Concrete mix Design

Concrete Mix Design

Basic considerations 
1-  The proportioning of concrete mixes consists of determination of quantities of different concrete-making materials necessary to produce concrete having the desired workability and 28-days compressive strength of concrete for a particular grade of concrete and durability requirements. Emphasis is laid on making the most economical use of available materials so as to produce concrete of required attributes at the minimum cost.
2-  Concrete has to be satisfactory both in fresh and hardened states.  The proportioning of concrete mixes is accomplished by the use of certain established relationships from experimental data which provides reasonably accurate guidance for selecting the best combination of ingredients so as to achieve the desired properties of the fresh and hardened concrete. Out of all the physical
The following basic assumptions are made in design of concrete mixes of medium strength:
a) For given aggregate characteristics, the workability of concrete is dependent on its water content.
b) The compressive strength of concrete is related to its water-cement ratio.
3-  For high strength concrete mixes, considerable interaction   occurs between these two criteria and validity   of. such   assumptions may become limited. Moreover, there are various other factors which affect the properties of concrete e.g. the quality and quantity of cement, water, aggregates and admixtures (if used);  procedures of batching, mixing, placing, compaction and curing etc.