By John Ramos

CONCORD (KPIX) — A 3,500-foot-long section of Highway 242 in Concord is being shut down for repaving on the weekends of July 10-11 and July 17-18. With temperatures reaching triple digits, the concerns are not just for the workers but for the roadway itself.

Caltrans has closed a portion of northbound Highway 242 in Concord this weekend and next, starting at 10 o’clock Friday night and reopening at 10 a.m. Monday.

Caltrans spokesman Pedro Quintana said the shutdown is happening so the repaving job doesn’t have to drag on for weeks or months.

“We’re not coming back every weekend to get this job done,” he said. “We’re going to get it done, hopefully, by these two weekends.”

Normally the temps would be in the 80s or 90s but on Saturday the heat soared past 105 degrees Fahrenheit. Workers left work trucks running so they could retreat to the air conditioning, said Caltrans area construction manager Andrew Baskerville.

“Especially when you’re dealing with the asphalt that’s coming into the job site at around 300 degrees Fahrenheit,” he said. “You’ve got the hot materials as well as the hot air temperature. It can be overwhelming.”

Baskerville said the weather affects the roadway, as well. The project has an unusual design called “cast-in-place” lane replacement, where 12 inches of high performance mixed concrete is poured over a bed of asphalt and steel rebar. The problem is, both those materials can heat up beyond 150 degrees during midday heat.

“So, the concrete would actually crack right along the reinforcing steel if we were to pour wet concrete on hot reinforcing steel in really hot temperatures,” Baskerville explained. “It would just crack completely.”

As a result, the actual pouring will be done at night after the temperature dips below 85 degrees. Engineers think the concrete will then be set by the time it reaches 85 the next morning. When finished, the new roadway will be stronger and, because it’s one continuous pour, drivers won’t feel the familiar “thump-thump” of other concrete highways that some people call “washboarding.”

“With the continuously-reinforced concrete pavement, you don’t have any of that because you don’t have any joints in the pavement,” said Baskerville. “We’re hoping it’s very smooth for a long time.”

For more information, visit the project’s website at http://dot.ca.gov/caltrans-near-me/district-4/d4-projects/d4-concord-242-rehabilitation