ACI 211.4 (R1998) StdPract SelectProps HSConcrete PortCementFlyAsh

7/30/2019 ACI 211.4 (R1998) StdPract SelectProps HSConcrete PortCementFlyAsh

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ACI 211.4R-93

(Reapproved 1998)

Guide for Selecting Proportions for High-Strength

Concrete with Portland Cement and Fly AshReported by ACI Committee 211

Olga Alonzo*

William L BarringerStanley G. BartonLeonard W. BellJames E. BennettMike Boyle*George R.U. BurgRamon L Carrasquillo*James E. Cook*Russell A. CookDavid A. Crocker

Guy Detwiler*

Gary R. MassChairman

Calvin L. Dodl

Thomas A. Fox*George W. HollowTarif M. Jaber*Stephen M. LaneStanley H. LeeMark Luther*Richard C. MeiningerJames S. PierceMike Pistilli*Sandor Popovics*

Steven E. RaganDonald E. Dixon

l Members of subcommittee who prepared the report.

Subcommittee Chairman.

This guide presents a generally applicable method for selecting mixture

proportions for high-strength concrete and optimizing these mixture propor-

tions on the basis of trial batches. The method is limited to high-stmngth

concrete produced using conventional materials and production techniques.

Recommendations and tables are based on current practice and infor-mation provided by contractors, concrete suppliers, and engineers who have

been involved in projects dealing with high-strength concrete.

Keywords: aggregates; capping; chemical admixtures; fine aggregates; fIy ash;

high-strength concretes; mixture proportioning; quality control; specimen size;

strength requirements; superplasticizers.

CONTENTS

Chapter 1-Introduction, pg. 211.4R-1

1.1-Purpose1.2-Scope

Chapter 2-Performance requirements, pg. 211.4R-2

2.1-Test age2.2-Required strength

2.3-Other requirements

ACI Committee Reports, Guides, Standard Practices, and

Commentaries are intended for guidance in designing, plan-

ning, executing, or inspecting construction and in preparing

specifications. References to these documents shall not be

Donald Schlegel

James M. Shilstone, Jr.*Paul R. StodolaWilliam X. SypherAva Shypula*Jimmie L Thompson*Stanley J. VirgalitteWoodward L VogtJack W. WeberDean J. White,Marshall S. Williams

John R. Wilson

Chapter 3-Fundamental relationships, pg. 211.4R-3

3.1-Selection of materials3.2-Water-cementitious materials ratio (w/c +p)

3.3-Workability3.4-Strength measurements

Chapter 4-High-strength concrete mixture proportion-

ing, pg. 211.4R-5

4.1-Purpose

4.2-Introduction4.3-Mixture proportioning procedure

Chapter 5-Sample calculations, pg. 21.4R-8

5.1-Introduction5.2-Example

Chapter 6-References, pg. 211.4R-13

6.1-Recommended references

CHAPTER l-INTRODUCTION

1.1.PurposeThe current ACI 211.1 mixture proportioning proce-

ACI 211.4R-93 became effective September 1.1993.

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211.4R-2 ACI COMMITTEE REPORT

dure describes methods for selecting proportions for nor-mal strength concrete in the range of 2000 to 6000 psi.Mixture proportioning is more critical for high-strengthconcrete than for normal strength concrete. Usually, spe-cially selected pozzolanic and chemical admixtures areemployed, and attainment of a low water-to-cementitiousmaterial ratio (w/c+p) is considered essential. Many trial

mixtures are often required to generate the data neces-sary to identify optimum mixture proportions. The pur-pose of this guide is to present a generally applicable

method for selecting mixture proportions for high-strength concrete and for optimizing these mixture pro-

portions on the basis of trial batches.

1.2-ScopeDiscussion in this guide is limited to high-strength

concrete produced using conventional materials andproduction methods. Consideration of silica fume andground granulated blast furnace slag (GGBFS) is beyondthe scope of this document. Information on proportion-ing of silica fume concrete is limited at this time. ACI

Committee 234,Silica Fume in Concrete, is developinginformation on the use of silica fume for a committeereport. Proportioning GGBFS concrete is discussed inACI 226-1R (now ACI Committee 233). When additionaldata becomes available, it is expected that an ACI guidefor proportioning concrete with these materials will bedeveloped. Currently, silica fume and GGBFS suppliers,as well as experienced concrete suppliers, represent the

best source of proportioning information for thesematerials.

High-strength concrete is defined as concrete that hasa specified compressive of 6000 psi or greater.This guide is intended to cover field strengths up to12,000 psi as a practical working range, although greater

strengths may be obtained. Recommendations are basedon current practice and information from contractors,concrete suppliers, and engineers who have been involvedin projects dealing with high-strength concrete. For amore complete list of references and available publica-tions on the topic, the reader should refer to ACI 363R.

CHAPTER 2-PERFORMANCE REQUIREMENTS

2.1-Test age

The selection of mixture proportions can be influencedby the testing age. High-strength concretes can gain con-siderable strength after the normally specified 28-day age.To take advantage of this characteristic, many specifica-tions for compressive strength have been modified from

the typical 28-day criterion to 56 days, 91 days, or later

based on field experience or laboratory trial batches. To

meet the specified strength requirements, the concretemust be proportioned in such a manner that the average

compressive strength results of field tests exceed thespecified design compressive strength by an amountsufficiently high to make the probability of low testssmall. When the concrete producer chooses to selecthigh-strength concrete mixture proportions based uponfield experience, it is recommended that the requiredaverage strength used as the basis for selection of

concrete proportions be taken as the larger value calcu-lated from the following equations

= + 1.34s

= + 2.33s

(2-1)

(2-2)

where s = sample standard deviation in psi.Eq. (2-l) is Eq. (5-l) of the ACI 318 Building Code.

