Concrete mix design submittals

[MacGruber22]

A bit of a polling...

1. How many of you regularly receive concrete mix designs with standard deviation test results?

2. How many of you regularly receive trial batches over a range of W/C ratios?

2a. Do these trial batch reports usually meet the strength requirements of ASC 318 table 5.3.2.2 (f'c + some overage)?

I ask, because my answers are:
1. No 99% of the time
2. Yes 99% of the time
3. No 75% of the time(in addition the batches are hardly ever performed across the project W/C ranges)

It is like pulling teeth to get the bare minimum ACI requirements from so many suppliers. And it seems odd to me, as they should have an amazing amount of data to prove strengths.

Thoughts?

 

[JAE]

1. On most major projects yes.
2. Not usually trial mixes but historical data on a particular mix that the supplier had previously developed.
2a. Yes.



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[MacGruber22]

Boy, what a short poll.

Thanks, JAE.

 

[JAE]

Can anyone else out there comment?

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[wannabeSE]

1. Until recently, the vast majority of submittals used field test data and properly documented. Sometimes the data was a little old.
2. Submittals with trial mixes has become very common. But, I am skeptical about many of the "trial mixes" used for these submittal. I have received field test results (set of cylinder breaks for an older project) used instead of trial mixes prepared and cured per ASTM C192.
2a. Yes, they meet the increased strength requirements.

I have become frustrated with these submittal. The mix design looks fine - no problems - typical 3000 to 4000 psi mixes. But, the submittals just don't have the required field test or trial mix data. Sometimes, I wonder if other engineers even look at this stuff.

 

[dcarr82775]

1. About half the time the submittal has the strength data. The other half I reject outright.
2. Never seen them
2a. The one time I got a trail mix it did conform.

 

[MacGruber22]

wannabeSE,

Yeah, I am very skeptical about them as well. And, yes the mix designs usually look fine; however, the data to prove it, not so much. I mean, at the end of the day, the supplier is still responsible for providing a product that meets the performance criteria, regardless of whether they send us less-than-adequate proof that they can do it.

For instance, attached is a trial batch curve we received recently for column repair (I didn't review this submittal - I am now inspecting the work). As far as I am aware, ACI 318-11 5.3.3.2 requires trial mixtures that envelope the project design W/C ratio and f'c + Table 5.3.2.2.

Our f'c was 4 ksi, so f'cr = 5.2 ksi.
Our specified maximum W/C ratio was 0.38

To, me that means that this submittal needed to be rejected (but wasn't), and resubmitted with a proper trial batch chart, as the regression "curve" doesn't envelope either of my values. Why did someone approve this submittal?? Am I being pedantic?

dcarr,

Your answers for 2 and 2a. confuse me. You have never seen a trial batch, but you received one once? Do you mean that it didn't look like my attached image? If so, how did they present the trial batch data?