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Portland Cement Association

Contents

Volume 19/Number 2

July 1998

5420 Old Orchard Road

Skokie, Illinois 60077-1083

Phone: (847) 966-6200

Fax: (847) 966-8389

Web Site:

www.portcement.org

Concrete Drying Time

Hot Weather ConcreteWorkability

Cement and ConcreteInternet Sites

New Literature

Building with InsulatingConcrete Forms

PL982

Building with Insulating Concrete Forms

by Donn ThompsonProgram Manager, Residential Technology,Portland Cement Association

Insulating concrete forms (ICFs) are still new to many homebuilders

and contractors. The simple suggestions given here highlight thepractical aspects of construction using ICFs.

ICF Systems

Two characteristics are used to clas-sify the various ICF systems that areavailable: the size and configurationof the forms, and the shape of theconcrete core created within theforms.

Types of Forms

Individual form units can be de-scribed as panels, planks, or blocks.Figure 2 illustrates these three typesof forms. Depending on the manu-

Residential contractors are lookingfor new ways to build. The contin-ued decline in the quality of framinglumber and unpredictable price fluc-tuations have placed innovative con-crete building materials in the fore-front as workable alternatives toconventional homebuilding tech-niques. Insulating Concrete Formbuilding systems, or ICFs, combine

ease of form assembly, and thestrength and mass of concrete, withthe energy saving and low infiltra-tion features of stay-in-place insulat-ing forms.

Fig. 1. Insulating concrete forms can take on many configurations;those shown here have the traditional gable that is popular in homes.(65711)

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facturer, all three types can bepreassembled in the factory and ar-rive ready for erection.

The connection between units de-pends on the configuration of theform edges. Panel and plank systemsusually have flat edges, requiring

separate connectors or fasteners tohold individual sheets together. Sinceblock systems are usually moldedproducts, it is possible to create moreelaborate edge profiles. Most blockshave edges that feature interlockingteeth or tongue and groove configu-rations, eliminating the need forseparate fasteners.

Form faces are held together byplastic or metal ties that are extendedout to the exterior faces of the form toprovide fastening surfaces for secur-ing finishes. Block systems may con-

tain integrally molded ties or may bedesigned with foam webs that con-nect the interior and exterior faces.Fastening of finishes for these sys-tems can involve additional furringor fastening strips installed in thejoints between each course of form.

Types of Concrete Walls

The type of concrete wall created bythe forms can be flat, grid, or post-and-beam systems. Figure 3 illus-trates these types of concrete walls.

Forms that are flat inside create acontinuous wall of constant thick-ness. The thickness of the concreteportion of the wall can vary from aslittle as 90 mm (3-5/8 in.) to a maxi-mum with some systems of 280 mm(11 in.) or more with custom forming.Steel reinforcement is placed hori-zontally and vertically within thecontinuous wall of concrete.

Grid systems create a wall profilethat consists of vertical posts andhorizontal beams running in a uni-

form pattern. These posts and beamsare connected with narrower webs ofconcrete. If the forms were strippedaway, the appearance of the wallwould resemble a breakfast waffle.Steel reinforcement is located in thepost-and-beam portion of the wall.

In addition to the flat walls andweb walls, there are perforated walls.These walls are post-and-beam wallsystems, distinct horizontal and ver-tical members that intersect at regu-lar intervals. Forms for these wallsare solid foam with vertical and hori-zontal cores for the concrete. Thespacing of the post-and-beam mem-bers can vary from fairly tight con-figurations similar to screen grid sys-tems without the solid concretewebs, to true post-and-beam systemswith wider spacing. Reinforcement is

placed within the separate horizontaland vertical members.

Wall Forming

Typically, three to four laborerscan construct an ICF home. At leastone member of the crew should beexperienced with carpentry and con-crete work.

Any conventional concrete or ma-sonry foundation system can accom-modate ICFs. The forms are placeddirectly on the footer, stem wall,

foundation wall, or slab.Short sections of rebar or dowelshould be embedded in the top of thefoundation, aligned with the ICFcavities above that will be filled withconcrete. Chalk lines are snapped,and base plates are set to align thefirst course of forms. Base plates canbe either strips of wood, like 2 x 4s,or metal guides that are attached tothe top of the footing.

