What happens to leftover concrete after the plant parking lot and driveways are all paved over? After the nearby landfills are filled? Nearly 130 producers replied to a Concrete Construction questionnaire on this subject. Dumping was the most widely practiced method of disposal with production of concrete products, large and small, in second place. Reclaiming, using either commercial systems or equipment devised by the ready mix producer, was a close third.
Some drivers dump small leftovers at the job site; others find a place between the job and the plant. For many the accepted method of dealing with this problem has been simply to dump returned mix in pits at the plant and haul away the dried material later to land fills. Shrinking availability of landfill sites and increased attention and regulation by environmental agencies is forcing a new look in many areas.
About 40 percent of companies responding to the survey reported that they use leftover concrete in small concrete products or large concrete blocks, referred to as ecology blocks in some parts of the country.
RECYCLING AND RECLAIMING
One of the simpler methods is to simply dump the remaining concrete and let it harden; then crush it and sell it for base material. More complex reclamation methods, which also incorporate disposal of truck wash water, are based on screw classifiers or drag tank systems to separate out and wash the aggregates.