The ingredient that helps give "salt & vinegar" potato chips that tangy snap is the key to a new waterproof coating for protecting concrete from water damage, according to a study scheduled for the August 1 issue of ACS' Industrial & Engineering Chemistry Research.

Awni Al-Otoom and colleagues in Jordan point out that concrete's unique properties have made it the world's most widely used structural material.

Concrete, however, is so porous that water soaks in, corroding steel reinforcing bars and meshes that strengthen concrete roads and buildings and causing cracks as water expands and contracts during freeze-thaw cycles. Sealants are commercially available, but they have serious shortcomings, the study notes.

In the new report, researchers describe the use of sodium acetate as an inexpensive and environmentally friendly concrete sealant. One of sodium acetate's many uses is in flavored potato chips.

In laboratory studies using freshly made concrete, the researchers showed that sodium acetate seeps into pores in concrete and then hardens and crystallizes upon exposure to water. The resultant swelling blocks entry of additional moisture, they said. Under dry conditions, the crystals shrink back to their original size and allow moisture to evaporate.

The net result is "a significant reduction in water permeability," that "can be expected to increase the service life of the concrete," the report said.

Article: "Crystallization Technology for Reducing Water Permeability into Concrete"