Corner forms are set first. Straightforms are then set adjacent to the cor-

ners until the entire first course hasbeen placed. Gaps between formsare filled with adhesive foam.

Placement of the first course iscritical. It must be accurately lev-eled, which is done by shimming orshaving the bottom of the formwork

as required. Units placed above thefirst course must be set carefully tomaintain proper alignment of thevertical cavities for the entire heightof the wall. This also ensures properalignment of ties and integral fasten-ing surfaces.

Curved walls are easy to form.Vertical strips of material are re-moved from one surface of the formso that it can be bent to create the in-side of the curve. The other formface (outside) is scored. The formcan then be bent to create the curved

wall section.Like conventional concrete foun-dation walls, below-grade ICF wallsmust be protected from moisture inthe ground. Unlike conventionalconcrete, foam forms are not com-patible with solvent-baseddampproofing or waterproofing ma-terials. The manufacturer of the formshould be consulted to identify ap-propriate materials to protect thefoam forms from ground moisture.

Wall Openings

At door and window openings,framework called a buck covers theends of the forms around the entireperimeter of the opening. The buckprevents concrete from flowing outof the open ends of the forms at wallopenings, and provides an attach-ment surface for the installation ofwindows or doors. During the place-ment of concrete, the bucks must bebraced. Usually, bucks are built withpressure treated lumber, but several

Fig. 2. ICF panel, plank, and block systems. Fig. 3. Cut-away views of flat, grid (uninterrupted),and post-and-beam systems that show both theformwork and the shape of the concrete wall.

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manufacturers make premolded plas-tic bucks that can be cut and slippedover the ends of the forms.

Framing

If the top of the wall will support aroof, the roofline is marked and theforms are cut. When the concrete isplaced, anchor bolts or hurricanestraps can be embedded for roofframing attachment.

If the wall will support intermedi-ate floor framing, there are two waysto attach the floor framing to thewallthe ledger method and thepocket method. With the ledgermethod, a framing member to receivethe floor joist ends is bolted to theconcrete wall with anchor bolts em-bedded in the concrete. If wood fram-ing is used, the ledger coming in con-

tact with the concrete must be pres-sure treated or protected from theconcrete by sheet plastic.

The pocket method involves slottingthe forms at the floor joist locationsand inserting wood blocks to createbearing pockets in the concrete foreach joist. The blocks are removed andjoists inserted in the pockets to bear onthe concrete walls. Wood joists willneed to be pressure treated or havewater-resistant coatings applied to theends bearing on the concrete.

Wall BracingBracing is required to maintainplumb, straight walls. Each manufac-turer has recommendations for loca-tions and spacing. In addition to cor-ners, bracing is placed at intermedi-ate locations along the walls and atany areas of potential weakness. Lo-cations with numerous smaller form-ing pieces are particularly vulnerable.The top of the wall should be bracedto prevent the forms from spreading.Bracing materials can consist of con-

ventional wood framing or speciallydesigned braces provided by theform manufacturer. Some systems in-corporate stand-off platforms sup-ported by the bracing to be used bythe crew at the top of the wall duringconcrete placement.

Concrete Placement

Concrete used for ICFs will vary de-pending on the configuration of thecore created by the formwork, and

ease of access around the construc-tion site. The concrete mix design rec-ommendations of the project engi-neer, architect, or the form manufac-turer should be followed. Flat wallsystems, having open forms and veryfew obstructions, can be filled with astandard residential mix made with19 mm (3/4 in.) coarse aggregate.These are the most economical mixes,but placement requires delivery ofthe concrete close to the wall so it can

be placed by bucket or chute. Moreoften, a pump mix with fairly highslump and smaller aggregate (peagravel) will be used. The concrete canthen be placed by boom or line pumpfrom greater distances and will havesufficient flow to penetrate smallercavities (see Fig. 4).

Adding water beyond what themix design allows to increase theflowability of the mix should not bedone since it will reduce the strengthof the concrete. The concrete suppliershould be provided with the specific

compressive strength, aggregate size,and slump required for the project toeliminate the need for adding waterto the mix. Plasticizers can help in-crease the slump of the concretewithout adversely affecting strength.

