Browsing by Subject "Repairing"

Now showing 1 - 3 of 3
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    BR27568 – Experimental Shear Capacity Comparison Between Repaired and Unrepaired Girder Ends
    (Minnesota Department of Transportation, 2018-02) Shield, Carol; Bergson, Paul
    Over time, the southbound exterior girder ends on each side of Pier 4 and Pier 26 of Bridge 27568 suffered significant corrosion damage that exposed transverse reinforcement, prestressing strands in the exterior side of the bottom flange and the sole plate anchorages. The girder ends were repaired in 2013 by encasing supplementary steel reinforcement in shotcrete over a 4 ft. length of the girder. The two repaired girders and two companion girders, removed when the bridge was replaced in 2017, were brought to the University of Minnesota and tested to failure in shear to determine the effectiveness of the repair. The laboratory testing showed that the repair was able to return the girders with significant corrosion damage to the strength of the companion girders, indicating that the repair was effective.
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    Evaluation of Concrete and Mortars for Partial Depth Repairs
    (Center for Transportation Studies University of Minnesota, 2014-11) Dave, Eshan V.; Dailey, Jay; Musselman, Eric
    Partial-depth patching mixes must rapidly gain strength to allow the roadway to be reopened to traffic quickly. A patch should also bond well to the substrate to prevent the patch from separating from the existing material and be durable enough to withstand harsh winters. The objective of the research described in this report is to develop improved guidelines for evaluation of pre-bagged commercial patching mixtures and to recommend effective construction practices. To achieve these objectives, 13 different cementitious materials were selected and tested to determine key properties including strength gain, shrinkage, bond strength, and durability. The impact of the proposed research will be a better performing patch material as well as performance criteria that can be used to compare the materials tested in this program to new materials that will certainly be developed in the future. This research was conducted in four main phases, literature review and development of a testing plan and three phases of laboratory testing campaigns. The most commonly available acceptance specification for partial-depth patching materials is the ASTM C928. This specification was followed and the outcomes of each of the recommended tests were evaluated in context of the performance of the patching materials. Several additional tests were developed and conducted to evaluate the bonding properties of patching materials; correlations between lab measured properties were also evaluated. Through aforementioned testing and analysis, a laboratory testing based acceptance procedure was developed for partial-depth patching materials to be used by MnDOT.
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    Optimized Taconite-Based Pavement Repair Compound and Deployment System
    (Minnesota Department of Transportation, 2019-12) Zanko, Lawrence M.; Post, Sara P.; Oreskovich, Julie A.; Geerts, Stephen Monson; Drazan, Jaqueline
    This project refined the Natural Resources Research Institute's (NRRI) patented taconite-based repair compound, explored equipment options, and field tested/demonstrated a low-cost mechanized system that can efficiently mix and place the repair compound in larger quantities while minimizing or eliminating direct contact and hand mixing by maintenance personnel. The rigid, taconite mineral-based, all season rapid-setting repair compound contains neither petroleum nor portland cement. As such, its environmental footprint is much smaller than cold-mix or hot-mix asphalt products, mastic, and portland cement-based repair compounds. The refined and optimized formulation utilizes relatively low-cost and abundant mineral byproducts and co-products, and the mechanized deployment system makes use of relatively inexpensive commercially available, i.e., off-the-shelf, equipment, compared to single-bucket mixing. Larger-scale continuous mixing remains a challenge and is still under investigation. The expected economic benefits include cost savings for both raw materials and maintenance labor. In addition, the rapid-setting nature of the formulation combined with a mechanized deployment system would allow pavement and pothole repairs to be conducted faster and with moving traffic control, thereby avoiding lengthy traffic-disrupting lane closures. Key project outcomes are lower costs, better-quality and longer-lasting repairs, and improved productivity.