Fine Sand for Usein

PC Concrete

Final Reportfor

MLR-88-6

March 1989

Highway Division

-----t:&tt.lowa Department-------~,of Transportation

Fine Sand For Use

In P.C. Concrete

Final ReportMLR-88-6

Kevi n JonesCement and Concrete Engineer

Office of MaterialsIowa Department of Transportation

March 1989

Abstract

Introduction

Objective

Materials

Scope

Testing

Discussion of Results

Conclusions

Recommendations

Appendix

Table of Contents

1

2

4

4

4

5

8

14

15

16

Disclaimer

The contents of this report reflect the views of the authorand do not necessarily reflect the official view of the IowaDepartment of Transportation. This report does not constitutea standard, specification or regulation.

Page 1

ABSTRACT

In several locations of Iowa, it is becoming more difficult to

produce concrete sand consistently at a reasonable cost. Both

ASTM and AASHTO have specifications for concrete sands that allow

a finer, poorer graded sand than Iowa specifications.

The objective of the study was to develop standard mix designs to

permit the use of finer graded sand for p.c. concrete. Three

hundred cylinders were made from five sands available in the

state. Based on the results of the study, the following is

recommended.

1. Create another class of concrete sand by:

a. Lowering the current mortar strength ratio from 1.5

to 1. 3

b. Raising the allowance for the percent passing one sieve

and retained on the next from 40 to 45.

c. Including a provision that 25 to 60 percent passing the

number 30 sieve is required for the sand.

2 • Modify the standard paving mixes with and without fly ash for

use with the finer sand as follows:

a . 8% more cement and fly ash for B-2 to B-5 mixes.

b. 7% more cement and fly ash for A-2 to A-5 mixes.

c. 5% more cement and fly ash for C-2 to C-5 mixes and

water reduced mixes.

Page 2

INTRODUCTION

The specifications for concrete sand in Iowa have been used for

many years with very good results. In several locations of the

state, it is becoming more difficult to produce concrete sand

consistently at a reasonable cost. Both ASTM and AASHTO have

specifications for concrete sands that allow a finer, less well

graded sand than the Iowa specification. An earlier study

included in Appendix B concluded that finer sand may be feasible

in Iowa concrete mixes with some modifications. The ASTM and

AASHTO specifications are based on the use of trial mix testing

prior to construction. Iowa does not currently use the trial mix

procedure.

Changes in the gradation requirements for concrete sand in Iowa

are shown in table I. The specifications published in the I94B

"Standard Specifications for Highway and Bridge Construction"

were quite different from the previous specifications.

The major changes were:

1. Limit the gradation so that not more than 40 percent shall

pass one sieve and be retained on the sieve with the next

higher number.

2. Increase the mortar cube strength ratio to 1.5.

3. Eliminate the option of designing special mixes using sand

failing to meet cube strength or gradation requirements.

4. Adopt a #200 sieve requirement of 0 to 2.5% passing.

The changes since 1948 have been to reduce the percent passing

the #200 sieve and open up the gradation requirements on the

Page 3

other sieves. Otherwise, little change has been made in the last

forty years.

Table 1. Gradation Changes to Concrete Sand Specificationsfrom 1924 to 1988

Percent Passing

3/8"#4#8#16#30#50#100#200

1924a

10095-10085-100

15-40

0- 5

1930a

10095-10080-100

15-40

0- 5

1937a

10095-10080- 95

20-40

0- 5

1948e

10095-10075- 95

20- 55

0-2.5

1960e

10095-10075-100

0-1.5

1977e

10090-10070-100

0-1 . 5

Mortar cStrengthRatio LOb 1. Od 1. Od 1. 5f 1.5 1.5

a. Sand failing gradation may be used if mortar strength isadequate.

b. Sand with a mortar strength ratio of between 1.0 and 0.75 dueto poor grading may be used provided that the cement isincreased to meet minimum compressive strength on concretemade with the project aggregates.

c. The proportions and testing of mortar cubes changed in the1940's.

d. Sand which fails mortar strength due to poor grading may beused in special mixtures designed by laboratory studies.

e. When fine aggregate is sieved through the following numberedsieves: 4, 8, 16, 30, 50 and 100, not more than 40 percentshall pass one sieve and be retained on the next highernumbers.

f. Sand which has shown satisfactory mortar strength may beaccepted without further mortar strength tests so long as itsfineness modulus is not less than that of the sand from thatsource which showed a satisfactory mortar strength minus 0.30.

