Waterproofing for Underground Structures Without Basement Drainage System: Assessing the Robustness of a Negative-Side Waterproofing Solution

The underground spaces are more than more exploited for constructions, especially in the big cities. One of the problems to be treated for underground structures is the waterproofing. The current technique today for underground levels is using the peripheric reinforced concrete (RC) diaphragm walls and disposes a basement drainage system to evacuate the water penetrating through the diaphragm walls. The basement drainage system composes of drainage channel with pipes and at least two pumps to evacuate the water from the underground levels to the water evacuation systems. Then, a secondary wall is usually built to hide the drainage channel and the diaphragm wall. Therefore, this current technique is expensive for the maintenance and consumes the spaces of the underground levels. This paper presents a direct technique which directly appliques a waterproofing mortar on the negative-side of the diaphragm wall. The direct method has several advantages, not only because it is cheaper than the conventional method but also because it prevents the flux through the diaphragm concrete walls and so decreases the internal erosion of the concrete which can deteriorate the concrete quality. The robustness of the direct negative-side waterproofing method is discussed and assessed in the present study, from laboratory tests to in-situ tests. The technique works also for positive-side waterproofing and has shown the robustness after more than 20 years on in-situ structures.