Experimental study of water flow behaviour in narrow fractures of cementitious materials

This paper reports an experimental investigation on water flow behaviour in narrow fractures of cementitious materials. A permeation device was developed especially for water flow in fractures. Five cementitious materials were retained, specimens were prepared in disk form and fractures were obtained by splitting specimens in three-point bending mode. The topography of fractured surfaces of specimens was scanned by laser profilometer and the surface roughness was quantified by 3D fractal dimension analysis. The fractured specimens were then closed and mounted into the permeation device for flow test by deionized water during 48 h. Furthermore, repetitive flow tests were performed on one fractured specimen to study the sealing effect of fractures. It is observed that the geometrical opening aperture in fractures is very different from the hydraulic equivalent value and the sealing effect of narrow fractures can be mainly attributed to the non-Darcian characteristic of liquid flow between rough surfaces under low pressure gradient.

► We develop an experimental device capable to study liquid flow in narrow cracks.
► We quantify the surface roughness of fractured surface of cement-based materials.
► The geometrical opening of cracks is 10 times of its hydraulic equivalent value.
► The crack sealing for flow is mainly due to non-Darcian flow characteristics.