Casting yard


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Casting yard

  1. 1. Casting Yard
  2. 2. Introduction A casting yard is a confined place where all the concrete structures like segments, parapets, I- girders/beams, boundary wall panels, cable troughs etc. Re-casted/manufactured, shifted to their stack yard, cured for the specific period/days and then shifted to the working site/viaduct after they gain their required strength.
  3. 3. Layout of Casting Yard
  4. 4. Requirements of a Casting Yard • Site for any Casting Yard should be easily accessible from all site locations. • Land should be available from 25 Acres to 40 Acres for establishing a casting yard. • Approach Road leading to Casting Yard should be easily identified. • Good Environmental conditions. • It should not more than 3 to 4 kms from working site. • Proper Drinking Water facilities for Engineers, Supervisors & Labours. • Canteen facilities for the staff & Labours. • Medical treatment Centre in case of emergency.
  5. 5. Casting methods • Long-Line Method • Short Line Method
  6. 6. Long Line Method • All segments of a span are manufactured on a fixed bed with the formwork moving along the bed for successive casting operation. • Shows profile of real structure at one time. • Pier segment is cast first between the fixed bulkhead and the removable formwork, then the segments.
  7. 7. Short Line Method • It is a match casting process. • Stationary forms are used next to the previously cast segment in order to get a homogeneous perfect fitting match-cast joint.
  8. 8. Match-cast segment To the stock yard
  9. 9. Match-casting for a vertical curve • Match cast segment first translated from its original position and then give a small rotation in the vertical plane w.r.t. the horizontal axis.
  10. 10. Match-casting for a horizontal curve • Match-cast segment is first moved to its position by pure translation and then the segment is rotated in plan w.r.t. the vertical axis.
  11. 11. Geometry Control • Establishment stations to the north and south side of the segment before the casting is must. • Tolerances are in the order of a fraction of a millimeter. Geometry control Program • • • • • Calculate the theoretical casting coordinates of segment n. Measure the actual casting coordinates Calculate error in casting Calculate correction to be made in casting n+1 match-casting with n Adjust match-casting of n to compensate for error while casting n+1
  12. 12. Batching & mixing of concrete       Raw material Cement (OPC grade 53) Fly Ash (Maximum 30% of cement) Water (between 0.1 & 0.4) Admixture (SP-430, SP-432) Fine aggregate Coarse aggregates of 10mm & 20mm size
  13. 13. Batching procedure • Batching plant may be of manually operated type or may be operated with the help of computer aided software. • The quantities are filled in the computer and start key is pressed, the sensors provided near the gates get into action and according to the load scale value, that much quantity of sand, 10mm aggregates, & 20mm aggregates are filled in a bucket. • When the required quantity of the aggregates is filled the gates get closed automatically and the bucket is pulled up.
  14. 14. For fine & coarse aggregate For cement & fly ash
  15. 15. • As the bucket reaches the top, its contents are put into a mixing pan, where it gets mixed with the cement, water & admixtures from their separate hoppers. Mixing tank
  16. 16. Quality Control Survey Procedures • Initial Set Up Survey - required for formwork setting and getting the match cast segment in “rough” position • Final Set Up Survey - required for final adjustments of the match cast segment and small adjustments to the formwork once the forms have been closed up to final position • As Cast Survey - required to obtain “as cast” data on the segment used to determine the positioning of the segment in the “match cast” position • Inputting Data – required for geometry control for the for the next segment to be cast
  17. 17. Test of concrete For Ordinary Concrete • Slump test • Setting time test Initial setting time Final setting time • Compressive strength test For self compacting Concrete • Flow test • V-funnel test • L box test
  18. 18. Result : 120 mm
  19. 19. Test cubes for compression test
  20. 20. Precast vs Cast in Place Concrete Precast High Quality Control Cast in place Less Quality Control Casting cannot be delayed due to weather It may be delayed. conditions Controlled pour conditions, strict quality control measures and factory strength testing ensure pre-cast concrete strength and durability specifications. Uncontrolled factors can decrease the strength and durability of freshly poured concrete. Flexibility to make changes to structure right up until the minute the concrete is poured in the form Last minute changes are difficult to make and cost money
  21. 21. THANK YOU!