Download or read book Testing Aggregate Backfill for Corrosion Potential written by Zachary Brady and published by . This book was released on 2016 with total page 55 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Kansas Department of Transportation (KDOT) has designed and constructed numerous mechanically stabilized earth (MSE) walls to support new and expanded highway projects throughout Kansas. MSE walls often contain galvanized steel strips as the mechanical reinforcement within layers of specified backfill material. Inclusion of these strips creates a stronger composite material connected to a visually appealing wall facing, but galvanized steel reinforcement is potentially vulnerable to corrosion. Corrosivity of MSE backfill is typically characterized using electrical resistivity among other properties. KDOT currently uses the American Association of State Highway and Transportation Officials (AASHTO) Standard T 288 (2012) to calculate the resistivity of MSE backfill. There is concern that this method may not reflect field conditions well, and thus may mischaracterize the corrosivity of backfill. AASHTO T 288 tests were conducted as a part of this research, and the condition of the samples at the time of testing was not consistent with expected field conditions. A new procedure has been proposed that appears to more accurately simulate field conditions. This new procedure (ASTM C XXX-XX) has been extensively tested and compared with AASHTO T 288 in this experimental study. The proposed ASTM test simulated expected field conditions more accurately than the AASHTO T 288 test. Results also appear to indicate the need for a larger resistivity box to accurately characterize the corrosivity of larger aggregates. Preliminary recommendations for box geometry are 8:1 minimum electrode spacing to maximum particle size and 3:1 minimum height to maximum particle size. It was also observed that increasing the number of soak/drain cycles of the material resulted in a substantial increase in resistivity.
Download or read book Investigation of Variations in Corrosion Potential in Mechanically Stabilized Earth Backfill Due to Migration of Fines written by Chase Breckwoldt and published by . This book was released on 2019 with total page 69 pages. Available in PDF, EPUB and Kindle. Book excerpt: Departments of Transportation have constructed thousands of mechanically stabilized earth (MSE) walls to support bridge abutments in highway projects and for other applications. These MSE walls often include metal strips or grids as reinforcement, typically galvanized steel strips within granular backfill meeting Federal Highway Administration (FHWA) and American Association of State Highway and Transportation Officials (AASHTO) standards. Utilization of steel strips or grids creates a stronger composite material; however, minerals within the backfill or salts applied at the surface can create a corrosive environment. Excessive corrosion can lead to distresses or premature failure of MSE structures. Corrosion may increase when cycles of water from precipitation promote migration of fines through the granular backfill. Migrating fines have the potential to accumulate at the base of the reinforced fill and clog drainage and retain water, which could accelerate the corrosion process. This study evaluated the potential for accelerated corrosion due to the accumulation of fines. Aggregate approved for use in MSE structures was placed in a test column with internal dimensions of 30 × 30 × 183 cm, which then had water flowed through it. The grain size distribution was measured at different elevations within the column and the resistivity of the aggregate, which is correlated with corrosion rate, was also evaluated at a series of elevations within the column after water has been passed through it. Results from the testing were compared with resistivity results from a test box consistent with current Kansas Department of Transportation (KDOT) use. All aggregates tested had a drained resistivity that was well above the 5,000-ohm-centimeter (ohm-cm) limit. The results of this study show that migration of fines can occur in KDOT aggregates, and that this migration can cause measurable changes in the grain size distribution, water content, and resistivity of the soil column. In addition, as the number of saturation and drained cycles increases for each material, the resistivity also increases. The current KDOT specification limiting the amount of material passing the No. 200 sieve is beneficial in that it limits the fines available for migration. Additional constraints within the specification could further limit the potential for suffusion.
