Gas permeability measurements of cement-based materials under hydrostatic test conditions using a low-transient method

Abstract

Argon permeability of a mortar, made with a water/cement ratio of 0 . 4, was measured cyclically as a function of confining pressure up to ó 3 ¼ À57 MPa. An original low-transient method was used, in which the time required to observe a slight gas pressure decay is measured. The mechanical behaviour and hydraulic response were both studied. The mortar seems crack-free and isotropic. It behaves elastically, even if a significant hysteresis, ascribed here to some microsliding between the C-S-H sheets and the movement of interlayer water acting as a lubricant, was observed. Similarly, the hydraulic response was shown to be, despite a slight delaying effect, entirely reversible. Surprisingly, permeability versus porosity changes is strongly nonlinear, which is not consistent with the predictions of random shrinkage modelling in which a power law relationship k / ö AE with AE ¼ 3 is obtained between permeability and porosity. The mortar permeability is decreased by 50% when the confining pressure is increased from ó 3 ¼ À3 MPa to ó 3 ¼ À57 MPa, while the overall porosity is only decreased by 2 . 5%. This high sensitivity is thought to be the result of some percolative effects within the interfacial transition zones owing to closure of slitlike pores.

Crack Width Estimation of Mortar Specimen Using Gas Diffusion Experiment

“…Gas permeability experiments have been used as an indirect measure to evaluate the durability of cementitious materials [13,14,15,16]. Because of the high penetration resistance of the cementitious material, the experiment proceeds very slowly under natural conditions, and therefore, experiments are usually carried out using high-pressure gas as a medium.…”

Evaluation of a permeability–porosity relationship in a low-permeability creeping material using a single transient test

“…Experimental study of Zhu and Wong [18] on Berea and Boise sandstones resulted in a variable α which increases when pressure increases. Meziani [19] performed an experimental study on the gas permeability of mortar under hydrostatic loading and found a strongly non-linear permeability-porosity relationship. The exponent α is found to be a decreasing function of the loading level, decreasing from 36 to 26 when the confining pressure is increased up to 57 MPa.…”

Effect of Dry-Wet Cycles on the Transport and Mechanical Properties of Cement Mortar Subjected to Sulfate Attack

“…The permeability of cement-based materials is one of the most important indicators of long-term durability [17,18], and the transport of internal material is closely related to changes in the pore structure [19][20][21]. There are many methods for measuring the permeability of cement-based materials [22][23][24][25][26], and among them, the gas permeability test method is easy to operate and has high accuracy [27]. Under the coupled activity of dry-wet cycles and sulfate attack, the morphology of the internal pore structure and the connectivity of the pore diameters of cement-based materials change gradually, and this method can reflect the characteristics of the connected pore structure and microcrack changes more sensitively.…”