What is the difference between lab test and field test of concrete mix ? Enumerate with examples. Which strength is to be considered in RCC design ?

the simple answer is that the lab test for concrete have two stages ,the first one is when doing trial mixes to achieve the required strength and match with the project specifications and general conditions.the second stages is the crushing for the cubes and all the chemical tests and any mechanical test as per the project specification .For the Field test it is the normal checking for the slump,temprature and checking the delivery note to be matcing with the approved mix design.

LABORATORY TESTS ARE DONE AT LABORATORY WHERE THE MANUFACTURERS MAINTAIN THE QUALITY AS DESCRIBED FOR THE TASK AND SENT TO THE CLIENT.

ON FIELD AFTER REACHING TO THE SITE QUALITY ANALYSYST AND QUALITY CONTROL INSPECT THE CONCRETE ORDERED AND RECEIVED IS AS PER REQUIREMENT FOR THE TASK

Lab tests are considered for RCC design. As curing has a major influence on concrete's strength, the Standards need a reference curing method otherwise the results would be misleading. This standard method can be provided only in labs. Field samples may be used for testing due to the producer's responsibility for the quality on consignment phase, not only on production phase, but the samples must be properly stored, cured and the next day properly transfered to a lab. Field samples may also be used for control of the real curing method by remaining on site and following the curing of the real structure. But you can't expect from them the strength of the lab-cured samples.

The lab results become the recipe for the concrete mix. The recipe becomes the mix for the plant batching, the results of the batching become the product. the plant results are review and modified to achieve desired characteristics. Lab test are a pure sterile enviroment, the plant is real world. Limits of the plant need to be considered when finalising the mix. That aside other factors that need to be considered is distance to site, placement method and ambient temperature, these things will be used to modify lab results and final mix design. The testing regime will determine statistical success or otherwise.