Ames Laboratory; Chemistry
Chemistry, Ames Laboratory
Cement and Concrete Research
Concrete grinding from highway maintenance operations produces large amounts of a highly basic liquid residue, posing a significant challenge to proper disposal. To discard this residue with little risk to human health or the environment, it should be solidified and its pH should be neutralized. Herein we present the serendipitous discovery that both goals can be met by treatment with citric acid. Through the use of 13C and 29Si solid-state NMR we determined that such treatment removes the calcium from the concrete structure, thus allowing the solubilization of its one-dimensional silica chains. These silica chains then cross-link in solution forming a highly porous silica material that is able to absorb the water from the residue. This new waste treatment process, which may utilize other acids with low water content, promises to facilitate a significantly improved methodology for the disposal of concrete grinding residue in a safe and environmentally friendly manner.
DOE Contract Number(s)
Department of Energy Subject Categories
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 54 ENVIRONMENTAL SCIENCES
Iowa State University Digital Repository, Ames IA (United States)