The best concrete mix design is the one which satisfies all the aspects for which it was designed
Strength
The strength of 95% cube cast after 28 days of curing should be greater than the characteristic strength for which concrete has been designed.
Workability and placing
As working condition changes so does the properties desired from concrete also changes the concrete which can be easily placed without segregation and with least compaction required.
Durability
The concrete must be durable enough to face harsh conditions of the atmosphere for which it has been designed. This is the main properties considered while designing concrete and the concrete designed satisfying such conditions can be called as best concrete mix design.
There are three types of mixes
1- Nominal mixes
The mixes which have fixed cement-aggregate ratio but the nominal mix concrete for given workability varies widely In strength.
2- Standard mixes
1- It is designated by codebook of IS456:2000
2- The minimum compressive strength has included.
3- May result in under and over rich mixes.
Designed mixes
1- The mix proportion are designed by the producer of concrete
2- The concrete is specified by the designers
3- It does not guarantee the concrete mix proportion for the prescribed performance.
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