If P is the standard consistency of cement, the amount of water used in conducting the initial setting time test on cement is
- A0.6 P
- B0.8 P
- C0.65 P
- D0.85 PCorrect
Solution
Concept
Water ratio for cement initial setting test
Formula
Water = 0.85 × P
Step-by-step solution
1. Standard consistency (P) is determined using Vicat's apparatus to find the water required for standard paste consistency. 2. For initial and final setting time tests, Vicat's apparatus is used with a specific water ratio. 3. The standard water quantity required for the setting time test is 0.85 times P (85% of standard consistency P). Answer: D
Explanation
Standard consistency P represents the water content required to prepare a cement paste of standard permeability using a Vicat apparatus. For determining both the initial and final setting times of cement, standard testing procedures specify mixing the cement with 0.85 times P by weight of water. This specific proportion ensures uniform testing conditions across laboratory evaluations.
Why the other options are wrong
A) 0.6 P is not a standard water percentage specified for cement testing. B) 0.8 P is not used for initial setting time tests under Indian Standards. C) 0.65 P is not the standard water content for initial setting time determination.
Shortcut
Initial and final setting time tests use 0.85P of water (where P is standard consistency).
Common mistake
Confusing the water percentage for initial setting time with the percentage used in soundness or compressive strength tests.
Correct answer: D) 0.85 P