Eq. (2-2) is a modified version of Eq. (5-2) = +

2.33s-

500) of the modified ACI 318 because, to date,job specifications for high-strength concrete have usually

more than 1 in 100 individual tests that will fall below 90percent of the specified strength. When job specificationscite ACI 318 acceptance criteria, Eq. (5-2) of ACI 318should be used instead of Eq. (2-2) of this report.

When the concrete producer selects high-strength con-crete proportions on the basis of laboratory trial batches,the required average strength may be determinedfrom the equation

(2-3)

Eq. (2-3) gives a higher required average strengthvalue than that required in Table 5.3.2.2 of the ACIBuilding Code (ACI 318). Experience has shown that

strength tested under ideal field conditions attains only90 percent of the strength measured by tests performedunder laboratory conditions. To assume that the average

strength of field production concrete will equal thestrength of a laboratory trial batch is not realistic, sincemany factors can influence the variability of strengths andstrength measurements in the field. Initial use of a high-strength concrete mixture in the field may require some

adjustments in proportions for air content and yield, andfor the requirements listed below, as appropriate. Oncesufficient data have been generated from the job, mixtureproportions should be reevaluated using ACI 214 and ad-

justed accordingly.

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HIGH-STRENGTH CONCRETE WITH PORTLAND CEMENT AND FLY ASH 211.4R-3

setting, h) method of placement, and i) workability.

CHAPTER 3-FUNDAMENTAL RELATIONSHIPS

3.1-Selection of materials

Effective production of high-strength concrete isachieved by carefully selecting, controlling, and pro-portioning all of the ingredients. To achieve higherstrength concretes, optimum proportions must be se-lected, considering the cement and fly ash characteristics,aggregate quality, paste proportion, aggregate-paste

interaction, admixture type and dosage rate, and mixing.Evaluating cement, fly ash, chemical admixture, andaggregate from various potential sources in varying pro-portions will indicate the optimum combination of mater-ials. The supplier of high-strength concrete shouldimplement a program of uniformity and acceptance testsfor all materials used in the production of high-strengthconcrete.

3.1.1 Portland cement-Proper selection of the typeand source of cement is one of the most important stepsin the production of high-strength concrete. ASTM C 917may be useful in considering cement sources. Variationsin the chemical composition and physical properties ofthe cement affect the concrete compressive strength morethan variations in any other single material. For anygiven set of materials, there is an optimum cement con-tent beyond which little or no additional increase in

strength is achieved from increasing the cement content.3.1.2 Other cementitious materials-Finely divided

cementitious materials other than portland cement, con-sisting mainly of fly ash, ground blast furnace slag, orsilica fume (microsilica), have been considered in theproduction of high-strength concrete because of the re-quired high cementitious materials content and loww/c+p. These materials can help control the temperaturerise in concrete at early ages and may reduce the waterdemand for a given workability. However, early strengthgain of the concrete may be decreased.

ASTM C 618 specifies the requirements for Class Fand Class C fly ashes, and for raw or calcined naturalpozzolans, Class N, for use in concrete. Fly ash proper-ties may vary considerably in different areas and fromdifferent sources within the same area. The preferred flyashes for use in high-strength concrete have a loss on

ignition no greater than 3 percent, have a high fineness,and come from a source with a uniformity meetingASTM C 618 requirements.

3.13Mixing water-The acceptability of the water for

high-strength concrete is not of major concern if potablewater is used. Otherwise, the water should be tested for

high-strength concretes are produced with normal weightaggregates. However, there have been reports of high-strength concrete produced using lightweight aggregatesfor structural concrete and heavyweight aggregates forhigh-density concrete.

The coarse aggregate will influence significantly thestrength and structural properties of the concrete. Forthis reason, a coarse aggregate should be chosen that issufficiently hard, free of fissures or weak planes, clean,and free of surface coatings. Coarse aggregate propertiesalso affect aggregate-mortar bond characteristics andmixing water requirements. Smaller size aggregates have

been shown to provide higher strength potential.For each concrete strength level, there is an optimum

size for the coarse aggregate that will yield the greatestcompressive strength per pound of cement. A 1 or 3/4-in.nominal maximum-size aggregate is common for produc-ing concrete strengths up to 9000 psi; and or 3/8-in.above 9000 psi. In general, the smallest size aggregateproduces the highest strength for a given w/c+p. How-ever, compressive strengths in excess of 10,000 psi arefeasible using a l-in. nominal maximum-size aggregatewhen the mixture is proportioned with chemical admix-tures. The use of the largest possible coarse aggregate isan important consideration if optimization of modulus ofelasticity, creep, and drying shrinkage are important.

3.1.5Fine aggregate-The grading and particle shapeof the fiie aggregate are significant factors in theproduction of high-strength concrete. Particle shape and

surface texture can have as great an effect on mixingwater requirements and compressive strength of concreteas do those of coarse aggregate. Fine aggregates of thesame grading but with a difference of 1 percent in voidscontent may result in a 1 gal. per difference in waterdemand. More information can be found in ACI 211.1.

The quantity of paste required per unit volume of aconcrete mixture decreases as the relative volume ofcoarse aggregate versus fine material increases. Becausethe amount of cementitious material contained in high-strength concrete is large, the volume of fines tends to behigh. Consequently, the volume of sand can be kept tothe minimum necessary to achieve workability and com-pactibility. In this manner, it will be possible to producehigher strength concretes for a given cementitious mater-ial content.

Fine aggregates with a fineness modulus (FM) in the

range of 2.5 to 3.2 are preferable for high-strength con-cretes. Concrete mixtures made with a fine aggregate thathas an FM of less than 2.5 may be sticky and result inpoor workability and a higher water requirement. It issometimes possible to blend sands from different sourcesto improve their grading and their capacity to produce

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crete, decreasing the w/c+p by decreasing the waterrequirement rather than by increasing the totalcementitious materials content, will usually producehigher compressive strengths. For this reason, use of

chemical admixtures should be considered when pro-ducing high-strength concrete (see ACI 212.3R andASTM C 494). In this guide, chemical admixture dosagerates are based on fluid oz per 100 lb of totalcementitious material (oz/cwt). If powdered admixturesare used, dosage rates are on a dry weight basis. The useof chemical admixtures may improve and control the rateof hardening and slump loss, and result in accelerated

strength gain, better durability, and improved workability.High-range water-reducing admixtures (HRWR), alsoknown as superplasticizers, are most effective in concretemixtures that are rich in cement and other cementitiousmaterials. HRWR help in dispersing cement particles,and they can reduce mixing water requirements by up to30 percent, thereby increasing concrete compressivestrengths.

