PRODUCING QUALITY MASS CONCRETE IN THE RCC PUGMILL ATSALUDA DAM

摘要

According to several credible sources, Barnard Construction Company, Inc. (Barnard) is the first contractor to successfully use a continuous mixing concrete plant to batch conventional mass concrete in the United States. Barnard has completed work on the Saluda Dam Remediation Project for South Carolina Electric and Gas (SCE&G) located near Columbia, South Carolina. This project required placement of more than 1.3 million cubic yards of roller-compacted concrete (RCC). Barnard opted to use two continuous mixing plants for RCC batching. The continuous mixing plants were Aran model Modumix II provided by Aran International PTY LTD out of Australia. Since the continuous mixing plants would be available on the project site, Barnard proposed using them for more than just RCC. Beginning on August 25, 2003, Barnard successfully completed the first mass concrete placement and ultimately placed over 35,000 cubic yards of mass concrete through the continuous mixing plants. This project required two different mass concrete mix designs. The majority of the mass concrete had a three inch nominal aggregate size and the second mix had an inch and a half nominal aggregate size, both required a 1900 psi. compressive strength at 90 days. Barnard also used the continuous mixing plants for a 2500 psi conventional leveling concrete mix and a bonding mortar mix. Barnard performed trial mixes for the RCC facing concrete and bedding mix through the continuous mixing plants. The mixes were acceptable, but were not used during production because of high utilization of the plants for RCC production. Mass concrete produced and placed at Saluda was of high quality, yielding low standard deviations and a low coefficient of variability for compressive strength test results. Pugging mass concrete at Saluda has set the stage for minimizing costs and improving production, while maintaining high quality standards for large dam projects.