Spheres Can Make Concrete Leaner, Greener (phys.org)

An anonymous reader quotes a report from Phys.Org: Rice University scientists have developed micron-sized calcium silicate spheres that could lead to stronger and greener concrete, the world's most-used synthetic material. The researchers formed the spheres in a solution around nanoscale seeds of a common detergent-like surfactant. The spheres can be prompted to self-assemble into solids that are stronger, harder, more elastic and more durable than ubiquitous Portland cement. He said the spheres are suitable for bone-tissue engineering, insulation, ceramic and composite applications as well as cement. The research appears in the American Chemical Society journal Langmuir.

In tests, the researchers used two common surfactants to make spheres and compressed their products into pellets for testing. They learned that DTAB-based pellets compacted best and were tougher, with a higher elastic modulus, than either CTAB pellets or common cement. They also showed high electrical resistance. [Rice materials scientist Rouzbeh Shahsavari] said the size and shape of particles in general have a significant effect on the mechanical properties and durability of bulk materials like concrete. He said increasing the strength of cement allows manufacturers to use less concrete, decreasing not only weight but also the energy required to make it and the carbon emissions associated with cement's manufacture. Because spheres pack more efficiently than the ragged particles found in common cement, the resulting material will be more resistant to damaging ions from water and other contaminants and should require less maintenance and less-frequent replacement.

Comments

this is huge

[Anonymous Coward]

It's paywalled. But if practical and economic, this is one of the biggest changes for the better in two decades of Slashdot. Concrete is so ubiquitous that maintenance and GHG emissions are tremendously significant.

Re:this is huge

[ShanghaiBill]

But three times the lifespan times twice the strength (numbers pulled out of my ass) means it'll sell if it costs no more than six times as much as conventional concrete.

You are not considering secondary effects. Let's say you are constructing a building. If it is twice as strong, you need half as much for the same strength. But if you need half as much on the upper floors, then you need less concrete on the lower floors to support the weight ... so you end up using much less than half as much. The reduced weight will also bring savings on the steel rebar and steel frame ... but maybe more cost for wind vibration damping.

There are also secondary effects of the longer life. If you are building a bridge, and the concrete is 50% of the cost, then a 3x lifetime increase saves you 6x not 3x (assuming concrete is the critical path item for longevity).

Re:Major difference, Cement doesn't need compactin

[pr0fessor]

I'm guessing you aren't very familiar with construction techniques. Concrete is compacted using vibration because air pockets make concrete weak and causes cracking.