Generally, high-strength concretes contain both a

conventional water-reducing or water-reducing andretarding admixture and an HRWR. The dosage of theadmixtures will most likely be different from the manu-facturers recommended dosage. Although only limitedinformation is available, high-strength concrete has alsobeen produced using a combination of chemical admix-tures such as a high dosage rate of a normal-set waterreducer and a set accelerator. The performance of the

admixtures is influenced by the particular cementitiousmaterials used. The optimum dosage of an admixture orcombination of admixtures should be determined by trialmixtures using varying amounts of admixtures. The bestresults are achieved generally when an HRWR is addedafter the cement has been wetted in the batching andmixing operation.

Air-entraining admixtures are seldom used in high-strength concrete building applications when there are no

freeze-thaw concerns other than during the constructionperiod. If entrained air is required because of severeenvironments, it will reduce significantly the compressivestrength of the concrete.

3.2-Water-cementitious material ratio (w/c +p)Many researchers have concluded that the single most

important variable in achieving high-strength concrete is

the water-cement ratio (w/c). Since most high-strengthconcrete mixtures contain other cementitious materials,a w/c+p ratio must be considered in place of the tra-ditional w/c. The w/c+p, like the w/c, should be cal-culated on a weight basis. The weight of water in HRWR

should be included in the w/c+p.

w/c+p for high-strength concretes typically have rangedfrom 0.20 to 0.50.

3.3-Workability

3.3.1Introduction-For the purpose of this guide,workability is that property of freshly mixed concrete thatdetermines the ease with which it can be properly mixed,placed, consolidated, and finished without segregation.

3.3.2 Slump-In general, high-strength concretesshould be placed at the lowest slump which can be prop-erly handled and consolidated in the field. A slump of 2to 4 in. provides the required workability for most appli-

cations. However, reinforcement spacing and form detailsshould be considered prior to development of concretemixtures.

Because of a high coarse aggregate and cementitiousmaterials content and low w/c+p, high-strength concretecan be difficult to place. However, high-strength concretecan be placed at very high slumps with HRWR withoutsegregation problems. Flowing concretes with slumps inexcess of 8 in., incorporating HRWR, are very effective

in filling the voids between closely spaced reinforcement.In delivery situations where slump loss may be a prob-lem, a placeable slump can be restored successfully byredosing the concrete with HRWR. A second dosage ofHRWR results in increased strengths at nearly all testages. This practice has been advantageous especially inusing HRWR for hot-weather concreting.

3.4-Strength measurements3.4.1Test method-standard ASTM or AASHTO testmethods are followed except where changes are indicatedby the characteristics of the high-strength concrete (ACI363R). The potential strength for a given set of materialscan be established only if specimens are made and testedunder standard conditions. A minimum of two specimensshould be tested for each age and test condition.

3.4.2Specimen size-Generally, 6 x 12-m cylindrical

specimens are specified as the standard for strength eval-uation of high-strength concrete. However, some 4 x 8-in.cylinders have been used for strength measurements. Thespecimen size used by the concrete producer to deter-mine mixture proportions should be compatible with theload capacity of the testing machine and consistent withthe cylinder size specified by the designer for acceptance.Measurements of strength using 6 x 12-m cylinders are

not interchangeable with those obtained when using 4 x8-in cylinders.3.4.3Type of molds--The typeof mold used will have

a significant effect on the measured compressive strength.In general, companion specimens cast using steel moldsachieve more consistent compressive strengths than those


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tions be the same type as that used for fiial acceptancetesting.

3.4.4Specimen capping--Prior to testing a cylinder, theends usually are capped to provide for a uniform trans-

mission of force from a testing machine platen into thespecimen body. Sulfur mortar is the most widely usedcapping material and, when properly prepared, is eco-nomical, convenient, and develops a relatively highstrength in a short period of time.

Cap thickness should be as thin as practical, in therange of to in. for high-strength concrete speci-mens. A commercially available high-strength sulfur

capping material has been used to determine concretestrengths in excess of 10,000 psi, with cap thicknessesmaintained at approximately in. When using a sulfurcapping material on high-strength concrete specimens, itis important that irregular end conditions are correctedprior to capping. Irregular end conditions and air voidsbetween the cap and the cylinder end surfaces can ad-versely affect the measured compressive strength. Someconcrete technologists prefer to form or grind specimen

ends to ASTM C 39 tolerance when compressivestrengths are greater than 10,000 psi.

3.4.5Testing machines--Testing machine characteris-tics, mainly load capacity and stiffness, can have asignificant influence on measured strength results. Goodtest results and minimum variation have been obtainedwhen testing high-strength concrete cylinders using atesting machine with a minimum lateral stiffness of

lb/ii. and a longitudinal stiffness of at least 107

lb/in.Testing machines that are laterally flexible can reduce themeasured compressive strength of a specimen.

CHAPTER 4-HIGH-STRENGTH CONCRETEMIXTURE PROPORTIONING

4.1-Purpose

Thisguide procedure for proportioning high-strengthconcrete mixtures is applicable to normal weight, non-air-entrained concrete having compressive strengths between6000 and 12,000 psi When proportioning high-strength concrete mixtures, the basic considerations arestill to determine the ingredient quantities required toproduce a concrete with the desired plastic properties(workability, finishability, etc.) and hardened properties

(strength, durability, etc.) at the lowest cost. Properproportioning is required for all materials used. Becausethe performance of high-strength concrete is highly de-pendent on the properties of its individual components,this proportioning procedure is meant to be a reasonableprocess to produce submittal mixture proportions based

Table 4.3.1 - Recommended slump for concretes withand without HRWR

Concrete made using HRWR*

Slump before adding HRWR 1 to 2 in.

