There is literally concrete evidence of their work." Tony Hawk says skateboarding was once a sport on the edge of society.

VOA: special.2009.09.11

The National Ready Mixed Concrete Association points out that using ash in cement is not a new idea.

VOA: special.2009.12.01

Men in two special factories worked day and night to make the concrete building material for the dam.

VOA: special.2009.08.12

Workers also used more than twenty million kilograms of steel to strengthen the concrete in the dam.

VOA: special.2009.08.12

Kahn was able to make the concrete material of the building look both solid and airy.

VOA: special.2009.12.13

The idea is to replace some of the portland cement traditionally used in making concrete.

VOA: special.2009.12.01

The Portland Cement Association says the gas from the limestone is reabsorbed as concrete ages.

VOA: special.2009.12.01

On June sixth,nineteen thirty-three, workers poured the first load of a building material called concrete.

VOA: special.2009.08.12

Portland cement is a material that holds together the sand and crushed stone in concrete.

VOA: special.2009.12.01

Costas Synolakis says Japan's concrete sea walls were not built to handle such high waves.

VOA: special.2011.03.21

For example,he created a triangle-shaped walkway of steps that sits inside a rounded concrete shell.

VOA: special.2009.12.13

Rock walls made of wood or concrete have places for the climber's hands and feet.

VOA: special.2009.12.09

Rajan Vempati thinks rice hull ash could help the concrete industry produce less carbon dioxide.

VOA: special.2009.12.01

A concrete bridge was built about two hundred seventy-five meters above the Colorado River.

VOA: special.2010.10.27