Including industrial by-products such as fly ash in concrete mixes offer the potential to treble the life of bridge decks, according to engineers from Pennsylvania State University. Decks could last 75 to 100 years, concludes the study which involved full scale testing of 10 mixes containing materials such as silica fume and an alkaline earth mineral admixture. The exact life will not be known for many years, but the mixtures produced concrete with substantially lower permeability, higher electrical resistivity and lower cracking potential than the standard mix used in the state, said the study’s leader Paul Tilalsky. Ten bridges on Interstate 99 will now be built using the mixes and then fully monitored as part of the “100 year highway” project.