Concrete made without HRWR

Slump 2 to 4 in.

l Adjust slump to that desired in the field through the addition ofHRWR.

strength. Guidelines for the selections of materials forproducing high-strength concrete are provided in ACI

363R.Before starting the proportioning of high-strength con-

crete mixtures, the project specifications should be re-viewed. The review will establish the design criteria forspecified strengths, the age when strengths are to beattained, and other testing acceptance criteria.

4.2-IntroductionThe procedure described inACI 211.1 for proportion-

ing normal strength concrete is similar to that requiredfor high-strength concrete. The procedure consists of aseries of steps, which when completed provides a mixturemeeting strength and workability requirements based onthe combined properties of the individually selected andproportioned components. However, in the developmentof a high-strength concrete mixture, obtaining the opti-mum proportions is based on a series of trial batches

having different proportions and contents of cementitiousmaterials.

4.3-Mixture proportioning procedureCompletion of thefollowing steps will result in a set

of adjusted high-strength concrete laboratory trial pro-portions. These proportions will then provide the basisfor field testing concrete batches from which the opti-mum mixture proportions may be chosen.

4.3.1 Step 1-Select slump and required concrete strength-Recommended values for concrete slump are given inTable 4.3.1. Although high-strength concrete withHRWR has been produced successfully without a mea-surable initial slump, an initial starting slump of 1 to 2in.prior to adding HRWR is recommended. This will insurean adequate amount of water for mixing and allow thesuperplasticizer to be effective.

For high-strength concretes made without HRWR, arecommended slump range of 2 to 4 in. may be chosenaccording to the type of work to be done. A minimumvalue of 2 in. of slump is recommended for concretewithout HRWR. Concretes with less than 2 in. of slumpare difficult to consolidate due to the high coarse

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Table 4.3.2- Suggested maximum-size coarse aggregate

Suggested maximum-sizeRequired concrete strength, psi coarse aggregate, in.

9000 to

* When using HRWR and selected coarse aggregates, concrete compres-sive strengths in the range of 9000 to 12,000 pi an be attained usinglarger than recommendednominal maximum-sizecoarseaggregates of upto 1 in.

Table 4.3.3- Recommended volume of coarse aggregate

per unit volume of concrete

Optimum coarse aggregate contents for nominalmaximum sizes of aggregates to be used with sand with

fineness modulus of 2.5 to 3.2

Nominal maximum size, in.I 3/4 I 1/2 I 3/4 I 1Fractional volume* ofoven-dry rodded coarse aggregate 0.65 0.68 0.72 0.75

* Volumes are ba sed on aggregates in oven-dxy rodded condition asdescribed in ASTM C 29 for unit weight of aggregates.

sixes for coarse aggregates are given in Table 4.3.2. ACI318 states the maximum size of an aggregate should notexceed one-fifth of the narrowest dimension betweensides of forms, one-third of the depth of slabs, northree-quarters of the minimum clear spacing between in-dividual reinforcing bars, bundles of bars, or prestressing

tendons or ducts.4.3.3Step 3-Select optimum coarse aggregate content

-The optimum content of the coarse aggregate dependson its strength potential characteristics and maximumsize. The recommended optimum coarse aggregate con-tents, expressed as a fraction of the dry-rodded unitweight (DRUW), are given inTable 4.3.3as a functionof nominal maximum size.

Once the optimum coarse aggregate content has beenchosen from Table 4.3.3, the oven-dry (OD) weight ofthe coarse aggregate per yd3 of concrete can be cal-culated using Eq. (4-l)

weight of coarse aggregate (O.D.) = (% x DRUW) x (DRUW x 27) (4-l)

In proportioning normal strength concrete mixtures,the optimum content of coarse aggregate is given as a

function of the maximum size and fineness modulus ofthe fine aggregate. High-strength concrete mixtures, how-ever, have a high content of cementitious material, andthus are not so dependent on the fine aggregate to sup-ply fiies for lubrication and compactibility of the freshconcrete. Therefore, the values given in Table 4.3.3 are

Table 4.3.4 First estimate of mixing water require-ment and air content of fresh concrete based on usinga sand with 35 percent voids

Mixing water,

Maximum-size coarse aggregate, in.

* Values given must be adjusted for sands with voids other than 35 per-cent using Eq. 4-3.

Mixtures made using HRWR.

gate, the quantity of cement, and type of water-reducingadmixture used. If an HRWR is used, the water contentin this admixture is calculated generally to be a part ofthe w/c+p. Table 4.3.4 gives estimates of required mixingwater for high-strength concretes made with to 1 in.maximum-size aggregates prior to the addition of anychemical admixture. Also given are the correspondingvalues for entrapped air content. These quantities ofmixing water are maximums for reasonably well-shaped,clean, angular coarse aggregates, well-graded within thelimits of ASTM C 33. Because particle shape and surfacetexture of a fine aggregate can significantly influence its

voids content, mixing water requirements may be dif-ferent from the values given.

The values for the required mixing water given inTable 4.3.4are applicable when a fine aggregate is usedthat has a void content of 35 percent. The void contentof a fine aggregate may be calculated using Eq. (4-2)

Void content, V, % =

l -Oven-dry rodded unit weight

Bulkspecific gravity (dry) x 62.4 x 100 (4-2)

When a fine aggregate with a void content not equalto 35 percent is used, an adjustment must be made to therecommended mixing water content. This adjustment maybe calculated using Eq. (4-3)

Mixing water adjustment, = (V-

35) X 8(4-3)

Use of Eq. (4-3) results in a water adjustment of 8of concrete for each percent of voids deviation

from 35 percent.4.3.5Step 5-Select w/c+p-In high-strength concrete

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Table 4.3.5(a)- Recommended maximum w/c + p for

concretes made without HRWR

w/c +p

Field strength

psi

28-day

7000 56-day

28-day

56-day

28-day

56-day28-day

10,000 56-day


1

0.42 0.41 0.40 0.39

0.46 0.45 0.44 0.43

0.35 0.34 0.33 0.33

0.38 0.37 0.36 0.35

0.30 0.29 0.29 0.28

0.33 0.32 0.31 0.300.26 0.26 0.25 0.25

0.29 0.28 0.27 0.26

* = + 1400.

