Thursday, May 13, 2010

Basics of Concrete

Concrete Mix Ratios - Cement : Fine Aggregate : Coarse Aggregate
  • M10 =1:3:6
  • M15= 1:2:4
  • M20 = 1:1.5:3
  • M25 = 1:1:2
The numbering denotes strength of the concrete. The higher the number the higher the strength.
For M30 and above, only design mixes are used.

Notes:
  • These mixes are based on OPC 43 cement. If OPC 53 or any other grade of cement were to be used then these ratios would change.

  • M10 means that the concrete mix should have a compressive strength of 10N/mm2 and so on

  • These ratios are based on a volumetric mix and not a mix based on weights of the ingredients

  • IS Code 456 deals with the various grades of concrete

  • RMC is Ready Mix Concrete supplied by the RMC plants to the construction site in transit mixer trucks

  • Cost of Ready-Mix-Concrete including transportation is Rs 3000 per cum

  • As the water to cement ratio increases, the strength and durability of concrete decreases. However adequate water to cement ratio must be used for workability of concrete.
Concrete is tested by:
  1. Cube Test for strength
  2. Slump Test for workability

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