Cement Hydration Catalysts / Mix-water Treatments

[Enhance ICD]

Chris,

The building system known as FC most certainly seems to be "green" from an overall standpoint simply due to the quantity of cement used being far lower than standard concrete structures but the standard FC mix design is by no means "green" at almost 50% cement.  We are going to start with Martin Iorns mix design possibly with and without the fly ash in order to ascertain what strength is acheived as a baseline and then go from there.  We do not believe increasing the cement content is the way to go, nor necessary, but quite the opposite as we believe strength is not going to be a problem even with simply less cement but also with variations of adding fly ash, calcium carbonate, zeolites (don't get distracted with this one as they are another type of pozzolan but it is just an idea at this point that we are already doing R&D on for other clients).  So, after some initial trial mix designs we'll go to work on economizing the cement content.  We can run all modulus properties for the samples including tensile and flexural strengths in order to chart a graph and hopefully pinpoint the most efficient mix design at what constituent proportions.  In the end, field trials must be performed in order to determine if an optimal lab mix design is also optimal in the hands of a tradesperson in the field so that's where you guys will come in once we have something we believe will work.

As we've discussed previously, if you can better utilize the mix-water and cement content you tend to obsolete most standard industry chemicals so from that standpoint, no, there are not any other chemicals that we admire (this doesn't mean that they are not very capable of doing what they are designed to do as some are very exceptional and intriguing but if they are no longer needed for what they do what good are they?). 

We are more prone to look to mix design engineering and constituent materials to accomplish the task of what the chemicals industry wants you to buy their technologies for, so things like calcium carbonate, zeolites, pozzolans, etc, are where we look for performance in addition to our own proprietory technologies.  That said, PMT with just OPC works great too.

In the case of FC, our goal is to try to come up with the simplest mix design so that it can be used in far and wide places but this will be an added challenge because I know from my own experiences in third world countries the biggest issue will be cement composition and quality and then availability of even the most basic materials.

The calcium carbonate that we are speaking of is readily available to big industry so we can easily get our hands on it but it is widely available as a bagged product in smaller quantities.  One such company would be Omya at www.omya.com.  I will get back to you as to where it may be the easiest to access it in smaller quantities relative to the tradesperson level.

Grant.

[Chris Glasspool]

Hi Grant,

The variations in cement ratio for fc range from basic 1 to 1 like Iorn's mix, all the way to 1 to 3.5, according to literature I've read. The reason that I've guessed that Martin Iorn's used the rich mix, wasn't for strength but for workability, and quality, the sand ratio is increased, of course it will take more water to wet the mix out. Since ultimate strength and quality are more tuned to the water ratio, then the amount of cement used in this case. If the Enhance product were to increase allowable water consumption by say the 12% percent that you mentioned as a possibility then we could leave the cement ratio as is with the assumption that the increased quality of the Enhance will allow the removal of the flyash to the mix, therefore allowing that the need for water to go down with the flyash removed, but the Enhance will allow some of this water to remain. As the flyash increases water usage, but also adds workability due to the so-called ball bearing affect. What such a mix would be like to handle is a guess. Martin Iorn's mix minus the flyash equals ten percent less water usage, plus the Enhance affect will increase water allowable by 12 percent equals what better or worse workability?

i did find one article on limestone nucleus use, but did not see a micron size suggestion, but the additive was about a 8% replacement for PC. This might have a bonus for fc, as I am guessing that the small aggregate might help in micro-cracking. Another mineral that is used in the same way is Basalt dust, and it has the additional benefit of acting like a weak pozzolan adding a small bump in strength in about three months after placing. both of these have the disadvantage of adding water usage with the Basalt having additional benefit over Limestone of adding a slight water ratio, as water ratio can be raised when using a pozzolan. Practical purposes of shipping milled basalt from Texas is not so good. In any case I would rather design a mix based on what works for all areas. What I've told people in the past is - look for the products that are nearest you; if El-chem is down the road in New York, then go get a ton of silica Fume, and if in Texas - Colorado then get Micron 3 Flyash, etc., but for a general design purpose let's assume that the Enhance can do away with these things, and go from there. I live in Eastern Washington, and Zeolite is near by, and  I too have a couple of tons of this material to play with. I actually was going to suggest that you get some of this material to play with as it can act as a slow chemical release agent, think suppling the mix with the Enhance product continuously all the way through the hydration stage. (whole 'nother topic)

The lack of continuity in quality in both sand and cement around the world is something that takes a general mix design for fc, and puts in the lowest common denominator for what will work for mix designs, and still the caveat would exist that if the sand is unwashed, not graded properly, then do not proceed, and if the cement has any lumps, or hardened areas, then do not proceed!

