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May 22, 2005
Paving of the south outside lane is almost complete

Sometimes I just get lucky, possibly because I simply cannot sit still. Just like a high temperature chemical reaction, I am often bouncing around exploring new ideas. As a kid, I would surely have been diagnosed with ADD. So today, I bounced up to the bridge and another big surprise was waiting for me - more paving since yesterday. So, Friday's, Saturday's and today's visit yielded big time progress with paving the outside south lane. Here is a summary of progress since Friday - A lucky view from above

New pavement curing from last (Saturday) night. Note the position of the 5th cable-stay anchor and scroll down to yesterday's (Saturday's) photos and compare with the launching position of the Bidwell paving machine.

The Bidwell paving machine is in the launching position for the next segment

Cleaning the next segment

I thought I would try to catch the paving this evening. The moon was full and here is the west pylon bathed in moonlight.

The Bidwell paving machine and the cement mixer were in their launching positions. The mixer truck is special and can add multiple components to the resultant concrete.

This is the mixer that mixes the aggregate, sand, cement, latex and water. Each component is measured (by volume) and dropped onto a src="http://s3.ravenelbridge.net/small conveyor belt near the back of the truck where it is rapidly mixed. The Styrafan latex 1186 is manufactured by BASF and adds flexibility and durability to the road surface.

The BAST article describes the paving process better than I can: "Cleco employed a straightforward process to install the latex-modified concrete bridge deck overlay. Modified Concrete Suppliers, LLC, Indianapolis, Ind., their latex concrete supply contractor for this project, used specially designed trucks equipped with computerized component metering and augers to mix the Styrofan 1186 latex, cement, sand, aggregate and water on site for application to the bridge deck surface. Following application to the bridge deck, Cleco employees used a Bid-Well finishing machine to spread and trowel the overlay to achieve thickness and surface smoothness specifications. Once installation of a section was completed, wet burlap was applied to the surface of the overlay, covered with polyethylene sheeting, and allowed to moist cure for 24 hours. This step controlled the rate of water evaporation from the overlay. After two days of dry cure, the surface was ready for use."

But there was a small problem. In order for the concrete to cure properly, i.e. no cracks, the evaporation rate must be below a limit which is determined by the temperature, humidity and wind velociy. Here Derek (left) has an instrument that measures all this. Here he and JW (right), from Cleco, are checking the wind conditions. In general, I am told, winds above 10 mph are problematic. After a bit of waiting - well it seems that tonight is not the night for paving ...

A digital sketch of night paving

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Attribution: C. Frank Starmer from http://ravenelbridge.net

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