Double Layer System for special Applications

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Suzanna Small
7 years ago
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1 Double Layer System for special Applications Constructions in high pressure ground water need very secure waterproofing. Such buildings can be hospitals, storing isotope materials, banks with safes, park decks and also tunnels in important depths. For such buildings a single layer waterproofing could be not sufficient as it should be taken into consideration that the waterproofing membrane could be damaged during the reinforcement and concrete works. Therefore a controllable and repairable waterproofing system should be applied in such cases. Advantage: A controllable and repairable waterproofing system consists of 2 layers of geomembrane with an empty space between the two layers. This empty space can be achieved by one structured geomembrane or by a separation layer placed between the 2 layers of geomembrane. System of Double Layer with structured geomembrane upper mem brane lo w e r m e mbra n e System of Double Layer with with separation layer upper mem brane Se p ara t io n l a ye r lo w e r m e mbra n e

2 . By using two layers of geomembrane the risk of damage is highly reduced. In case of damage mainly one layer will be affected so that still the other layer is fully functioning. In the worst case of a damage of both geomembranes there is still the possibility of repair through the injection system with liquid waterproofing material (PU, Acrylat). 2. The control and injection system allows examining the functioning of the double laid system and in case of a failure the repair of the system through injection of liquid waterproofing resin. This can be done without destroying the concrete. I. Prefabrication:. Double laid system with one structured geomembrane: Depending on the size of the construction prefabricated elements, existing of an upper structured geomembrane and a normal lower geomembrane, are welded together in a clean and dry surrounding. The upper geomembrane will be placed in a distance of around 20 cm parallel over the lower geomembrane. This overlap is needed to create the connection to the next double laid piece. It has to be assured that also the connection area of the elements will have the possibility of being controlled and injected. For this reason strips of geomembrane have to be welded onto the geomembrane at both borders of the prefabricated element. P ie c e P ie c e 2 P ie c e 3 Element C on n ec ti o n St ri p C on ne c ti o n S t ri p

3 In case elements have to be connected on the both head sides of a prefabricated element, the upper membrane will also be places in a distance of 20 cm inward from the head side of the lower element. Prefabricated Element We ld ing St rip -co nn ectio n wi th next element Second Layer-Upsi de First Layer - Downsi de Welding St rip Wel ding Upper Layer Downsi de Layer 2. Double layer system with separation layer The process of work to create double laid elements is the same as with the structured geomembrane with the difference that a separation layer will be positioned between the 2 geomembranes. The task of the separation layer is to create space between the geomembranes. This space is needed to achieve vacuum on one side and to inject liquid waterproofing material on the other side in case of damage. The prefabricated elements are transported to the site, brought into correct position and welded together.

4 II. Control and Injection system: This system helps to control the quality of welding and to detect leakages. In the same time it can be used as repair system. Injection and Control Device S y s tem wi th st ru c tured g eom em br ane I njec ti on t ube we lded to the inje c tion hose L iquid W el dingso luti on ( TH F) Inj ec tion hose (p ipe) W eldin g Ho le W el ding S tr uctur ed Ge om embr ane G eo m em bra ne

5 Injection and Control Device Sys te m w ith s epar ati on l ayer I nject ion tub e w elde d to th e in jecti on h os e Liqu id W eldin gs olut ion (TH F) In jec ti on h ose ( pipe ) Weldi ng H ole W eldin g Ge om em br ane Sepa rat ion Layer G eomembr ane The injection pipe can have different forms depending on the product. A small hole will be cut into the upper geomembrane and the injection pipe will be welded completely to it. Injection pipes can be welded to the elements already in the prefabrication but also on site depending on the structure to be lined. Will such system be applied in tunnels it is recommended to install the injection pipes completely in prefabrication, then the vacuum test has to be executed to control all weldings. In case one welding is not correct it will not be possible to create the vacuum. Due to the vacuum both geomembranes stick together and the elements can be installed to the vault as a single layer system. On site the injection tubes are welded to the injection pipe by THF. III. Connection of the prefabricated elements on site. The prefabricated elements are placed into the correct position on site and welded together. All weldings on site beside details should be welded with a welding automate.

6 Element 2 Element Element 3 RENOLIT ALKORGEO Connection Strip Connection Strip Connection Strip Connection Strip Site welding Welding in Prefabrication XXXX Detail of Connection between elements: Connection between 2 prefabricated Elements Element 2 Element 2 2 Welding in Prefabr ic ation Doublewelding on Site 2 After the connection of all elements the concrete can be poured over the waterproofing system. The injection tubes can be guided to a central box connected to vacuum gauges in order to control the functioning of each element.

7 Injectionsystem for double laid Waterproofing Watertight Plug of injectiontube Styrofoam cube Protection tube Reinforcement steel Injection tube Welding with THF Reinforced concrete Injection pipe Complete Welding XXXXX Complete Welding XXXXX Geomembrane Geomembrane Lean concrete Hole in geomembrane Geotextile IV. Repair In case of a failure the vacuum of the elements will break down. It can happen if only one layer of the 2 geomembranes is damaged or if a welding would open. Over the injection pipes it can be controlled if both layers are damaged as water will appear through the injection tubes. In case of leakage in one of the layers, no water will enter but the vacuum will break down. That means the waterproofing is still working but only with one layer of geomembrane and there is no reason to make any repair. If both layers are damaged the space between the two layers of geomembrane has to be repaired. The repair in general is done by injecting acrylate, PU or water tightening cement. The injection work has to be executed from a specialist as it is a very sensitive work. The ideal mixture (viscosity), the force of pressure and the speed of the injection has to be coordinated in a sorrowful way. On one hand the injection material has to flow through the whole space between the 2 layers of membrane easily to fill the damage on the other side it must not be to liquid in order to be washed out by the incoming water. The viscosity of the injection material has to be determined exactly.

Waterproofing of Tunnels under Water Pressure

Waterproofing of Tunnels under Water Pressure 1 1. INTRODUCTION...3 1.1. General...3 1.2. Products of RENOLIT...3 1.3. Requirements of the waterproofing materials...3 1.3.1. Water tightness...3 1.3.2. Flexibility...3 1.3.3. Chemical resistance...3