Thanks for the link. I will study later. - chris

[Enhance ICD]

For anyone interested, GCC (ground calcium carbonate) can be sourced through SMI (Specialty Minerals Inc), www.specialtyminerals.com

Also, can anyone clarify for me what range of compressive strength is desireable for various FC applications at day 7 and then at day 28?

It has been mentioned that 5000psi - 10000psi would be desireable under certain circumstances for certain applications which I am assuming is referencing the 28 day strength.

Chris has just mentioned that some FC mortars have sand to cement ratio's similar to standard stuccos and mortars at as high as 3.5:1


Not as part of our initiative for FC mix design but as general mix design analysis and engineering that we are performing for a Scandanavian client who shipped us their local cement and sand for a no large aggregate concrete mix design, effectively a mortar with a ratio of 4:1.  The basic mix design is, as of now, 700lbs cement, 2836lbs sand,  w/c of .52, and PMT.   The compressive strengths acheived as an average for day 7 were as follows:

Control:  4620psi;  PMT-1-RM:  4690psi;  PMT-1-OS:  4920psi

Now, it is important to remember that PMT's are not utilized, or marketed, for compressive strength gain but in the majority of cases this is one of the results, the least important result.  Depending upon the cement composition and quality there can be a slight decrease in compressive strength but this is not considered critical due to the fact that in all cases paste development has been improved which has many more positive implications than a perceived negative implication of slightly decreased compressive strength.  In reality, compressive strength is never a good indication of concrete quality or durability whereas microstructure, and by extension, permeability is.  PMT has never yet met a cement that it hasn't improved the paste development and thus overall quality and durability of the end product whereas it has met a couple where compressive strength was slightly reduced. 

When it comes to our mix design engineering services and if our client has very specific performance requirements we always request that they ship their local mix constituents to our lab facilities so we can ascertain the specific performance characteristics of the constituents, particularly the cement, that PMT will be interacting with.  In the rare instance that compressive strength is slightly reduced and if this is a concern to our client it is simply designed around, but again, it is a rare instance where this is necessary.

Regards,

Grant. 

[clint]

     Hello Grant, Forgive me if this question has been answered and I overlooked it but this has been a pretty long thread and it would take me a bit to go back over it completely again to find out. 
     If we use your product to cancel the need for superplatisizer and to allow better hydration of cement particles with additional water, would we still need acrylic admix added for projects that can't be covered to prevent pre-mature evaperation of needed water?
     I have thoroughly enjoyed reading all the post under this heading and intend to order some product to try soon.  I am also going to glanse back to see the purpose of the GCC, but if not already expained could you mention it,(again)?  Thank You Much, Clint
     

[Enhance ICD]

Clint,

It’s good to hear that you are enjoying the subject matter on this thread, hopefully you will soon be able to put into practice what you are learning and see it in action.

PMT enhances the natural ability of cement to consume and utilize water thus converting free mix-water that would be subject to evaporation into chemically bound water that is locked in the form of C-S-H (calcium silica hydrate) that is not subject to evaporation.

That said, this process is simply a more efficient version of the basic chemical reaction known as cement hydration so all the normal processes of quality control and good building technique still apply in reference to ensuring that this process is not damaged.  This would include proactive measures taken to protect hydration in excessively cold and hot temperatures.

I don’t want to be dogmatic as I am new to FC myself but where cement hydration is concerned the impact PMT effects upon any cementitious structure we have been exposed to there has rarely been a need for any other technologies to be employed.  From this standpoint I would say that it would be very unlikely that latex or polymer products would be necessary when PMT has been employed.

Moving on to GCC, it’s role is multi-faceted in that it performs the function of a non-pozzolanic particle packing material which physically densifies the pore system.  It doesn’t directly promote hydration but it does act as a nucleation site for additional hydrate growth thus densifying the paste microstructure which can also aid in strength properties.  In addition, it improves the rheology of a mixture due to it’s very small particle size.  It is very complimentary to the impact afforded by PMT.

