� Modernizing Concrete Education

Phoenix

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Amodern art sculpturelocated in front of a

learning institution, thePhoenix Public Library, isan appropriate symbol oflocal concrete producers’efforts to modernize theirown recommendations forconcrete specifications.Through a systematicapproach, they hope tomake it easier for speci-fiers to pursue the truthabout concrete andchoose it as the preferredbuilding material.

About 20 years ago,the Arizona Rock ProductsAssociation developedsimilar recommendations,but much has changedsince then. Admixture andplacement technologieshave improved the per-formance of both plastic

and hardened concrete,and producers havelearned about these tech-nologies by working withthem every day. If con-crete is to become thepreferred building materi-al, specifiers must acquirethe same knowledge.

It will take time, butlocal producers know thatif they are persistent, themany hours they’ve spentas educators will pay hugedividends for the industry.

� Phoenix-area producers are systematically increasing specifiers’concrete knowledge with a concise manual and ‘show and tell’

To the concrete producer in Phoenix,it’s almost as if a scorching desert sunhas baked and hardened local precon-

ceptions of concrete properties and mademany local specifiers seek refuge under theshady tree of familiarity. In the case ofhighway paving, for example, the shade isalmost completely black, as concrete hasan estimated statewide market share of lessthan 10%.

Phoenix-area members of the ArizonaRock Products Association (ARPA) Con-crete Promotion Committee know theyface a particularly tough task in upgradingmany specifiers’ concrete sophistication.They realize that the changes won’t occurovernight; it’s going to take a methodicaleffort, involving trips to specifiers’ ownbackyards, to draw specifiers out into thesunlight of knowledge.

The committee recently completed a2-year updating of “Arizona Recom-mended Specifications for NormalWeight Ready Mixed Concrete” in printand on CD-ROM. The specifications aredesigned as comprehensive resources forarchitects and engineers and are a sort oflocalized version of the “Optional Re-quirements Checklist” in ACI 301,“Specifications for Structural Concrete.”

The manual has a two-column format:one column is organized according to ACI301 and references the same standards,and the other column is titled “Notes toSpecifier.” The manual elaborates wherenecessary in the latter section, often sav-ing specifiers the trouble of referring tothe other standards. This section usesyears of committee members’ field experi-ence with concrete, and either providessupplementary information on, or refutesthe need for, some recommendations.

The manual is only part of the equa-tion. Just as important are presentationson concrete basics the committee startedmaking to architectural and engineeringfirms last spring. Sure, it would be quickerand easier to direct-mail the manual anddisk to every architect and engineer whospecifies concrete projects in Arizona, butthe committee members are convincedthat theirs is a more effective, albeit slow-er, approach.

New and improved promot ionThe scattershot approach was the

method of choice about 20 years ago. Backthen, a since-disbanded ARPA concretetechnical committee, led by ChesterMiller, technical service manager for

CliffsNotes for Concrete

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The Ar izona Rock Products Associat ion(ARPA) Concrete Promot ion Commit tee isupdat ing i ts recommended normal-weight concrete specs for speci f iers,wi th pos i t ive ear ly returns. Some keypersonnel invo lved in commit tee presen-tat ions inc lude ( top row, from le f t)Meghaen M. Duger, ARPA; Joe Nonno,Hanson Aggregates of Ar izona; ThorntonKel ley, Vu lcan Mater ia ls Co. , WesternDiv is ion ; (bot tom row, from le f t) Dav idPalmer, Un i ted Metro Mater ia ls ; TerryRainey, Rock So l id ; and J im Wi l lson,P.E . , Ar izona Cement Associat ion .

“By rewriting the specs, those ofus with a lot of experience withconcrete can accomplish twogoals: one, a quality product, andtwo, a savings to the con-crete contractor and theowner.” —Terry Rainey,Rock Solid

Arizona Portland Cement Co., completedand distributed the first recommendedspecs. The promotion committee, formedin the mid-1990s, is revisiting the specs.Wisely, the committee got its presenta-tions certified as continuing educationcredits, as mandated by the AmericanInstitute of Architects.

“The last time we did this—and itwas just handing out the brochures andanswering questions—it made a dramaticimpact on the local scene,” says ThorntonKelley, quality control manager at VulcanMaterials, Western Division in Phoenix,who has worked in the industry for morethan 30 years. “We updated it for currentrecommendations through ACI, and wedidn’t have the computerization we havenow. All we did was make up the note-book and hand it out to the specificationwriters, the architects, and the engineers,and request that they work with us in fol-lowing ASTM C 33 [‘Standard Specificationfor Concrete Aggregates’] in their specs.”

Of course, much has changed sincethen, particularly in concrete admixtureand placement technology. In many cases,producer committee members say, concretespecifications are burdensome or contra-dictory. “A lot of spec writers are giving us

minimum cement contents, water-cementratios, and strength, and a lot of times, theydon’t go hand in hand,” says Kelley.“They’ll say 500 pounds of cement orcementitious material, a water-cementratio of 0.40, and a strength of 3000 psi.Well, the 0.40 will give you 5500 psi, andif you use the 0.40, you’re gonna use 750pounds of cement.”

Worse, specifiers often combineoptions A, B, and C for mix-proportioningresponsibility contained in ASTM C 94,“Specification for Ready-Mixed Concrete.”“Most of the commercial projects today areusing a combination of A, B, and C, whichis making it very difficult to provide con-crete the way they want us to,” says Kelley.The goal, he says, is to get more specifiersto choose option C, which makes the pro-ducer responsible for mix proportioning.“That’s what we’re shooting for with oureducation program, not just with our archi-tectural groups, and we’re trying to get outin front of the engineering community aswell,” he says.

One hurdle the manual and CD-ROM can overcome is the time-consum-ing process of referencing several differenttexts. It’s human nature to play it safe,specify whatever has worked before, and

save time. However, notes Terry Rainey,who works in sales at Chandler-based RockSolid, this inflexible mind-set often resultsin more expensive bids, since it doesn’tallow for the cost savings that new tech-nologies and producers’ expertise often canprovide.

“They’re looking at specifications thatwere written years and years ago,” he says.“They’re under the impression that a lowwater-cement ratio is good, a high water-cement ratio is bad, a high cement contentis good, and a low cement content is not sogood. By rewriting the specs, those of uswith a lot of experience with concrete canaccomplish two goals: one, a quality prod-uct, and two, a savings to the concretecontractor and the owner.”

Speci f ic po in tsThe manual elaborates on several

specific references in the manual’s “Notesto Specifier” section. The notes reinforcethe members’ in-depth presentations onthese topics.

Fly ash. The manual referencesASTM C 618, “Standard Specification forCoal Fly Ash and Raw or CalcinedNatural Pozzolan for Use as a MineralAdmixture in Concrete,” and aims to dis-pel myths regarding fly ash use:

“Fly ash is commonly and successfullyused in Arizona. ADOT, the UniformBuilding Code, and M.A.G. [MaricopaAssociation of Government, an association ofMaricopa County and municipal bodies with-in it] allow fly ash replacement in all mixes.Class F fly ash is primarily used in Arizona.”

“In Phoenix, there’s pretty much acanned spec that many architectural andengineering firms use when they say no flyash in flatwork or architecturally exposedconcrete,” says David Palmer, sales repre-sentative at Phoenix-based United MetroMaterials and chairman of the committee.“They’re going by the old rule of thumb:‘If it ain’t broke, don’t fix it,’ and they’reignoring the benefits of fly ash.”

“One thing that sticks in my craw andprobably will until it’s changed forever is‘No fly ash, no fly ash,’” Rainey adds.“Properly used, you get a more dense con-crete, a higher-quality concrete, and a less-

expensive concrete with fly ash. Theseguys didn’t know what fly ash was; they justhad this impression that fly ash was bad.”

“If you can minimize the amount ofcement by using fly ash, you’ll minimizethe water because you’ve reduced theamount of cement,” adds Kelley. “There arealso advantageous reasons to use fly ashonce the concrete has touched the groundout here, because the ground is so alkaline.The fly ash of today is substantially differ-ent from the fly ash used 10 years ago—it’smostly processed material now—and wehave a lot better understanding of how thefly ash reacts with the cement.

“Sometimes we’ll have a big mat foot-ing that’s 6 feet thick; you can generate alot of heat in 5000 yards of concrete. If wecan use fly ash and get the spec changedfrom 28 to 56 days, we can do a lot ofthings that are positive for the concrete.”

Air entrainment. The manual refer-ences ASTM C 260, “Standard Specificationfor Air-Entraining Admixtures for Concrete,”under “Admixtures,” and adds a note ofcaution:

“Air entrainment normally is not requiredfor durability in work located in valley areasat elevations below about 3000 feet, exceptwhere it is desired to improve the imperme-ability, sulfate resistance, or workability; or in

work which will not be exposed to freeze/thawexposures at high elevations. Air entrainmentshould be required in all exposed work at ele-vations above 3000 feet.”

“A lot of companies that are from, say,Chicago have a Chicago architect, andthey want to build a distribution center orsome stores in Phoenix; they don’t thinkabout Phoenix,” notes Kelley. “The onlytime I see it is with specs for, say, a Wal-Mart where they use the same set of specsnationwide,” adds Rainey. He often sub-mits a mix design that has performed wellin the past, knowing it will be rejected.“Then I’ll resubmit with some backup datashowing our 3000-psi mix, 0.58 water-cement ratio, fly ash, and strengths of 3500or 4000. More often than not, when theysee the backup data, it’s accepted.”

Quality-assurance testing. In thissection, the “Notes to Specifier” distin-guish testing of cylinders for replication ofthe as-delivered properties vs. the in-serv-ice properties of concrete:

“Field-cured specimens should not beused to determine compliance of the concreteas delivered with the specifications. Testing offield-cured specimens is helpful in determiningthe effect of job climactic conditions and cur-ing procedures on the quality of the in-place

hardened concrete, and in determining whenthe in-place concrete has developed sufficientstrength to permit form removal or when thestructure may be placed in service.”

Later, the notes refer to standardASTM C 31, “Standard Practice for Makingand Curing Concrete Test Specimens inthe Field.” “...ASTM C 31 is universallyrecognized as the standard method of curing tobe employed for specimens used in tests,which will serve as a basis of acceptance ofconcrete as delivered.”

Vulcan Materials, for example, oftendoes comparative testing, based on theinitial curing provision found in C 31 thatincludes use of insulated boxes, to distin-guish between as-delivered and in-serviceconcrete. Specifiers need to recognize thisdistinction. “The difference is daylightand dark; it’s a very critical difference,”says Kelley. “To put the structure in serv-ice, there is some minimum strength thatyou have to have to post-tension; 3000psi—that’s the norm. We do the samething for fast-track highway projectswhere they want to open a lane in 3 hoursor 5 hours. But say there’s a second specthat says the strength of that slab has gotto be 5000 at 28 days. If we use the 28-daybreaks of cylinders stored in a Zonolitebox, we might not hit 5000,” becauserapid strength gain occurs early, then slowsto a crawl after the first few days.

When curing the cylinders withoutan insulated box, however, “We’ll get6000 because you gain strength moreslowly, and it continues to gain, whereasthe other cylinders have a rapid acceler-ation. What we’re trying to do with theZonolite cylinders is duplicate the cur-ing of the concrete in place. A lot of ithas to do with heat generation; the gen-eration in mass concrete is a lot greaterthan in a 4x8-inch cylinder.”

Hot-weather concreting. Besidesserving as “CliffsNotes for Concrete,” themanual shares producer committee mem-bers’ knowledge of local conditions as theyapply to concrete properties.

Kelley is looking forward to an anti-cipated change in the ACI recommenda-tion that will increase the as-delivered

“Many architecturaland engineering firmssay no fly ash in flat-work or architecturallyexposed concrete.” — David Palmer,United MetroMaterials

concrete temperature limit to 95° F.“Around here, it sometimes takes morethan 60 minutes just to get to the site, sowe’re out of tolerance even before we getthere, even though it’s still plastic, viableconcrete,” says Kelley. “We are reallyfighting hard to maintain under-90° Ftemperatures here in Phoenix for anyextended period of haul. Some of theserecommendations are being modified orwe’re getting exemptions from them.”

Taking the ir act on the roadPreparing a presentation for a partic-

ular firm requires a little tweaking—andadditional hours to those the committeemembers already have invested in updat-ing the manual. Also, besides the“Fundamentals of Concrete” presentation,the committee is developing a seminar ondecorative concrete and three others onsubjects yet to be determined.

The presentations remain a work inprogress, as the committee members useaudience feedback on evaluation forms tomake changes. The committee beganmaking presentations in front of smallerfirms, which have schedules that are easi-er to coordinate, but it did appear beforenearly 100 members of the CentralChapter of the Structural Engineers ofArizona last April.

One of the first attendees, TerrySewell of OBA, an architectural firm inScottsdale, says the presentation wasworthwhile. “I had some preconceptionsabout fly ash; I thought it was just like put-ting sawdust in,” he says. “I appreciate andunderstand a lot better now that it’s anintegral part of things. It’s helpful to thecomposition instead of just there. I’ll prob-ably just use their spec from now on.”

Systematic successes like this will nodoubt keep the committee going as mem-bers tackle such a daunting task, one firmat a time, one topic at a time.

“Two years from now, we shouldstart seeing some major results fromthis,” says Kelley. “The more people weget out in front of, the more word ofmouth we’re gonna have, and it’s justgonna accelerate.”

“This is a large city, and it’s gonnatake a while, but I’m really excited andenthused about it,” adds Rainey, who wasinterviewed on his cell phone. “For exam-ple, I’m on the way to about a 500-yardparking lot. I’ve worked with the concretecontractor and the owner, and all we haveto do is hit 3000 psi. Now if I had to meet4000 psi and a ridiculously low water-cement ratio, this job would be the blackstuff and not concrete.”

For a copy of ARPA’s recommended concretespecs, circle 1 on the reader service card.

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