Table 4.3.5(b)- Recommended maximum w/c + p ratiofor concretes made with HRWR

w/c +p


Field strength

psi 1

Note: A comparison of the values contained in Tables 4.3.5(a) and

4.3.5(b) permits, in particular, the following conclusions:

1. For a given water cementitious material ratio, the field strength ofconcrete is greater with the use of HRWR than without it, and this greater

strength is reached within a shorter period of time.2. With the use of HRWR, a given concrete field strength can be

achieved in a given period of time using less cementitious material thanwould be required when not using HRWR.

to achieve different compressive strengths at either 28 or56 days. The use of an HRWR generally increases the

compressive strength of concrete. The w/c+p values giveninTable 4.3.5(a)are for concretes made without HRWR,and those inTable 4.3.5(b)are for concretes made usingan HRWR.

The w/c+p may be limited further by durability re-quirements. However, for typical applications, high-

4.3.6Step 6-Calculate content of cementitious material-The weight of cementitious material required perof concrete can be determined by dividing the amount ofmixing water per of concrete (Step 4) by the w/c+pratio (Step 5). However, if the specifications include aminimum limit on the amount of cementitious materialper of concrete, this must be satisfied. Therefore, themixture should be proportioned to contain the largerquantity of cementitious material required. When thecementitious material content from the following tablesexceeds 1000 lb, a more practical mixture may be pro-duced using alternate cementitious materials or propor-

tioning methods. This process is beyond the scope of thisguide.

4.3.7Step 7-Proportion basic mixture with no othercementitious material-To determine optimum mixtureproportions, the proportioner needs to prepare severaltrial mixtures having different fly ash contents. Generally,one trial mixture should be made with portland cementas the only cementitious material. The following stepsshould be followed to complete the basic mixture pro-portion.

1. Cement content-For this mixture, since no othercementitious material is to be used, the weight of cementequals the weight of cementitious material calculated inStep 6.

2. Sand content-After determining the weights perof coarse aggregate, the cement and water, and the

percentage of air content, the sand content can be cal-

culated to produce 27 using the absolute volumemethod.

4.3.8Step & Proportion companion mixtures usingflyash-The use of fly ash in producing high-strength con-crete can result in lowered water demand, reduced con-crete temperature, and reduced cost. However, due tovariations in the chemical properties of fly ash, thestrength-gain characteristics of the concrete might beaffected. Therefore, it is recommended that at least two

different fly ash contents be used for the companion trialmixtures. The following steps should be completed foreach companion trial mixture to be proportioned:

1.Fly ash type-Due to differing chemical composi-tions, the water-reducing and strength-gaining character-istics of fly ash will vary with the type used, and itssource. Therefore, these characteristics, as well as avail-ability, should be considered when choosing the fly ash to

be used.2. Fly ash content-The amount of cement to be re-

placed by fly ash depends on the type of material to beused. The recommended limits for replacement are givenin Table 4.3.6, for the two classes of fly ash. For eachcompanion trial mixture to be designed, a replacement

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211.4R-8 AC I COMMITTEE REPORT

Table 4.3.6- Recommended values for fly ash re-

placement of portland cement

Fly ashClass FClass C

Recommended replacement

(percent by weight)15 to 2520 to 35

manufacturer may be tolerated without segregation. Also,since the time of addition of the HRWR and concretetemperature have been found to affect the effectivenessof the admixture, its use in laboratory trial mixtures mayhave to be adjusted for field conditions. In general, it hasbeen found that redosing with HRWR to restore worka-bility results in increased strengths at nearly all test ages.

sen. The remaining weight of cementitious material cor-responds to the weight of cement. Therefore, for eachmixture, the weight of fly ash plus the weight of cementshould equal the weight of cementitious materials calcu-

lated in Step 6.4. Volume offly ash-Due to the differences in bulk

specific gravities of portland cement and fly ash, thevolume of cementitious materials per will vary withthe fly ash content, even though the weight of the cemen-titious materials remains constant. Therefore, for eachmixture, the volume of cementitious materials should becalculated by adding the volume of cement and the vol-ume of fly ash.

3.Coarse aggregate content-Once the concrete trialmixture has been adjusted to the desired slump, it shouldbe determined if the mixture is too harsh for job place-ment or finishing requirements. If needed, the coarseaggregate content may be reduced, and the sand content

adjusted accordingly to insure proper yield. However, thismay increase the water demand of the mixture, therebyincreasing the required content of cementitious materialsto maintain a given w/c+p. In addition, a reduction incoarse aggregate content may result in a lower modulusof elasticity of the hardened concrete.

5. Sand content-Having found the volume of cementi-tious materials per of concrete, the volumes perof coarse aggregate, water, and entrapped air (Step 7),the sand content of each mixture can be calculated usingthe absolute volume method.

4. Air content-If the measured air content differssignificantly from the designed proportion calculations,the dosage should be reduced or the sand content should

be adjusted to maintain a proper yield.

Using the preceding procedure, the total volume ofcement and fly ash plus sand per of concrete is keptconstant. Further adjustments in the mixture proportions

may be needed due to changes in water demand andother effects of fly ash on the properties of the concrete.These adjustments are determined during trial mixing, asdiscussed in Section 4.3.10.

