Technical Support
Pre Stressed Slab
 
Overviews
Structural Bearings
Structural Expansion Joints
Pre Stressed Slab
 
 
Methodology
PROFILING
Profile marking on the shuttering according o the drawing
Fixing of chairs on the bottom rebars according to the vertical co-ordinates.
Fixing of guide cones to the side shuttering at the locations specified.
Laying of sheathing pipe as per the profile marked.
Threading of the strands inside the pipe.
PVC taping to each and every joint to make joints water tight.
Fixing of air vents and grouting nipples.
Fixing of bursting reinforcement.
Concreting.
 
STRESSING
After concrete has achieved the require strength, remove the shuttering.
Clean the extra length of the strands with the petrol.
Fix the bearing plates and grips on the strands.
Fix the jack on the strand and make necessary connection.
Apply the necessary pressure so as to give the require load to the strand.
Note down the readings and find out the elongation.
Apply the same procedure for all the strands.
Permissible tolerance for the pressure and elongation is + 5%
 
GROUTING
After 24 hours of stressing extra length should be cut.
Seal the anchorage pocket with cement mortar.
Cure the mortar for one more day.
Make proper arrangement of grout pump and agitator.
Wash the cable with lime water.
Mix the cement with w/c ratio not less than 0.4 .
Pump the grout with help of grouting pump until grout flows at the other end.
Close the outlet and apply a pressure of 5 kg/cm².

COLUMN DROP SHUTTERING
BAND SHUTTERING & REINFORCEMENT

BOTTOM AND TOP REINFORCEMENT AT COLUMN DROP AND CANTILEVER PORTION
BOTTOM AND TOP REINFORCEMENT AT COLUMN DROP AND CANTILEVER PORTION

CONCRETING
CONCRETING

STRESSING OPERATION
STRESSING OPERATION

FINISHED BOTTOM OF SLAB
 
VSIL is Manufacturing of following Prestressing Anchorages (Hardware)
Bearing Plates: 37K13, 27K15, 27K13, 19K15, 19K13, 12K15, 12T13, 7K15, 7K13, 4K15 (For Bridges, Nuclear Reactors, Silos, Rock Anchors, etc.) & 4S15, 4S13 (For Flat Slabs in Commercial Buildings) (In-house manufacturing)
C. I. Guides: 37K13, 27K15, 27K13, 19K15, 19K13, 12K15, 12T13, 7K15, 7K13, 4K15 (For Bridges, Nuclear Reactors, Silos, Rock Anchors, etc) & 4S15, 4S13 (For Flat Slabs in Commercial Buildings).
Single use Grips: (permanent grips) for P.C.Strand 12.7 mm dia and 15.2 mm dia. (to be used in the above respective Bearing Plates).
(In-house manufacturing).
Multi-use Grips (temporary grips) to be used with the range of Prestressing jacks.
(In-house manufacturing)
Sheathing/Duct: of C.R.C.A. Strips of varying Diameter from 39mm to 110 mm.
(In-house manufacturing)
 
Developing of new products and their prequalification as per International codes in Indian as well as International laboratories for infrastructure development.
Pre-qualification Tests for Prestressing Anchorages (As per BS 4447 and FIP Recommendation) include:
Anchorage Efficiency Test (Static)
Load Transfer Test
Anchorage Efficiency Test (Dynamic)
Pre-qualification Tests for HDPE Corrugated Sheathing Ducts (As per IRC18 -2000 and FIB Recommendation
Test for Friction coefficient
Test for Wobble coefficient
Wear Test
Bond Test
The above prequalification tests have been independently executed.
 
Fully aware of quality Assurance, Vendor development, Production, Planning, Services, Contracting and sub contracting activities.

Quality Assurance :
Formulating of Quality Assurance Plans for Prestressing Anchorage (Bearing Plate, Guide and Grips), Sheathing Ducts , Jacks, neoprene bearings, etc and implementation of the same.

Vendor Development :
Vendors for manufacture of grips (single use and multi use), Prestressing jacks, grout pumps, bearing plates, guides, lifting jacks, Neoprene Bearings, PTFE Sliding bearings have been developed nearby the factory and have been educated to control quality as per our Quality Assurance Plan.

 
Conducting of various quality control test for the range of product at I.I.T. Bombay, I.I.T. Chennai and various test House in India.

Pre-qualification Tests for Anchorage Systems conducted at IIT Mumbai & IIT Chennai and Pre-qualification of HDPE Sheathing Ducts conducted at Mumbai by IIT Bombay.

Testing of Neoprene Bridge Bearings, PTFE-SS Sliding Bearings at IIT Bombay & IIT Chennai.
Periodic Testing of the systems in-house for various clients as per contractual and codal requirement.
Maintaining all quality control records of products manufactured in-house as well as by vendors.
Also undertake technology transfer management studies for client's Engineers/Technician and contractors with use of Prestressing system in construction technology.