Returned-concrete treatment cleans drums, forms recycled aggregate

Sources: CP staff; General Resource Technology Inc., Eagan, Minn.

Short for “Returned Concrete, Zero Impact on the Environment,” Mapei’s Re-Con Zero is a mineral and admixture kit whose seven-minute agglomeration and hardening process converts mixer drums’ leftover concrete to semi-spherical aggregates—recyclable as they are for base or re-used as new concrete aggregate.

Re-Con Zero Component A is a porous, hydrophilic material introduced through water soluble bags at 0.5 kg (1.1 lb.) per cubic meter (1.3 yd.) of returned mix. The mineral works a four-minute agitation cycle, after which Component B, an accelerating agent, is dosed at 6 kg (13.2 lb.) per cubic meter. Also packaged in water soluble bags, the accelerator fosters formation of cement paste-encased, pebble-like nodules in a three-minute cycle.

The returned concrete’s transformation from plastic to hardened state is evident in sound reverberating from the mixer drum wall. Typically sized in the ½-in. to 1-in. range, the product is discharged from the mixer and suited for use as recycled concrete aggregate—at 10-20 percent of coarse aggregate volume in select mixes—or stockpiled for base course use.

Re-Con Zero kits are presently packaged for international markets by Mapei SpA, shipping in boxes similar to conventional synthetic fibers, and stocked by General Resource Technology. The product debuted in North America at World of Concrete 2015 following commercialization in Europe and fall 2014 demonstrations with select interested companies. Milan-based Mapei acquired GRT in mid-2014, aiming to grow the regional admixture manufacturer and fiber company’s North American footprint through expanded distribution and product innovations. Re-Con Zero is the first Mapei SpA formulation established in overseas markets to enter the GRT channel. — General Resource Technology Inc., Eagan, Minn., 800/324-8154;