Here is an excerpt from an independent laboratory analysis of PMT but also where GCC is commented upon:

“Interground limestone (GCC - ground calcium carbonate) grinds preferentially compared with clinker, resulting in a very fine powder that provides nucleation sites on which hydration product can grow. Although this may not be as effective a provider of nucleation sites compared with PMT-induced C-S-H formation, it will still be beneficial.

A mix without PMT will not have these widespread additional nucleation sites, although it will have other nucleation sites in the form of fine cement particles, other hydration products and other materials such as fine limestone, if present. A mix with PMT using the same cement will have these nucleation sites as well as the additional C-S-H.”


Hope that helps,

Grant.

P.S.  I had the pleasure of personally meeting Paul Sarnstrom yesterday.  For those of you who haven't yet had the privilege he is about 6 foot 6, 325 pounds and full of muscles.  It would seem to me that he is the perfect fit as an FC website moderator! 

[clint]

Grant,
    Thank you for your clear and thorough responce to my questions.  No complaints from me , by the way, as for as this being a long thread.  A lot of good information I am reading and adding to my arsenal.
    I regularly use, and have abundant access to a very high grade C-ash.  I could hardly get along without it since I use high % quantities in my mixes.  Am I getting the same basic benefits from it as I would from the GCC or is there a difference in particle size or other differences?
    Should I talk to you direct to place an order or do I just need to go to your web site and go from there?  Thanks again for your time!  Clint Coleman
        P.S.  I agree with your positive analysis of Paul, Giant Gentleman

[Chris Glasspool]

Grant, and Anyone,

You mentioned in this long thread, that sometimes limestone powder - aggregate is used as nucleus material for better quality mortar. Have you thought about an alternative of just using stale cement when available? I suspect that like me, many have purchased more cement than needed at one time , or another, and have stored it properly in a dry area, but now they discover that it isn't fresh anymore (stiff in texture - not fluffy); not rock hard like improperly stored material, just very stale. For our applications this isn't very good material to use, but it seems to me that this would make just as good a nucleus material as un-calcined limestone with the added benefit of being somewhat to very cementious.
 Maybe increasing the amount of cement used by 10 percent in the mix, with another ten percent being a replacement for fresh cement powder, would find both a use for the stale and enhance the mix design for porosity and flexural strength; What do you think? Thanks, chris

[Enhance ICD]

Chris,

I understand your thought process behind your question but it wouldn't be that simple for two reasons:

1.  It would make calculated mix design engineering very challenging not knowing just how much of this stale cement is still reactive and to what extent.

2.  The particle size of cement is much larger than ground limestone (calcium carbonate) so wouldn't have the dispersion throughout the mixture in the same manner so wouldn't provide nearly the same nucleation site impact as GCC.  Also, some cement particles are very fine but "stale" cement probably means that it is air-set, ie: lumpy, and these fine particles are stuck together or already hydrated. Air-set lumps often don't break up on mixing and can be seen in hardened concrete as clusters of cement grains.

This is not to say it couldn't be attempted but stale or hydrated cement particles couldn't be counted on to perform in the same manner or to the same level of efficacy as GCC.  Hope that answers your question.

Grant.

[Chris Glasspool]

Hi Grant,

Totally understand your answer, and you answered to what I thought might be a problem. for the reason you mentioned I keep hoping to find a small used ball mill at a bargain price. I'm betting that stale cement at 3 microns might change the game. So far the mills I see are either rock tumblers, or 3 tons. Thanks for the answer, chris

[Enhance ICD]

Hello all,

Just an update on the average compressive strength results from the 4:1 mortar mix trials (not specifically for FC) for which I posted 7 day results earlier on this thread which were:

"Control:  4620psi;  PMT-1-RM:  4690psi;  PMT-1-OS:  4920psi"

Now, 28 day results:

"Control:  6050psi;  PMT-1-RM:  6245psi;  PMT-1-OS:  6060psi" 

Whenever I post compressive strength results on the site I will reiterate that compressive strength is in no way an indicator of end product quality or durability but as it is one form of measurement most will at least want to know what the results are. 

As microstructure is the best measure of quality and durability, for which we have abundant analysis, I am entertaining the possibility of having this type of analysis performed on some of the FC mixtures we are trialing but as microanalysis is a substantially more involved form of analysis I would like to know if anyone feels that this is in reality a necessity due to the testing and confirmation previously performed.

Regards,

Grant.

[upston]

Hi Grant,

i hope you trip is going well.

