Graduation Semester and Year
Fall 2024
Language
English
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Civil Engineering
Department
Civil Engineering
First Advisor
Dr. Himan Hojat Jalali
Second Advisor
Dr. Surendra P Shah
Third Advisor
Dr. Melanie Sattler
Fourth Advisor
Dr. Erika La Plante
Abstract
This dissertation investigates the use of wastewater from various treatment stages in concrete production to promote sustainable construction practices. Concrete prepared with potable water (PW) served as a control, while wastewater from plant final effluent (FE), chlorine contact basin (CL), secondary clarifier effluent (SC), primary clarifier effluent (PC), and bar screen effluent (BSE) was evaluated.
A comprehensive testing program was implemented to assess performance, including compressive strength tests, water absorption measurements, X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Results showed that wastewater from advanced stages (FE, CL, SC) had minimal impact on strength and durability, comparable with the control batch. Concrete made with primary wastewater stages (PC, BSE) exhibited reduced strength and increased porosity due to impurities, particularly nitrites.
To address these performance deficiencies, supplementary cementitious materials (SCMs), including Ultra-Fine Fly Ash (UFFA) and Metakaolin (MK), were incorporated into the PC and BSE specimens. The use of SCMs, particularly MK, significantly improved the microstructure by refining pore distribution and enhancing hydration, leading to significant enhancements in compressive strength and reduced water absorption. The effectiveness of MK can be attributed to its higher alumina (Al2O3) content, which interacts with nitrite ions to form stable nitrite-AFt phases, enhancing the microstructure and reducing porosity. UFFA also enhanced water absorption resistance and compressive strength.
The findings demonstrate that treated wastewater from later treatment stages can be utilized in concrete production, while SCMs play a critical role in improving the performance of concrete produced with wastewater from primary treatment stages. Furthermore, a review of wastewater treatment plants revealed that secondary treatment and sludge management contribute significantly to greenhouse gas emissions. By selecting wastewater treatment stages with lower emissions, concrete production's carbon footprint can be reduced, supporting sustainable construction practices.
Keywords
Wastewater, Sustainable construction, Metakaolin (MK), Ultra-fine fly ash (UFFA), Concrete durability, Microstructure enhancement, Compressive strength, Environmental impact.
Disciplines
Civil Engineering | Structural Engineering
License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
Soltanianfard, Mohammadamin, "Sustainable Use of Wastewater in Concrete Construction" (2024). Civil Engineering Dissertations. 503.
https://mavmatrix.uta.edu/civilengineering_dissertations/503