2004-6-6
This is Robert Cohen with the VOA Special English Development
Report.
Each year, road accidents kill a million people and injure
millions more. The economic costs are greatest for developing
countries. Earlier this year, the United Nations called for a
campaign to improve road safety.
One way to avoid accidents is
better driving. Another is better roads and bridges. Engineers in
the United States have designed ten new concrete mixtures that they
think could make bridges last longer.
Professor Paul Tikalsky leads the experiments by a team at
Pennsylvania State University. He says bridges made of concrete now
last about twenty-five to thirty-five years. But he says the new
mixtures might extend that to seventy-five or even one-hundred
years.
Concrete is made of stone, sand, water and cement. The materials
in the cement hold the concrete together. Ancient Romans built with
concrete. Yet strengthened concrete bridges did not appear until the
late eighteen-hundreds. People keep looking for new ways to improve
concrete. Professor Tikalsky says it is one of the most complex of
all chemical systems.
The new mixtures designed by his team contain industrial waste
products. He says these make the concrete better able to resist
damage from water and salt over time. One of the products is fly
ash. This is released into the air as pollution when coal is burned.
Professor Tikalsky says particles of fly ash are almost exactly
the same size and chemical structure as Portland cement. This is the
most costly material in concrete. So using fly ash to replace some
of it would save money.
Over the next two years, engineers will study ten bridges in
Pennsylvania. These were built from the different cement mixtures
designed by Professor Tikalsky's team. He says longer-lasting
bridges could save the state more than thirty-five-million dollars a
year. And he says the materials would be environmentally friendly.
The federal government is paying for part of the research.
Engineers anywhere can use the technology. Professor Tikalsky says
some of the ideas have already been put to use in China, the
Philippines and other countries.
You can find more about this research on the Pennsylvania State
University Web site. The address is www.psu.edu. Again, the site is
www.psu.edu.
This VOA Special English Development Report was written by Jill
Moss. This is Robert Cohen.