Yesterday in the field we had some trouble with the bleeding in our concrete, the bleeding was adjudicated to the admixture (we use sikament 450 at .08% per weight of cement), here is some data:
· We were constructing a part of a bridge column of 200 cubic meters, the F´c was targeted at 350 kg/cm^2, the concrete slum was aimed at 18 +3 cm.
· Mix design
400 kg Cement
957 kg Gravel (3/4”) M.F. 6.7
783 kg River Sand M.F. 2.7
210 lt Water
3.2 Lt Sikament 450 (low range water reducer)
The aggregates satisfy the regulations and codes, but due to the severity of the bleeding, i want to find out:
1) The probable source of the bleeding (I think it is the excessive use of dispersion admixture)
2) How can I stablish the severity of the bleeding?
3) Is the color or the bleeding water normal?
How to determine the severity of concrete bleeding?
First of all,
1. How bleeding is occur? you have to look to Fine aggregate to Coarse aggregate in your testing about F to C 1:1.2..one of the factore effecting for bellding..
2. 210 water is very high to reach 35 MPa??
3. Why you used sikament .08% of cement.. if you have 210 water... I think you have to reduce water to add sikament .08% ...So in you case workability is very high it means slump is collapse...Very high workablity? If you reduce the amount of water then you can add sikament .08% then you get less bleeding...Compressive strength increase...
Which mix design you are used?
https://www.researchgate.net/publication/266475760_CONCRETE_TECHNOLOGYScience_and_Research_Concrete_mix_design_using_the_double-coating_method?ev=prf_pub
Article Concrete mix design using the double-coating method
Thank you very much for your answer, if i wanted to design a concrete for such properties i would use this design instead using the ACI 311
Cement 416 kg
Water 184 Lts
Gravel 1187 Kg
Sand 606 Kg
2.1 Lts Sikament 450.
However, i´m supervising the concrete quality, i have performed a series of test and the concrete F´c is around 450 kg/cm^2 (with the mix of 210 lts of water), i´m no sure if the mix desing is beeing applied at the concrete plant since i have a 50 kg/cm^ standard deviation.
I´ve also done the ASTM C 642 a total of 26 test and the average Volume of Permeable Voids is 8%, which is very good.
Also when we use a concrete retarder, we do not see any bleeds (with the same mix).
I know that reducing the admixture and water, will stop the bleeding, how could I address the severity of the bleed, do I have to worry about the concrete loosing it´s properties? is there a way to test the bleeding on the field?
Also and a completely unrelated question I am trying to do a study with your double coating method for mix design, and a couple of others, we are trying to determine which one is the more economical that provides durability (less VPV, and a low permeability to chloride Ions) and the target strength.
We are testing these mix design methods:
ACI 311
Double-coating method
Fuller´s
Vitervo Oreilly
Do you have any advice on how should I approach your method?
According to your question.
How to test the bleeding on the field?
You have to see and to control during your casting the concrete if the water is going up ..sometimes no need vibration (compaction)... If the workablity is very high ..This is very very important to avoid segregation and bleeding.....
Dear
The measure problem with your case is that you are using an extremely high water to cement ratio which was 0.525 at your first mix and 0.44 on your second mix. actually the w/c ratio when using sika should not exceed 0.3, since the sika will give you the required workability and also will support the early strength of concrete (at 7 days). the color of the bleeding water is light brown as demonstrated in the photos supplied which indicates that your fine aggregates may contain excessive fine materials (silt or may be clay) which you should check. however i think that sticking to w/c ratio of 0.3 and the use of Sika will solve your problem.
You can collect the water at top of the mold after the concrete has been cast through pippet for measurement purpose of bleeding.
Dear.
I am working now on an research using high strength concrete with w/c ratio of 0.30 ,silica fume, steel fibers and superplasticyzer (flocrete pc 200 (2% of cement weight),but I don't got any bleeding.SoI agree with the suggestion submitted by Mr. Saad Sarsam by reducing the quantity of water
The color of the water is normal.
Bleeding is often a result of an "unstable" mix design. Sometimes the mix could be borderline, and with addition of an "overdosing" of admixture (which might still be within the manufacturer's recommendation), could result in bleeding as well.
Usually you might want to increase your powder to course agregate ratio, and/or your fine aggregate to course aggregate ratio.
I agree that the water of the mix could be cut as well, since the mix could be at risk of segregation as well with high water & water reducing admixture.
The colour of the water is most likely due to the water reducing admixture.
.08% for a low range water reducer is very high and has most likely resulted in excessive retardation which would have contributed to bleed. Your water content is also too high. To produce 180mm slump I suggest you use a high range water reducer to lower your water content and reduce retardation thereby reducing bleed.
Dear David Flores Vidriales
I think this article is benefit for you.
Check the following reference Please.. it might's assist you in your question … Regards…
http://demo.webdefy.com/rilem-new/wp-content/uploads/2016/09/1552.pdf
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