Volatile organic compounds effective diffusion coefficients and fluxes estimation through two types of construction...

Area of Science:

• Environmental Science
• Geochemistry
• Building Science

Background:

• Volatile organic compounds (VOCs) migrating from contaminated soil and groundwater into buildings present significant human health risks.
• Understanding the passive migration of VOCs through building materials is crucial for accurate health risk assessments.

Purpose of the Study:

• To quantify the effective diffusion coefficients and fluxes of selected VOCs (chlorinated solvents and BTEX) through concrete and geo-membrane materials.
• To evaluate the efficacy of common building isolation materials in preventing or attenuating VOC vapor intrusion into indoor environments.

Main Methods:

• A laboratory-scale experiment was conducted to simulate VOC diffusion from contaminated subsurface sources into buildings.
• Effective diffusion coefficients and mass fluxes of specific VOCs were measured through concrete (anhydrite screed) and geo-membrane samples.

Main Results:

• The study demonstrated that building sealing materials cannot entirely prevent VOC diffusive transfer but can attenuate it.
• Concrete attenuated VOC transfer to a certain degree, while geo-membranes reduced it to non-detectable levels.
• Effective diffusion coefficients varied significantly, ranging from 3.17 × 10(-2) to 5.90 × 10(-5) cm(2)/s for concrete and 5.47 × 10(-6) to 5.50 × 10(-8) cm(2)/s for geo-membranes.

Conclusions:

• The mass flux of VOCs through building materials is a significant factor in indoor air contamination.
• The utilization of concrete and, more effectively, geo-membranes can substantially reduce VOC migration into buildings.
• The research provides essential data on effective diffusion coefficients for VOCs in building materials, aiding in predictive modeling for health risk assessments.