Managing Quality: Concrete strength example

Question 1

What tests can be used for measuring concrete strength?

Answer 1

ASTM C39 cylinder test

ASTM C109 cube test

Question 2

Which test is typically preferred in the UK and why?

Answer 2

ASTM C109 cube test as it aligns with British Standards

Question 3

What does a quality management plan traditionally consist of 6 steps (general)?

Answer 3

1. What quality elements need to be managed on a micro scale to achieve macro scale results!
2. Identifying what will be measured
3. How quality will be managed - you know the methods
4. Repeat process every time new batch comes to site (PDCA - Kaizen)
5. Control quality
6. Consider residual risk!

Question 4

What does an XBar-R chart do and how can it control quality?

Answer 4

• Controls quality performance
• Analysis produces an index value which can be compared to a threshold capability value
• If less than the capability value, it indicates a deficiency in capability

Question 5

What steps should be performed to test concrete strength of a batch?

Answer 5

1. Perform a slump test in accordance with BS EN 206:2013 and reject if it does not conform
2. Perform ASTM C109 cube test on 2 inch cube and check against min strength

Question 6

At what point should a focus be placed on managing quality of concrete strength and why?

Answer 6

• During construction
• As assuming no deteriorating factors are present, compressive strength of concrete increases with age

Question 7

What residual risks could still exist with concrete even if QMP is satisfied?

Answer 7

• Quality of pouring the concrete could affect strength. Educate concrete gang!
• If deteriorating factors are present, concrete could be affected. Use self healing concrete if appropriate, or inspect frequently for issues.