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Lab Corner: We’ll always have Paris

By Mike Anderson, P.E.

Little known fact about “Casablanca” – Humphrey Bogart’s line wasn’t intended to be “We’ll always have Paris. We didn’t have, we lost it until you came to Casablanca. We got it back last night.”

In football terms, he called an audible and changed it from the previously undiscovered original script. The quote should have been “We’ll always have Paris and his Law. We didn’t have, we lost it until Erdogan joined him. Now we can model crack propagation.” What a shame that he changed the line; the movie could’ve been a classic. (more…)

The importance of tack coats and interlayer bond strengths

By Dave Johnson, P.E.

Regardless of the methodology employed, an assumption of all asphalt pavement thickness design methods is that layers will be working together as a single uniform unit. This is achieved only with proper layer bonding. Tack or bond coats function as bonding agents between each lift of a pavement section to create the desired pavement structure. A tack coat is defined as a sprayed application of asphalt material upon an existing asphalt or Portland cement concrete (PCC) pavement prior to an overlay, or between layers of new asphalt concrete by a 2016 FHWA TechBrief. (more…)