Equipment World Digital Magazine
Issue link: http://read.dmtmag.com/i/726012
September 2016 | EquipmentWorld.com 58 biggest challenge for concrete pavement contractors, accord- ing to Leif Wathne, executive vice president of the American Concrete Pavement Association. "A lot of the issues with plant operation is aggregate handling, so the loader opera- tor becomes a key feature of a concrete mix operation," he says. "If your loader operator knows what he's doing, you're going to be much more likely to have a consistent mix that performs the way it's designed, and is proportioned properly." That also factors into mak- ing sure contaminants don't get into the aggregate and making sure the aggregates are not segregated, which falls under stockpile management. Moisture content is a big issue in this process, Wathne says. "A lot of plants will put Stockpile management • Pile the material in lifts. • Complete each lift before beginning the next. • Do not dump material over the edges of a stockpile. • Minimize free-fall heights of aggregates to avoid segregation. • Only stockpile as much material as is practical. • Minimize crushing of the aggregate by the loader. • Manage the stockpile carefully to obtain close to saturated surface dry condition. For example, thoroughly wet the aggregate, then let it stand an hour before batching. • Monitor the moisture content of the aggregate using probes in the stockpile. Managing aggregate is a top management concern in concrete production, as it is the most unpredictable component of a mix. Here are a few stockpile management tips. Source: Integrated Materials and Construction Practices for Concrete Pavement, Federal Highway Administration Publication No. HIF-07-004 Cement silo and mixers. Robert Smith Incorporated placing a roller-compacted concrete road- way at Volkswagen's Chattanooga, Tennessee, plant. road science | continued Arizona DOT