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Perma Inject STC – Resin / Catalyst



Perma Injection STC is a polyurethane injection grouting system. It consists of two components one being prepolymer resin and the other being a catalyst. These two components are mixed together and injected into the concrete or RCC structure using a single component pump whether manual or motorized. Perma Inject STC when injected into the concrete forms a semi-rigid and semi flexible foam when it comes in contact with water or moisture. This foam effectively stops leakages from the structures.


When injected in the concrete Perma Inject STC reacts with water or moisture to form semi-rigid foam which is about twenty times larger than the reacting components. During this reaction with water there is a formation of carbon dioxide gas which makes the foam penetrate deep into the fine crevices of the concrete and seals them effectively. It also fills up all capillaries and honeycombs in the concrete to discourage accumulation of water in these pockets at a later stage. Perma Inject STC is more suited for static cracks and in situation of heavy leakages.


  • Perma Inject STC seals leakages in all difficult situations such as basements, tunnels and heavily leaking massive structures.
  • Perma Inject STC is free from solvents and fillers. It is resistant to hydrolysis and is suitable for use in potable water tanks.
  • The product is supplied as two components. The reactor/catalyst can be adjusted from six to ten percent to allow on site adjustment of gel time.
  • Perma Inject STC stops the leakage then and there only instantly, after injection, there is no waiting period to wait for curing times etc.


Clean the surface to be waterproofed and remove the plaster or loose concrete in the area. Assess the leaky area and decide the injection nozzle pattern. The leakage could be either from a horizontal or from a vertical crack. Drill holes on either side of the crack at an inclination of 45° inclined towards the center of the crack at an interval of 8 inches centre to centre. Always start from the lowest point and progress upwards. In the drilled holes fix the packers effectively. In weak concrete the drilled holes becomes larger than desired, in such cases the packers may not fit tightly to leak- proof it. If this happens then grout the surrounding of the packers with the stiff consistency paste of Perma Plug. Mix the two components the prepolymer resin and the catalyst. The catalyst can be adjusted between 6 to 10% to adjust the gel time depending upon the speed and the site conditions. Inject the product into the packer from the manual or motorized high pressure pump till the foam is observed from the neighboring holes. Keep the counter pressure on through the nozzle nipples till the reaction is complete and the foam has formed and set. Move on to the next packer and continue the process. Clean the pump and the equipment with Perma Inject Clean a special material specially developed for cleaning polyurethanes.


Prepolymer Reactor Norm
Specific Gravity 1.158 0.889 21 EN ISO 2811 -2:2002
Viscocity 96 mPa.s 21mPa.s EN ISO 3219:1994
Flash Point > 150°C > 150°C


Quantity Of Catalyst Reaction Seconds Polymerisation Seconds
6% 15 70
8% 12 55
10% 09 45


The workers should use face masks and hand gloves to avoid direct breathing of the toxic vapors and to avoid direct contact with skin. Ventilate the working area adequately and maintain over all hygienic conditions. Clean the tools and the pumps immediately after use.


Perma Inject STC is available in packing of 20 kg & 1 kg for prepolymer resin and the catalyst in 2 ltr & 100 ml packs.


Perma Inject STC has a shelf life of 24 months from the date of manufacture. These products are both temperature and moisture sensitive. Hence it is of utmost importance that these products are stored in DRY CONDITIONS BETWEEN TEMPERATURES 10 to 30°C.


PERMA warrants that all products are free from any defects of manufacture and comply with the specifications given in their respective technical data sheet. No warranty can be given as to the results of use because conditions of use, such as site conditions, surface preparations, workmanship, weather, structural issues and other factors are beyond the control of PERMA. Purchaser agrees to seek the advice of qualified professionals to carry out tests & take trials to determine the suitability of products for their intended purpose prior to full scale usage of PERMA products and assumes all risks.

The company does not assume any liability for unsatisfactory results, arising from the use of our products. Purchaser’s sole liability is limited to replacement of product or refund of the purchase price paid if any product proven defective. No other warranties, express or implied, shall apply including any warranty of merchantability or fitness for a particular purpose.
PERMA shall not be liable for any consequential damages arising from the use of our products for unsatisfactory results.

The information supplied in this datasheet is based on our experience through extensive research and is given in good faith in order to help prospective users. We reserve the right to update the information provided in our technical data sheet at any time without prior notice within the scope of technical progress or new developments.

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