5. w/c+p-If the required concrete compressivestrength is not attained using the w/c+ p recommended inTable 4.3.5(a) or (b), additional trial mixtures havinglower w/c+ pshould be tested. If this does not result inincreased compressive strengths, the adequacy of thematerials used should be reviewed.

4.3.9 Step 9--Trialmixtures-For each of the trial mix-tures proportioned in Steps 1 through 8, a trial mixtureshould be produced to determine the workability andstrength characteristics of the mixtures. The weights ofsand, coarse aggregate, and water must be adjusted to

correct for the moisture condition of the aggregates used.Each batch should be such that, after a thorough mixing,a uniform mixture of sufficient size is achieved to fab-ricate the number of strength specimens required.

4.3.11Step 11-Select optimum mixture proportions-

Once the trial mixture proportions have been adjusted toproduce the desired workability and strength properties,strength specimens should be cast from trial batchesmade under the expected field conditions according totheACI 211.1 recommended procedure for making andadjusting trial batches. Practicality of production andquality control procedures have been better evaluatedwhen production-sized trial batches were prepared usingthe equipment and personnel that were to be used in the

actual work. The results of the strength tests should bepresented in a way to allow the selection of acceptableproportions for the job, based on strength requirementsand cost.

4.3.10Step l0-Adjust trial mixture proportions-Ifthedesired properties of the concrete are not obtained, theoriginal trial mixture proportions should be adjusted ac-cording to the following guidelines to produce the de-

sired workability.

CHAPTER 5-SAMPLE CALCULATIONS

5.1-Introduction1.Initial slump--If the initial slump of the trial mix- An exampleis presented here to illustrate the mixture

ture is not within the desired range, the mixing water proportioning procedure for high-strength concrete dis-

should be adjusted. The weight of cementitious material cussed in the preceding chapter. Laboratory trial batch

in the mixture should be adjusted to maintain the desired results will depend on the actual materials used. In this

w/c+p.Thesand content should then be adjusted to in- example, Type I cement having a bulk specific gravity of

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to the close spacing of steel reinforcement in the the water in the HRWR.

columns, the largest nominal maximum-size aggregate 5.2.5 Step 5 - Select w/c+p-For concrete to be made

that can be used is 3/4 in. A natural sand that meets using HRWR and 1/2-in. maximum-size aggregate, andASTM C 33 limits will be used, which has the following having an average compressive strength based on labora-

properties: fineness modulus FM = 2.90; bulk specific tory trial mixtures of11,600 psi at 28 days, the requiredgravity based on oven-dry weightBSGdry= 2.59; absorp- w/c+p chosen from Table 4.3.5(b) is interpolated to be

tion based on oven-dry weight Abs = 1.1 percent; dry- 0.31. It should be noted that the compressive strengths

rodded unit weight DRUW = 103 lb/ft3. Also, a HRWR listed in Tables 4.3.5(a) and (b) are required averageand a set-retarding admixture will be used. field strengths. Therefore, although the required strength

5.2.1 Step 1-Select slump and required concrete of laboratory trial mixtures is 11,600 psi, the value to be

strength-Since an HRWR is to be used, the concrete will used in the tables isbe designed based on a slump of 1 to 2 in. prior to theaddition of the HRWR. (0.90) X (11,600) = ~~ 10,400 psi

The ready-mix producer has no prior history with high-strength concrete, and therefore will select proportions 5.2.6 Step &Calculate contentofcementitious material

based on laboratory trial mixtures. Using Eq. (2.3), the -The weight of cementitious material per yd3of con-

required average strength used for selection of concrete crete is

proportions is

f(9000 + 1400)

=

cr 0.90= 11,556psi ,... i.e., 11,600psi

The specifications do not set a minimum for cementi-

5.2.2 Step 2-Select maximum size of aggregate-

Based tious materials content, so 977 lb/yd3 of concrete will beon the guidelines in Table 4.3.2, a crushed limestone used.having a nominal maximum size of1/2in. is to be used. Itsmaterial properties are as follows: bulk specific gravity atoven-dry, BSGdry= 2.76; absorption at oven-dry, Abs =0.7 percent; dry-rodded unit weight, DRUW= 101 lb/ft3.The grading of the aggregate must comply with ASTM

C 33 for size designation No. 7 coarse aggregate.

5.2.3 Step 3-Select optimum coarse aggregate content-

The optimum coarse aggregate content, selected fromTable 4.3.3, is 0.68 per unit volume of concrete. The dry

weight of coarse aggregate per yd3of concrete Wdry, isthen

5.2.7 Step 7-Proportion basic mixture with cement only

1. Cement content per yd3 = 977 lb.

2. The volumes per yd3 of all materials except sand are

as follows:

Cement = (977)/(3.15 x 62.4)=

l

4.97 ft3

Coarse aggregate = (1854)/(2.76 x 62.4) = 10.77 ft3

Water = (303)/(62.4) = 4.86 ft3

Air = (0.02) x (27) = 0.54 ft3

Total volume =I

21.14 ft3

Therefore, the required volume of sand per yd3 of con-(0.68) x (101) x (27) = 1854 lb, using Eq. (4.1) crete is (27 - 21.14) = 5.86 ft3. Converting this to weight

of sand, dry, per yd3 of concrete, the required weight of5.2.4Step 4-Estimate mixing water and air contents- sand is

Based on a slump of 1 to 2 in., and 1/2-in. maximum-size

coarse aggregate, the first estimate of the required mixingwater chosen from Table 4.3.4 is 295 lb/yd3of concrete,

(5.86) x (62.4) x (2.59) = 947 lb.

and the entrapped air content, for mixtures made usingHRWR, is 2.0 percent.

However, using Eq. (4-2), the voids content of thesand to be used is

Cement

l977 lb

l -103

]x l 00 =

(2.59) x (62.4) 36 percent

Sand, dry 947 lb

Coarse aggregate, dry 1854 lb

Water, including 3 oz/cwt* retarding

admixture 303 lb

* Hundred weight of cement.

