concrete mix design
Advantages of mix design
Mix design aims to achieve good quality concrete at site economically.
I. Quality concrete means
• Better strength
• Better imperviousness and durability
• Dense and homogeneous concrete
II. Economy
a) Economy in cement consumption
It is possible to save up to 15% of cement for M20 grade of concrete with the help of concrete mix design. In fact higher the grade of concrete more are the savings. Lower cement content also results in lower heat of hydration and hence reduces shrinkage cracks.
b) Best use of available materials:
Site conditions often restrict the quality and quantity of ingredient materials. Concrete mix design offers a lot of flexibility on type of aggregates to be used in mix design. Mix design can give an economical solution based on the available materials if they meet the basic IS requirements. This can lead to saving in transportation costs from longer distances.
c) Other properties:
Mix design can help us to achieve form finishes, high early strengths for early deshuttering, concrete with better flexural strengths, concrete with pumpability and concrete with lower densities.
Requirements of mix design
Concrete mix design is the method of correct proportioning of ingredients of concrete, in order to optimize the above properties of concrete as per site requirements.
The site engineer should give following information while giving material for mix design to the mix design laboratory: -
a) Grade of concrete (the characteristic strength)
b) Workability requirement in terms of slump
c) Other properties (if required): -
i. Retardation of initial set (to avoid cold joints in case of longer leads or for ready-mix concrete) ii. Slump retention (in case of ready mix concrete) iii. Pumpability (In case of ready mix concrete) iv. Acceleration of strength (for precast members or where early deshuttering is desired)
v. Flexural strength (normally required for concrete pavements)
d) Ascertain whether
Mix design aims to achieve good quality concrete at site economically.
I. Quality concrete means
• Better strength
• Better imperviousness and durability
• Dense and homogeneous concrete
II. Economy
a) Economy in cement consumption
It is possible to save up to 15% of cement for M20 grade of concrete with the help of concrete mix design. In fact higher the grade of concrete more are the savings. Lower cement content also results in lower heat of hydration and hence reduces shrinkage cracks.
b) Best use of available materials:
Site conditions often restrict the quality and quantity of ingredient materials. Concrete mix design offers a lot of flexibility on type of aggregates to be used in mix design. Mix design can give an economical solution based on the available materials if they meet the basic IS requirements. This can lead to saving in transportation costs from longer distances.
c) Other properties:
Mix design can help us to achieve form finishes, high early strengths for early deshuttering, concrete with better flexural strengths, concrete with pumpability and concrete with lower densities.
Requirements of mix design
Concrete mix design is the method of correct proportioning of ingredients of concrete, in order to optimize the above properties of concrete as per site requirements.
The site engineer should give following information while giving material for mix design to the mix design laboratory: -
a) Grade of concrete (the characteristic strength)
b) Workability requirement in terms of slump
c) Other properties (if required): -
i. Retardation of initial set (to avoid cold joints in case of longer leads or for ready-mix concrete) ii. Slump retention (in case of ready mix concrete) iii. Pumpability (In case of ready mix concrete) iv. Acceleration of strength (for precast members or where early deshuttering is desired)
v. Flexural strength (normally required for concrete pavements)
d) Ascertain whether