Browsing by Subject "ASR"
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Item Characterization of fly ash for evaluating the alkali-silica reaction resistance of concrete(2012-12) Jasso, Andres Jose; Folliard, Kevin J.; Ferron, RaissaFly ash has been used extensively to control deleterious alkali-silica reaction in concrete. The majority of fly ashes can be used to control ASR induced expansion. Fly ashes with high CaO contents are less effective at reducing expansion and fly ashes with high alkali contents can be counter active. Class C fly ashes are less effective at reducing the pH of the pore solution because they are less pozzolanic. The pozzolanic reaction in Class F fly ashes enhances the ability for the hydration products to bind alkalis. This prevents the availability of these alkalis for ASR. This project aims to characterize fly ash in a way that best predicts how it will perform in concrete with an emphasis on ASR. Fly ashes with a variety of chemical compositions were evaluated using a range of analytical and characterization techniques. Research data from several universities were used to correlate their long term data with this project’s accelerated tests. This research aimed at evaluating the mineralogical, chemical, and physical characteristics that most affect the ability of a given fly ash to prevent ASR-induced expansion and cracking.Item Durability testing of rapid, cement-based repair materials for transportation structures(2014-05) Garcia, Anthony Michael; Folliard, Kevin J.; Drimalas, Thanos, 1980-For repairing concrete transportation infrastructure, such as pavements and bridges, much importance is placed on early-age strength gain as this has a major impact on scheduling and opening to traffic. However, the long-term performance and durability of such repair materials are often not satisfactory, thus resulting in future repairs. This research project focuses on the evaluation of the durability of various rapid-setting cementitious materials. The binders studied in this project include calcium aluminate cement (CAC), calcium sulfoaluminate cement (CSA), Type III portland cement, alkali-activated fly ash (AAFA) , and various prepackaged concrete materials. In addition, selected CAC and CSA mixtures were further modified with the use of a styrene-butadiene latex. The durability aspects studied include freezing-and-thawing damage and the implications of air entrainment in these systems, alkali-silica reaction, sulfate attack, and permeability of the concrete matrix and potential corrosion.Item Evaluation of concrete structures affected by alkali-silica reaction and delayed ettringite formation(2012-08) Giannini, Eric Richard; Zhu, Jinying; Folliard, Kevin J.; Bayrak, Oguzhan; Fowler, David W.; Fournier, Benoit; Rivard, PatriceAlkali-silica reaction (ASR) and delayed ettringite formation (DEF) are expansive reactions that can lead to the premature deterioration of concrete structures. Both have been implicated in the deterioration of numerous structures around the world, including many transportation structures in Texas. As a result of considerable research advances, ASR and DEF are now avoidable in new construction, but evaluating and managing the existing stock of structures damaged by these mechanisms remains a challenge. While the published guidance for evaluating structures is very effective at diagnosing the presence of ASR and DEF, there remain significant weaknesses with respect to the evaluation of structural safety and serviceability and nondestructive testing (NDT) is a minor component of the evaluation process. The research described in this dissertation involved a wide range of tests on plain and reinforced concrete at multiple scales. This included small cylinders and prisms, larger plain and reinforced concrete specimens in outdoor exposure, full-scale reinforced concrete beams, and core samples from the outdoor exposure specimens and full-scale reinforced concrete beams. Nondestructive test methods were applied at all scales, and the full-scale beams were also tested in four-point flexure to determine the effects of ASR and DEF on flexural strength and serviceability. Severe expansions from ASR and DEF did not reduce the strength of the full-scale beams or result in excessive deflections under live loads, despite significant decreases in the compressive strength and elastic modulus measured from core samples. Most NDT methods were found to be effective at low expansions but had difficulty correlating to larger expansions. Two promising NDT methods have been identified for future research and development, and guidance regarding existing test methods is offered.Item Evaluation of the aquifer storage and recovery pilot project in Liwa area, Emirate of Abu Dhabi, UAE(2010-12) Khezri, Solaleh; Charbeneau, Randall J.; Herrmann, RolfEmirate of Abu Dhabi is located in an arid region, where the main source of fresh water is desalination plants. The vulnerability of desalination