Tasty Chips for Safer Construction

A tangy flavorant in junk food keeps concrete bricks and bridges from disintegrating

by Luis Bruno; Allan Siew; Thierry [Latter two photographs are licensed to the public under the Creative Commons Attribution-Sha

Luis Bruno; Allan Siew; Thierry [Latter two photographs are licensed to the public under the Creative Commons Attribution-Share Alike 2.0 license]

Catastrophic bridge collapses in Minnesota, China and elsewhere have killed at least 58 people this year, and concrete weakened by water is partly to blame. A new study points to a waterproofing solution that lies close at hand-or, er, mouth: sodium acetate, the ingredient that gives salt-and-vinegar chips their delicious zing.

Water seeps through concrete's pores, cracking its exterior and damaging the steel beams within. Sodium acetate seals these pores from the inside, says researcher Awni Al-Otoom of the Jordan University of Science and Technology in Irbid, Jordan. When brushed onto concrete as part of a watery solution, the salty substance sinks in and forms crystals, partially plugging the pores. The crystals create an even better barrier when wet, since moisture-a drop of rain, say-makes them swell to fill openings more snugly. The salt costs half as much as glue-like polymers and other common sealants. If Al-Otoom's results hold up in real-world tests, potato-chip tang could be protecting bridges within a few years.