Quake Predictor (04.29.05) - What if you could check the earthquake forecast the way you check the weather? Scientists drilling into the San Andreas Fault this summer hope to learn whether earthquakes are predictable.
Quake Swarms (03.08.05) - Clues to future earthquakes in the tsunami-ravaged areas around the Indian Ocean might just come from studies done off the west coast of the United States. Studies are finding that there's a pattern to that area's largest earthquakes.
Volcano Lessons (11.11.04) - While Mount St. Helens may be keeping tourists happy and civil defense officials nervous, it's also doing a pretty good job as a lab for those who study volcanoes.
A new type of cement could make buildings that can better withstand earthquakes and highways with fewer potholes. This ScienCentral News video has more.
It Bends, But It Doesn't Break
Without warning a rumble builds and the room begins to shake. Buildings sway in unnatural ways, waves rock and warp groaning bridges, and the ground shifts beneath you.
But, engineer Victor Li has developed a bendable, or ductile, concrete-like material that he says can withstand the severe stress, or "loading," that happens when an earthquake hits.
As was reported in Discover Magazine, the high-tech concrete, called Engineered Cement Composites (ECC), can be mixed and applied using traditional methods for concrete, but it is stronger, longer lasting, lighter, more flexible and less likely to crack than the concrete generally used to build roads, bridges and building.
"This material has been designed at the micro-structural scale. In other words all the ingredients have been… tailored according to a theory which tells us how these components work together in the material internal structure," Li says.
Traditionally, the usual mix of cement, water and sand or gravel is reinforced with metal rods or bars to provide the strength needed for bridges and buildings. Li's concrete-like composite looks like regular concrete, but incorporates super fine (100 microns in diameter) silica sand, and tiny plastic — polyvinyl alcohol or PVA — fibers covered with a very thin, nanometer-thick, slick coating.
PVA
"This surface coating allows the fiber to begin slipping when they are over loaded so they are not fracturing. It prevents the fiber from rupturing which would lead to large cracking," Li explains. "[ECC] can deform much more than normal piece of concrete without fracturing into pieces."
Under intense strain, the fibers slide within the concrete, giving under the pressure rather than breaking apart. The fibers behave somewhat like your body's ligaments, holding things together in a flexible manner.
More than that, the different components work together to share the load.
"They essentially collaborate, if you will, so that when the material is overloaded they provide a give in transferring the load elsewhere to its neighbor, so its neighbor also helps in supporting the load," says Li.
In lab tests the ECC proved to be 500 times more flexible than traditional concrete, and 40 times lighter, which Li believes could even influence design choices in skyscrapers.
The new cement costs three times the price of regular concrete, but Li says because it's so forgiving builders can use much less of it, and since it's so durable, maintenance will cost less. But the hefty price tag is probably the last thing anyone would be worrying about when the earth starts to shake.
The material is already being used in earthquake-prone areas of Japan and Korea, and is set to make it's American debut in fall, 2005 on a section of the Grove Street Bridge in Ypsilanti, in Michigan.
delicious
digg
magnolia
reddit
newsvine
netscape
netvibes
