Diffusion and sorption of volatile organic compounds through soil-cement materials

Abstract

This paper presents a laboratory study that assesses the diffusive and sorptive parameters of three volatile organic compounds (benzene, ethylbenzene and trichloroethylene) though cured, monolithic soil-cement materials. A double-reservoir diffusion test setup is used to determine the effective diffusion coefficient (D e) and distribution coefficient (K d) for laboratory-prepared soil-cement specimens at three water-to-cement ratios. Batch testing was also performed to provide a measure of the distribution coefficient independent of the diffusion testing. Values of K d determined from batch testing, diffusion testing and theoretical estimates from the literature ranged from 0 to 1·3 cm3/g and were in general agreement. Values of D e determined from laboratory testing ranged from 1·50 × 10−10 m2/s to 3·0 × 10−10 m2/s. Practical applications of the laboratory testing methodology and results are discussed with respect to how they may be used in the pre-design and design phases of cement solidification/stabilisation (s/s) treatment. An illustrative example shows how the laboratory testing results could be used to estimate contaminant transport from a site and to provide an indication of the relative importance of the diffusive and sorptive parameters obtained from laboratory testing.