If 1500g of water is required to have a cement paste 1875 g of normal consistency the percentage of water is..............
💧 Calculating Water Percentage
The percentage of water for normal consistency is always calculated as a percentage of the weight of dry cement, not the weight of the paste. The formula is:
Percentage of Water = (Weight of Water / Weight of Cement) × 100
A cement paste is simply the combination of dry cement and water. Therefore, Weight of Paste = Weight of Cement + Weight of Water.
⚠️ Important Note on the Question's Wording
The question as stated is likely incorrect. It says "1500g of water," which would imply a cement weight of only 375g, leading to a water percentage of 400% - an impossible scenario. As noted in the original answer key, the question should have stated "1500g of cement" to get a logical answer.
We will proceed by solving the question with this necessary correction.
📝 Detailed Calculation (with correction)
Given Data (Corrected):
- Weight of Cement = 1500 g
- Weight of Cement Paste = 1875 g
Step 1: Find the weight of water.
Weight of Water = Weight of Paste - Weight of Cement
Weight of Water = 1875 g - 1500 g = 375 g
Step 2: Calculate the percentage of water.
Percentage of Water = (Weight of Water / Weight of Cement) × 100
Percentage of Water = (375 / 1500) × 100
Percentage of Water = 0.25 × 100 = 25%
Based on this calculation, the correct percentage of water is 25%, which corresponds to option (b).
💡 Study Tips
- Read Carefully: Always be cautious of poorly worded questions in exams. If a calculation seems to give an absurd result, re-read the question to see if there's a likely typo.
- Master the Formula: The formula for water percentage is fundamental. Always remember it's based on the weight of dry cement.
- Check for Reasonableness: Know that the normal consistency 'P' for OPC is typically between 25% and 35%. If your calculation falls far outside this range, you have likely made an error or the question is flawed.