Award of Excellence: Industrial Category
Blue Circle Cement Silo Repair and Upgrade
Submitted by Structural Preservation Systems, Inc.
Thirty years ago, six reinforced concrete silos were built to store Blue Circle Cement’s product in the Boston area. An inspection revealed concrete spalls and structural cracks. Over 30% of the vertical and hoop steel was missing due to design and construction oversights. As a result, the owner was limited to filling the silos only half way.
Due to the shared walls of the clustered silos, access around the entire perimeter of the silos was limited. To address this detail in an effective, constructible, and cost-efficient manner, a new composite form, the FRP rod, was utilized to strengthen the silo. The FRP rod was doweled into the shared wall to ensure complete development of the rod. The rods were inserted into grooves and embedded in an epoxy adhesive. The 150-foot (45 m) long rods could be handled in single pieces due to their lightweight properties. A second layer of adhesive was applied on top of the FRP rod. Overall, about 10 miles (19 km) of FRP rod was installed. The rod option provided near surface-mounted reinforcement that could restore the missing steel and offer the durability benefits of FRP sheet. To monitor the performance of the existing reinforcement and FRP, a new fiber optic strain gauge was installed into the grooves of concrete. The silos were then coated with a breathable, acrylic topcoat for durability and aesthetics.
An open, common goal-oriented relationship between the owner, engineer, contractor, and material supplier was formed. The team allowed a true design-build environment to produce the most viable and cost-efficient solution. The process of building solutions and addressing challenges was limited only to the team’s collective imagination, common sense, and technical expertise.