Date on Master's Thesis/Doctoral Dissertation

8-2021

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Civil and Environmental Engineering

Degree Program

Civil Engineering, PhD

Committee Chair

Sun, Zhihui

Committee Co-Chair (if applicable)

Bhaskar, Nageshwar R.

Committee Member

Bhaskar, Nageshwar R.

Committee Member

Rockaway, Thomas D.

Committee Member

Sathitsuksanoh, Noppadon

Author's Keywords

Multi-functional green pervious concrete (MGPC); stormwater management; polycyclic aromatic hydrocarbons (PAHs) removal; best management practices (BMPs); organoclay; adsorption

Abstract

Stormwater runoff induced Polycyclic Aromatic Hydrocarbons (PAHs) contaminant increasingly imperils the groundwater quality and the sustainable development of human society due to the potential carcinogenic risks. Pavement can be considered as the first line of defense for contaminant removal of the stormwater runoff. New construction materials with stormwater runoff quantity and quality control are in urgent demand for updating the existing pavement system. An innovative material called Multi-functional Green Pervious Concrete (MGPC) was developed in the department of Civil and Environmental Engineering at University of Louisville. This material uses organoclay as the amendment to enhance the PAHs removal capacity of conventional pervious concrete. The objective of this study is to evaluate the potential implementation of MGPC as a pavement material with the groundwater contamination remediation functions. The study was performed in five stages. First, The PAHs remediation function of MGPC was tested by introducing organoclay [bis (hydrogenated tallow alkyl) dimethyl ammonium modified montmorillonite] to the conventional pervious concrete. After test and verification, the mix proportion of MGPC was designed to meet the compressive strength and hydraulic conductivity requirements of pervious concrete. A small amount of organoclay addition was found not to adversely affect the compressive strength and hydraulic conductivity of MGPC. The preliminary study of the PAHs removal functions of MGPC was conducted in stage two. The isothermal batch sorption test was conducted to quantify the sorption capacity of the organoclay modified cement paste, and the column test was performed to investigate the transport mechanism and retardation behavior of PAHs in MGPC. It was found that the developed MGPC with a small addition of organoclay could substantially remove PAHs contaminants and it also has much stronger adsorption and retardation capacity than the conventional pervious concrete. In stage three, a series of comprehensive laboratory-scale tests were conducted to examine the effectiveness of stormwater induced PAHs removal by using the MGPC pavement. The results indicated that the initial concentrations of the PAHs and the flow rates would impact the removal efficiency of MGPC. The tests showed that the MGPC still maintained considerable sorption capacity after 50 PAHs sorption and desorption cycles. An ideal site under steady-state groundwater conditions was generated to simulate the long-term performance of MGPC on PAHs removal by using the finite element method in stage four. The laboratory experiments were used to determine the physicochemical parameters of MGPC, and three sorption isothermal models (linear, Freundlich and Langmuir) were fitted to the sorption test data. The computer simulation revealed that the MGPC had significant remediation efficiency on the PAHs contaminant. Other than the material properties of MGPC, the efficiency of contaminant remediation of MGPC was also found to be influenced by the permeability of the subbase and the initial concentration of PAHs. It was also found that the linear isotherm model would overestimate the removal efficiency of PAHs with higher concentration sources. At last final fifth stage, a Pavement Environment and Performance Index (PEPI) was proposed to evaluate the environmental impacts of three different types of pavements (impervious concrete, conventional pervious concrete, and MGPC). The data from experiments and the Environmental Footprint Database was used to calculate the PEPI. Based on the Life Cycle Assessment (LCA) results, it was found that the MGPC pavement was much more environmentally friendly with relatively lower greenhouse gas emissions and energy consumption, and better environmental performance comparing with the other two types of pavements.

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