Cement:

Page 4

OBJECTIVE

The objective of the study was to determine the necessary

modification to the standard mix designs to permit the use of

finer, less well graded sand for concrete mixes.

MATERIALS

The following materials were used in the study:

Type I, standard laboratory blend of eight portland

cements available in Iowa (AC7-350).

Fly Ash: Ottumwa, Class C (ACFB-93)

Air Entraining Agent: Ad Aire, Single Strength,

Carter-Waters Corp.

Coarse Aggregate: Martin Marietta (Fort Dodge A94002) (AAC7-29)

Fine Aggregate: 1. Martin Marietta (West Des Moines A77510)(AASB-112)

2. Giese Construction (Conn A55520) (AASB-123)

3. Van Dusseldorp (Colfax (A50502) (AASB-117)

4. Finley (Shenandoah A73504) (AASB-155)

5. Vulcan Materials (Oxford Mills A53516)(AASB-154)

SCOPE

Five sands were chosen to represent the range of fine sands in the

state. Each sand was tested for gradation, coal, shale,

absorption, organic impurities, x-ray diffraction and mortar

strength. To build the sands to proper gradations for testing,

Page 5

fines from the concrete sand were obtained. No fines were

available from the Conn Pit. Instead, a portion of the concrete

sand was graded and blended into the remaining concrete sand. The

gradation chosen and the mortar strength obtained are in Table 2.

All aggregate test results are in the Appendix.

It should be mentioned that the fine gradation of Shenandoah sand

was tested twice for mortar strength. The first test showed a

ratio of 1.50, the same as the coarse gradation. The second test

was performed to verify the results. The second run was 1.40.

The two results are well within the single-laboratory coefficient

of variation for ASTM test procedure C109.

TESTING.

Thirty mixes were made according to ASTM C1n and 300 cylinders

were cast and tested for the project. The mixes are as follows:

Mix Mix Cemen~ Fl y As ~ Coarse Concrete FineNo. Designation (H/yd. ) (H/yd. ) Agg. ( %) Sand ( %) Sand ( %)

A C-3-C 513 91 55 45

B B-3-C 407 72 55 45

C C-3-C 513 91 55 45

D B-3-C 407 72 55 45

E C-3-C Mod 529 104 55 45

F B-3-C Mod 418 82 55 45

The test results are shown in Table 3.

Page 6

TABLE 2. SUMMARY OF SAND DATA

SOURCE , W. DES MOINES CONN COLF AX SHENANDOAH OXFORD MILLS,COUNTY POLK KOSSUTH JASPER PAGE JONESOPERATOR I MARTIN MARIETTA GIESE VAN DUSSELOOPH FINLEY VULCAN MATERIALS

LAB NO COARSE SAND

AASB-II2 AASB-123 AASB- II7 AASB-155 AASB-I543/B 100 100 100 100 100#4 99 100 91 96 95#B B8 94 81 90 89#16 11 14 13 15 14#30 43 46 41 43 43#50 12 18 12 1.2 9.6#100 1.5 1.9 0.1 0.2 0.8#200 0.2 0.3 O. I O. I 0.3

FINE MODULUS 2.86 2.66 2.83 2.89 2.89

MORTAR STR RATIO 1.12 1.50 1.68 I. 50 1.63STRENGTH 7920 6890 1110 6910 1490~ WATER 41 44 42 41 42~ FLOW 115 1I0 115 110 110

MORTAR SANDLAB NO AAS8- I13 NONE AAS8-118 AAS8- IS1 AAS8-156

LAB NO FINE SAND

AAS8-158 AAS8-244 AAS8-Z43 AAS8-241 AAS8-2423/8 100 100 100 100 100#4 99 100 98 98 91#8 93 95 90 9S 94#16 83 19 80 85 85#30 62 51 60 51 58#50 19 19 15 14 13#100 3.3 1.5 1.5 0.8 1.2#200 0.4 0.2 0.2 0.3 0.3

FINE MODULUS 2.41 2.48 2.56 2.51 2.52

MORTAR STR RATIO I. 30 1.34 1.45 1.4 1.42STRENGTH 5910 6150 6660 6460 6530i WATER 44 49 42 43 43i FLOW lID lID II0 101 110

TABL

E3

.SU

MM

ARY

OF

TEST

RES

ULT

S

MIX

SAN

OCE

MEN

TFL

YAS

HW

/C+

FAA

IRSL

UM

PC

OM

PRES

SIV

EST

R.

