On 6/16/2014 11:57 AM, Richard Aiken wrote:

On Sun, Jun 15, 2014 at 1:02 PM, David Shaw <dj.shaw@btconnect.com> wrote:
Over here in the UK, the standard tarmac/asphalt layer is the Blaw Knox, as pictured on the Wikipedia Blaw Knox page.

Interesting. The short wiki article says: "This machines was essentially a self-propelled tailgate spreader that closely followed the truck."

I wonder if the design changed (so that the reversing truck began following the spreader) or the wiki author just got it wrong? Given the spelling - "this" rather than "these" - I'm tempted to go with the latter option.

Richard Aiken

The design looks like the standard type where the truck will back up to the hopper, and then both will move forward while the spreader (I'm used to hearing it called a lay down machine) lays the asphalt down.

You wouldn't want to go backwards over the freshly deposited asphalt as it has to be measured every so often for consistent thickness before compression. How thick it is depends on the expected traffic load. Standard side streets would be about a 2 inch uncompressed (about 1.25 inches compressed) up to 5 inches for a heavy traffic load (3 inches after compression). Driving over it would cause partial compression but enough to cause it to cool faster so it couldn'[t be compressed as easily. All thicknesses assume a properly prepared road base.

Musing... I really need to see how much the prices have risen and get my driveway repaved. Back in 1994 when I was doing that job, side street/driveway thickness was about $0.44/square foot (concrete was more than four times that price).