Used Sandblasting Material Finds Concrete Purpose
Construction engineers at NASA's Kennedy Space Center in Florida mixed a small amount of used sandblasting material into concrete to find out whether the debris can go into driveways and sidewalks instead of the landfill.
Workers mixed almost three tons of the sandblasting material, known in the industry as spent blast media, into the concrete and used it to make a driveway and ramp near the Propellants North facility near the Vehicle Assembly Building. The sandblasting material, basically sand pulverized into dust, replaced about 42 percent of ordinary sand in a typical concrete formula.
Though formal testing won't be completed until mid-April, the early signs are promising, said Mick Barth, Construction of Facilities design engineer.
"The concern is the final product wouldn't be as structurally sound as regular concrete, but I don't think that's a concern anymore," Barth said.
The pilot project is intended to show whether the concrete with spent blasting material is a suitable replacement in some instances for traditional concrete. At this point, it doesn't look like it would cost less, at least in small-scale cases, but it would help the center meet a presidential goal of cutting the waste that goes into landfills by 50 percent, Barth said.
"We want to see if this is going to be viable in a lot of different uses, not just at Kennedy, but across the Agency for different applications," said Jahn Dussich, a senior engineer with contractor ITB Inc. and project manager at the NASA Technology Evaluation for Environmental Risk Mitigation Principal Center office, or TEERM.
The alternative concrete would be a candidate for use in foundations, driveways and sidewalks, Barth said, but may not meet the demands of a runway or taxiway.
The spent media comes from large-scale refurbishments such as the cleaning of the water tower at Launch Complex 39B to the material used by specialized machines to cut metal precisely, Dussich said. Along with the powdered sand, the media includes a tiny amount, less than 1 percent, of the paint chips or other material cleaned by the blasting. So only blast media deemed non-hazardous was used in these concrete mixes.
The amount of sandblasting residue created at Kennedy varies each year, Barth said.
The process has been used by the Defense Department and by some state departments of transportation, but not at Kennedy or other NASA facilities, Barth said.
"I like the idea of limiting or eliminating waste streams ," Barth said. "The challenge is in making it cost less or at least not making it cost more. I don't think we're there yet."
Barth said the center and NASA overall have grown increasingly receptive to creative ideas to recycle materials. For example, concrete chunks from demolition projects have been used to reinforce seawalls.
"It's more acceptable to do it now than even five years ago," Barth said. "Now it's not a new thing anymore, so it's easier."
NASA's John F. Kennedy Space Center