Develop a multi-functional green pervious concrete (MGPC) pavement with polycyclic aromatic hydrocarbons (PAHs) removal function.

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