Characterizing Porosity and Diffusive Properties of Monolithic Cement-Based Solidified/Stabilized Materials

Abstract

This paper presents the application of a single reservoir diffusion test to determine the effective porosity of the soil-cement matrix and the diffusivity of tritium through saturated, monolithic, cement solidified/stabilized wasteforms. Testing was performed on a laboratory mixture of cement paste, sand, and kaolinite. The influence of porosity on the proper interpretation of the diffusion tests was examined. Results of tests on three replicate specimens were consistent and indicate effective porosities of 0.26 to 0.28 and effective diffusive coefficients of 2.5×10-10 m 2 /s to 3.0×10-10 m 2 /s. The effect of curing time is discussed. Products of the effective diffusion coefficients and porosity (n e D e) decreased by 22% from specimens cured for 14 days to specimens cured for 28 days prior to testing while from 70 days to 126 days of curing n e D e only changed by 8%. This suggests that curing should be carried out for greater than 70 days prior to conducting these tests.

Effect of Freeze/Thaw Cycles on the Performance and Microstructure of Cement-Treated Soils

“…Each f/t cycle consisted of 24 hours of three-dimensional freezing at -10±1 o C followed by thawing in a 100% humidity room at a temperature of 22±1 o C. All specimens were saturated in a set-up presented in method A of ASTM-D5084 (2010) under a minimum back-pressure of 524 kPa and a confining pressure of over 558 kPa for a duration of at least seven days before f/t exposure. Previous work by Goreham et al (2012) showed how for similar cement contents, β -value measurements were greater than 95% for the saturation conditions 101 employed in this work. 102…”