Cement Hydration Catalysts

<< < (14/22) > >>

Enhance ICD:
Chris,

This is how the director of one independent micro-analysis laboratory described PMT:

"It (PMT) is not a “liquid pozzolan”, it is more a diluted form of the product of the pozzolanic reaction....."

Now this might be getting into semantics as to whether PMT is a liquid pozzolan, pozzolanic, or the product of the pozzolanic reaction but the results afforded by the implementation of PMT are undeniably equivalent to or greater than standard pozzolan materials as indicated by this same lab director below:

"After mixing, PMT is likely to produce C-S-H rapidly in the pore fluid on contact with lime (calcium hyroxide). (Pozzolanic reaction) The C-S-H.....will have a very high surface area and act as nucleation sites for the formation of further hydration product from cement hydration.  A mix without PMT will not have these widespread additional nucleation sites.

PMT therefore produces C-S-H in minute quantities throughout the pore fluid that then acts as a “marker,” encouraging more hydration products to form around it as the cement hydrates. This encourages the development of a more uniform microstructure; the “C-S-H seeding process” tends to fill pores more efficiently."

A second director of a different independent micro-analysis laboratory reported these findings:

"The observed variations in the concentration of these phases within the PMT-1 sample relative to the control specimen can only be explained in light of the polozzonic mix-water treatment additive.  The PMT-1 sample exhibits a cement fraction characterized by an 80% relative increase in the abundance of hydrated calcium silicate (tobermorite / C-S-H), and a 57% relative decrease in the observed concentration of calcium hydroxide (portlandite)." (Pozzolanic reaction)

"This comparative evaluation of the PMT-1 and control test samples demonstrates that the PMT additive has served to promote a number of significant modifications in the mineralogy, texture, porosity distribution and apparent permeability of the concrete.  These modifications include: 1) a dramatic increase in the degree of calcium silicate hydrate (C-S-H) formation, with a commensurate reduction in the relative concentration of (non-hydrated) calcium hydroxide, (Pozzolanic reaction) 2) an increase in the average crystal diameter of the calcium silicate cement constituents, 3) a reduction in the abundance and apparent interconnectivity of intercrystalline macro and micropores, and 4) a pronounced reduction in the magnitude and distribution of ‘shrinkage envelopes’ that locally flank the aggregate grain margins, and 5) the apparent elimination of shrinkage fractures within the grain-supporting cement materials."

My next post will get really exciting:  Darcy and Millidarcy, units of permeability.

Grant.          

Enhance ICD:
Chris,

All of the specimens that have been tested for permeability have contained no pozzolan materials in order to confirm that it is the pozzolanic nature of PMT that has afforded the pozzolanic reaction.

How is this measured?

Henry Darcy is the gentleman that developed what is known as Darcy's Law.  In his honour the unit of permeability was named a Darcy, and by extension, a Millidarcy.  I won't go into any further detail as all the information one could want is readily available on the internet.  www.wikipedia.com is a good starting point and then go from there.

The performance of PMT and EPC to improve impermeability is demonstrated in the following data as derived from independent permeability testing performed by the previously mentioned laboratories:

Control .40 w/c = 171 md (millidarcies)
PMT .40 w/c = 1.14 md
PMT .50 w/c = 0.577 md
PMT .60 w/c = 4.58 md

These are enormous reductions in permeability in comparison with the control specimen.  PMT affords this by making the microstructure of the pore system extremely torturous by transforming the normally well inter-connected pore system into that of being very poorly inter-connected.

The director of the microanalysis laboratory reported:

"The following conclusions can be derived from a review of these various data elements:

1.)   The test samples treated with the Enhance PMT & EPC products exhibit increased proportions of calcium silicate hydrate (tobermorite + amorphous material) relative to the control concrete.

2.)   Helium porosity was reduced in each of the samples treated with the Enhance PMT & EPC products relative to the control concrete.

