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Surface Preparation
All the loose cracked & de-laminated concrete shall be removed by chipping or other mechanical means. The extremities of repair locations shall be cut behind the reinforcement or saw cut to a depth of at least 10 mm to avoid feather edging. The areas to be repaired shall be profiled to get rectangular or square shape with an inward tapering edges
Clean the surface to remove all traces of dust, oil, paint, grease, algae etc. Oil & grease deposits can be removed by steam cleaning, detergent scrubbing or by using de-greaser.
The area cleaned shall be washed with water to remove all traces of dust, loose particles etc.
Surface preparation of steel
Steel reinforcement encountered during repair shall also be cleaned to remove all traces of rust, corrosion scales etc. using wire brush / emery paper. If sand blasting is allowed it can be resorted to. Extra steel if necessary shall be provided. If chlorides are anticipated then high pressure washing with water shall be carried out.
Reinforcement Priming
The exposed and cleaned reinforcing bar shall be provided with anti corrosive coat of Dr.Fixit Zinc Epoxy Primer such that the coated film will have a dft of 40 microns. The film shall be continuous especially in the regions where pitting, imperfections etc. are presents on the surface of the bars. It is important that the rear portion of the bars should not be left over without coating. A second coat if needed may be provided to achieve a uniform and continuous film
Priming Concrete Surface / Bonding agent
The exposed concrete surfaces shall be cleaned to remove any traces of dust, loose concrete etc. with the help of compressed air. The substrate shall be thoroughly washed with water jet to remove any traces of contamination. The surface shall be primed with Dr.Fixit Pidicrete MPB an Acrylic based bonding agent
Acrylic Emulsion Based bonding agent (Dr. Fixit Pidicrete MPB) The material must be stirred well inside the container before using. Apply neat coat on a well prepared and cleaned concrete substrate whist the surface is damp. The material should be applied using stiff nylon brushes by scrubbing it well into the substrate. The applied material should not be allowed to dry. The repair mortar should be applied when the bond coat is still tacky. In case the applied bond coat dries, an extra coat should be applied before application of repair mortar
Preparation of polymer modified mortar
Polymer modified mortar shall be prepared at site in the following proportion
Cement – 50 kg
Sand - 150 kg (Screened river sand or quartz sand of Zone II & I)
SBR / Acrylic polymer – 10 ltrs Water - 10 ltrs
Mixing
Forced action mixer like pan mixer or heavy duty drilling machine (slow speed) with paddle attachment shall be used for the mixing. Add first water and polymer and then add dry mix of cement and sand into the mixer. Mix the material for 3 to 5 minutes till homogeneous mix is obtained. Add extra water if required at site to achieve the required constancy.
The river sand shall not contain any silt or similar contamination. It shall be washed, screened and dried before using. Alternatively for better results quartz sand of zone i & II also can be used in 1:1 proportion.
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