MOR

TAR

FIN

EN

ESS

SP

EC

IFIC

"NO

(#/Y

03

)(1

1/'(0

3)(;

0(I

N.)

7-0A

Y28

-0A

YST

REN

GTH

1100

Ulll

SSU

RFA

CE

'"<0 (J)

---lA---WESrJJ:f·r:------S13-------9r-----O:392-----S:0-----r:-SO------4830------S4S0------1:-7------S:-Sr-------12~~37--

-.J

IBW

EST

O.M

.40

;772

0.4

72

6.0

1.0

041

5054

001

.75

.51

12..3

7lC

WES

TD

.M..

51

391

0.4

02

6.4

1.5

050

9060

301

.35

.31

15..6

610

WES

TO

.M.

407

720

.50

96

.51

.25

4000

4990

1..3

5.3

11

5.6

6IE

WES

TD

.11.

52

910

40

.39

96

.21

.25

5120

6520

1.3

5.3

115

..66

IFW

EST

D.M

.41

882

0.4

88

6.4

1.2

540

5053

001

.35

.31

15

.66

2ACO

NN51

391

0.4

75

6.0

1.2

548

1065

601

.55

.43

13

.77

28CO

NN40

772

0.5

84

6.0

1.0

036

2052

101

.55

.43

13

.77

2CCO

NN5

13

910

.46

66

.51

.25

4590

6280

1.3

5.3

41

4.7

120

CONN

40

772

0..5

83

6.6

1.2

530

6045

501

..35

.34

14

.71

2ECO

NN52

910

40

.44

36

.41

.50

4790

6380

1..3

5.3

41

4.7

12F

CONN

418

820

.59

25

.81

.25

3550

4910

1.3

5.3

41

4.7

1

3ACOlFA~:

51

391

0.3

82

5.8

1.5

053

2064

601

.75

.50

12

..37

38CO

LFA

X40

772

0.4

60

6.2

1.2

541

5053

101

.75

.50

12..3

73C

COLF

AX

51

391

0.4

07

6_

31

.50

5210

6400

1.4

5.3

814

..17

30CO

LFA

X40

772

0.4

91

6.5

1.2

538

6050

801

.45

.38

14

.17

3ECO

LFA

X5

29

104

0.3

85

6.0

1.2

554

9063

601

.45

.38

14..1

73F

CO

lFH

X41

88

20

.47

66

.21

.25

4420

5600

1.4

5.3

81

4.1

7

4RSH

ENAN

OOAH

51

391

0.3

82

6.1

1.5

049

9060

201

.55

.53

11..

454B

SHEN

ANOO

AH40

77

20

.46

66

.21

.50

3690

4760

1.5

5.5

311

..45

4CSH

ENAN

OOAH

51

391

0.4

02

6.0

1.2

550

5061

301

.45

.36

14..0

240

SHEN

ANDO

AH40

772

0.4

84

6.5

1.2

540

8050

301

.45

.36

14

.02

4ESH

ENAN

DOAH

52

910

40

.38

56

.31

.50

5180

6660

1.4

5.3

61

4.0

24F

SHEN

ANOO

AH41

882

0.4

76

6.5

1.2

542

205

33

01

.45

.36

14

.02

SAO

X.

11Il

lS5

13

910

.38

25

.51

.25

5450

6610

1.6

5.5

31

2.0

258

OX

.H

IllS

407

720

.46

65

.91

.25

4750

5630

1.6

5.5

31

2.0

25C

OX

.M

IllS

513

910

.39

76

.01

.25

5160

6350

1.4

5.3

61

4.0

350

OX

.11

IllS

407

72

0.4

84

6.6

1.2

536

8045

501

.45

.36

14

.03

5EO

X.

