Sources: CP staff; Prairie Material, Bridgeview, Ill.
Coupling a portable 8-yd. horizontal shaft, spiral blade mixer and conventional tilt drum model, Prairie Material’s Indianapolis flagship plant opened May with 6,500 yd. of roller compacted concrete mix for an Indiana Rail Road Co. pavement.
The producer peaked at 185 yd./hour during the three-day project, where contractor K-Five Construction placed 14,000 sq. yd. of pavement in three 6-in. lifts. With engineering and mix design assistance from American Concrete Pavement Association Illinois Chapter Executive Director Randell Riley, P.E., Prairie Material Marketing/Product Specialist Theron Tobolski persuaded the railroad to use 18 in. of RCC in lieu of 42 in. of compacted aggregate.
The RCC pavement serves a yard that Indiana Rail Road will test over the next five years as an intermodal facility candidate, just south of downtown Indianapolis. Although carrying a premium above the initial pavement budget, the asphalt-like concrete was presented as a robust, low-maintenance alternative to the thicker aggregate-only structure—certain to require frequent repair of ruts and voids from heavy yard vehicle traffic and settlement.
The rail yard is about three miles from Prairie Material’s main Indianapolis plant, operating at Martin Marietta Aggregates’ Kentucky Ave. quarry. As part of a Haganator Travel-All portable plant, the horizontal shaft, spiral blade mixer—or ribbon mixer—was staged adjacent to stockpiles serving central mixed and transit mixed alleys. The ribbon model handled at least 75 percent of contract volume, producing 8-yd. loads in 30-second cycles and charging dump trucks in 10- to 15-second intervals. Underscoring the tilt drum’s speed limitations for the extremely dry RCC pavement material, the central mixed plant loaded dumps in two 4-yd. cycles, each requiring 90 seconds’ mixing time.
Prairie Material added the 8-yd. ribbon mixer-equipped Haganator in 2012 to support conventional concrete contracts throughout its Chicago-area operations, plus an RCC pavement program launched in 2009. The equipment proved pivotal for five rail yard and parking area projects, totaling more than 17,000 yd. of RCC mixes, Prairie Material logged last year from its Bridgeview (headquarters) and Joliet (leased), Ill., sites. A key asphalt contractor in the Chicago market, Lemont, Ill.-based K-Five Construction handled one of those projects. After that inaugural RCC placement, K-Five crews were set for a second job—a few hours to the south in Indianapolis.