Concrete is Flexible

If paving roads is a dry weather sport, why are we starting new projects in the rainy season?  Because concrete isn’t as picky as asphalt.  That’s the simple answer.  More specifically, asphalt is commonly applied at a temperature of 300-degrees-plus and if it cools down too fast the result isn’t stable (compaction, the best indicator of asphalt longevity, is compromised).  Also, steam rises from hot asphalt if it’s applied to cold or wet ground, creating voids in the roadway.  Concrete, on the other hand, is a hardier sort. 

Crews doing concrete work downtown

Crews doing concrete work downtown

Though sensitive to scorching heat, concrete can be poured in cold, wet weather with a few adjustments.  Don’t laugh, but those adjustments include covering it with warm blankets while it cures (at least it doesn’t ask for chicken soup).  In any event, the blankets are only needed in below 40-degree (Fahrenheit) weather because concrete has the added benefit of generating its own heat.  Yup, sure does.  After it’s poured and starts curing, the chemical reaction in the process creates heat that helps the substance solidify.  Granted, the emitting heat couldn’t brown a marshmallow, but every little bit helps and makes concrete projects more flexible (to schedule).   Paving Program Manager Jessica Murphy uses that flexibility for planning projects like Fourth Avenue between Jackson and Olive, originally set for 2010 but started in 2009 as part of the Mayor’s economic stimulus package to create jobs.  Because the project is all concrete, it can start in yuck weather.  However, as helpful as concrete is, it still can’t inherently avoid schedule conflicts (that’d be some fancy curing!).  The phasing of the Fourth Avenue Central Business District South project to begin just after this year’s Torch Light Parade and end before next year’s is due to Jessica’s fancy footwork.