The concrete sump is an indicator of the workability of the concrete. Concrete slump classes are used to specify the applicable ranges of a slump and their acceptable deviations.
The slump of the concrete is tested at the time of concrete arriving at the site. Based on the acceptable criteria finalized at the mix design is used to check the slump before concrete pouring.
BS 8500 provides a detailed guideline for concrete slump classes.
Further, there are limitations for each slump class to vary. The following figure extracted from the BS 8500 Part 1 shows the allowable limits.
A similar kind of specification is used for the flow test. Let’s see the floor classes as per the BS 8500 Part 01.
As discussed above, there are limits for the flow classes too.
Further information, BS 8500 could be referred.