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Testing The amount of testing required was substantial. Concrete/shotcrete samples were taken in accor- Lars Balck is a Senior Vice dance with the British Standards and rodded into President of The Crom Corpo- metal cube molds 6 x 6 x 6 in. (150 x 150 x 150 mm), ration, a company that specializes which weighed about 20 lb (9 kg) before adding in the design and construction concrete samples. Every truck was sampled and of prestressed concrete tanks measured for slump and temperature. Shooting using shotcrete for the wall just 100 yd (91.44 m) required taking nearly 60 construction. He has been samples. Samples were kept on site in a special involved in the design and temperature-controlled environment large enough construction of over 550 tanks over the past to hold several hundred samples because samples 40 years. He received his bachelor’s degree in had to be kept on site for 7 days. A chain of custody civil engineering from the University of Florida had to be maintained until the samples were and served with United States Army as First received by the testing laboratory. Over the course Lieutenant in Vietnam as a Combat Engineer. of the job, about 5000 samples were taken, stored, Balck is a Past President of ASA. He is Chair of and handled. ACI Committee 506-C, Shotcreting-Guide, a past Chair and current member of ACI Committee 506, Shotcreting, and member of ACI Committees 376, Concrete Structures for Refrigerated Liquefied Gas Containment; 563, Specifications for Repair of Structural Concrete in Buildings; and C660, Shotcrete Nozzleman Certification. Robert (Bobby) Oyenarte is the Vice President and General Manager of Crom International LLC (Qatar), and Vice President and Principal of The Crom Corporation (USA), designer and builders of prestressed concrete tanks for water and wastewater storage. He currently heads The Crom Corporation’s International Operations based in Doha, Qatar. Oyenarte is responsible for the supervision of a team of 50 engineers, construc- tion managers, and tank builders. He is a licensed professional engineer with 17 years of experience in the industry. In his 14 years with CROM, Oyenarte has managed the design and construction of over Fig. 2: Exterior shotcreting from the ground 100 prestressed concrete tank projects. Buddy Williams has been Summary Operations Manager for Crom Placement of 21,000 yd3 (16,000 m3) of shotcrete International for 2 years. He was completed in just 10 months, although tem- has over 22 years of experience peratures at times reached 115°F (46°C) in the in shotcrete and prestressed day. Weather in the form of sandstorms and fog concrete water tanks and has forced a halt to the shotcrete operation and forced been an ACI Certified Nozzleman the crew to regroup and set up for the following for 10 years. evening. Heat, silica fume, maximum dosage of HRWR, and inconsistent wet-mix concrete T. J. Williams is a Supervisor delivered to the job caused many loads to flash-set. for Crom International. He is Ingenuity, determination, and teamwork an ACI Certified Nozzleman enabled our crews to work through the problems and has 9 years of experience and meet the aggressive construction time frames. in constructing prestressed All eight tanks were leak tested and passed on concrete water tanks. He has the first try—a feat we understand is unique for been involved in construction the region. of large water tanks. Shotcrete • Spring 2014 11


2014SprShotcreteEMag
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