Download or read book Measuring Corrosion Conditions in Mechanically Stabilized Earth Walls written by Robert L. Parsons and published by . This book was released on 2021 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt: KDOT extensively utilizes mechanically stabilized earth (MSE) walls, typically with coarse aggregate backfill. Previous projects K-TRAN: KSU-15-6 and K-TRAN: KU-15-5 tested the aggregate material from MSE walls under construction. KU identified that several of the clean aggregate samples contained some fines, likely from crushing of the aggregate, and two of the walls contained over 10% fines. Aggregate backfill is specified because it allows for free drainage, limiting the pore water pressure buildup behind the wall. There is the potential for these fines to migrate towards the base of the wall over time. This migration of fines would not only increase the potential for water retention, but it would also increase the localized corrosion potential of the backfill. This joint project measured the backfill corrosion conditions of 12 MSE walls selected by KDOT. Walls were surveyed using a variety of non-destructive resistivity arrays and by cutting through the wall face, sampling the backfill, and inspecting reinforcing strap conditions. Multiple walls with potentially corrosive backfills (low resistivity) were identified, and several walls had reinforcement with visible corrosion in progress. The resistivity survey method and the physical sampling method were generally consistent in identifying backfills with low resistivity. The results support the potential of using a modified four-electrode electrical resistivity measurement to identify corrosive environments in MSE walls. If used by KDOT, this will improve KDOT’s geotechnical asset management of MSE walls. Results from the physical testing of backfills showed that the finest fraction of the backfill (D10) was strongly correlated with low resistivity values, particularly with the sand backfills. High chloride concentrations were also measured in the three samples with the lowest resistivity. These results support the current recommendation that the percentage of fines (material smaller than the #200 sieve) be limited to a maximum of 5%, and encourages the consideration of an additional specification that the percentage passing the #100 sieve be limited to 10%.
Download or read book Electrical Resistivity Measurements of Mechanically Stabilized Earth Retaining Wall Backfill written by Michael Andrew Snapp and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In Kansas, mechanically stabilized earth (MSE) retaining walls are typically backfilled with coarse aggregate. Current backfill material testing procedures used by the Kansas Department of Transportation (KDOT) utilize on-site observations for construction quality assurance and the American Association of State Highway and Transportation Officials standard T 288-12 ("Standard Method of Test for Determining Minimum Laboratory Soil Resistivity"). AASHTO T 288-12 is designed to test a soil sample's electrical resistivity (ER) that correlates to its corrosion potential. However, the test, based on material passing through a No. 10 sieve, is inappropriate for coarse aggregate typically used by KDOT as the aggregate will be retained on a No. 10 sieve and potentially leads to over-conservative designs. However, ER imaging provides a two-dimensional (2D) profile of bulk ER of backfill material, thereby yielding more information regarding backfill uniformity compared to traditional sampling. The objective of this study was to characterize bulk ER of in-place MSE wall backfill aggregate. In this study, MSE walls selected by KDOT were tested using ER imaging during construction to determine bulk ER of the backfill. Variations within backfill ER may be a result of varying aggregate material, inclusions of fines, thoroughness of compaction, and the presence of water. ER imaging was used on five walls: four MSE walls and one gravity retaining wall that contained no reinforcement. One MSE wall contained metal reinforcement, while the other four walls contained geosynthetic. The ER imaging field method produced a 2D profile that depicted ER uniformity for bulk analysis. A post processing algorithm was generated to remove the subjective nature of the ER imaging results. The program determines the bulk ER based upon the ER imaging results. These results indicate that the laboratory analysis of AASHTO T 288-12 under-estimates the bulk ER of in-situ backfill material. Identification of a material's bulk ER will help characterize the ER of aggregates in a complementary KDOT project. Results of this study will be used to recommend an in-situ test method for aggregate used by KDOT.
Download or read book Direct Evaluation of Corrosion Potential in Concrete Made with Marine Limestone Coarse Aggregates written by Mrinmay Biswas and published by . This book was released on 1994 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Corrosion Effects of Cement Stabilized Backfill on Galvanized Steel Earth Reinforcements written by Derek V. Morris and published by . This book was released on 1994 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cement stabilization of backfill has been used for some time in mechanically stabilized earth type retaining walls. However, there has been no data on the corrosion life of galvanized steel reinforcement in this environment, which is intermediate in pH between normal soil and pure cement. Field observations had indicated a potential corrosion problem at a particular site in District 12. As a result of the test program conducted during this project, the following conclusions were made. First, cement addition to backfill in the usual quantities (i.e. 7% or more) raised the pH environment to values close to that of normal concrete. At these levels corrosion rates of zinc coatings were not significantly accelerated -- if anything, corrosion rates were less than for unstabilized fill. Second, very small amounts of cement addition, of the order of 1% to 4% producing pH values significantly less than 12, could cause limited acceleration of corrosion. It is, therefore, advisable to control minimum cement levels and to encourage efficient mixing. Third, elevated corrosion rates were associated primarily with the presence of inorganic ions, both for stabilized and unstabilized fill. In the case of the problem site in District 12, this appeared to be the result primarily of unusually high sulfate content in the fill. Fourth, the use of crushed concrete as backfill did not accelerate corrosion. This material, therefore, appears to be acceptable for this application.
