General Precautions

Before casting of slab
  • Check concealed electric conduit work, junctions and all electrical points, positions of fan points, MS boxes as per electrical layout plan
  • Check the reinforcement and obtain approval from RCC consultant
  • Check the standby arrangement for water in case of electricity failure
  • Decide the position of concrete joints in case of a big slab after consulting the RCC consultant
  • Ensure removal of wooden pieces, paper, nails, etc. from slab/ beam before casting
  • Ensure that shuttering, support and scaffolding is firm and proper
  • Ensure all joints in formwork are properly sealed to avoid slurry leakage. Instead of using mud, jute, paper, etc. it is desirable to use putty of used grease and cement (50 : 50). It effectively seals joints and remains intact during vibration of concreting. Strips of aluminium foil can also be used to cover gap -
    1. Make arrangement of wooden planks and steel chairs and place them on slab for labour movement. Do not allow labour to directly walk on reinforcement
    2. Check if vibrator is in working condition and adequate labour is available
    3. Sprinkle little water over shuttering just before placing the concrete
    4. Ensure sufficient light arrangements in case of late evening/night concreting and provide safety measures
    5. Ensure that concrete cover blocks of proper size & type are provided at site as per requirement of BIS standards
 

At the time of casting

  • Check and ensure that the position of cover blocks are intact and not disturbed during concreting operations
  • Closely supervise the proper batching of ingredients, water content, mixing and testing of fresh concrete in case of concrete made at site. However, for UltraTech Concrete this aspect is taken care of as the degree of quality control is very high
  • Beams should be cast first in layers and properly compacted with vibrators
  • One carpenter & helper should be present below slab shuttering to ensure that props/supports are not disturbed and shuttering remains intact in position during & after concreting also
  • One bar bender should be present to ensure that no displacement of steel reinforcement takes place
  • Do not allow very smooth finish to concrete slab. Do not allow sprinkling of dry cement for finishing, to avoid micro shrinkage cracks
  • Ensure that top reinforcement bars (for negative movement) are not disturbed during concreting by placing the chairs firmly and properly
  • Avoid formation of cold joints in the slab
  • For concreting during summer season, cover freshly casted slab with moist gunny    bags after 4-5 hours of casting
  • In case of rain, high winds and hot temperature, cover the slab with tarpaulin to    protect it from getting damaged
  • Do not allow drastic drying of green concrete to avoid plastic shrinkage cracks
  • Closely supervise the compaction and finishing process of concrete
 

After concreting of slab

  • Deshuttering of vertical sides of beam, columns only after 24 hours
  • Curing of slab for 14 to 20 days depending upon the type of structure
  • Deshuttering of slab after 7, 10 or 15 days depending upon span of slab and type of cement used
  • Deshuttering of beams after 14 or 21 days depending upon span
  • Checking all spots of honeycombing and finishing the same with rich cement sand mortar