Dear Angelin

In modern concrete systems, including SCC, usually powder content is high and mixing water content is low (w/c in range of 04-0.45). Therefore you need a third generation PCE based suplasticizer. Depending on the level of flow and aggregate grading you might encounter bleeding and segregation. Therefore you might need VEA also. In order to minimize compatibility issues, use all chemical admixtures of the same company. You may use chemical admixtures from BASF or Sika or some good manufacturer. If you want to receive more guidance, you may write me directly at [email protected]

wishing you sucess in making SCC. Prof. Rizwan

Polycarboxylate superplasticizer is now the best for making SCC. You can select the products of Grace, BASF and Sika according to their availability in your place.

Rizwan and Ma, thanks for the answers.

In my last test I used a BASF superplasticizer called Glenium 51, you have used?

Angelin. PCE stands for polycarboxylate ester. I have used both BASF Melflux 2651 L and Glenium 51 of Sika(Both are PCE Based super-plastcizer). Both look OK. Please consult technical data sheet of the super-plasticizer and see how much is total solids content (Usually it is between 40-50% which means that remaining 60-50% is water which must be accounted for in W/c or w/cm ratio). I hope you are using liquid type super-plasticizer

Rizwan, I checked the data of Glenium 51 from BASF. It is liquid and chemical basis of polycarboxylic ether. Its solids content is 30%.

For self compacting concrete, the best Superplasticizer is an admixtures based in Polycarboxilates, do not guide by the brand of the admixtures because each producer have the personnal name, The composition must be based in ethers of  Polycarboxilates, the last generation of chemical superplastizicer admixtures.  Is possible that must use two and admixture modificator of the viscosity, specially if you do not have fines enough in the concrete dosification.

Hello Juan!

Thanks for the advice!

You have a viscosity controller to indicate or specify?

Best regards,

Andressa.

Hello Andressa:

Really I do not know what is the specific chemical compositions of this viscosity modificators of the concretes but you must to talk with any admixture producers that sure can help you. If you do not have this kind of admixtures and your concrete mix do not have fines enough, the superplasticizer based in polycarboxilates may provoque an strong segregation of your mix. In this case in my experiences I have obtained a self compacting concrete using another kind of admixtures based in Vinilics or acrlilates.

Glenium 30% solids is OK. I use chemical admixtures of a good brand becuase they care about their reputation. Use it.  I have experience of making SCC in Laboraory, then tested it for flow after plant mixing(please ensure that SCC needs slightly higher mixing time . I used 2 minutes mixing time while for conventional concrete, it is 34 seconds in France, 40 seconds in Germany (mixing time at plant). I also used Glenium 51 and Melflux 2651 L from BASF in making SCC. Both gave me more or less similar results. SCC was used in field placement in an under ground German tunnel of a teaching mine by means of pumping from ground level. The formulation has to be revised at each stage.Juan is trying to say similar things  i guess.PCE based super-plasticizer is the 3rd stage admixture and it may be improved in future , who knows . I wont call it the last generation of super-plasticizer.A good technician can have an idea about bleeding or segregation using Abrams Cone flow test, though many tests exist, If you suspect inadequate viscosity then you may either increase sand content or use VEA or both. Can you tell me the ratio of fine aggregates to the total aggregate content?

My first test was (in mass):

1 (cement) : 0.1 (silica fume) : 2.75 (sand) : 0.48 (fine aggregate) : 2.26 (stone) : 0.016 (plasticizer) : 0.6 (water)

The formulation looks OK. Do you get bleeding and segregation? I hope you should not. By fines do you mean limestone powder or fly-ash?are your flow times(slump cone time, v-funnel time, L-Box and J-rings times) within acceptable limits?do you have some problems or questions?

I use limestone powder. Yes, in all trials got the lower limit, but I believe it can improve.

Andressa you mentioned lightweight? What are you using to give you the lightweight? All Ingredient's I see in your formulation is normal weight . Secondly if I look at the W/C ratio this isn't a very strong mix either? Am I missing something? I am not a SCC expert and want to learn from what you did (I am a lightweight expert though) What is the density that you have achieved with your mix?

Hello Derek!

First I'm trying to hit my reference mixture, although it will work with the lightweight self-compacting concrete later on. As the water/cement ratio is too high, actually, I was wondering what other researchers used as a plasticizer, just to lower that number.