The mixing water adjustment, calculated using Eq. (4-3), 5.2.8 Step 8-Proportion companion mixtures using

is cement and fly ash1. An ASTM Class C fly ash is to be used which has

(36 - 35) x 8 = + 8 lb/yd3of concrete a bulk specific gravity of 2.64.2. The recommended limits for replacement given in

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Companionmixture #1 20 percentCompanion mixture e

Companion mixture #3

Companion mixture # 4

25 percent

30 percent

35 percent

3. For companion mixture #l, the weight of fly ashper of concrete is (0.20) x (977) = 195 lb. thereforethe cement is (977) - (195) = 782 lb. The weights ofcement and fly ash per of concrete for the remainingcompanion mixes are calculated in a similar manner. The

values are as follow:

4. For the first companion mixture, the volume ofcement per yd3 of concrete is (782)/(3.15 x 62.4) = 3.98

and the fly ash per yd3 is (195)/(2.64 x 62.4) = 1.18The volume of cement, fly ash, and total cementitious

material for each companion mixture are:

5. For all of the companion mixtures, the volumes ofcoarse aggregate, water, and air per of concrete arethe same as for the basic mixture that contains no other

cementitious material. However, the volume of cementi-tious material varies with each mixture. The requiredweight of sand per of concrete for companion mix-ture #1 is calculated as follows:

Component Volume (per cubic yardof concrete.

Cementitious material 5.16

Coarse aggregate

Water (including 2.5 oz/cwtretarding mixture)

Air

10.77

486

0.54

Total volume 21.33

companion mixture are as follows:

Companion mixture. #1


Companion mixture 33


As shown in this example, the dosage rate of chemicaladmixture may or may not need to be adjusted whenother cementitious materials are used. There are noexisting guidelines to be followed when doing this adjust-ment other than experience. The proportioner needs tobe aware of the possible need for this adjustment. Duringtrial batches, verify proper dosage rates for all chemicaladmixtures.

5.2.9Step 9-Trial mixtures-Trial mixtures are to be

conducted for the basic mixture and each of the fourcompanion mixtures. The sand is found to have 6.4 per-cent total moisture, and the coarse aggregate is found tohave 0.5 percent total moisture, based on dry conditions.Corrections to determine batch weights for the basic mix-tures are done as follows: sand, wet = (947) x (1 +0.064) = 1008 lb; coarse aggregate, wet = (1854) x (1 +0.005) = 1863 lb; and water, correction = (303) - (947)

(0.064-

0.011)-

(1854)(0.005 -

0.007) = 257 lb.Thus the batch weight of water is corrected to accountfor the excess moisture contributed by the aggregates,which is the total moisture minus the absorption of theaggregate.


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Companionmixture# l

Cement

Fly ash

Sand

Coarse aggregate

Water (including 2.5 oz/cwt

retarding admixture)


Cement

Fly ash

Sand

Coarse aggregate

Water (including 25 oz/cwt



Cement

Fly ash

Sand

Coarse aggregate




Cement

Fly ash

Sand

Coarse aggregate



Dry weights

782 lb

195 lb

916 lb

1854 lb

303 lb

Dr y weights

733 lb

244 lb

908 lb

1854 lb

303 lb

Dry weights

684 lb

293 lb

900 l b

1854 lb

303 lb

Dry weights

635 lb

342 lb

892 lb

1854 lb

3 0 3 lb

Batch weights

782 lb

195 lb

975 lb

1863 lb

259 lb

Batch weights

733 lb

244 lb

966 lb

1863 lb

259 lb

Batch weights

684 lb

293 lb

958 lb

1863 lb

259 lb

Batch weights

635 lb

342 lb

949 lb

1863 lb

259 lb

The size of the trial mixture is to be 3.0 The reducedbatch weights to yield 3.0 are as follows:

Chemical admixtures (included as part of the mixing water)

5.2.10Step 10--Adjust trial mixture proportions-The

batch weights for each trial mixture were adjusted to ob-tain the desired slump, before and after the addition ofthe HRWR, and the desired workability. The adjustmentsto the batch weights for the basic mixture and companionmixture #4 will be shown in detail. Those for the otherthree companion mixtures will be summarized.

Correcting these to dry weights gives:

Cement 108.56lb

Sand, dry (112.00)/(1.064) = 105.26 lb

Coarse aggregate, dry (207.00)/(1.005) = 205.97 lb

Batch water (29.56 + 5.58*- = 34.73 lb

*= Sand moisture correction.= C/A moisture correction.

The actual yield of the trial mixture was:

Cement

Sand

Coarse aggregate

Water

Air

(108.56)/(3.15 x 62.4) = 0.55

(105.26)/(2.59 x 62.4) = 0.65

(205.97)/(2.76 x 62.4) = 1.20

(34.73)/(62.4) = 0.56

(0.02)(3.0) = 0.06

Total volume 3.02

Adjusting the mixture proportions to yield 27 gives:

Cement 971 lb

Sand, dry 941 lb

Coarse aggregate, dry 1841 lb

Water (including 2.5 oz/cwt retarding admixture) 311 lb

The new mixture proportions result in a w/c+p of 0.32.To maintain the desired ratio of 0.31, the weight of ce-ment should be increased to (311)/(0.31) = 1003

of concrete. The increase in volume due to the adjust-ment of the weight of cement is (1003 -971)/(3.15 x62.4) = 0.16 which should be adjusted for by re-moving an equal volume of sand. The weight of sand tobe removed is 0.16 x 2.59 x 62.4 = 26 lb. The resultingadjusted mixture proportions are:

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HRWR to the adjusted mixture at a dosage rate of 8oz/cwt produced a slump of 6 in., 11 oz/cwt produced aslump of 10 in., and 16 oz/cwt caused segregation of thefresh concrete. In all cases, a constant dosage rate of

retarding admixture (2.5 oz/cwt) was also added to themixture with the mixing water. The HRWR at a dosage

rate of 11 oz/cwt was added approximately 15 min afterinitial mixing.

