Steps Involved in Mix Proportioning as per IS 10262:2009 (with solved example)

Steps Involved in Mix Proportioning as per IS 10262:2009 (with solved example)

Mix Proportioning as per IS 10262:2009

Mix Proportioning as per IS 10262:2009

 

General Steps Involved in Mix Proportioning

Step 1. Choice of Slump

  • Stiffest possible consistency that can be easily placed and compacted without segregation
  • Pumping are typically designed for 100 mm to 150 mm slump

Step 2. Choice of Max. Size of Aggregate

  • For given volume of coarse aggregate,

Step 3. Estimation of the mixing water content and air content

Depends on ,

  • The maximum particle size of the aggregate
  • Entrained air

Step 4. Selection of water-cement ratio

  • Develop the relationship between strength and water-cement ratio for the materials to be used actually
  • Checked for durability criteria

Step 5: Calculation of the cement content

  • Computed by dividing the mixing water content by the water-cement ratio
  • Adjustments to Min. cement content for aggregates other than 20 mm nominal max. size, as per IS 456: 2000

Step 6: Estimation of the coarse aggregate content

  • Estimated from Maximum aggregate size & fineness modulus of fine aggregate
  • Dry weight obtained by multiplying with Dry Rodded unit weight
  • Range in proportions of materials used in concrete, by absolute volume

Step 7: Estimation of the fine aggregate content

  • Weight Method
  • Absolute volume Method

Step 8: Adjustments for the aggregate moisture

  • Mixing water reduced depending on Free Moisture
  • Amounts of aggregates increased accordingly

Step 9: Trial batch adjustments

  • Mixture satisfying the desired criteria of workability and strength is obtained
  • Mixture proportions of the laboratory-size trial batch are scaled up for producing full-size field batches

Data required for Proportioning

Road Aggregates

  • Grade Designation
  • Type of Cement
  • Maximum Nominal size of Aggregate
  • Minimum Cement Content
  • Maximum w/c ratio
  • Workability in terms of Slump
  • Exposure conditions
  • Method of placing
  • Type of aggregate
  • Maximum cement content
  • Test data of Materials
  • Admixture type and condition of use if any

Mix Proportioning as per IS 10262:2009

  • Target strength for mix proportioning
  • Selection of w/ c ratio
  • Selection of water content
  • Corrections in water content
  • Calculation of cement content
  • Proportion of volume of coarse aggregate and fine aggregate content
  • Corrections
  • Mix calculations

Design stipulations for proportioning

  • Grade designation   : M20
  • Type of cement   : OPC 43 grade, IS 8112
  • Max. nominal size of agg.   : 20 mm
  • Minimum cement content  : 320 kg/m3
  • Maximum water cement ratio   : 0.55
  • Workability   : 75 mm (slump)
  • Exposure condition   : Mild
  • Degree of supervision  : Good
  • Type of agg.   : Crushed angular agg.
  •  Maximum cement content   : 450 kg/m3
  • Chemical admixture   : Not used

REFER last part of ppt for worked out example and better understanding

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