As lightweight aggregate I used expanded clay.

Dear Andressa,

I have read carefully the responses of our colleagues and I agree with them. But perhaps supplementary information can help you to evaluate the performance of superplasticizer i.e. to choose the best superplasticizer among the available. You can do a compatibility test with cement you wish to use. You could be use a Marsh cone in case of the cement paste or even testing your concrete mortar phase with adapted V funnel and slump flow tests. For these last tests I recommend you take a peek in the paper “Methodology for mix design of the mortar phase of self-compacting concrete using different mineral additions in binary blends of powders”, http://www.sciencedirect.com/science/article/pii/S095006181100290X

Hi Andressa, 

I presume you have worked with lightweight materials before, but to first get a reference mixture and then go from there to lightweight? I am not sure about that Lightweight Aggregate respond different to all properties of normal weight aggregates. and then the lightweight aggregate absorb about 14 to 18 % of your water, so allow for that before you start mixing then the work-ability of lightweight concrete give different values then normal concrete for the same work-ability material. Luckily we don't have that type of material here freely available for concrete, because the little bit I have worked with imported material gave me enough grey hair. Good luck though.

Derek 

Thanks Oliveira! I will read very carefully.

Yes Derek, work with lightweight aggregates is not easy. In my master's I worked with them making structural concrete, evaluating the optimal percentage of this material.

Now, the PhD, the challenge is even greater. I've never worked with SCC, so many doubts are emerging.

Fortunately some doubts are being remedied. Let exchanging our experiences, especially to know what to do and what not to do.

E-mail is maybe a better way to communicate because you don't want people to get Idea's on the type of questions you ask to steal the novelty of your research. Only if you want to. ([email protected])

But of course we will exchange more ideas. My email became available also ([email protected]).

basf gelnium is best pce for SCC . pCE shows different results as grde of concrete changes.some pce shows bleeding & seggregation , becoz they are more sensitive even 0.1 dosages LBWB increases.

Oi  Andressa. I will answer your in portuguese, our mother language, ok? Glenium (tarde mark da BASF ou MasterBuild) ou qualquer outro aditivo water reducer de 4ª geração, e que seja da classe polycarboxylate graft poliéter (tecnicamente, do ponto de vista químico, um co-polímero de enxertia com cadeia principal de poliacrilato, e uma cadeia lateral de polioxietileno) são os mais fortes dispersantes e redutores de água (ou redutor de viscosidade). A empresa SIKA, ou a GRACE também tem similares. Para pasta de cimento, sem agregados miúdos nem graúdos, é muito fácil chegar a relações w/c < 0.22 ou até menos. Mas em caso de overdose do "superplastifier", pode ocorrer segregação das partículas do cimento. Espero ter ajudado. Metacaulim pode servir para corrigir overdose, para evitar perda da trabalhabilidade e impedir segregação.

try for 30% sodium lignosulphote SBWB. increase the dosage to get proper flow and test results. setting type issue may be differ on C3A level of cement used.

In my oppinion the best superplaticizer for this use in selfcompacted concrete is the based in the policarboxilate polymers

Hi Andressa, The question is what sort of lightweight concrete? one with aggregates or one made with Foam? Most of the suppliers of the new supers use de-trainers in the product that increase the density of Foam concrete and causes you to end up with too high a density. Using lightweight aggregate and go to workable might cause the aggregate to float to the top giving you a density and strength difference from top to bottom. I know I am not answering your question but I only advise you on more possible problems. What you can do is go with this to a big supplier and they might be able to combine two admixtures that can help you. Hope you come right

you may use Synthetic Foaming agent to produce light weight concrete utilizing same constituents and portions 1 (cement) : 0.1 (silica fume) : 2.75 (sand) : 0.48 (fine aggregate) : 2.26 (stone) : 0.016 (plasticizer) : 0.6 (water) . to have a lighter mix replace the stone with sand .start with experimenting small volumes and low speed mixer (or even hand mixing)

The best plastizicers is a Carboxilate Mofied.

Now a days there are products available with PCE based superplaticizers blended with VMA....may be used effectively after compatibility studies.

The best superplastiszicer is the Policarboxilate

The Policarboxilate