3. It was determined that the concrete mixture with a10-in. slump had adequate workability for proper place-ment, so no adjustment was necessary to the coarse

aggregate content.4. The air content of the HRWR mixture was mea-

sured at 1.8 percent, so no correction was necessary.5. Note that the addition of the HRWR might require

an adjustment in the cementitious content and yield of

the mixture to account for the additional volume of ad-mixture. Under normal dosage rates, 10 to 15 oz/cwt, thecorrection needed is negligible and not shown in thisexample.

6. The 28-day compressive strength of the basic mix-

ture was found to be 11,750 psi, which satisfied the re-quired laboratory test strength of 11,600 psi.

5.2.10.2 Companion mixture #4

1. The actual amount of mixing water required (in-cluding 2 oz/cwt retarding admixture) to produce a 1 to2-in. slump was less than that calculated for this mixture.The actual batch weights were:

Correcting these by dry weights gives:

The actual yield of the trial mixture was:

Cement

Fly ash

Sand

Coarse aggregate

W t

(70.56)/(3.15 x 62.4) = 0.36

(38.00)/(2.64 x 62.4) = 0.23

x 62.4) = 0.61

(205.97)/(2.76 x 62.4) = 1.20

(32 67)/(62 4) 0 52

Water (including 2.5 retarding admixture)

The new mixture proportions result in a w/c+pof 0.30.The desired ratio was 0.31, so the weight of cementitiousmaterial may be reduced. The percentage of fly ash forthis mixture is 35 percent, and should be maintained. Thenew weight of cementitious material is (296)/(0.31) = 955

lb. Of this, 35 percent should be fly ash, giving 334 lb offly ash and 621 lb of cement. The change in volume dueto the reduction in ccmentitious material is:

(639 -621)/(3.15 x 62.4) +

(344 -334)/(2.64 x 62.4) = 0.15

Therefore, 0.15 of sand should be added, which in-creases the weight of sand by (0.15)(2.59)(62.4) = 24

of concrete. The adjusted mixture proportions are:

2. In adding HRWR to the adjusted mixture to pro-duce a flowing concrete, it was found that 9 oz ofHRWR per 100 lb. of cementitious material produced aslump of 9 1/2 in. under laboratory conditions. A retardingadmixture (2 oz/cwt) was added to the concrete withmixing water, and the HRWR was added approximately

15 min after initial mixing.

3. The HRWR mixture had adequate workability, sono adjustment to the coarse aggregate content was

necessary.4. The air content of the HRWR mixture was mea-

sured at 2.1 percent.5. The average-28-day compressive strength of

specimens cast from the laboratory trial mixture wasfound to be 11,370 psi.

5.2.10.3Summary of trial mixture performance-Thefollowing is a summary of the results of the adjusted

laboratory trial mixtures.

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* C.M. =companion mix.

Note: This table has intentionally omitted the water in HRWR to avoidconfusion. Section 3.2 of this guide suggests this be done to properly

determine w/c + p.

5.3.11Step 11-Select optimum mixture proportions-Companion mix (c.m.) #4 was the only trial mixture thatwas significantly less than the required compressivestrength of 11,600 psi at 28 days. Field trial batches weremade for all of the others. The mixtures were adjusted tothe desired slumps, both before and after addition of theHRWR, and strength specimens were cast. Concretetemperatures were also recorded. The test results areshown below.

28-day compressive ConcreteMixture strength, psi temperature, deg F

Basic 10,410 94

C.M. #1 10,570 93

C.M. #2 10,530 89

C.M. #3 10,490 84

Although all mixtures produced the required fieldstrength of 10,400 psi at 28 days, the reduced concretetemperature and cementitious material content of com-panion mix #3 made it more desirable to the ready-mixproducer. As ambient conditions or material propertiesvary, additional field adjustments may be necessary.

CHAPTER6-REFERENCES6.1-Recommended references

The documents of the various standards-producingorganizations referred to in this document are listedbelow with their serial designation.

The preceding publications may be obtained from thefollowing organizations.

American Concrete InstituteP.O. Box 19150Detroit, MI 48219

American Society for Testing and Materials1916 Race StreetPhiladelphia, PA 19103

American Concrete Institute (ACI)211.1

212.3R214

226.1R

301

318

363R

Standard Practice for Selecting Proportions forNormal, Heavy Weight, and Mass Concrete

Chemical Admixtures for ConcreteRecommended Practice for Evaluation ofStrength Test Results of ConcreteGround Granulated Blast Furnace Slag As aCementitious Constituent in ConcreteSpecifications for Structural Concrete for Build-ingsBuilding Code Requirements for ReinforcedConcreteState-of-the-Art Report on High-Strength Con-crete

American Society for Testing and Materials (ASTM)

C 29

C 33

C 39

C 94C 494

C 618

C 917

Standard Test Method for Unit Weight andVoids in AggregatesStandard Specification for Concrete Aggregates

Test Method for Cylindrical Strength of Cylin-drical Concrete SpecimensSpecification for Ready Mixed ConcreteStandard Specification for Chemical Admixturesfor ConcreteStandard Specification for Fly Ash and Raw orCalcined Natural Pozzolan for Use as a MineralAdmixture in Portland Cement ConcreteStandard Method of Evaluation of CementStrength Uniformity from a Single Source

CONVERSION FACTORS1 in. = 25.4 mm

1 psi = 6.8 kPa1 lb/in.3 = 2.768 x1 = 0.59

ACI211.4R-93 was submitted to letter ballot of the committee and approved

in accordance with ACI balloting procedures

Copyright American Concrete InstituteProvided by IHS under license with ACI Licensee=Aramco HQ/9980755100

Not for Resale, 01/22/2006 07:51:27 MSTNo reproduction or networking permitted without license from IHS

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Documents

ACI 211.4 (R1998) StdPract SelectProps HSConcrete PortCementFlyAsh