Can you explain the differences in the last 2 mixes ie
PMT-1-RM
vs
PMT-1-OS

I looked above but missed it.

Thanks again for all the time your company is spending on this.
brad

[Enhance ICD]

Brad,

PMT-1-RM (Ready Mix) and PMT-1-OS (On-site) were developed to address different scenarios. 

RM has a lower reactive silica content than OS and was developed for addition at the Ready-mix plant where mixing times due to transportation were longer thus allowing a longer interaction time between the cement and water.  Additionally, the lower silica content was developed for mix designs where cement content was more standard. 

OS has the highest reactive silica content and was developed for applications where PMT was dosed on-site.  Due to shorter mixing times (no time in the mix during transporation) a more potent shot of silica would do the job of RM at a faster rate.  Additionally, the higher silica content was also developed for mix designs where cement content was elevated over standard levels.

Hope that helps,

Grant.

[Chris Glasspool]

Hi Grant,

The compressive strength of fc mortars needs to meet a 5000+ psi according to Dr. Naaman to hold or grab the steel in the most ultimate way. I assume that a weaker psi would also work, but not be as strong, and am guessing that a psi that was too much higher than this could be worse than that which that didn't meet the 5000 mark, as one attribute of fc is it's flexural strength, and high psi mixes might not meet that goal.

The goals of a good fc mix as I understand, are to lock the many layers of steel mesh together, yet remain as flexible as possible. The porosity needs to be low enough to protect the mesh at only a a 2 to 5 mm covering. The set time, and pH needs to accommodate as little hydrogen out-gassing as possible if galvanized mesh is used. It is preferable if a naturally  occurring chromium is a part of the cement makeup. The aggregate size should be small enough to pass through the mesh hole size.

I'm thinking that the Enhance product might help greatly in meeting these goals.

For my own goals, I would like to know more about the specifics of the interaction between the Enhance product and polymers - like when a grfc mix is used. I will be asking you more about that later when I'm actually mixing....

Thanks, chris

[Enhance ICD]

Hello everyone,

We now have the first round of FC mix design trial results.  8 mix designs were prepared and the data to 28 days is as follows:

FERROCEMENT TEST DATA

Mix #   1   2   2B   3   4   5   6   7   8
Date   11-Feb   11-Feb   11-Feb   11-Feb   18-Feb   18-Feb   18-Feb   18-Feb   18-Feb
CEMENT   1350   1350   1350   1350   1350   1350   1000   800   800
FLY ASH   230   230   230   230   230   230   175   137   137
W/SAND   1604   1604   1604   1397   1397   1195   2012   2223   2223
WATER   520   520   520   600   600   678   500   500   500
APP SLMP   1.5-2.0   1.5-2.0   1.5-2.0   5.5-6.0   5.5-6.0   7.0-7.5   7.0-7.5   8.5-9.0   8.5-9.0
7 DY ST   7140   6690   6690   6520   6560   6100   5260   4320   4330
28 DY ST   9430   9010   8990   8690   8520   8590   7840   6170   6200
7 DY SH   0.0005%   0.0002%   0.0003%   0.0003%   0.0007%   0.0005%   0.0005%   0.0012%   0.0025%
28 DY SH   0.0192%   0.0063%   0.0165%   0.0118%   0.0302%   0.0224%   0.0212%   0.0251%   0.0566%
W/C RAT   0.33   0.33   0.33   0.38   0.38   0.43   0.43   0.53   0.53
PMT OZ   0   189.6   189.6   189.6   0   189.6   141   112.4   0
                        


All mix designs were prepared and tests conducted as per ACI / ASTM test procedures.  Mix 2B was air cured from day 1 for shrinkage measurements.  All other specimens were water-bath cured until day 7.

Regards,

Grant.

[Paul Sarnstrom]

Hi Grant,

Thank you very much for doing these trials and posting the results.

I understand most of the abbreviations but I must confess I do not know what the abbreviations SH and PMT OZ stand for. 

The 7 day and 28 day ST refers to strength and I assume this is compressive strength.

Interesting trends regarding water/cement ratio are the expected increase in slump as well as the not so expected is the logarithmic character of decrease in strength as the water content rises.

I am interested in any observations of 'workability' for the lowest slump mixes in the 1.5-2 range. I realize 'workability' is not quantifiable, as the other measurements are. I'm just attempting to get some idea if it was closer to a dry pack mix in workability or if it was somewhat 'softer' than that.

thanks again,
Paul