Any Road Builders Out There?

I've been watching a construction crew widen the road by the Park & Ride I commute from, and they did something recently that I've never seen before. Usually, they smooth and grade the road, lay down the steel rebar internal road framework, and then pour concrete. This time, they got finished grading, and ran a road roller over it. (Don't y'all prefer the word steamroller? Too bad they all run on diesel now!)

After the road was packed down, the crew sprayed something all over the roadbed. I dunno what it was, but it was blinding white in color, and was steaming hot when they laid it down. It looked like a slurry of quicklime or chalk and hot water, but I'm kinda clueless here.

I came back that afternoon, and they had laid down asphalt on top of it instead of concrete, so there was no rebar installed. I think it's a temporary section while they work on the other side later.

Anybody have a clue about why they'd whitewash a roadbed?