Thesis
Fly ash based ultra high-performance concrete as encapsulation grout in nuclear applications
Washington State University
Master of Science (MS), Washington State University
05/2019
DOI:
https://doi.org/10.7273/000003966
Handle:
https://hdl.handle.net/2376/125351
Abstract
Ultra-High-Performance Concrete (UHPC) is a fiber reinforced, super plasticized, silica fume-cement mixture with a very low water-to-cementitious materials ratio that exhibits compressive strengths greater than 17,000 psi at 28 days. The present work involves the development of UHPC mixtures using locally available materials with fly ash as a complete replacement for silica fume. In UHPC mixtures, silica fume is commonly used as a supplementary cementitious material. This work investigates the possibility of replacing expensive silica fume with less expensive class F fly ash in UHPC mixtures to reduce the cost. Use of fly ash as a replacement of silica fume is not only cost-effective, but it helps in producing eco-friendly UHPC. In this research, UHPC mixtures were developed using local materials. Specifically, local sand with a top size of 600 μm, locally available Type I/II/V portland cement and class F fly ash, silica fume, domestic steel fibers, and a high range water reducing admixture. After developing initial UHPC mixtures with silica fume as supplementary cementitious material, mixtures were further optimized by gradually replacing silica fume until totally replaced with fly ash. Fresh and hardened UHPC properties were studied for all the mixtures. Fly ash based UHPC Mixtures were developed with and without steel fibers and tested to study the effect of steel fibers on strength and durability properties. The fly ash-based UHPC achieved a compression strength of 17,960 psi. Factors such as age and curing regimen that influence strength were also investigated. Chloride permeability of UHPC was also investigated and found that the permeability was negligible to very low. Resistance of UHPC to alkali silica reaction (ASR) was studied and found that the ASR expansions were well within the threshold value of 0.1% The UHPC mixtures were developed with a focus on not only mechanical strength and durability properties but also on improving workability so that this innovative material can be used as grouting material for encapsulation of nuclear waste and shear keys in bridges. The results include mixture optimization, characterization of fresh and hardened properties, and durability of UHPC with class F fly ash as 100% supplementary cementitious material.
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Details
- Title
- Fly ash based ultra high-performance concrete as encapsulation grout in nuclear applications
- Creators
- Levi L. Gilbert
- Contributors
- Srinivas Allena (Advisor) - Washington State University, Department of Civil and Environmental Engineering
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Civil and Environmental Engineering
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Identifiers
- 99900890804201842
- Resource Type
- Thesis