Better Roads Digital Magazine
Issue link: http://read.dmtmag.com/i/206514
RoadScience permanently mounted on concrete pads, mobile-tracked crushers permit recycled material producers to relocate piles while continuing to ship, removing RCA or RAP from existing piles while creating new ones and improving traffic flow, all while eliminating the need to move a stockpile with loaders or other equipment. Creating separate RAP stockpiles from different milling jobs is recommended because multiple sources may be subject to more rigorous testing than RAP from a single source. For all RAP stockpiles, the asphalt binder content and aggregate gradation must be determined, which may be decided according to AASHTO T308 or AASHTO T164. The most common method for determining the asphalt cement in a sample of RAP is to use the ignition-oven method specified in AASHTO T308. A different challenge with RCA Production of RCA poses a different challenge. Processing of RAP usually takes place at an asphalt plant, but RCA processing often takes place at the demolition contractor's equipment yard or via a portable plant set up at the demolition site. The stockpiled, processed recycled concrete aggregate is sold directly by the demolition contractor, either from his yard or from the jobsite. The material is neither tested to determine its chemistry or mortar content nor rigorously screened to remove dirt or deleterious material. "Concrete pavement recycling is a viable, successful and proven technology," says Mark B. Snyder, Ph.D., P.E., vice president of the Pennsylvania Chapter of the American Concrete Pavement Association (ACPA). "However, RCA must be treated as an engineered material and not as a straight-up replacement for natural aggregate. The properties of recycled concrete aggregate can vary greatly, depending on the original aggregate source and the production techniques. Therefore, it's necessary to characterize the material so it's used properly." In particular, the physical and mechanical properties of RCA vary with the quality and quantity of reclaimed mortar, which may affect the design of the structure or concrete mixture. These effects can be significant when maximizing reclamation efficiency by including lots of mortar or minimal when efforts are made to eliminate as much reclaimed mortar as possible. RCA is composed of virgin aggregates and mortar (cement paste, sand, air and admixtures). The crushing process results Leverage your bottom line... with every lift! At Vacuworx, the objective is very simple – to provide the safest, most efficient heavy-duty lifting equipment in the industry. Vacuworx lifters increase load and unload cycles 7-12 times, with a fraction of the number of ground personnel vs. ...the global leader in innovative lifting solutions. Phone 1-918-259-3050 | requests@vacuworx.com | www.vacuworx.com 10105 East 55th Place, Tulsa, Oklahoma 74146 USA 20 November 2013 Better Roads conventional methods. Vacuworx offers financing and rental options, and our service and parts departments are available 24/7 365 days a year. With 14 years of proven track record, no one offers a better selection or quality than Vacuworx.