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2013SprShotcreteEMag

flexural properties of the shotcrete material. The timely manner. I think a statement made by a specification called for minimum levels of silica member of Wildish Standard Paving sums it up best: fume and cement, but we decided we needed to “Our shotcrete applicator was committed to rethink this. achieving the very best mix design that could be This is typically where I’ve seen a great developed. From the original mix we reduced the number of projects become dysfunctional. The silica fume content; used other supplemental focus changes from getting the job done correctly cementitious material, including fly ash and added to minimizing the damage and protecting one’s fiber; and a W R Grace retarder to slow the set best interest. The parties become more adversarial time. After developing eight different trial batches than trying to work together to solve the problems for the project, they were able to identify a concrete and move forward. Fortunately, with this project, mix that exceeded the requirements of the the Oregon Department of Transportation (ODOT) specifications, while offering better adhesion and and its team stepped up not only financially but also more elasticity than originally specified. Were it (and more importantly) remained focused on not for their perseverance in obtaining the best finding the best solutions. I believe their role was possible product, the shotcrete applied to the instrumental in allowing both the contractors and bridge might have met the original project suppliers the means to find the best answers in a specification, but would not have been as durable over the years. From the original mix, which produced a 10 to 30 psi (0.07 to 0.21 MPa) bond pulloff strength, we increased to getting over 300 psi (2.1 MPa) with the final mix.” I would add, it was really the commitment of all the parties to achieve the best quality and durability that allowed this to take place (refer to Fig. 9). As a result of the efforts by many, including Wildish Standard Paving, Johnson Western Gunite, CEMEX, and ODOT, the project team rehabilitated a beautiful historic landmark of the region in a safe and effective manner. Through working together toward a mutually desired end goal, I believe we produced a durable, serviceable, and aesthetically pleasing project that will be enjoyed by many generations to come. For information on the concrete mixture designs and specific test results, please contact ASA. Fig. 8: Overhead finishing Marcus H. von der Hofen, Vice President of Coastal Gunite Construction, has nearly two decades of experience in the shotcrete industry as both a Project and Area Manager. He is an active member of Amer- ican Concrete Institute (ACI) Committees 506, Shotcreting, and C660, Shotcrete Nozzleman Certification. He is a charter member of ASA, joining in 1998, and currently serves as Secretary to the ASA Executive Committee. Fig. 9: The finished product 24 Shotcrete • Spring 2013


2013SprShotcreteEMag
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