Pinholing in terrazzo matrix

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Author Message Tracy Van Niel, FCSI, CCS Senior Member Username: tracy_van_niel Post Number: 339 Registered: 04-2002 Posted on Thursday, August 06, 2015 - 10:45 am:    Has anyone run into pinholing in a terrazzo matrix? We are currently finishing up a new building project where terrazzo was used on a previous project (University work separate building). The mix used above the first floor developed pinholes in the matrix. A change was made to the chip mix on the first floor and there was no pinholing in that location. The terrazzo product company has stated that the chip/aggregate mix wasn't approved by them and that it caused the pinholing. Experts brought in by the owner say that it is a workmanship issue that caused the pinholing. I've been trying to google pinholing in terrazzo to see if it truly is a chip mix/aggregate issue, but can't find anything ... unless I'm searching for it wrong. Has anyone ever had pinholing in the terrazzo matrix occur on any of their projects? Tracy L. Van Niel, FCSI, CCS Ronald L. Geren, FCSI, AIA, CCS, CCCA, SCIP Senior Member Username: specman Post Number: 1333 Registered: 03-2003 Posted on Thursday, August 06, 2015 - 11:34 am:    It sounds like they may have skipped the grouting step between rough grinding and fine grinding. I know you said "pinholes," but what is the average actual size of the holes? Ron Geren, FCSI, AIA, CCS, CCCA, SCIP www.specsandcodes.com J. Peter Jordan Senior Member Username: jpjordan Post Number: 858 Registered: 05-2004 Posted on Thursday, August 06, 2015 - 11:41 am:    You did not say what type of terrazzo this way, epoxy or cementitous (I am guessing epoxy). When you say "Experts", were these people from the NTMA? If not, I would suggest that you contact Richard Bruns at the NTMA. It does seem like Ron may be on to something. Tracy Van Niel, FCSI, CCS Senior Member Username: tracy_van_niel Post Number: 340 Registered: 04-2002 Posted on Thursday, August 06, 2015 - 02:08 pm:    Ron, I'd need to ask the project architect, I'm getting information second hand. Peter, don't know if the experts were from NTMA, again, I'm getting second hand information and was only told that the owner had brought in 'experts'. Thanks for responding. Sounds like no one else has had the problem though ... Tracy L. Van Niel, FCSI, CCS Ronald L. Geren, FCSI, AIA, CCS, CCCA, SCIP Senior Member Username: specman Post Number: 1334 Registered: 03-2003 Posted on Thursday, August 06, 2015 - 02:58 pm:    Tracy, Peter's question regarding the type of matrix may be important. If the terrazzo is epoxy, air bubbles may have been introduced when the two components were mixed. After grinding, these bubbles may be exposed as small pinholes. If grouting did occur, the holes may have been too small to fill with the grout matrix. Just some observations from a non-expert. Ron Geren, FCSI, AIA, CCS, CCCA, SCIP www.specsandcodes.com James Sandoz, AIA, CSI, CCS, CCCA Senior Member Username: jsandoz Post Number: 173 Registered: 06-2005 Posted on Friday, August 07, 2015 - 08:48 am:    This may belong in the "coffee pot and water cooler" area but a key word caught my attention. Last night, over dinner, my wife and I were musing over the use of the work expert. I was once introduced as an "expert" and I told my wife I thought at the time the label may have been a bit overstated. Perhaps it was acknowledgement that I new slightly more about the subject than others in the group. :-) That said, I highly respect the knowledge Ron, Peter, and many others on this forum bring because I have seen how they approach their work and their advice, as in this instance, has always been on point and useful. Many times the input from this panel of (true) experts leads us to new ideas and innovative ways of solving a problem. We are, after all is said and done, problem solvers. Many times the comments and advice from this forum remind us of lessons we already have learned but just got buried in the everyday bustle of our work. Here is a big thank you to all my colleagues who have been so un-selfish with their expertise. You've made my work better and my job easier and more personally rewarding. Jerome J. Lazar, RA, CCS, CSI, SCIP Senior Member Username: lazarcitec Post Number: 1440 Registered: 05-2003 Posted on Friday, August 07, 2015 - 10:01 am:    Here, Here Exactly why this forum is a must read on a daily basis, kudos to Colin too. Lynn Javoroski FCSI CCS LEEDŽ AP SCIP Affiliate Senior Member Username: lynn_javoroski Post Number: 2038 Registered: 07-2002 Posted on Friday, August 07, 2015 - 10:33 am:    Jerome, you have stated what we all think (I think). Thank you. Greta Eckhardt Senior Member Username: gretaeckhardt Post Number: 19 Registered: 08-2013 Posted on Friday, August 07, 2015 - 12:38 pm:    Assuming that we are talking about resinous-matrix terrazzo, "pinholes" might be gas bubbles caused by one or more issues: inadequate mixing of the epoxy components in the matrix; chemical reaction between epoxy matrix and some atypical particle type in the aggregate mix; irregular surfaces on aggregate particles that trap air bubbles. While I agree that expertise has been shown by the questions and observations of other specifiers above, in this case the appropriate "expert" may be a chemist. J. Peter Jordan Senior Member Username: jpjordan Post Number: 859 Registered: 05-2004 Posted on Friday, August 07, 2015 - 06:27 pm:    NTMA has a guy on staff who has very good qualifications in the resinous terrazzo area. He will probably be the one to field the question if it is epoxy terrazzo. Michael Chusid, RA FCSI CCS Senior Member Username: michael_chusid Post Number: 66 Registered: 10-2003 Posted on Saturday, August 08, 2015 - 03:09 pm:    While the discussion about causes is important, I am curious how the particular floor was repaired. My naive assumption is that more resin can be spread and the surface reground. Michael Chusid, RA FCSI CCS www.chusid.com www.buildingproduct.guru Russ Hinkle, AIA, CDT, LEED BD+C Senior Member Username: rhinkle Post Number: 138 Registered: 02-2006 Posted on Tuesday, April 12, 2016 - 11:08 am:    We have an owner that has an existing installation done about 10 years ago and it is full of pinholes(they call them pot holes). This experience has led them to be very cautious about the quality of the next installation. Looking on the NTMA website I found guide specifications, but no standard for finish quality. I do plan to contact the NTMA. Can anyone comment on if there is any kind of finish standard out there? Russ Hinkle David E Lorenzini Senior Member Username: deloren Post Number: 175 Registered: 04-2000 Posted on Tuesday, April 12, 2016 - 11:45 am:    Russ, If this installation was cement-based, it was filled with pinholes throughout its thickness. The original finished surface was a pure cement coating that was troweled on and allowed to cure. Then it was ground and polished with the pinholes filled to match the original cement. The appearance of pinholes will return after years of heavy foot (shoe leather) traffic. If they appear more frequent in the more heavily trafficked areas, then they just have to repeat the final polishing method. The main problem may be to match the original cement color. If the pinholes appear where there is no traffic, then they may not have been filled in the original installation and dirt may expose their existence. David Lorenzini, FCSI, CCS Architectural Resources Co.