Water vapour and liquid permeability measurements in cementitious samples

Abstract

This paper shows how water permeability may be calculated from measurements of drying under a vacuum. The results obtained are for water vapour transport at low pressures and gas slippage theory is then used to compare them with liquid water permeability measurements on samples of the same mixes. The experimental work includes the drying procedure and also the initial surface absorption test (ISAT), a standard absorption test using a partially immersed sample and a 'through flow' high-pressure test for direct permeability measurements. The results from these tests are compared and additional gas and liquid permeability data from the literature is included for comparison. It is concluded that, with appropriate analysis, all of the procedures give comparable values for intrinsic permeability.Notation AE porosity b, â 1 and â 2 constants for the Klinkenberg equation cross-sectional area through which the transport is taking place (m 2 ) e viscosity in (Pa s) F flux (m 3 /s) h head of water (m) k coefficient of permeability, also known as the hydraulic conductivity (m/s) K intrinsic permeability (m 2 ) K g gas intrinsic permeability of concrete (m 2 ) K l water intrinsic permeability of concrete (m 2 ) K v intrinsic permeability for the vapour (m 2 ) M mass (kg) P pressure (Pa) P m mean pressure at which gas is flowing (atmospheres) r typical pore radius (m) r density of liquid water (kg/m 3 ) s surface tension of water (N/m) t time (s) V Darcy velocity for the fluid (m/s) W F ratio of the water vapour volume to the volume of the same mass of water as a liquid x distance (m)

Non-Destructive Imaging of Water Permeation through Cementitious Materials Using MRI

“…To observe the depth of water permeation through concrete, the concrete specimen can be split to measure the depth of the surface colour changes [1] [2]. However, the determination of water permeation depth in concrete is difficult because 70% to 80% of the split surface area is aggregate, and the colour change due to permeated water is generally only visible in the cement paste.…”

Opening of Microcracks and Air Permeability in Concrete

“…The permeability of concrete is directly dependent on the system of pores and cracks (Li et al 2011) and it is influenced by many aspects -selection of materials, design of fresh concrete composition, its placement, compaction, and influence of an extreme load (Pavlík et al 2007). Due to various influences, the cracks in concrete mutually interconnect and thus increase its resulting permeability (Aldea et al 1999;Stehlík et al 2005;Claisse et al 2009;Akhavan et al 2012).…”

Enhancing the Durability of Concrete Made of Concrete Recyclate by Additives and Admixtures

“…Permeation processes of covercrete are affected by transport processes and they correspond directly to the character of pores in the structure of concrete (Zaharieva et al 2003). The evaluation of durability is therefore derived directly from its permeation properties (Claisse et al 2009). The permeation properties include mainly Journal of Civil Engineering and Management, 2014, 20(2): 270-279 271 the structure permeability for gas and water, sorptivity, initial absorption capacity, water tightness, diffusion, etc.…”