Concrete Strength Development as per Indian Standard Specification
(A) 7 days
(B) 14 days
(C) 21 days
(D) 28 days
As per IS 456:2000, concrete is considered to achieve its full strength after 28 days of curing. The strength gain is a gradual process, with approximately 65–70% of the strength achieved within the first 7 days and the remaining strength developing over time. The 28-day period is the standard benchmark for compressive strength testing of concrete.
Compressive Strength Gain Over Time
Below is the typical compressive strength gain of Ordinary Portland Cement (OPC) concrete over time, expressed as a percentage of its 28-day strength, according to IS 456:2000:
| Age of Concrete | Strength (% of 28-day strength) |
|---|---|
| 1 day | 16% |
| 3 days | 40% |
| 7 days | 65% |
| 14 days | 90% |
| 28 days | 100% |
Key Notes
- These values apply to concrete made with OPC 43 or OPC 53 grade cement.
- The actual strength development may vary slightly depending on factors such as cement type, water-cement ratio, ambient conditions, and curing methods.
- Early strength gain is faster in OPC 53 grade cement compared to OPC 43.
- Cube tests are typically conducted on the 7th and 28th day to assess compressive strength.
- Proper curing is critical to ensure full strength development.
Note: Always ensure proper curing practices to achieve the desired concrete strength as per IS 456:2000 standards.
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