Caltrans and University of Missouri researchers are testing a theory that says a bridge support column might not need as much steel.
Concrete pump trucks have been directing grout down steel columns and into the base of test holes at the intersection of highways 99 and 70 for several days. They are part of a research project that is trying to determine if grout and concrete can be poured into the earth beneath a steel pipe to provide the same support bridges have now.
“Pump grout under pressure into the base of the shaft and that develops more resistance for the shaft. It increases its bearing capacity,” Caltrans Senior Research Engineer Tom Schantz said. “For a given bridge we can build smaller foundations, which will reduce costs."
He says crews in Hawaii have reduced the depth required to set columns for bridges by nearly half, which cut the cost of those columns by an equal amount.
UC Berkeley researchers are also working on the project.
“They are working on a new technology that uses fiber optic cables to measure strength," Schantz said. "We are also measuring temperature in the shaft. Because temperature is kind of the new technology to detect possible defects in the shaft.”
Schantz says crews will continue load testing through the end of February, with findings coming six months after that.
Bridges that are built using piles as a base would still be built the old-fashioned way.