Ordinary Portland Cement, 43 grade- specification
1989 Edition

Per IS 8112 (1989), the chemical composition limits for 43 grade OPC are as follows:

• The lime saturation factor, calculated as (CaO - 0.7 × SO3) divided by (2.8 × SiO2 + 1.2 × Al2O3 + 0.65 × Fe2O3), must range between 0.66 and 1.02.
• The ratio of alumina (Al2O3) to iron oxide (Fe2O3) must be at least 0.66.
• Insoluble residue should not exceed 4.0% by mass.
• Magnesia (MgO) content must be under 6.0% by mass.
• Loss on ignition is limited to a maximum of 5.0% by mass.
• Chloride content must remain below 0.1% by mass.
• Alkali content for prestressed concrete applications is capped at 0.05% by mass.

These parameters ensure balanced chemical properties for strength and durability of the cement.

The standard mandates the following physical and strength properties for 43 grade OPC:

• Fineness: minimum specific surface area of 225 m²/kg (370 m²/kg for 43-S grade).
• Soundness: Le Chatelier expansion not exceeding 10 mm and autoclave expansion limited to 0.8% maximum.
• Setting times: initial setting time no less than 30 minutes (60 minutes for 43-S grade) and final setting time no more than 600 minutes.
• Compressive strength requirements: minimum 23 MPa at 72 hours, minimum 33 MPa at 168 hours (37.5 MPa for 43-S), and between 43 to 58 MPa at 672 hours.

These ensure adequate workability, durability, and performance of the cement in construction.

Performance improvers are regulated under the following conditions:

• The total amount of performance enhancers, including additives, must not exceed 5% by mass.
• When multiple improvers are used, their combined total must remain within the 5% limit.
• Manufacturers must hold a BIS license to use the Standard Mark, confirming compliance with the BIS Act.
• Upon request, manufacturers must provide a test certificate specifying the type and percentage of any performance improvers included.
• Test certificates, excluding the 28-day strength report, should be delivered within 10 days.

This framework maintains transparency and quality control regarding additives in OPC.

Cement packaging must adhere to the following requirements:

• Packaging materials can include jute sacks (IS 2580), multi-wall paper bags (IS 11761), lightweight jute bags (IS 12154), HDPE or PP woven sacks (IS 11652), or other approved composite bags.
• Bags should be in sound condition at the time of inspection.
• Typical net quantities per bag are 50 kg, with allowance for other sizes such as 25, 10, 5, 2, and 1 kg, subject to specified tolerances.
• Each bag must be clearly and indelibly marked with the manufacturer’s name and trademark, cement grade (Ordinary Portland Cement, 43 Grade or 43-S Grade), net weight in kilograms, the phrase "Use no Hooks," batch or control unit number detailing packing date, manufacturer’s address, and details of any performance enhancers added.
• For export consignments, packaging and quantity may vary according to purchaser agreement.

These guidelines ensure traceability and compliance with quality standards.

Sampling and testing of cement are governed by the following procedures:

• Sampling is conducted following IS 3535 and IS 4905 standards, using random selection of bags based on batch size as specified in Annex B (ranging from 20 to 200 bags depending on batch size).
• Testing includes physical tests (fineness, soundness, setting time per IS 4031 series), chemical analysis (IS 4032, IS 1760 Part 3), compressive strength tests (IS 4031 Part 6 & 8), and pozzolanic material assessments (IS 1727).
• Manufacturers must ensure cement conformity with IS 8112, providing test certificates within 10 days after testing (excluding 28-day strength results).
• Cement stored for more than 6 months in bulk or 3 months in bags after initial testing requires retesting before use.

This protocol guarantees consistent cement quality and compliance before deployment in construction.