Concrete must be consolidatedduring placement. Tapping on theside of the forms, rodding the con-crete, or vibration of concrete arethree effective methods. Each formmanufacturer has recommendationsfor consolidation. Excessive vibration

or rodding can weaken the form, re-sulting in form rupture as concretepushes through weak spots. This iscalled blowout, and if it occurs, theplacement of concrete in this areamust be stopped immediately. Thensteps must be taken to repair andshore the weakened section of form.

Utility Installation

The installation of electrical wiringand plumbing involves the notchingor routing of the form surface to cre-ate chases for the placement of utili-ties. Careful planning is required tolocate sleeves where needed for anythrough-wall penetrations.

Finishes

Interior finishes are attached to fas-

tening surfaces provided by ties, orwith furring attached to the foamforms. Kitchen cabinets are installedwith blocking or plywood embed-ded flush with the interior face ofthe form. Exterior siding is securedlike interior finishes. Brick or stoneveneers require masonry ties at-tached to the wall, and cementstucco requires the attachment ofmetal lath.

Summary

Concrete wall systems for residentialapplications offer advantages toboth builders and homeowners.Building concrete homes with ICFsrequires some of the same skills ofhomebuilding with lumber, as wellas some new skills. A few of the newor different skills associated withICF construction are highlighted inthis article.

References

1. VanderWerf, Pieter A. and others,In-

sulating Concrete Forms for ResidentialDesign and Construction, McGraw-Hill, New York, 1997, 326 pages.[Available from Portland Cement As-sociation as SP208.]

2. VanderWerf, Pieter A. and Munsell,W. Keith, Insulating Concrete FormsConstruction Manual, SP202, PortlandCement Association, Skokie, Illinois,1996, 150 pages.

Fig. 4. The concrete should beworkable so that it flows easilyinto form cavities and aroundreinforcement. (67278)

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Concrete Drying Time

by Gran Hedenblad, Ph. D.,Lund Institute of Technology, Sweden

Predict concrete drying times before placing floor coverings.

ratio of the concrete and thetarget RH of the concrete.The target RH of the concretefloor is usually based on thetype of floor covering andtype of adhesives to be in-stalled; more impermeablecoverings require lower RHconditions. Consult the floorcovering manufacturer as to the ap-propriate relative humidity for spe-cific products. From the water-ce-

ment ratio and the target RH, thenumber of drying days can be esti-mated. As Table 1 shows, it will takeapproximately twice as long to reach85% RH as it will to reach 90% RH.These values will be modified by thecorrection factors shown in Tables 2through 5.

Member Thickness

As members become thicker, thedrying time increases, as shown bythe correction factors in Table 2.

Type of DryingDrying can occur from one or bothsides of a concrete member: fasterdrying occurs when it takes placefrom two sides (see Table 3). Typicalconcrete members are slabs andwalls. Except for basements, wallsusually dry from both sides. Floorscan dry from one side (top) or fromboth sides (top and bottom). Sus-pended structural slabs, as used inmultistory buildings, have two-sided drying. Concrete slabs placed

directly on the ground, on a vaporretarder, or on a metal deck haveone-sided drying.

Drying Conditions

The drying conditions are a combi-nation of air relative humidity andair temperature. Warm, dry air driesconcrete faster than cool, humid air.In general, the effect of air tempera-ture is more pronounced than thelevel of moisture in the air, because

cooler air does not dry concrete aswell as warm air at a given relativehumidity.

Type of Curing

Concretes that are to receive floorcoverings will dry faster if they areexposed only to moist air (up to fourweeks) or if they receive very littlecuring. Wet curing, simulating twoto four weeks of rain, adds time tothe drying period for the three wa-ter-cement ratio levels tested asshown in Table 5.

Estimating Drying Time

To obtain an estimate of drying time,the base drying time (from Table 1)is multiplied by the correction fac-tors (Tables 2 through 5), yieldingthe number of days after curing re-quired to reach the desired relativehumidity of the concrete.

An example follows.

