Aci Concrete Mix Design from civildigital.com

1
ACI CONCRETE MIX DESIGN
Downloaded from CivilDigital.com

• Presentation by-
• Rupesh Gawas.
• Pankaj Kumar.
• Narsi Ram Gurjar.
• Date of presentation- 26/08/2011

2
ACI CONCRETE MIX DESIGN
Downloaded from CivilDigital.com

• Presentation by-
• Rupesh Gawas.
• Pankaj Kumar.
• Narsi Ram Gurjar.

3
About ACI
Downloaded from CivilDigital.com

• The most common method used in North America is
  established by American Concrete Institute.

4
Basic Consideration
Downloaded from CivilDigital.com

• Economy
• The material cost are most important in
  determining the relative costs of different
  mixes.
• Since cement is more expensive than aggregate it
  is clear that cement should be minimized.
• Workability
• A good mix design must be capable of being placed
  compacted with minimal bleeding segregation
  be finishable.

• Strength Durability
• In general the minimum compressive strength a
  range of W/C ratios are given for given concrete
  mix.
• Possible requirements for resistance to
  freeze-thaw and chemical attack must be
  considered.

5
Mix Design Input
Downloaded from CivilDigital.com

• Required material information --
  Sieve analyses of both fine and coarse
  aggregates, unit weight, specific gravities, and
  absorption capacities of aggregates.

• Choice of slump -- Generally specified for a
  particular job. However, if not given, an
  appropriate value may be chosen from Table 1. As
  a general rule, the lowest slump that will permit
  adequate placement should be selected.

6
Recommended Slumps for Various Types of
Construction
Downloaded from CivilDigital.com
7
Estimation of mixing water and air content
8
Approximate mixing water (lb/yd3) and air
content for different slumps and nominal maximum
sizes of aggregates
Downloaded from CivilDigital.com
9
Water/cement ratio
Downloaded from CivilDigital.com

• This component is governed by strength and
  durability requirements

10
Water/cement ratio using Table
11
Calculation of cement content
Downloaded from CivilDigital.com

• Once the water content and the w/c ratio is
  determined, the amount of cement per unit volume
  of the concrete is found by dividing the
  estimated water content by the w/c ratio.
• weight of cement weight of water /(w /c)
• However, a minimum cement content is required to
  ensure good finishability, workability, and
  strength.

12
Estimation of coarse aggregate content
13
Estimation of fine aggregate content
Downloaded from CivilDigital.com

• To establish the fine aggregate content by
  "volume" method.
• Vfa 1- (Vcement Vwater Vcoarse agg.)
• Adjustment for moisture in the aggregate.
• Decrease/Increase the amount of water required by
  surface moisture content of the weight of the
  fine aggregate
•  Increase/decrease the amount of aggregate by the
  amount equal to the surface moisture

14
Trial batch
Downloaded from CivilDigital.com

• The fresh concrete should be tested for slump,
  unit weight, yield, air content, and its
  tendencies to segregate, bleed, and finishing
  characteristics. Also, hardened samples should be
  tested for compressive and flexural strength.

15
The End