×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Compressive Strength % of 28-day moist-cured Concrete Chart
4

Compressive Strength % of 28-day moist-cured Concrete Chart

Compressive Strength % of 28-day moist-cured Concrete Chart

(OP)
Hello.

I'm looking for data to put into excell to create the Compressive strenght, percent of 28-day moist-cured concrete chart to get results for crushed cylinders on days other than 7-day and 28-day.  

I cursh machine was done I had to catch up on the crushes.  I have the paper chart/graph, but I would like to be able to create that graph to use in excell.  I can get more accurate results if I could.

Anyone know where to get this?

Matt

P.S. The graph should be age/days vs Percent

RE: Compressive Strength % of 28-day moist-cured Concrete Chart

Just so I have the story straight:  Your concrete break machine was inoperable and you were unable to make cylinder breaks when they were actually due.   Now that your concrete break machine has been restored to working order (and presumably calibrated) you have gotten caught up on the breaks and you want to back-calculate the 7 day and 28 day breaks from the numbers that you have.  Seeing as how different mixes cure and gain strength at different rates, won’t you need a different chart for each supplier and mix?

How many days were you behind and how many tests are we talking about?

RE: Compressive Strength % of 28-day moist-cured Concrete Chart

(OP)
The machine is fully calibrated and such.  I have about two weeks worth of test 7-day & 28-day.

This is the chart I'm looking for in excell.

http://www3.mb.sympatico.ca/~hclark/chart.jpg

Matt


RE: Compressive Strength % of 28-day moist-cured Concrete Chart

There is no one chart like that for all concrete.  As boffintech said, you will need a separate chart for each concrete mix that is represented by the cylinders that you have.  You might be able to create a chart using other breaks on the same mix and the supplier may be able to suplement your data.

RE: Compressive Strength % of 28-day moist-cured Concrete Chart

TWO WEEKS WORTH!  OUCH!

RE: Compressive Strength % of 28-day moist-cured Concrete Chart

If you try to publish data that was not actually collected at the time of the break, you are publishing fraudulent data. give the people paying for the tests data you got on day 11,23, or whatever.

Richard A. Cornelius, P.E.
WWW.amlinereast.com

RE: Compressive Strength % of 28-day moist-cured Concrete Chart

I agree with disksewerrat - when you break the tests, you have to report the actual day (e.g., 21-day break, etc.).  Then, in a letter report, you can provide the estimated 7-day/28-day strength(s) based on a rational and industry accepted trend.  As GeoPaveTraffic states, you should have one for each class of concrete.  The concrete supplier might have such specific charts that he has developed for his internal use if you are using commercial supplier.  While not ideal, they may help.  You are in a bit of a dilemma, but you must be up-front about it.  When this has happened to us, we went to another lab and had them break the cylinders for us on the correct day.  Might have cost you some money (or trade in kind later) but it would have been a better decision on your part, I believe.

RE: Compressive Strength % of 28-day moist-cured Concrete Chart

(OP)
Thanks for everyone's input.  I thought the Percent/Age chart was a standard chart to be used when crush dates or not on 7-day/28-day.  I don't understand how there can be a chart for each concrete mix.  It's just a ratio chart, and is used to determine the strenght by adjusting your f'c value be the standard percent value.

Maybe I'm wrong, but I have used this chart in the past and I have seen other use it as well.  http://www3.mb.sympatico.ca/~hclark/chart.jpg

I guess we we'll just post the results for the actuall days ie. 35 days, 10, days ect.

Thanks again

Matt

RE: Compressive Strength % of 28-day moist-cured Concrete Chart

While I am not familiar with the chart you have posted, I assume that it was a general chart prepared to show how concrete cures in average.  However, depending on the amount of cement, flyash, admixtures, etc. in the concrete the actual shape of the curve will be different.  

RE: Compressive Strength % of 28-day moist-cured Concrete Chart

(OP)
How would I create the chart with the data I have.

I have cement powder, admixtures, water.  The chart doesn't seem to care about whats in the mix, its just based on Percent.  ie.  Usually your 7-day is 75% of your 28-day strenght.  Isn't this chart a standard?

RE: Compressive Strength % of 28-day moist-cured Concrete Chart

“Usually your 7-day is 75% of your 28-day strength.  Isn't this chart a standard?”

The chart is not standard.  Say a mix has a quantity of flyash substituted for cement.  This mix might reach only 50% at 7 days and only 90% at 28 days.

Every mix cures and gains strength at different rates.  Otherwise every 7 day break for every 3000 psi mix would be exactly the same.

RE: Compressive Strength % of 28-day moist-cured Concrete Chart

(OP)
We don't use flyash and our mix design is the same everyday.  What kind of data would I need to have to create that chart?

Here are our results.  We only spec 35MPa after 28-days.

Pour #        kN    Mpa        Actual Day Crushed            Required Day Crush    
163A        328    40        8-Sep    14-Day        1-Sep    7-Day
164A        329    41        8-Sep    13-Day        2-Sep    7-Day
165A        331    41        8-Sep    10-Day        5-Sep    7-Day
166A        300    37        8-Sep    9-Day        6-Sep    7-Day
167A        305    38        8-Sep    8-Day        7-Sep    7-Day
168A        289    36        8-Sep    7-Day        8-Sep    7-Day
                                    
148B        325    40        8-Sep    35-Day        1-Sep    28-Day
148C        355    44        8-Sep    35-Day        1-Sep    28-Day
149B        357    44        8-Sep    34-Day        2-Sep    28-Day
149C        352    43        8-Sep    34-Day        2-Sep    28-Day
                                    
169A        296    37        12-Sep    10-Day        9-Sep    7-Day
150B        364    45        12-Sep    35-Day        5-Sep    28-Day
150C        360    44        12-Sep    35-Day        5-Sep    28-Day
151B        349    43        12-Sep    34-Day        6-Sep    28-Day
151C        351    43        12-Sep    34-Day        6-Sep    28-Day
152B        322    40        12-Sep    33-Day        7-Sep    28-Day
152C        319    39        12-Sep    33-Day        7-Sep    28-Day
153C        331    41        12-Sep    32-Day        8-Sep    28-Day
154B        357    44        12-Sep    31-Day        9-Sep    28-Day
154C        345    43        12-Sep    31-Day        9-Sep    28-Day



RE: Compressive Strength % of 28-day moist-cured Concrete Chart

Well even your 7 day breaks appear to meet the 28 day requirement.  Why not just report what you have?

RE: Compressive Strength % of 28-day moist-cured Concrete Chart

(OP)
I reported all the data and made notes about the actual crush date.  

"Well even your 7 day breaks appear to meet the 28 day requirement.  Why not just report what you have?"

My 7-days were more like 10-day crushes.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources