Concrete Mix Designs

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Author Message Scott Mize Senior Member Username: scott_mize_ccs_csi Post Number: 72 Registered: 02-2009 Posted on Wednesday, August 21, 2013 - 09:31 am:    Colleagues, In your practice of specification writing, which of the following do you use in specifying cast-in-place concrete: (1) A mix design submittal requirement in Part 1. (2) A "MIXES" or "MIX DESIGN" article in Part 2. (3) Requirement for submittal of mix design to testing agency under "FIELD QUALITY CONTROL" in Part 3. (4) Schedule or form describing the mix design appended to the end of the section. (5) Some combination of the four options above. Every real-world project on which I worked -more complicated than a Quikrete footing for a fence post or swing set, that is - required (1). I rarely saw (3) and (4). I never saw (2). That said, I write master guide specifications now. I have to keep in mind that, within the voluntary standards set by various industries and good specification-writing practices, different people can take different approaches to the same work result. Thanks in advance for your feedback. Richard L Matteo, AIA, CSI, CCS Senior Member Username: rlmat Post Number: 602 Registered: 10-2003 Posted on Wednesday, August 21, 2013 - 11:51 am:    Generally 1 & 2, rarely, if at all, 3 & 4. The inclusion in Part 2 is usually for larger projects as determined by the Structural Engineer. Steven Bruneel, AIA, CSI-CDT, LEED-AP, EDAC Senior Member Username: redseca2 Post Number: 405 Registered: 12-2006 Posted on Wednesday, August 21, 2013 - 12:10 pm:    Scott, My specification writer career has been with one large firm working on large projects of similar types. I prepare the architectural specifications and coordinate consultants preparing various specification Divisions, including our own structural engineers or consulting structural engineers (The rest of the time I am usually saying "you can't do that" in an agitated fashion, for which I have a task number for my time cards called "Quality Assurance"). I am very used to seeing all four, or perhaps more commonly I see the mix schedule included as part of the mix design article in Part 2. A project on my desktop and underway right now includes 9 concrete mixes: Drilled Piers; Foundations; SOG, curbs, pads; Walls; LWC fill over deck; Stair fills; Underpinning; High strength fill over deck; and topping slab. Lynn Javoroski FCSI CCS LEEDŽ AP SCIP Affiliate Senior Member Username: lynn_javoroski Post Number: 1681 Registered: 07-2002 Posted on Wednesday, August 21, 2013 - 12:19 pm:    Our Structural Engineers usually require #1, #2, and #3, while #4 is included in Part 2, if what you mean is a description of the mix for each type of building element, including compressive strength, air content, reinforcement, etc. Some time ago, before I started here, one of the S.E.s edited a master section to become what he considered should be our company standard. And that's where we typically begin. Ronald J. Ray, RA, CCS, CCCA Senior Member Username: rjray Post Number: 121 Registered: 04-2004 Posted on Wednesday, August 21, 2013 - 02:03 pm:    My specifications include: 1 2 In my opinion, products, or mix designs, belong in PART 2 of the specifcation, not under Execution (your item 4) like MasterSpec so often does. Mark Gilligan SE, Senior Member Username: mark_gilligan Post Number: 597 Registered: 10-2007 Posted on Wednesday, August 21, 2013 - 02:10 pm:    The project structural engineer will have a lot of say especially if your SE consultant uses his own master. In Part 1 I indicate the need to submit mix designs for review and list the type of information I want in the submittal. This is where I would place a requirement that the reviewed mix design submittal be provided to the Special Inspector. In Part 2 there should be an article containing technical criteria related to mix designs. Most engineers will have a schedule on the drawings that defines various concrete properties that are unique to the different mixes. Since this information should not be duplicated in the specifications there needs to be agreement on what is in the specifications and what is on the drawings. In my experience these mix design schedules are not in the specifications. IMHO it is an abomination for the structural consultant to use the Architect's master specifications for most structural specifications including CIP Concrete. It reflects poorly on the engineer and the architect. J. Peter Jordan Senior Member Username: jpjordan Post Number: 603 Registered: 05-2004 Posted on Wednesday, August 21, 2013 - 03:02 pm:    I think you should take a look at CSI's SectionFormat. Karen L. Zaterman, CCS, LEED-AP, SCIP Senior Member Username: kittiz Post Number: 105 Registered: 10-2005 Posted on Wednesday, August 21, 2013 - 03:04 pm:    I agree with Mark. Although we never had more than 3 mix designs so we only used the specs, not the drawings. However I think a schedule on drawings is a good idea, easier for SE and specifier. I would not use PT 3 either. Mark, Scott is talking about guide specs so presumably it would go to the SE for editing. Karen L. Zaterman, CSI, CCS, SCIP-Affil, LEED AP BD+C spiper (Unregistered Guest) Unregistered guest Posted on Wednesday, August 21, 2013 - 02:19 pm:    We typically include (1) and (2). We include a testing agency requirement in Part 3 but we do not typically send the mix design to them unless there is an issue meeting the specified strength, slump, etc. As for (4):we have considered adding a form because some submittals fail to include some of the information we have in Part 2. We have had some plants complain when we are asking for verification on the compressive strength of their mix design because it does not show up on their submittal. One actually responded with a rather agitated: "with the water-cement ratio we submitted of course it meets 4,000 lbs." Valid point on their part but still why not state as much on your submittal. Newbie (Unregistered Guest) Unregistered guest Posted on Wednesday, August 21, 2013 - 10:49 am:    (1) and (2) Mark Gilligan SE, Senior Member Username: mark_gilligan Post Number: 600 Registered: 10-2007 Posted on Wednesday, August 21, 2013 - 05:26 pm:    In order to comply with the special inspection requirements in the code, yes they do exist, the special inspector needs to verify that the mix provided is that which is in the reviewed mix design. The building code makes it clear (ACI 318) that the strength of the mix design mix design be verified by technical data. Scott Mize Senior Member Username: scott_mize_ccs_csi Post Number: 73 Registered: 02-2009 Posted on Friday, August 23, 2013 - 04:40 pm:    Thanks for your input, everyone.