"A normal road project would have washed out but where we had cement, it didn't wash out," says Greg Howard, a Texas Dept. of Transportation area engi­neer in the Carrizo Springs office. Crews allowed the cement-treated sections to dry out a little and then went right back to work, says Howard, calling cement "pret­ty good insurance." "Uninsured" areas didn't fare as well.

Some untreated sections where crews placed new base "completely washed out," says Roger Benavides, assistant engineer for the office. "Cement really does hold it together."

The two identically designed projects - US 277 near Carrizo Springs and US 83 near Crystal City - represent the office's first effort at mixing cement with existing materials. The process, known as "full-depth recycling with cement," is rapidly becoming the choice for rebuilding dete­riorating asphalt roads in Texas. It involves pulverizing the existing asphalt surface and granular base and mixing the material with a low volume of cement.

Not only did the decision to use cement save the project from floating away, it also saved money. Before start­ing me project, TxDOT engineers explored using asphalt and asphalt-stabilized base to rebuild the roads.

"We considered going with just asphalt base but you needed so much, something like 20 inches of new base," says Bena­vides about the outcome of a roadway design program used by the office. Like­wise, the initial construction cost for an asphalt-stabilized road would have been 35 percent, or another $1.25 million, more than the cement option, according to Benavides.

Reconstruction also adds headaches, says Cliff Coleman, superintendent, San Antonio-based E.E. Hood & Sons. "You run into a lot more problems on a rebuild. These (recycling projects) are pretty much cut and dry," says Coleman. One reason is the simplicity of the recycling process. "It's a heck of a lot faster than remove/replace construction because you're using what's here. As long as you get enough water in the cement, I don't see how you could screw it up," says Coleman.

Rebuilding the roadway involves four or five more steps before reaching the top of the construction cycle again.

"My crews sleep at night and forget!" jokes Coleman, preferring recycling's repetitive process. "Once you get the crew trained, you can cut them loose," he says.

After blading it to grade, the contrac­tor allows the new base to sit for at least 24 hours before micro-cracking it. Micro-cracking is a new practice that reduces the potential for shrinkage cracks in the newly bonded base by inducing a stress-relieving network of hairline "micro"-cracks.

To prime the new base, E.E. Hood crews place a thin chip seal. Twenty-four hours later, workers top the roadway with another seal coat. At the end of the projects, E.E. Hood will finish the new highways with a 2-inch hot mix asphalt overlay.