3.)   Air permeability was dramatically reduced (by a factor > 2 orders of magnitude) in the Enhance PMT & EPC treated concrete samples, relative to the control concrete.

4.)   The thin section and SEM samples evaluated for these samples provide a qualitative validation of the routine core analysis data.  The micropores within the Enhance PMT & EPC treated concrete samples are relatively smaller & much less well inter-connected, as compared with the control concrete.

5.)   The test sample with a 0.5 water/cement ratio that was treated with Enhance PMT & EPC (‘B1’; MI#25348-07) exhibits the most favorable pore system attributes (i.e., low porosity & air permeability) within the test suite."

As previously mentioned, we have consistently seen even better performance from real world projects despite the exceptional results we've seen in the lab.  A recent project at the end of 2008 where impermeability was the #1 priority performance criteria for our client for environmental reasons produced these results.  No control samples were tested in this instance as the client is a regular user of our technologies so simply wanted a report for documentation purposes.

The microanalysis lab reported:

"The results of the helium porosity and air permeability analysis are summarized in Table I.  The helium porosity values obtained for these core samples range from 7.0-10.7 %, and reflect the presence (& relative abundance) of 1) intercrystalline micropores that are co-mingled with the cement paste constituents, and 2) air-entrapment macropores that are irregularly scattered within the concrete framework.  The air permeability analysis evaluates the transmission efficiency of (dry Nitrogen) gas that is forced to flow through the void system within the concrete core cylinders.  Air permeability values for the core samples range between 0.208-0.406 millidarcies (md).  The air permeability measurements assess the relative interconnectivity of all void types contained within the samples.  The porosity & permeability values reported in Table I indicate that the pore networks contained within the concrete samples are extremely poorly interconnected.   Gas permeability values for concrete samples generally exceed fluid permeability equivalents by as much as an order of magnitude, indicating that the concrete structure in question is essentially impervious to the transmission of water in an aqueous state.  These findings further indicate that the densely interlocked nature of the cement paste will contribute to protection of the re-enforcing steel embedded within the slab."

The mix design in this instance was again at a .50 w/c but produced permeability readings of 0.208 - 0.406 md which is less than the comparable .50 w/c mix design produced in a laboratory setting at 0.577.  

Regardless, these are both phenomenal reductions in permeability afforded by PMT.  We still implement other pozzolan materials in many of our mix designs for a multitude of reasons but in many cases they are not necessary when you have PMT at your disposal.

Sorry for the novels but this is fun for me.

Regards,

Grant.  

  

Chris Glasspool:
Grant,

Truly is phenomenal. The pocketbook often rules in masonry work. If I understand the dosing instructions for PMT...8 to 12 ounces per concrete sack, and a minimum packaging of 5 gallons (640 ounces), this gives one 80 sacks maximum per bucket pf PMT. This by my calculation gives a extended cost of the mix by a little over $3.00 a 94 pound sack. Having purchased Flyash from Texas because the Northwest was in short supply was more than this cost by many times. So, I suggest that PMT as a replacement for pozzolans may be the cheapest route to take for increased permeability. With only a 5 MM mortar covering on fc, I would recommend members consider trying PMT. - chris  

upston:
Hi All,

Thanks to Grant and Chris for all the questions and answers, it helps me to follow along. Grant, like Chris I would like to suggest a no Ash mix and perhaps some step sized aggregates ending at sand and starting ??? I recall you had mentioned this in and early post about lime I think.

Looks like the big answer is just add water , cool.

Brad

Chris Glasspool:
Grant,

I'm curious has to whether you have done testing with Type 3 portland cement. I did three PVA-ECC floors this winter; two with type 3, and third with Type 1. The one with type one seems to have a dustier/porous surface and had significantly more shrinkage (all floors were the identical shape and size), then the other two. Type 3 cement is a finer grind for winter pouring, and also increases set, and cure speed, but I wasn't aware that it actually also produced a better product in general; Have you done any testing that would suggest this? - chris

Navigation

[0] Message Index

[#] Next page

[*] Previous page