APSC AE WRD 2019 PYQ: Portland Cement Residue

Portland Cement Residue Multiple Choice Question

Question: The percentage of residue left after sieving good Portland cement in a 90-micron sieve should not exceed:
(A) 5%
(B) 10%
(C) 20%
(D) 30%

Answer: (B) 10%

Explanation

According to the Indian Standards (IS 4031 (Part 1):1996 and IS 269:2015), for Ordinary Portland Cement (OPC), the maximum residue retained on a 90-micron sieve should not exceed 10% by weight. This ensures the cement is finely ground for adequate reactivity and strength development.

Residue Limits for Different Cement Types

Cement Type	Standard	Max Residue on 90-micron Sieve	Notes
Ordinary Portland Cement (OPC)	IS 269:2015	10%	Standard cement for general construction.
Rapid Hardening Cement (RHC)	IS 8041:1990	5%	Finer grinding for faster strength gain.
Portland Pozzolana Cement (PPC)	IS 1489 (Part 1):2015	5%	Finer due to pozzolanic materials like fly ash.

Key Notes

• The 90-micron sieve test measures the fineness of cement, which affects its reactivity and strength development.
• RHC and PPC have a stricter 5% residue limit due to finer grinding, enhancing early strength and performance.
• OPC allows up to 10% residue, suitable for most general construction applications.
• Fineness testing is critical in civil engineering to ensure cement quality and suitability for structural applications.

Note: The 10% residue limit for OPC on a 90-micron sieve, as per IS 269:2015, ensures optimal performance in concrete and masonry work, while RHC requires a stricter 5% limit per IS 8041:1990 for enhanced fineness.

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