plants renders planning for an alternative source of freshwater essential. In this study the feasibility of aquifer storage and recovery in the Liwa area, in Emirate of Abu Dhabi, United Arab Emirates was investigated. Based on operational data collected from the pilot project, the model was set up and calibrated. The calibrated model was used to study the affect of various operational parameters, namely storage duration, pumping rate, screen location, multiple cycle operation and periodic recharge, as well as some aquifer characteristics factors: dispersion and salinity profile. This study can be utilized to optimize the operation of the Liwa ASR project.Item Monitoring of an outdoor exposure site : evaluating different treatment methods for mitigation of alkali-silica reactivity in hardened concrete(2011-05) Resendez, Yadhira Aracely; Folliard, Kevin J.; Drimalas, ThanoThis research project, funded by the Federal Highway Administration, entails the construction of an outdoor exposure site in order to evaluate various methods for mitigating alkali-silica reaction (ASR) in hardened concrete. The exposure site, built at the Concrete Durability Center at the University of Texas at Austin J.J. Pickle Research campus, included a series of bridge deck, column and slab elements. The specimens were cast in 2008, allowed to expand to predetermined expansion levels and then treated with various mitigation measures, after which the specimens were monitored for expansion, humidity, and deterioration.Item The role of aquifer storage and recovery (ASR) in sustainbility(2010-12) AlRukaibi, Duaij; McKinney, Daene C.; Maidment, DavidKuwait is an arid country situated at the head of the Arabian Gulf and its water resources can be classified into three significant types: (1) natural (groundwater) and (2) artificial (desalinated sea water and treated wastewater). In the absence of surface water bodies, groundwater constitutes the most important natural water resource in Kuwait with TDS [less than or equal to]10000 mg/L in central and south Kuwait. Only in the north can one find fresh water lenses. Brackish groundwater are used for irrigation, landscaping, construction work, non-potable use in households and mixing with desalinated water up to 10%, to make it potable. The occurrence of usable groundwater is limited to the Kuwait Group and Dammam Formation. Due to over-pumping of groundwater over the last few years, the levels and quality of groundwater are deteriorating. Kuwait is described as the poorest country in terms of water availability (UN World Water-2003). The current rates of water consumption are very high, with 459.6 L/C/d and almost 91 L/C/d for fresh and brackish water, respectively. The water budget of the water resources, represented as percentages is 59% from desalination sea water plants, 32% from groundwater with the possibility to increase the use of this resource and 9% from waste water reuse plants. Although Kuwait does not have any surface water, but it depends on technology to produce water recourses to meet the demand. The best solution for solve the issues of declining water levels and increasing salinity is artificial recharge. Artificial recharge has been applied in Kuwait in different groundwater fields since the 1980s. In addition, the available surface storage capacity of 11.7 Mm³ freshwater is sufficient to meet demand for about 7 days. So, Aquifer storage and recovery (ASR) can be used to store the water in aquifers instead of surface storage. ASR entails storing water in aquifers during wet times and recovering the water from the same well during drought times. Surface storage needs construction resources and vast land. In contrast, storing water in aquifer storage does not need that and it can decrease salinity and keep the water table constant. The water availability for artificial recharge can come from desalination and wastewater plant. The capacity and production of desalination plants are 1.425Mm³/day (525.125Mm³/yr) and 1.31Mm³/day (478.15 Mm³/yr), respectively from 5 stations. The excess capacity is 115000 m³ per day and could reach 290000 m³ per day in the winter season. Wastewater treatment plants produce from 3 plants around 0.337 Mm³/day (123.342 Mm³/yr) and the newest plant (operating by RO system) produces 0.32 Mm³/day (117.12 Mm³/yr) and will reach 0.643 Mm³/day (235.338 Mm³/yr) in 2015. The water produced from wastewater treatment plants has good quality and can be used for irrigation, greening enhancement, landscaping, recreation (artificial river and lakes) and artificial recharge. Also, using water treated for artificial recharge will improve the quality of injected water that has been successfully treated with soil aquifer treatment technology. Groundwater pumping is 200 Mm³ annually and is likely to reach 280 Mm³ in the future. This research will explore and create a database for water resource by GIS software using its tool to select and display suitable areas for ASR