsavari said. "But when it comes to cement and concrete, it is extremely difficult to control their bottom-up assembly. Our work provides the first recipe for such advanced synthesis.

"The seed particles form first, automatically, in our reactions, and then they dominate the process as the rest of the material forms around them," he said. "That's the beauty of it. It's in situ, seed-mediated growth and does not require external addition of seed particles, as commonly done in the industry to promote crystallization and growth."

Previous techniques to create ordered crystals in C-S-H required high temperatures or pressures, prolonged reaction times and the use of organic precursors, but none were efficient or environmentally benign, Shahsavari said.

The Rice lab created well-shaped cubes and rectangles by adding small amounts of positive or negative ionic surfactants and calcium silicate to C-S-H and exposing the mix to carbon dioxide and ultrasonic sound. The crystal seeds took shape around surfactant micelles within 25 minutes. Decreasing the calcium silicate yielded more spherical particles and smaller cubes, while increasing it formed clumped spheres and interlocking cubes.

Once the calcite "seeds" form, they trigger the molecules around them to self-assemble into cubes, spheres and other shapes that are orders of magnitude larger. These can pack more tightly together in concrete than amorphous particles, Shahsavari said. Carefully modulating the precursor concentration, temperature and duration of the reaction varies the yield, size and morphology of the final particles.

The discovery is an important step in concrete research, he said. It builds upon his work as part of the Massachusetts Institute of Technology team that decoded cement's molecular "DNA" in 2009. "There is currently no control over C-S-H shape," Shahsavari said. "The concrete used today is an amorphous colloid with significant porosity that entails reduced strength and durability."

Concrete is one focus of Shahsavari's Rice lab, which has studied both its macroscale manufacture and intrinsic nanoscale properties. Because concrete is the world's most common construction material and a significant source of atmospheric carbon dioxide, he is convinced of the importance of developing "greener" concrete.

The new technique has several environmental benefits, Shahsavari said. "One is that you need less of it (the concrete) because it is stronger. This stems from better packing of the cubic particles, which leads to stronger microstructures. The other is that it will be more durable. Less porosity makes it harder for unwanted chemicals to find a path through the concrete, so it does a better job of protecting steel reinforcement inside."

The research required the team to develop a method to test microscopic concrete particles for strength. The researchers used a diamond-tipped nanoindenter to crush single cement particles with a flat edge.

They programmed the indenter to move from one nanoparticle to the next and crush it and gathered mechanical data on hundreds of particles of various shapes in one run. "Other research groups have tested bulk cement and concrete, but no group had ever probed the mechanics of single C-S-H particles and the effect of shape on mechanics of individual particles," Shahsavari said.

He said strategies developed during the project could have implications for other applications, including bone tissue engineering, drug delivery and refractory materials, and could impact such other complex systems as ceramics and colloids.

Research paper


Comment on this article using your Disqus, Facebook, Google or Twitter login.

Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

.


Related Links
Rice University
Space Technology News - Applications and Research






Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Previous Report
TECH SPACE
Shape matters when light meets atom
Singapore (SPX) Dec 06, 2016
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what you're looking at. Some photons reflect off, reaching your eyes. Others get absorbed. The main decider of which happens is the photon's energy - its colour. But look closely at the moment that light meets matter, and there's more to be disco ... read more


TECH SPACE
Bill Gates urges Trump to inspire Americans like JFK did

ESA to supply Service Module for first crewed Orion mission

American space legend John Glenn dead at 95

Space gardener Shane Kimbrough enjoys first of multiple harvests

TECH SPACE
Russian authorities inspecting crashed spacecraft debris

ULA receives $269m contract modification for launch vehicle production

Airbus Safran Launchers Becomes a 74% Shareholder in Arianespace

Arianespace's Vega scores its eighth success in orbiting Gokturk-1 for Turkey

TECH SPACE
ExoMars orbiter images Phobos

Mars One puts back planned colonisation of Red Planet

Opportunity team plot path forward to the 'Gully'

Curiosity Rover Team Examining New Drill Hiatus

TECH SPACE
Chinese missile giant seeks 20% of a satellite market

China-made satellites in high demand

Space exploration plans unveiled

China launches 4th data relay satellite

TECH SPACE
European ministers ready ESA for a United Space in Europe in the era of Space 4.0

Nordic entrepreneurial spirit boosted by space

LeoSat and Globalsat Group Sign Strategic Worldwide Agreement

India's Space Program Makes Steady Gains

TECH SPACE
Decoding cement's shape promises greener concrete

Deep-frozen helium molecules

Shape matters when light meets atom

NASA awards contract for refueling mission spacecraft

TECH SPACE
Meta musings on the origins of life

ALMA measures size of seeds of planets

New telescope chip offers clear view of alien planets

Could There Be Life in Pluto's Ocean?

TECH SPACE
New Perspective on How Pluto's "Icy Heart" Came to Be

New analysis adds to support for a subsurface ocean on Pluto

Pluto follows its cold, cold heart

New Analysis Supports Subsurface Ocean on Pluto




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News






The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement