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Certifiable Consistency

Capital Ready Mix Concrete recently opened a second plant and new flagship on a site bordering Pittsboro, N.C., strategic to work in the Research Triangle, so named for the nearby Duke University, Durham; N.C. State University, Raleigh; and, University of North Carolina, Chapel Hill. Anchoring the operation is a CEI Fusion batch plant, engineered to weigh and convey optimal coarse and fine aggregate blends to meet target design strengths without excess cement volumes.

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A Duke University MBA candidate, Sara Lochren scouted Pittsboro sites for the new Capital Ready Mix headquarters office and plant, pegging the property of a former chicken processing facility. The centerpiece of the well-appointed office she helped tailor is a conference table comprising a single slab of Indonesian chamcha wood.
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The Pittsboro site affords Capital Ready Mix Concrete a new flagship plant, along with a footprint in markets west of Raleigh. The producer runs upward of 30 rear and front discharge mixers between Pittsboro and the original site in Knightdale, N.C., east of the capital city.
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Load consistency with the CEI Fusion plant starts with precise aggregate weighing and blending. A Jonel Engineering controls package records Fusion bin and belt weighing accuracy.

“We first saw the Fusion plant at the World of Concrete, [then] flew to California to see one in operation,” says Executive Vice President Sara Lochren, daughter of Capital Ready Mix founder James Lochren. “My dad likes to keep up with the latest advancements in technology; to stay ahead of the curve. [He] was excited to be the first to bring one of these plants into North Carolina.”

Her father “has always been an entrepreneur. He started driving concrete trucks as a teenager with his brother. In the late 1980s, he opened his first concrete plant. He only had one truck. He’d drive the truck himself; batch the concrete himself ... He worked to grow that business to the almost 30 mixers it has today.”

Sara Lochren helped locate the property that now houses the company headquarters and positions Capital Ready Mix to the west of Raleigh, while the company’s charter plant, in Knightdale, serves areas east of the capital city. She handled Pittsboro permitting and has been heavily involved with the business expansion. Staying ahead of the concrete production technology curve brings its own challenges, she adds, citing her father’s pursuit of approval to supply work for the North Carolina Department of Transportation, which recognizes National Ready Mixed Concrete Association plant certification.

James Lochren hired an independent professional engineer to inspect the Fusion equipment and coordinate certification with NRMCA. In the report that sealed NCDOT approval, Stephen Ackerman, P.E. affirmed: “Total weights of all materials included in each individual load of mix are recorded and compared with batch target values to verify compliance with ASTM C-94 tolerances … Batch records indicate excellent compliance with the tolerances outlined in Section 2.5 of the NRMCA Plant Certification Checklist.”

STANDARD DEVIATION?

“The best measure of quality in a concrete plant is consistency,” observes Capital Ready Mix Plant Manager Kevin Cox, who calls the Pittsboro transit mixed operation “the most consistent plant I’ve ever seen. In many cases, it has produced better mix than a central mix plant.”

“When you weigh rock by dropping it several feet into a weigh hopper, you inevitably have a certain amount of variation. With the Fusion, we’ve seen that drop noticeably. It’s a very consistent plant,” adds Technical Services Manager Jason Holland.

The core of the Fusion is the aggregate blending system. A series of in-line bins holds multiple grades, each releasing to its own dedicated feed belt. Each feed belt is fitted with its own scale to weigh sand and gravel or stone, then charge a full-length collector conveyor below. In this manner, aggregates are precisely blended in ribboned layers, then fully blended before they being discharged into the mixer truck.

The collector conveyor bears on load cells. During calibration, scale technicians hang weights on the collector conveyor, just as they would a collection hopper on other types of plants. The plant operator can then use the collector conveyor to calibrate the feeder belts, a process performed in minutes and netting highly accurate batch weights.

Behind the four-belt aggregate blending and volumetric flow metering is a Jonel Engineering Archer Batch control system. Since the CEI Fusion eliminates traditional gates and air cylinders, maintaining the flow of each of the materials is critical in order to reduce truck mixing and improve batch cycle times.

The batch controls integrate with CEI’s proprietary VFD style motor controllers using a unique logic sequence to ensure materials are batched on the weigh belt and transfer conveyor according to the optimal aggregate layering method, prescribed by each mix design. The sequence ensures a cleaner loading plant and less material segregation compared to traditional dry batch plants. — CEI Enterprises, Albuquerque, N.M., 423/867-4210; www.ceienterprises.com