Concrete inFocus - Summer 2013 - (Page 8)

equipment From Hand Shovels Evolution of the modern concrete plant Gary Mullings A t about the same time the ready mixed industry began in 1913, the paving of concrete roads was just beginning to emerge. Machines and methods to batch and mix the materials used in concrete paving were just being developed. A steam-powered concrete “paver” that mixed concrete on site and moved with the other paving machines as the work progressed gained wide acceptance as the preferred method of producing concrete for pavement. The paver preceded paving batch plants by several years. The means to mix the concrete materials was there, but how to best deliver the materials to the “paver” skip hoist was left up to the emerging batch plant industry. Concrete Plant Park was established in Bronx, NY, in 2009 and was home to a working concrete batch mix plant sitting on the western bank of the Bronx River. Concrete manufacturing began at this site after 1945 and ran until 1987. The Transit Mix Concrete Corporation built the silos, hoppers and conveyor structures that still stand at Concrete Park today as a reminder of the park’s industrial history. Polygon . . . Before 1913 concrete was mixed at the construction site. Hand Shoveling At first, wheelbarrows were used to “batch” and load the paver’s skip hoist. Five-ton dump trucks would haul the sand and stone to the work site and dump the materials in piles along the roadside. Then the workmen would handshovel the materials into wheelbarrows that also served as volumetric measures needed to load the skip hoist for the two-bag (about 11 cubic feet) steam-powered concrete mixer (paver). Grand Rapids Gravel Co. twin paving central mixers, 1929, with a 1922 Mack AC dump truck. 8 ı SUMMER 2013 Bags of cement were also spaced along the roadside and hand-dumped into the skip hoist in proportion to the wheelbarrow loads and batch size. A water pipe was usually laid the entire length of the job with multiple outlets to provide water for the mix. It was a slow, back-breaking process, but it got the job done and produced many concrete roads of acceptable quality for the early lightweight cars and trucks. Seattle plant, 1927, with Bucket elevators for aggregates and Kenworth trucks. Volumetric Hoppers The next step in batching for concrete pavement occurred in about 1920. The effort centered on reducing labor and eliminating the wheelbarrow. A mobile (steel wheels) belt conveyor arrangement was devised with threeor four-wheeled volumetric hoppers located over the belt. Materials continued to be piled along roadsides and workers continued to Avril Tru-Batch Co. C, 1932, Cincinnati, OH, with one of the first aggregate conveyor belt systems. Bag cement loading by hand, 1933.

Table of Contents for the Digital Edition of Concrete inFocus - Summer 2013

Corporate Suite
From Hand Shovels to Keystrokes
Walking on Art
NRMCA’s Design Assistance Program Works for Producers
Maryland Ready Mix Producer Gives Back to Community
Structures That Last
Responsible Sourcing Through CSR Reporting
Index of Advertisers
Responsible Sourcing Through CSR Reporting
White Cement Delivers Beautiful, Profi table Mixes
Impact of Concrete Quality on Sustainability
Tulsa Driver Named NRMCA Driver of the Year

Concrete inFocus - Summer 2013