On August 9, 2019, Tyson Foods' Holcomb, Kansas beef plant experienced the first large fire in the meat processing industry in nearly 20 years. The long-burning fire precipitated the collapse of a portion of the high roof over the mechanical mezzanine, which housed equipment for numerous critical plant processes. This took portions of the plant, the second largest in the United States, out of operation for months. The pressures of substantial business interruption costs, as well as the market consequences for cattle feeders from the Southern Plains region, necessitated a rapid response. This presentation highlights the investigation into the extent of damage to precast members, including visual inspection, nondestructive and laboratory evaluations, testing, simulation, and analyses. Based on this investigation, members were identified for repair or removal and replacement.
Concrete is the most widely used construction material and can be durable for hundreds of years; however, the main cause of concrete deterioration is from corrosion of reinforcing steel. Steel is thermodynamically unstable and will eventually oxidize to a lower energy state. The rate of deterioration in new and existing structures can be modeled to predict the service life based on the severity of the service environment, the concrete quality, the ingress of deleterious materials, and other factors to various degrees of success. This presentation will provide an overview of many of the service life models currently in use and provide an evaluation protocol for their application related to both new and existing structures.
In new construction, cracks can appear for variety of reasons: curing, temperature deviation, pressure from adjacent conditions, or settlement. This presentation will outline various types of cracking, how to plan to avoid them, and how to address them after concrete has been placed.
This webinar will review issues that should be addressed when preparing a specification for concrete repair. ICRI developed an editable specification titled “Guide Specification for Structural Concrete Repairs” that can be used by design professionals. The webinar reviews the specification and discusses decisions that should be considered when developing a concrete repair specification.
Richard Miller Treatment Plant is a 240 mgd cap. potable water treatment facility located in the California area of the Cincinnati, Ohio, US. After installing an advanced ultraviolet (UV) disinfection treatment system in 2013, GCWW became the largest water utility in North America to use UV light following sand filtration and granular activated carbon. The concrete filter gallery building was originally constructed in 1907 with 26 filters, with a 14-filter addition in 1937 and 7 filters added in 1964. After over 110 years of service, the structures started showing significant signs of deterioration, most commonly concrete spalling and reinforcing steel corrosion. This case study will highlight the methods used to evaluate the structures that involved conventional methods such as sounding, crack mapping, chemical and petrographic examinations, along with technology such as Half-Cell Potential/ICOR, Impact-Echo, Ground Penetrating Radar, and UAS (Drone) services.
After only six years of service, a 6-foot long narrow piece of concrete spalled off an exposed slab edge of a 680-foot tall high-rise in Texas, and fell 160 feet to the podium below. The spall was attributed to premature corrosion at the drip edge. The building featured approximately 9,200 feet of exposed slab edge over its height. Given the potential risk to safety and property of additional concrete spalls, the Owner requested forensic investigations, which (1) identified other areas with signs of similar distress and (2) determined the underlying problem of low reinforcement cover at the drip edge was pervasive. In response, repair options were developed to address the problem and restore intended durability. Given the building height, difficult exterior-only access, downtown environment, and post-tensioning anchors along the slab edge, the repair design and construction both had unique challenges to consider and overcome.
This webinar will discuss the keys to proper surface preparation including establishing the appropriate level of surface profile, evaluating the concrete substrate and the material being installed to determine the correct level of preparation as well as the correct methods and tools to achieve that level.
The prestressed beams in the Hampton Roads Bridge Tunnel Approach Spans were fabricated in about 1960 (west bound lane) and 1970 (east bound lane). The spans are 50-ft and 75-ft, respectively. The brackish water environment caused corrosion and failure of the bottom strands and deterioration and spalling of the cover concrete in many beams. A project in 2018 strengthened 30 of the more deteriorated beams as an alternative to posting or replacing the bridges. Carbon fiber composite wrap (CFCW) and external post-tensioning (PT) were used to strengthen the beams. Prior to construction, a PT mockup was done with one 50-ft (flexible filler) and one 75-ft (grout) beam to demonstrate that the contractor had the materials, equipment and staff to successfully do the external PT. This presentation describes the project’s mockups and construction and the anticipated increase in strength to be obtained from application of the CFCW and external PT.
Construction errors such as the misplacement of reinforcing steel and modifications like the addition of openings traditionally required intrusive repair methods. The addition of structural steel support or enlargement of the concrete elements is often not aesthetically pleasing or practical and the cost and time impacts are onerous. FRP strengthening solutions are non-intrusive, practical, and can be implemented quickly without major impact on the other building trades. The presentation will guide the audience through the feasibility assessment of FRP strengthening and implementation of the strengthening solution. The roles of the various parties, including the Engineer of Record, the FRP Design Engineer, the General Contractor, the Structural Contractor, and the FRP Installer, will be illustrated. Photographs of completed repairs will be presented.