Download or read book Specifications for Structural Concrete ACI 301 05 with Selected ACI References written by American Concrete Institute and published by American Concrete Institute. This book was released on 2005 with total page 660 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ACI Manual of Concrete Practice written by American Concrete Institute and published by . This book was released on 2002 with total page 1068 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Coal Combustion Byproducts written by United States. Congress. House. Committee on Small Business. Subcommittee on Rural Development, Entrepreneurship, and Trade and published by . This book was released on 2010 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The subcommittee has called this hearing so that members might learn more about coal ash, the small businesses that turn coal ash into useful products and the concerns that these businesses have about the proposed Federal regulations that they believe may have a negative effect on their industry ... The EPA has recently issued two proposals for regulating coal ash. One would regulate coal ash as a solid waste and would provide very limited Federal enforceability and may not provide adequate protection of the environment and human health. The other would list coal ash as a special waste under the Hazardous Waste Subtitle in the Resource Conservation and Recovery Act, Subtitle C. The second option is one that we will focus on ... since it has generated great concerns among small businesses across this country. These businesses, many of which are represented here today, have reason to believe that regulating coal ash under Subtitle C, even as a special waste, will open recycling operations to added litigation and a stigma that will discourage the ... use of the products made with recycled coal ash."--P. 1-2.
Download or read book Chloride Corrosion of steel in concrete written by D. E. Tonini and published by ASTM International. This book was released on 1977 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electrochemical Test Methods to Evaluate the Corrosion Potential of Earthen Materials written by Kenneth L. Fishman and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electrochemical properties of earthen materials such as electrical resistivity, pH, salt concentrations, and organic contents are commonly used to characterize the corrosion potential of buried metal elements that are in direct contact with the surrounding soil. The TRB National Cooperative Highway Research Program's NCHRP Research Report 958: Improved Test Methods and Practices for Characterizing Steel Corrosion Potential of Earthen Materials proposes a protocol describing best practices for sampling, testing, and characterizing the steel corrosion potential of earthen materials. The protocol incorporates alternatives to the current AASHTO test standards for measuring electrochemical properties.
Download or read book Proceedings of the Annual Road School Held at Purdue University written by and published by . This book was released on 1960 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: Includes proceedings of various conferences sponsored by the University.
Download or read book Foundation Engineering Handbook written by Hsai-Yang Fang and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 935 pages. Available in PDF, EPUB and Kindle. Book excerpt: More than ten years have passed since the first edition was published. During that period there have been a substantial number of changes in geotechnical engineering, especially in the applications of foundation engineering. As the world population increases, more land is needed and many soil deposits previously deemed unsuitable for residential housing or other construction projects are now being used. Such areas include problematic soil regions, mining subsidence areas, and sanitary landfills. To overcome the problems associated with these natural or man-made soil deposits, new and improved methods of analysis, design, and implementation are needed in foundation construction. As society develops and living standards rise, tall buildings, transportation facilities, and industrial complexes are increasingly being built. Because of the heavy design loads and the complicated environments, the traditional design concepts, construction materials, methods, and equipment also need improvement. Further, recent energy and material shortages have caused additional burdens on the engineering profession and brought about the need to seek alternative or cost-saving methods for foundation design and construction.
Download or read book Proposed Practice for Alternative Bidding of Highway Drainage Systems written by Michael L. J. Maher and published by . This book was released on 2015 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: "TRB's National Cooperative Highway Research Program (NCHRP) Report 801: Proposed Practice for Alternative Bidding of Highway Drainage Systems explores the application of a performance-based process for selection of drainage pipe systems. The selection process is based on satisfying performance criteria for the drainage system while considering the full range of suitable pipe materials." -- Publisher's description.
Download or read book Advances in Design and Implementation of Cementitious Backfills ADICB written by Erol Yilmaz and published by Frontiers Media SA. This book was released on 2022-10-05 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Corrosion Abstracts written by and published by . This book was released on 1982 with total page 686 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development of a Recommended Practice for Use of Controlled Low strength Material in Highway Construction written by Kevin J. Folliard and published by Transportation Research Board National Research. This book was released on 2008 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Explores the use of controlled low-strength material (CLSM) in highway construction applications, in particular, as backfill, utility bedding, and void fill and in bridge approaches. The report also examines a recommended practice for the use of CLSM that was developed through a series of full-scale field experiments. This report presents the full text of the contractor's final report of the project and three of the five appendices, which present the test methods (Appendix B), specifications (Appendix C), and practice (Appendix D) recommended for implementation. The corrosion study (Appendix A) and implementation plan (Appendix E) are available online as NCHRP Web-Only Document 116.
