Practice Compressive Strength Requirements (1.1) - Acceptability Criteria in Concrete Mix Design

Practice: Compressive Strength Requirements

Lesson 1.1Acceptability Criteria in Concrete Mix Design

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9 questions

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2 cards from this section. Quick, good the night before a test.
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6 questions · about 4 min · pass mark 70%. Hints available.
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3 questions · about 2 min · pass mark 70%. Hints available.
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6 sample questions

Question 1.
What does target mean strength (f'ck) represent?
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Think about the average desired strength considering variations.
Question 2.
Define characteristic strength (fck).
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Consider it the acceptable minimum strength.
3Question 3.
What is the significance of the tolerance factor in concrete mix design?
- It guarantees 100% strength
- It accounts for material variability
- It reduces costs
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Think about variability in materials.
4Question 4.
True or False: Characteristic strength is defined as the strength below which no more than 5% of test results are expected to fall.
- True
- False
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Focus on the definition of characteristic strength.
Question 5.
A concrete mix has a characteristic strength (fck) of 30 MPa and a standard deviation (s) of 4 MPa. Calculate the target mean strength (f'ck) using a tolerance factor (t) of 1.65. What do these values imply for the safety of the mix?
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Remember to use the formula to find the unknown strengths.
Question 6.
If a concrete sample fails to meet the characteristic strength of 25 MPa, what steps should be taken to ensure structural safety?
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Think about what went wrong in the mixing process.

5 more questions in this section. Enroll free to practise them all.