operation. Artificial recharge in Kuwait has used the concept of injection and recovery of water in one cycle, while here we will apply the multi-cycle concept to avoid increasing the piezometric head and clogging the porous media. The injected water will be from wastewater treatment plants with a TDS content of less 500 ppm and the TDS of recovered water in each well less than 1500 ppm. Moreover, there are criteria for selecting a domain for artificial recharge, for example, moderate transmissivity, The TDS of the aquifer should not exceed 5000 ppm, and the horizontal and vertical hydraulic gradient should be as small as possible and close to the stations suppler and demand center. The success of artificial recharge will depend on the recovery efficiency (RE) in every cycle which will increase if artificial recharge done in the correct way. The RE increases with a decrease in time between the stopping of injection and the starting of the recovery operation. Aquifer storage and recovery can play an important role as sustainability tool to resolve water resource problems, improving water quality, better than surface water storage since it minimizes construction of new infrastructure and uses that cost to initiate new desalination or waste water plants. At the end of this research we will have demonstrated the concept of the process of ASR including the volume and time for injection and recovery of water in multi-cycles and in different suitable sites.Item The role of aquifer storage and recovery (ASR) technique in sustainability: A case study for Kuwait(Center for Research in Water Resources, University of Texas at Austin, 2010-12) AlRukaibi, Duaij S.; McKinney, Daene C.Item Shear performance of ASR/DEF damaged prestressed concrete trapezoidal box bridge girders(2010-08) Wang, Tz-Wei; Jirsa, J. O. (James Otis); Bayrak, Oguzhan; Ghannoum, Wassim M.; Wheat, Harovel G.; Zhu, JinyingConcrete bridges in Texas have developed large cracks in bent caps and pretensioned trapezoidal bridge girders. The bridges show premature concrete deterioration due to alkali-silica reaction (ASR) and delayed ettringite formation (DEF). There is concern that deterioration due to ASR/DEF may lead to a loss of structural capacity. However, there are no quantitative guidelines to relate the level of concrete deterioration due to ASR/DEF to structural performance. Using such guidelines, the need for rehabilitation of beams with ASR/DEF cracking can be assessed. The goal of this research was to determine the shear capacity of pretensioned trapezoidal box girder specimens exhibiting varying degrees of ASR and/or DEF cracking and to use the shear testing results to evaluate the severity of the problem that may exist in Texas bridge structures. To achieve this goal, beams that were severely deteriorated due to ASR/DEF over a period of more than ten years were transported to the University of Texas for testing to failure. Both severely deteriorated and uncracked beams were tested in shear. The test results were used to evaluate the shear performance of trapezoidal box beams affected by ASR/DEF. In addition, three different types of forensic analyses were conducted on the beams to understand the nature of the ASR/DEF cracks and severity of the deterioration. After testing, it is found that the shear capacity of the test specimens was not significantly reduced even with heavy ASR/DEF cracking. Assessment using current US design provisions for bridges or buildings (ACI 318-08 and AASHTO LRFD 2008) and the proposed provision from an earlier project (TxDOT Project 5253) yielded conservative estimates of strength. Results from forensic analyses provided a qualitative indication of ASR/DEF damage but did not correlate with the observed levels of ASR/DEF deterioration.Item Structural performance of ASR/DEF damaged prestressed concrete trapezoidal box beams with dapped ends(2010-08) Larson, Nancy Anne, 1986-; Bayrak, Oguzhan, 1969-; Jirsa, James O.Across the State of Texas and many other areas of the world, relatively young concrete structures have developed signs of premature concrete deterioration. Large cracks form on the surface of the concrete due to expansive forces from alkali-silica reaction (ASR) and delayed-ettringite formation (DEF). The goal of this project is to assess the effect of ASR/DEF on the trapezoidal box beam bridges in the US 59 corridor and Katy Central Business District (CBD) HOV lanes in Houston, TX. Five dapped-end beams were rejected during the casting process and have been in storage at a local precast yard for nearly fifteen years. These beams have been subject to accelerated deterioration and represent the potential severity of the ongoing ASR/DEF distress within the dapped end regions of the in-service trapezoidal box beams. The results from five load tests, corresponding strut-and-tie models, and forensic investigation are used to provide insights into the relationship between the severity of the deterioration and the capacity margin.