Sand layer in SCC concrete

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Sand layer is generally found when segregation occurs in a concrete mix. A certain portion of the casted wall/slab is found to contain only sand & somewhere the aggregates are found free from binding materials.

Repairing methodology for sand layer:


·        First we have to determine the extent of sand layer in a particular structural member.
·        Secondly, using chisel/steel wire brush we have to get rid of the loose sand till we find good concrete.
·        If the depth of the damage is less than 5 mm then the void shall be filled with finish materials such as gypsum/putty as per client's instruction.
·        If the depth is more than 5 mm but less than 10 mm, then the void shall be cleaned properly followed by application of concrete bonding agent such as Fosroc Nitobond EP. After which modified cement mortar such as Sika Microcrete 4 or Sika 122 top HS shall be used to fill up the void.
·        If the depth is more than 10 mm but less than the actual cover provided, then the void shall be cleaned properly followed by application of concrete bonding agent such as Fosroc Nitobond EP. After which modified cement mortar such as Sika Microcrete 4 or Sika 122 top HS mixed with 10 mm coarse aggregate in the ratio (1:4) shall be used to fill up the void.

However, in the last case & cases where the depth is more than cover the engineer in-charge shall be notified and suggestion shall be taken for carrying out repairing work. Approval from the structural engineer / consultant shall also be taken before commencing.


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