Question
If on-site slump test fails, is it necessary that engineers allow a contractor to continue concreting works?

Answer
This is an extremely traditional question raised by many graduate engineers. In fact, there are two schools of idea regarding this issue.

The first school of thought is rather straightforward- contractor fails to fulfil with contractual requests and therefore as per G. C. C. Clause 54 (2) (c) engineer might order suspension of entitled to any claims of charge which is core concern for mainly engineers.
This is contractual power given to Engineer in case of any failure in tests essential by contract; although some engineers argue that slump tests are not as major as other tests similar to compression test.

The second school of thought is to let the contractor to continue their concreting works and later on request the contractor to prove that the finished works comply with other requirements as in compression test. This is based upon a belief that workability is mostly necessary to achieve design concrete compression strength. In case compression test also fails, contractor has to demolish and reconstruct works accordingly. In fact, this is a passive method of treating construction works and is not recommended since of following cause-

(i) Workability of freshly placed concrete is related not only to strength but also to stability of material. Still if in future compression test passes, failing in slump test point out that it might have adverse impact to stability of completed concrete structures.

(ii) In case compression test fails, contractor has to position extra time and resources to remove work and reconstruct them on one occasion again and this slows down progress of works significantly. Hence, present of such likely probability of occurrence, why shouldn't Engineer exercise his power to stop contractor and save these extra time and cost?