Important Rules for Concrete Mix Design



FOUR RULES IN CONCRETE MIX DESIGN:

Rule-1: High cement and Low aggregate proportion
Concrete mixes with high cement content and low aggregate proportions produce sticky concrete.
Increasing cement content increases the cost of concrete.
Much cement in the mix also causes for shrinkage cracks in hardened concrete.
Cement and aggregate proportion should be balanced in mix-design.

Rule-2: Low cement & High aggregate
Concrete mixes with low cement content and high aggregate proportions produce poor workable and harsh concrete.
Cement quantity should not be lower in mix-design.

Rule-3: High Water-Cement  ratio
High Water-Cement  ratio causes for segregation thus reduces the strength of concrete. But it increases workability of concrete.
High water content increases porosity and permeability of cured concrete.
Water content shouldn’t be much in mix-design.

Rule-4: Low Water-Cement  ratio
Low water-cement ratio increases the strength and durability of concrete. But reduces the workability.
Workability is required for good quality concrete. So, water content and workability should be balanced.
Water content shouldn’t be less in mix-design.
The purpose of mix-design is to produce most economical concrete product with desired strength. And that is done by tweaking the above rules. If required, chemical admixture can be mixed with concrete for not avoiding the rules.

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