Dallas City Hall and Plaza are recognized by many due to the opening scenes of Dallas, the television show. What is less known is that the structure is a significant early example of bonded post-tensioned concrete which was utilized throughout the superstructure and two-story parking garage constructed beneath the plaza. Opened in 1977, the parking garage is a two-way bonded post-tensioned concrete slab with unreinforced drop panels supported by flared circular concrete columns. The garage covers two city blocks, extends under two adjacent multi-lane streets, and supports mature landscaping, pool, fountain, and up to 11’-0” of soil. In 2017, several square feet of a drop panel fell from the structure and subsequent observations found multiple locations of drop panel and column capital failures. A structural investigation including destructive and non-destructive testing, and analysis of the existing structure was undertaken to determine the cause of the failures.
Selection of the most appropriate, professional tools for the setting of foam backer rod at the correct, consistent depth, without puncturing the skin, is the first step in creating a sealant joint that is long lasting and meets sealant manufacturer specifications. Next is the selection of the optimal sealant dispenser and nozzle. The size and orientation of the joint and the viscosity of the specified sealant will guide an installer to the most efficient drive, material containment unit (MCU) and nozzle for the application. Lastly, the selection of the most appropriate caulk finishing spatula and the technique employed are critical for the sealant to adhere and perform to specification.
Demonstration will show what an acceptable CMU substrate for application of air barrier materials looks like, how to prepare Sprayable Cat 5 air barrier coating for application, discuss proper pump specifications for spraying the material, and demonstrate best practices for spraying Sprayable Cat 5, a Silyl-Terminated Polymer air barrier to a CMU substrate, while providing “tips & tricks” along the way.
The demonstration will include historical products and processes used for repair of tilt-up wall and precast concrete structures, new technology developments, proper material selection, and application methods.
Alkali-Silica Reaction (ASR) can cause significant damage to concrete structures including bridges, roadways, airport runways, and nuclear power plants. When reactive aggregates are included in a mix, the presence of moisture initiates a reaction between the alkaline cement paste and reactive amorphous silica. The result is a gel that continues to dilate, which may cause cracks in the concrete mass. A research program was undertaken at the University of Toronto to investigate the effects of ASR on large-scale and small-scale concrete specimens. Several specimens were constructed using reactive (ASR) concrete and non-reactive (regular) concrete, and their short-term and long-term structural and mechanical behavior were compared. In this presentation, we will discuss the results of the research program, will offer best practices to minimize the risk of ASR in concrete during placement, and will propose several strategies for repair of structures that have been degraded due to ASR.
Presentation will discuss Vision 2020 (Development, Successes and Challenges) as well as items which still need to be completed. This portion of the presentation will be followed by an overview of the presenter's perspective on the future needs for the concrete repair industry. All attendees will be invited to participate in a workshop to develop a complete list of industry needs (consensus if possible).
The FRCM externally bonded Composite Strengthening Systems repair and reinforcement solution combines high-performance sprayable mortar with a carbon-fiber grid that creates a thin structural layer without significantly increasing the structure's weight or volume. With FRCM, contractors can effectively repair, protect, and strengthen concrete and masonry structures in a single application for a fraction of the installed cost of traditional shotcrete.
The Ituango dam is an embankment dam that is currently under construction on the Cauca River in Colombia. The largest hydroelectric power plant in Colombia’s history. Three large diversion tunnels used to divert the water from the river around the construction site during construction collapsed as a result of heavy rainfalls. The nearly completed pump house had to be flooded to accommodate premature water build-up in the reservoir. These tunnels would need to be permanently sealed. “Pre-stoppers” would need to be constructed in place to serve as bulk heads between which would ultimately be excavated and back-filled with concrete to permanently seal the tunnels. Additional to standard anti-washout properties, the grout had to withstand swiftly flowing water and exhibit an extended working time at temperatures above 32 degrees C. A custom grout was developed for this application. In the end, hundreds of grout micropiles were tremied, consuming more than 1,650 tons of grout, to produce...
The installation of externally applied FRP systems has been slow to evolve due to limitations of materials used in the field. This demonstration will show how to make the most out of the materials with efficient application methods that will save time and money.
Three precision epoxy grouts: E3-Deep Pour, E3-Xtreme and E3-Flowable will be demonstrated. These products are precision grouts used to support equipment and machinery in demanding environments. The demonstration will explain why and where epoxy grouts are used, how they are tested, project preparation, mixing and application, and other considerations. The features and benefits of each product will be described, and newly patented dust-limiting aggregate technology will be introduced.