Concrete:water-cement ratio = 0.6100-mm (4-in.) thickplaced on vapor retarder (imper-vious base)need 85% RH before covering

Curing conditions:4 weeks moist air

Climate:air at 70% RH at 25C (77F)From Table 1, with 85% RH and

water-cement ratio of 0.6, the basedrying time is 135 days.

From Table 2, the correction forthe thickness is 0.4.

Excess floor moisture at the time ofinstallation is one of the main causesof failure for floor coverings, result-ing in blisters and discoloration (Fig.1). Repairing the problem can becostly and may require temporarilyvacating the building during repair.Allowing concrete sufficient time todry reduces the possibility of failedfloor coverings.

How Does Concrete Dry?

The drying of concrete is primarily afunction of the amount of mix waterand imperviousness of the concrete.This involves four interrelated fac-tors: water needed for hydration(chemically combined water), waterneeded for placing, the permeabilityof the concrete, and the shape of thedesorption isotherm. Drying of con-crete, or the removal of uncombinedwater, starts at the concrete surfaceand proceeds inward. Measurablefactors that affect drying are the wa-

ter-cement ratio (w/c) of the con-crete, the thickness of the concretemember, whether the concrete driesfrom one or two sides, the relativehumidity (RH) and temperature ofthe air, the desired concrete RH (themoisture condition of the concrete atthe time a covering is applied), andhow the concrete was cured. To esti-mate drying time of concrete by themethod described below, you musthave all of this information.

Drying Time

Based on laboratory research, re-searchers at Swedens Lund Univer-sity, Division of Building Materials,predict the drying time (starting afterconcrete curing) of ordinary portlandcement concrete (Reference 2). Thepredicted drying time is based on areference concrete to which correc-tion factors are applied, as discussedbelow.

Two pieces of information thatmust be known are the water-cement

Fig. 1. Floor covering delaminationcaused by excess floor moisture. Photocredit: B. Pashina. (68130)

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Table 4. Correction Factors for Climate(Relative Humidity and Temperature)

Relative humidity Air temperature, C (F)of the air, %

10 (50) 18 (64) 25 (77) 30 (86)

35 1.2 0.8 0.7 0.650 1.2 0.9 0.7 0.660 1.3 1.0 0.8 0.770 1.4 1.1 0.8 0.780 1.7 1.2 1.0 0.9

From Table 3, one-sided drying yields a factor of 2.6.From Table 4, the combined temperature and hu-

midity give a factor of 0.8.From Table 5, the factor is 1.0 for curing.

The amount of time needed to dry this slab after cur-ing is estimated to be:

135 x 0.4 x 2.6 x 0.8 x 1.0 = 112 days, or about 16 weeks

Silica fume can be used as an ingredient in the mix toreduce the drying time: 5% addition of silica fumeleads to about a 50% reduction in drying time for a wa-ter-cement ratio of 0.5 or lower. Higher doses of silicafume can lead to greater reductions in drying time.

Moisture Measurement

The moisture level in concrete can be expressed asrelative humidity, moisture content, or moisture ratio.After the estimated drying period, the relative humid-ity of the slab should be measured prior to installationof a floor covering to verify that the required relativehumidity is achieved. To determine in-place relative

humidity, a moisture sensor may be placed in a borehole drilled into the concrete, a core drilled from theconcrete may be tested (and used to calibrate a mois-ture sensor), or an in-situ meter can be used.

In all types of moisture measurement, there can be dif-ferent sources of errors. To minimize errors, only trainedprofessionals should measure moisture in concrete. Re-fer to references 2 and 4 for information on test methods.

Summary

Water in concrete is necessary for hydration of thecementitious materials and for workability, but someof the free water must dry before floor coverings can

be installed. There are many interrelated factors affect-ing drying time, and the Swedish approach accountingfor each of these factors can help estimate at what agethe proper moisture level in the concrete can bereached. This will increase the chances of a successfulfloor covering installation.

References

1. Hedenblad, Gran, Drying of Construction Water inConcreteThe Swedish Experience,Issues in Moisture Mi-

gration in Concrete, ACBM Technology Transfer Day, NSFCenter for Advanced Cement-Based Materials (at North-western University), Evanston, Illinois, April 1998.

2. Hedenblad, Gran, Drying of Construction Water in Con-creteDrying Times and Moisture Measurement, T9, SwedishCouncil for Building Research, Stockholm, 1997. [Avail-able from Portland Cement Association as LT229.]

3. Butt, Thomas K. Avoiding and Repairing Moisture Prob-lems in Slabs on Grade, The Construction Specifier, Alex-andria, Virginia, December 1992.

4. Kosmatka, Steven H., Floor-Covering Materials andMoisture in Concrete, Concrete Technology Today, PL853,September 1985.

Table 2. Correction Factors for Thickness

Thickness, Water-cement ratiomm (in.)

0.4 0.5 0.6 0.7

100 (4) 0.4 0.4 0.4 0.4150 (6) 0.8 0.8 0.8 0.7180 (7) 1.0 1.0 1.0 1.0200 (8) 1.1 1.1 1.1 1.2250 (10) 1.3 1.4 1.5 1.8

Table 1. Drying Times for Concrete

Relative humidity Water-cement ratioof the concrete, %

0.4 0.5 0.6 0.7

85 50 days 90 days 135 days 180 days90 20 days 45 days 65 days 95 days

Table 3. Correction Factors for Type of Drying(One- or Two-Sided)

Drying from: Water-cement ratio

0.4 0.5 0.6 0.7

One side 2.0 2.3 2.6 3.2Two sides 1.0 1.0 1.0 1.0

Table 5. Correction Factors for Curing

Curing conditions Water-cement ratio

0.5 0.6 0.7

Drying concrete torelative humidity of: 85% 90% 85% 90% 85% 90%

One day moist air 1.0 0.5 1.0 0.5 1.0 0.7

Two weeks rain,two weeks moist air 1.0 1.0 1.0 1.0 1.0 1.0

Four weeks moist air 1.0 0.5 1.0 0.7 1.0 0.8

Four weeks rain 1.4 1.0 1.4 1.3 1.4 1.3

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Hot Weather Concrete WorkabilityControl concrete workability when temperature changes occur.

tion of concrete temperature. Con-crete A has a nearly linear responseto temperature. Slump decreases ap-proximately 20 mm for each 10C in-crease in temperature (0.8 in. foreach 20F temperature increase).Concrete B shows more sensitivityto temperature than Concrete A.Summer construction temperaturescan vary from 10C (50F) in theearly morning to over 30C (86F) inthe afternoon. This figure showshow different concretes respond tothese typical temperature changes.

Temperature Control

For most concrete projects, slump isan important indicator of concreteworkability. As concrete tempera-tures rise, workability can be re-duced. If no other modifications aremade to the concrete mix, it is likelythat water will be added at the jobsite, and if the water-cement ratio ofthe concrete mix design is exceeded,lower strengths can result.

When warmer temperatures ar-

Fig. 2. Effects of casting temperature on slump.

At a given water content and water-cement ratio, fresh concrete becomesless workable as temperatures rise.

There are a number of other poten-tial negative effects of higher con-crete temperatures, such as:

Accelerated slump loss Faster rate of setting Increased plastic shrinkage

cracking Difficulty in maintaining air

content

This article briefly reviews the re-lationship between workability(slump) and temperature.

Temperature EffectsReference 1 compared two concretemixes made with two ASTM C 150Type I cements. The maximum ag-gregate size was 19 mm (3/4 in.). Acement content of 356 kg/m3 (600pcy) was used along with a water-cement ratio of 0.45.

Figure 2 presents slump results(constant water content) as a func-

rive, anticipate the changes in con-crete workability. Options to controltemperature include the following:

Use cool mix water or substituteice for part of the mix water

Sprinkle aggregate piles and/orstore them in shaded areas

Avoid placing concrete during thehottest part of the day

Time delivery properly so thattrucks are unloaded withoutdelay

Spray the outside of mixingdrums with cool water

Use light-colored trucks to mini-mize heat gain (from the sun)

Reference

1. Burg, Ronald G., The Influence of Cast-ing and Curing Temperature on the Prop-erties of Fresh and Hardened Concrete,RD113, Portland Cement Association,1996.

Fig.1 Summertime requires attention to concreteworkability for ease of placement and finishing. (68163)

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Cement and Concrete Internet SitesWeb sites provide quick online resources to concrete information.

New web sites make your computerone of the best resources for cementand concrete information such asspecifications, standards, and guide-

lines. A more extensive list of websites is available on the PCA web siteat www.portcement.org.

Industry and ProfessionalOrganizations

American Coal Ash Associationhttp://www.acaa-usa.org

American Concrete Institute (ACI)http://www.aci-int.org

ACI Committee 318 http://ce.ecn.purdue.edu/~aciAmerican Concrete Pavement Asso-

ciation (ACPA)http://www.pavement.com

American Concrete Pipe Associationhttp://www.concrete-pipe.org

American Concrete Pressure PipeAssociationhttp://www.wateronline.com/compa-nies/accpa/accpa.html

American Road & TransportationBuilders Associationhttp://www.artba-hq.org

American Society of Civil Engineershttp://www.asce.org

ASCE Committee on Emerging

Materials (Materials EngineeringDivision)

http://www.cemr.wvu.edu/-wwwcfc/asce

Brick Industry Association (formerlyBrick Institute of America)http://www.bia.org

British Cement Associationhttp://www.bca.org.uk

Building Research Establishment (U.K.)http://www.bre.co.uk

Canadian Portland Cement Associationhttp://www.cpca.ca

Cembureau (European Cement

Association)http://www.cembureau.be

Civil Engineering Research Foundationhttp://www.cerf.org

Concrete Homeshttp://www.concretehomes.com

Concrete Reinforcing Steel Institutehttp://www.crsi.org

Concrete Sawing and Drilling Asso-ciationhttp://www.csda.org

The Construction SuperNetwork(Aberdeen Group)http://www.supernetwork.net

Council for Masonry Research

http://www.masonryresearch.orgElectric Power Research Institute

http://www.epri.comExpanded Shale, Clay & Slate Institute

http://www.concreteworld.com/escsiFly Ash Resource Center

http://www.geocities.com/CapeCanaveral/Launchpad/2095/index.html

High-Performance Concrete Networkof Centres of Excellence (Canada)http://www.usherb.ca/concrete

Institute for Research in Construction(National Research Council of

Canada)http://www.nrc.ca/irc

International Cement MicroscopyAssociationhttp://www.cemmicro.org

International Code Council (BOCA,ICBO, SBCCI)http://www.intlcode.org

International Concrete Repair Institutehttp://www.concrete-repair.org

The Masonry Societyhttp://www.masonrysociety.org

National Association of Home Buildershttp://www.nahb.com

Builder Magazine (NAHB)http://www.builderonline.comNational Concrete Masonry Association

http://www.ncma.orgNational Precast Concrete Association

http://www.precast.orgPortland Cement Association

http://www.portcement.orgPrecast/Prestressed Concrete Insti-

tute (PCI)http://www.pci.org

Tilt-Up Concrete Associationhttp://www.tilt-up.org

Standards

AASHTO, American Association ofState Highway Officialshttp://www.aashto.org

American National Standards Insti-tute (ANSI)http://web.ansi.org

American Society for Testing andMaterials (includes searchable in-dex of standards, also Directory ofTesting Laboratories)http://www.astm.org

International Organization for Stan-dardization (ISO)http://www.iso.ch

University/Library Sites

Advanced Cement-Based Materials(at Northwestern University)http://www.civil.nwu.edu/ACBM

Canadian Institute for Scientific andTechnical Informationhttp://www.cisti.nrc.ca/cisti

Government Sites

National Institute of Science andTechnologyhttp://www.nist.gov

NIST Building & Fire Research Labo-ratory

http://www.bfrl.nist.govOccupational Safety and Health Ad-

ministration (OSHA)http://www.osha.gov

Ontario Ministry of Transportationhttp://www.mto.gov.on.caStrategic Highway Research Program

