The City of San Antonio is wielding a new tool to rebuild failing city streets. Officials selected a 1/2-mile stretch of Saltillo Street near downtown San Antonio as one of its first recycling projects. "Full-depth reclamation using cement just poses a whole new tool in our toolbox to be able to combat problems with our soils," says Rocky Aranda, operations manager for the city's streets and drainage department. "Many of the city streets sit atop expansive, clayey soils", he adds, which can wreak havoc on untreated roadways.

The city hired local firm Drash Consulting Engineers to design and monitor the rehabilitation of the old street. "We drilled borings to determine the existing materials, took samples of the subgrade and characterized its strength, and then designed the new road according to traffic counts given to us be the city," says Chuck Gregory, a principal at the firm. Gregory says using cement offers two major benefits: "It improves the strength of the base material so you need a thinner section to carry the same number of wheel loads. The second thing is that it helps to make the base material a lot less susceptible to damage from water, which makes the pavement last longer."

With no new materials to haul in and no disposal costs for old material, the process offers environmental and cost savings over removing and replacing a street, says Aranda. "Removing and replacing is very time consuming, very inefficient, and very expensive. It also has a negative impact on the environment when we have to properly dispose of old material," says Aranda. "Full depth recycling actually minimizes the need to buy virgin material," Gregory agrees. "Instead of filling up a landfill somewhere, which is not environmentally friendly, we're re-using materials in-place and in the process, saving money for the city and the taxpayers."

City crews assisted by local contractor Olmos Construction worked together to build the project. The process entailed pulverizing the existing granular materials and asphalt surface, mixing in a cement slurry, and then grading and compacting the new base. A new hotmix surface topped the street. "The construction process is very simple and straightforward," says Gregory. And it allows the city to quickly return the street to its residents. Says Aranda: "With this option, we actually recycle and replace all in one day. It's really revolutionary for the process of reconstructing streets."