TREATMENT OF THE SECOND STAGE HONEYCOMBED CONCRETE AND HONEYCOMBED PIER REGIONS, LEAKED CONSTRUCTION JOINTS OF SPILLWAY PIERS AND BUCKET PORTION FOR VENT NOS 1 TO 25 OF MAIN SPILLWAY AND A1 TO A5 OF ADDITIONAL SPILLWAY OF NARAYANPUR DAM
Client: Krishna Bhagya Jala Nigam Limited
Location: Narayanpur, Distt. Yadgir (Karnataka)
This is a complex dam and is divided into two portions. One is the main area & the other is the additional area. The repair work here involves grouting of overflow section & piers, resurfacing of the damaged area, repair of cracks by using micro concrete and surface treatment & repair of the ogee & bucket portion of both the areas of the dam. The repair in the pier portion is a very typical job and requires special scaffoldings to be manually put in place for the workers to climb and do the work. The old concrete is first chipped off and then cleaned with a high-pressure water jet & air. The cement mixture is then applied to the prepared surface. The work involves frequent shifting of scaffoldings to cover the entire area. To repair the ogee & bucket area, the surface preparation involves first cleaning the surface manually and then hacking the old concrete. The surface is again cleaned with high-pressure water jet & air. The bonding material is then applied followed by the spraying of anti-abrasive mortar by high-pressure air over the prepared surface. A team of 10- 15 workers is deployed at a given time for this work.
To repair the overflow section, the surface is manually raked to a depth of 30 - 50 cm, cleaned, washed and then shuttering is installed in the correct shape & size. Then the high strength micro concrete is put manually on the prepared surface.
The major component of this work involved injection of specialized 2 component polyurethane material, which is a hydrophobic material and forms a hard substance with a strength of M-75. This was injected in the pier portion to fill the cavities and increase the structural strength of the piers. The other major component of this work involved anti-abrasion coating on the ogee of the dam which was eroded due to continuous water flow along with the debris and riverine deposits. This coating is done by using a special pre-mix material that has high strength and high abrasion resistance.
To repair the overflow section, the surface is manually raked to a depth of 30 - 50 cm, cleaned, washed and then shuttering is installed in the correct shape & size. Then the high strength micro concrete is put manually on the prepared surface.
The major component of this work involved injection of specialized 2 component polyurethane material, which is a hydrophobic material and forms a hard substance with a strength of M-75. This was injected in the pier portion to fill the cavities and increase the structural strength of the piers. The other major component of this work involved anti-abrasion coating on the ogee of the dam which was eroded due to continuous water flow along with the debris and riverine deposits. This coating is done by using a special pre-mix material that has high strength and high abrasion resistance.
This is then placed by spraying with pneumatic pressure with a special worm machine.