(SHRP)http://www.hend.com/shrp

Transport Canadahttp://www.tc.gc.ca

Transportation Research Boardhttp://www.nas.edu/trb

Turner Fairbank Highway ResearchCenterhttp://www.tfhrc.gov

U.S. Army Corps of Engineers Infor-mation

http://www.usace.army.milU.S. Army Engineer Waterways Ex-periment Station: REMR Database

http://www.wes.army.mil/cgi-bin/remr.wais.pl

U.S. Bureau of Reclamation MaterialsEngineering Research and Labora-tory Grouphttp://www.usbr.gov/merl

U.S. Environmental ProtectionAgency (EPA)http://www.epa.gov

U.S. EPA: Envirofacts Warehousehttp://www.epa.gov/enviro/html/

emci/emci_query.htmlMiscellaneous

AggMan Online (AggregatesManager)http://www.aggman.com

Engineering News Recordhttp://www.enr.com

Materials Safety Data Sheets (MSDS)http://www.chem.uky.edu/Resources/MSDS.html

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PL982.01T

Sent to you compliments of:

Intended for decision makers associatedwith design, management, and construc-tion of building projects, Concrete Technol-ogy Today is published triannually by theConstruction Information Services Depart-ment of the Portland Cement Association.

Our purpose is to show various waysof using concrete technology to your

PUBLISHER'S NOTE: Direct all correspondence toSteve Kosmatka, Editor

Jamie Farny, Assistant EditorConcrete Technology TodayPortland Cement Association5420 Old Orchard RoadSkokie, Illinois 60077-1083Phone: 847/966-6200 Fax: 847/966-8389E-mail: steve_kosmatka@portcement.orgE-mail: jamie_farny@portcement.org

Printed in U.S.A.

This publication is intended SOLELY for use by PROFESSIONAL PERSONNEL who are competent to evaluate the sig-nificance and limitations of the information provided herein, and who will accept total responsibility for the applicationof this information. The Portland Cement Association DISCLAIMS any and all RESPONSIBILITY and LIABILITY for theaccuracy of and the application of the information contained in this publication to the full extent permitted by law.

advantage and avoiding problems. If thereare problems or ideas readers would likediscussed in future issues, please let us

know. Items from this newsletter may bereprinted in other publications subject toprior permission from the Association. Forthe benefit of our readers, we occasionallypublish articles on products. This does notimply PCA endorsement.

New LiteratureThe following publications are now

available. To purchase any of these,in the United States, contact Port-land Cement Association, OrderProcessing, P. O. Box 726, Skokie, IL60076-0726; telephone 1-800/868-6733, or fax 847/966-9666 (24 hours aday, 7 days a week). In Canada pleasedirect requests to the nearest re-gional office of the Canadian Port-land Cement Association (Halifax,Montreal, Toronto, and Vancouver).

Leas Chemistry of Cementand Concrete, LT132

Extensive reference on cement,concrete, and concrete ingredients.Edited by P.C. Hewlett. Publishedby Arnold. (1080 pages, 1998)

Cement Chemistry, LT134

Discusses cement manufacture,

cement chemistry, hydration,admixtures, and concrete durability.By H. F. W. Taylor. Published byThomas Telford. (480 pages, 1997)

Properties of Concrete, LT139

Comprehensive text on concreteproperties. By A. M. Neville. Pub-lished by Wiley. (858 pages, 1996)

Concrete Petrography - AHandbook of InvestigativeTechniques, LT226

Covers all aspects of the petro-graphic study of hardened concreteand related materials. Authored bySt. John, Poole and Sims. Publishedby Arnold. (608 pages, 1998)

Concrete ConstructionEngineering Handbook, LT227

Discusses concrete materials, struc-tural design, and concrete construc-tion. Edited by E.G. Nawy. Publishedby CRC Press. (1,010 pages, 1997)

Strength and RelatedProperties of Concrete aQuantitative Approach, LT228

Demonstrates how to fine-tune thecomposition of concrete to maximizeits strength and improve concretequality. By S. Popovics. Published byWiley. (535 pages, 1998)

Drying of Construction Water inConcrete, LT229

Discusses concrete drying time andmoisture measurement to prevent floorcovering problems. By G. Hedenblad.Published by Swedish Council forBuilding Research. (54 pages, 1997)