HIl

lS52

910

40

.37

46

.11

.25

5310

6270

1.4

5.3

61

4.0

35F

OX

.H

IllS

418

820

.45

87

.51

.50

3670

4650

1.4

5.3

61

4.0

3

NO

TES:

MIX

AAN

D8

ARE

WIT

HCO

ARS

ESA

NO

I'1IX

CTH

ROUG

HF

ARE

WIT

HFI

NE

SAN

DST

REN

GTH

AV

ERA

GES

ARE

8ASE

DON

FIV

EC

YlIN

OE

RS

Page 8

DISCUSSION OF RESULTS

The test results are shown graphically in Figures 1 through 5.

The trend for most of the sands was:

1. The fine sand produced lower strength mixes.

2. Adding 5 percent cement and fly ash to the fine sand mixes

increased the strength.

With the Shenandoah sand this trend did not exist. The strength

was consistently higher when the fine sand was used in place of

the concrete sand. The results would be consistent with the data

obtained from the mortar strength testing on the sand. The mortar

strength changed little despite the changed gradation. Figures 1

through 5 also indicate that the B mix is more noticeably affected

by the change in sand gradation.

Table 4 shows the overall averages for the six different mix

types. The difference between the C mix with coarse sand and the

C mix with fine sand is 180 psi at 28 days. A statistical signif­

cance test was performed assuming normal distribution and standard

deviations of 300 psi. A 180 psi difference in the average

strengths is significant at the 0.05 level of significance.

Page 9

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Page 14

Table 4 Overall Average, Compressive Strength

ABC

C7-day508050205180

Mix28-day642062406440

BDF

B7-day407037403980

Mix28-day533048405160

Based on the averages in Table 4, the projected required increase

in cementious material factor to obtain equivalent compressive

strength with the fine sand =

1. 9%

4.5%

=

=S 1 -(6440(6420

5%

(5080 psi - 5020 psi)(5180 psi - 5020 psi)

5%C mix (7-day)

C mix (28-day)

B mix (28-day) = 7.6%

( 7 day) 3940 = 6.9%

CONCLUSIONS

The followin9 conclusions can be obtained from the research:

1. Use of a finer sand grading in concrete will in most instanceslower compressive strength.

2. The reduction in compressive strength with finer sand gradingmay be more severe for leaner mixes.

3. The 7-day compressive strengths were less affected by thegrading change than the 28-day.

4. Increasing the cement and fly ash content by a small amountcan offset the strength reduction caused by the finergradation.

Page 15

RECOMMENDATIONS

The following recommendations are suggested.

1. Add to the specifications a class of sand that is the same as4110 sand except:

a. lower the mortar strength ratio from 1.5 to 1.3.

b. allow 45 percent instead of 40 percent passing one sieveand retained on the next.

c. Include a provision that material passing the number 30sieve shall be 25 percent or more and 60 percent or less.

The specification would read as follows:

Section 4111. Class Z Fine Aggregate for Concrete.

4111.01 DESCRIPTION. Class Z fine aggregate for concreteshall be used in mixes specifically permitting its use. Class Zfine aggregate shall meet the requirements of 4110.01 and 4110.02.

4111.02 GRADATION. Class Z fine aggregate for concrete shallmeet requirements of Section 4109 for gradation number 1. Inaddition, when the fine aggregate is sieved through the followingnumbered sieves -4, 8, 16, 30, 50 and 100 - not more than 45percent shall pass one sieve and be retained on the sieve with thenext higher number.

4111.03 MORTAR STRENGTH. Class Z fine aggregate from anapproved source shall have a historic record of mortar strength,determined by Laboratory Test Method 212, of not less than 1.3times the strength of mortar in which standard sand is used.

2. Modify Section 2301 of the specifications to allow the use offine sand with a modification to the concrete mixes. Themodified mixes should be as follows:

a . 8% more cement and fly ash for B-2 to B-5 mixes.

b. 7% more cement and fly ash for A-2 to A-5 mixes.

c . 5% more cement and fly ash for C-2 to C-5 mixesincluding water reduced mixes.

The increase in cementitious material will be one half fly ashand one half cement by weight.

Page 16

APPENDIX A

Page 17

SUMMARY OF SAND TESTING

Tes ts w. D. M. Conn Colfax Shenandoah OXford Mi 11 s

Absorption 0.25 1. 06 0.30 0.25 0.45

Spec. Gravity 2.66 2.63 2.67 2.64 2.66

Coal 0.1 0.0 O. 1 0.0 0.0

Shale O. 1 O. 1 0.1 0.1 0.1

Color #1 #1 #1 #1 #1

Page 18

COARSE AGGREGATE GRADATION

Sieve Size

1"3/4"1/2"3/8"#4#200

% Passing

100774012

0.5O. 3

~ <.0-o s» <0 CD

WES

TDE

SM

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SPI

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17

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31

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0-70

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Page 24

APPENDIX B

Page 25

A

Study of

Fine Sand From Nine Mile Island

At Dubuque

Kevin Jones

Cement and Concrete Engineer

May, 1988

8

Page 26

INTRODUCTION

The specifications for concrete sand in Iowa have been used formany years with very good results. In several locations of thestate, it is becoming more difficult to produce concrete sandconsistently at a reasonable cost. Both ASTM and AASHTO havespecifications for concrete sands that allow a finer, poorergraded sand than the Iowa specification. The ASTM and AASHTOspecifications are based on the use of trial mix testing priorto construction. Iowa does not currently use the trial mixprocedure.

Changes in the gradation requirements for concrete sand in Iowaare shown in table 1. The specification published in the I948"Standard Specifications for Highway and Bridge Construction"were quite different from the previous specifications.The major changes were:

1. Limit the gradation so that not more than 40 percent shallpass one sieve and be retained on the sieve with the nexthigher number.

2. Increase the mortar cube strength ratio to 1.5.

3. Eliminate the option of designing special mixes using sandfailing to meet cube strength or gradation requirements.

4. Adopt a #200 sieve requirement of 0 to 2.5% passing.

The changes sinc~ 1948 have been to reduce the percent passingthe #200 sieve and open up the gradation requirements on theother sieves. Otherwise, little change has been made in the lastforty years.

Page 27

Table 1. Gradation Changes to Concrete Sand Specificationsfrom 1924 to 1988

Percent Passing

1924a 1930a 1937a 1948e 1960e 1977e

3/8" 100 100 100 100 100 100#4 95-100 95-100 95-100 95-100 95"100 95-100#8 85-100 80-100 80- 95 75- 95 75-100 70-100#16#30 15-40 15-40 20-40 20-55#50#100 0-5 0-5 0- 5#200 0-2.5 0.1.5 0-1.5

Mortar cStrengthRati 0 LOb 1. Od 1. Od 1. 5f 1.5 1.5

a. Sand failing gradation may be used if mortar strength is adequate.

b. Sand with a mortar strength ratio of between 1.0 and 0.75 due to poorgrading may be used provided that the cement is increased to meet minimumcompressive strength on concrete made with the project aggregates.

c. The proportions and testing of mortar cubes changed in the 1940's.

d. Sand which fails mortar strength due to poor grading may be used inspecial mixtures-designed by laboratory studies.

e. When fine aggregate is sieved through the following numbered sieves: 4,8, 16, 30, 50 and 100, not more than 40 percent shall pass one sieve andbe retained on the next higher number.

f. Sand which has shown satisfactory mortar strength may be accepted withoutfurther mortar strength tests so long as its fineness modulus is not lessthan that of the sand from that source which showed a satisfactory mortarstrength minus 0.30.

Page 28

OBJECTIVE

The objective of the study was to determine the feasibility ofusing a finer sand than is now allowed by Iowa D.O.T.specifications in portland cement concrete.

MATERIALS

The following materials were used in the study:

Cement: Type I, standard laboratory blend of eight portlandcements available in Iowa (AC7-350).

Fly Ash: Ottumwa, Class C (ACF8-22).

Coarse Aggregate: Martin Marietta (Fort Dodge A94002)(AAC7-28).

Fine Aggregate: 1. Cordova, IL AIL502 (AAS7-D196)2. Nine Mile Island, Dubuque A31502

(AAS8-0003)3. Nine Mile Island, Dubuque A31502

(AAS8-0004).

Air Entraining Agent: Ad Aire, Single Strength,Carter Waters Corp.

PROCEDURE

Five mixes were made and tested as shown in Table 2. Mixes 1through 3 are the standard C-4-C mix proportions. Mix 4 and 5are mixes with 5 percent more cement and fly ash than mixes 1through 3. Table 3 is the aggregate gradations for the mixes.The strength results are shown graphically in Figure 1 and 2.

-0

TABL

E2

MIX

RESU

LTS

'"<D fi) N <.0

Air

Str

engt

h(P

SI)

Mix

Sand

Cem

ent

Fly

Ash

W/C

+C

onte

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ump

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pres

sive

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xura

lN

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Yd.

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%(I

n.)

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ay28

Day

7D

ay28

Day

1D

ubuq

ueFi

ne52

995

0.38

06.

51.

2550

5062

5074

079

0I

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ueC

oars

e52

995

0.37

66.

21.

055

7064

8078

084

0

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ordo

va52

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0.37

26.

51.

2554

2070

6079

088

0

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ueFi

ne55

610

00.

363

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1.25

5370

6450

840

850

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rse

556

100

0.36

76.

01.

2555

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6083

085

0

Page 30

TABU 3 AGGREGATE GRADATONS

(Percent Passing)

Sieve No. Nine Mile Island Nine I~ile Island Cordova Fort DodgeFine Coarse Coarse Aggr.

1" 1003/4" 771/2" 403/8" 100 100 100 12#4 99 94 99 0.5#8 93 75 93 0.3#16 81 60 79#30 58 47 44#50 12 18 8.5#100 0.6 2.3 1.0#200 0.3 0.8 0.2

Fineness Modulus 2.56 3.04 2.75Mortar Stren9thRatio 1.4 1.3 1.6

Combined Grading (Percent Pas s inq )

1" 100 100 1003/4" 88 88 881/2" 70 70 703/8" 5.6 56 56#4 50 47 50#8 47 38 47#16 41 30 40#30 29 24 22#50 6.2 9.2 4.4#100 0.4 1.3 0.6#200 0.3 0.6 0.2

Fineness Modulus 4.82 5.06 4.92Specific Surface(Sq. Ft./Lb.) 14.9 14.2 13.4

FIGU

RE1.

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Page 33

TEST RESULTS

The fine sand from Dubuque tested about 5 percent lower onstrength in the C-4-C mix than the coarse sand from Dubuque.The hi gher cement factor mi x with the fi ne sand compared veryfavorably with the C-4-C mix and coarse sand. Strengths for thehigher cement factor mix and fine sand were within 30 psi on the28-day compressive and 10 psi on the 28-day flexural of those forthe standard C-4-C mix with coarse Dubuque sand.

Results on the higher cement factor mix and coarse Dubuque sandwere different than expected. The mixes were repeated and thesame result of no strength increase with the higher cement andfly ash content occurred. In order to realize a strengthdifference, the water to cement ratio (w/c) would normally needto go down. The reduction in wlc for the coarse sand was abouthal f that of the fine sand mix.

Results on the mix with Cordova Mississippi sand were asexpected. The fineness modulus of the Cordova sand was betweenthat of the two Dubuque sands. Because the Cordova sand had lessmaterial passing the #30 through #200 sieves, the surface area ofthe aggregate was less which contributed to a slightly lower wlcratio. The 28-day compressive strength was 580 psi higher thanany of the other mixes.

SUMMARY

Aggregate shape, texture and grading do have an affect onconcrete strength and workability. The thrust of the study hasbeen to look at the affect of fine aggregate gradation on theconcrete strength~ A lower compressive and flexural strength wasobserved at both 7 and 28 days for the C-4-C mix with finer,poorer graded sand. To reduce the water cement ratio and offsetthe affects of the fine sand, more cement and fly ash were addedto the mix. Five percent of additional cement and fly ash wassufficient to increase the strength of the mix to what the C-4-Cmix was with a coarser sand.

RECOMMENDATIONS

From the limited study it appears that finer concrete sands mayhave application in Iowa provided that adjustments to theconcrete mixes are made. Based on this study, the following workshould be done:

1. Perform tests on at least five other sources of sandrepresentative of sands available from around the state.

2. Examine the effect of silt and organic matter on mortar cubestrengths and concrete strengths with finer sand.

3. Formulate specifications and mix designs to provide concretemixes using finer concrete sand comparable in quality to thecurrent concrete mix designs and specifications.