Shrinkage crack or Flexural crack?

Is it important? Just have a look on the consequences:

Shrinkage crack means that it is not caused by applied load. Just fill cracks with epoxy to protect reinforcement from potential corrosion, then end of story.

Flexural crack means the bridge does not behave like what it's been designed for. It could means underdesign or nonconfirmity to technical drawing and specifications (position of strands, reinforcement, post-tension force applied in every stage, concrete quality...). A lot of people will be questioned, thousands of details are to be checked, hard decission making and then then following by a series of messy and expensive remedial works (or do nothing as well)

As we are only concern about safety of using the bridge, flexural crack may means:

1) The bridge is not perfect, but based on other favorable factors, it is still safe to be used.

2) It is a sign of unfavorable happenings.

All of us need some reliable answer now. How to get it? From the press statement? From this non-sense blogger's unwarranty information? Or from the Consultant's press statement? None of them in fact.

I would like to recall one powerful ancient method to ease your tension. This method has brought human to current level of civilization, even bringing human to the moon and Mars: Basic Scientific Method. Be prepared of squeezing your mind for the rest of discussion.

PART 1 – Observation through Hypothesis
1. Curious Observation
2. Is There a Problem?
3. Goals and Planning
4. Search, Explore, & Gather the Evidence
5. Generate Creative & Logical Alternatives
6. Evaluate the Evidence
7. Make the Educated Guess

Part II – Challenge through Suspend Judgment
8. Challenge the Hypothesis
9. Reach a Conclusion
10. Suspend Judgment

This will be our basis of the following discussion. Anything that is not helping, e.g . emotional word dumping, 14th floor stories etc are strictly prohibited in the comments column. Put your comments here only if you find that is following the above 10 steps. Thank you.

Let me start first:

1. The curious observation is cracks found at Puchong interchange (and now also found at TTDI interchage, which has been painted, check it out).

2. Problem: What are those cracks? (shrinkage crack or flexural crack)

3. Final goal: Recognize the safety level of the bridge; Planning milestone 1: Identify type of crack; Planning milestone 2 to be decided after conclusion from milestone 1 is achieved.

4. Search, explore and gather the evidence.

4a. Hypothesis 1: Those cracks are shrinkage crack

Supporting evidence:

4a1: shrinkage cracks, therefore those cracks could be a shrinkage crack.

4a2: shrinkage crack is normal in concrete.

4a3: Somebody said it is shrinkage crack

Opposing evidence:

4a4: Plastic shrinkage occur within 0 to 2 days of placement, while those observed one occured after years after placement. So they are not plastic shrinkage.

4a5: Autogeneous shrinkage occurs also when the concrete is young. So those cracks are unlikely an autogeneous shrinkage.

4a6: Shrinkage crack does not show significant direction as observed. So, those cracks are not shrinkage crack

4a7: Gradient of thermal fluctuation at the side face of bridge is greater than that of soffit underneath. Thermal shrinkage is more likely to occur at the side face rather than concentrated at the soffit. Therefore, it is not shrinkage crack.

4b. Hypothesis 2: Those crack are flexural.

Supporting evidence:

4b1: Crack lines of a beam/slab under sagging moment are perpendicular to the spanning direction. The crack lines found are perpendicular to the spanning direction, thus they are flexural crack.

4b2: Flexural crack lines of a beam/slab under sagging moment start from the mid span soffit and spreading toward supports. The occurence under observation matches, therefore they are flexural cracks.

Opposing evidence:

4b3: Several crack lines doesn't occur perpendicular to the spanning direction, therefore they are not flexural crack lines.

5. Creative and logical alternative: would it be act of god? (sounds creative, but I can't elaborate more from this)

6. Evaluate the evidences.

>4a1: flexural crack also cracks, so those crack should not only be shrinkage crack

>4a2: flexural crack also normal in concrete, so those crack should not only be shrinkage crack.

>4a3:Somebody could say it as any other thing. The property of cracks is not based on who say it.

I have no objection about the rest of statements.

7. Educated guess (yes, you can question whether I'm educated or not, no problem); it is flexural crack.

8. Challenge the hypothesis. Hypothesis 1 and 2 are both counter-challenging already, I have no Hypothesis 3 to challenge anymore.

9. So, based on my little knowledge, I have no objection that those are flexural crack. (Legal defense notes: I do not have any intention of diverting or influencing anyone to believe in this statement or do any decision based on this statement. Please don't make me liable of anything, this is just purely an academic discussion, or an exercise of basic scientific method)

10. Suspend judgement: The following discussion about the safety level of the bridge can be done based on judgement of this discussion: those are flexural crack.

Buddies, now is your turn. Question those statement, provide more evidence, alternative theories, alternative hypothesis, alternative guess or alternative conclusion. Please be reminded again: no emotional words, no political words etc (ISA applied here). Just purely basic scientific method.