MISCELLM4EOUS PAPGR S.7&.16

COMPACTION STUDY OFZERO-SLUMP CONCRETE

Cocil D. Burns

Soil and Pavements LAwbweuU. S.Army Gagioe. Yateways Expedmeot Stat;.

P.O0. Box 631, Vicksburg, Miss. 39180

Augst 1976Rleal Reet

*gpw re Feb Muir. Ulsu11s Umsi

Pmumilfu Offha CW of &*%owq$ U.S Army D D C

umis Prelec H& 4078012AQ61 1 i1 1

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SECURITY CLASSIFICATION OF THIS PAGE (Whan 1. Pn.~Cd)

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It.CONROLINGOFFICE NAME ANO ADDRESS 2RPR A

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IS-. OECLASSIFICATION!OOWNGRAOINGSCHEDULE

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I? 17 UION STATEMENT (off StBock 20, It differmnt fromRpol

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C I't 1h' rtlawi cemeiit.

X&. AmTW ACT I Cawlft -im roee e.lt H neeey Rbd idmUffy by block ntaimb.r)

W't .r' i' ' t. t'o' 11 1. Army Engineer Waterways Fxper-.ment Stationin *-Ietth.r 1 9'(, tiet,terriirie the effectiveness of vibratory and static

mV r-r II II; it, thfe cmpict ion of zero-slump portland cement concretepavIempent.;. It w~tll ttrmirted that. heavy vibratory rollers were very effec-tiv- in rtj~tn the try-mix concrete and that the strength properties

(cm;r~o~ v1 trIrIj11A anl flexural strength) were somewhat higher than wouldhatve bt-r ',1t1,itii with it eonventional mix of' the same cement content having

(Continued)

DOD~T 13 EDITION OF I O 5I II9TEunclassified

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';(. Aj11.ITkACT' (C(ontirnue,l).

U slumnp in exc.:,s ()f I in. The surface smoothness, surf'ace texture, andriding quality f the paverment were considered adequate f'or wearing surfar-s-f sec.-ndary r-a:-ls al streets, hul roads, service entranes, tank trail-,etc., and a: a base f,r tny pavement system. Indications are that con-siderable cost reductions inl the construction of portland cement concretepavementLs c:n be realized by ase of dry (zero.-slump) -.,ncrete mixturesplaced and spread by base course or asphalt spreaders and compacted withheavy vibr-a -ry , 1cr.

.- OCT 19

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1

Preface

The study reported herein was sponsored by the Office, Chief of

Engineers, U. S. Army (OCE), under military construction Project No.

4KO78012AQ61, "Compaction Study of Zero-Slump Concrete." The study was

conducted during the period September 1975-March 1976.

Engineers of the U. S. Army Engineer Waterways Experiment Station

(WES) who were actively engaged in the planning, testing, and reporting

phases of this study were Messrs. Ronald L. Hutchinson, Alfred H. Joseph,

Kenneth L. Saucier, and Cecil D. Burns. The work was performed under

the general supervision of Messrs. James P. Sale and Richard G. Ahlvin,

Chief and Assistant Chief, respectively, of the Soils and Pavements

Laboratory. Mr. A. F. Muller was technical monitor for OCE. This re-

port was prepared by Mr. Burns.

Directors of WES during the conduct of the study and preparation

of this report were COL G. H. Hilt, CE, and COL John L. Cannon, CE.

Mr. F. R. Brown was Technical Director.

2

LJ......

Contents

Page

Preface ............ ............................. .

Conversion Factors, U. S. Customary to Metric (SI) Units ofMeasurement ........... ...........................

Introduction ............. .......................... 5

Background ............ ......................... 5Objectives ............ ......................... 5Scope .............. ............................ 5

Test Section ............. .......................... 6

Concrete mixture ........... ...................... 6Placement of concrete .......... .................... 7Compaction of concrete ......... . ................. 7Visual observations .......... ..................... 8

Density and Strength Determinations ....... ............... 8

Performance .............. ........................... 9

Conclusions .......... ........................... 10

Table 1

Photos 1-6

Plate 1

3

-7 .

Conversion Factors, U. S. Customary to Metric (SI) Units of Measurement

U. S. customary units of measurement can be converted to metric (SI)

units as follows:

Multiply BY To Obtain

inches 25.4 millimetres

feet 0.3048 metres

miles (U. S. statute) 1.609344 kilometres

cubic yards 0.7645549 cubic metres

tons (2000 lb mass) 907.1847 kilograms

pounds (mass) 0.4535924 kilograms

pounds (mass) per cubicfoot 16.01846 kilograms per cubic metre

pounds (force) per squareinch 6.894757 kilopascals

pounds (force) per square

inch per inch 27.144713 pascals per metre

4

, S %m ,

COMPACTION STUDY OF ZERO-SLUMP CONCRETE

Introduction

Background

1. The cost of constructing portland cement concrete pavements is

continually rising due to increasing costs of both labor and materials.

A concept involving the use of zero-slump (dry-mix) concrete as a

pavement has been under consideration at the U. S. Army Engineer Water-

ways Experiment Station (WES) for some time. Dry-mix concrete has

been used successfully in England as a base course of both rigid and

flexible pavements and has also been investigated for use in concrete

dams. It is theorized that with proper proportioning a dry concrete mix

will produce higher strengths at lower cement factors than the more

plastic concretes. The water content of concrete is normally higher

than necessary for cement hydration simply to provide workability and

to permit consolidation, which is normally achieved with vibrators.

Thus, if consolidation can be achieved using vibratory or static com-

paction rollers as opposed to internal or pan-type vibrators, it may be

possible to reduce the water content and increase the concrete strength,

which would result in a cost savings. However, probably the most attrac-

tive facet of dry-mix concrete would be that construction cost could

be reduced since there would be no need for side forms and expensive

paving trains.

Objectives

2. The objectives of this study were (a) to determine the

effectiveness of vibratory and static compaction rollers in the compac-

tion of zero-slump portland cement concrete and (b) to evaluate the

strength and surface smoothness of the compacted pavement.

Scope

3. The objectives of the study were accomplished by the construc-

tion of a test section of zero-slump concrete which was incorporated

into a newly constructed road at WES. Two different vibratory rollers,

5

a Buffalo-Bomag BW210-A (Photo 1) and a Dynapac CC-50A (Photo 2), were

used in the study. A 25-ton,* self-propelled, pneumatic-tired roller

(Photo 3) was also used in compacting one item of the test section for

comparison purposes. For each of the vibratory compactors, two thick-

nesses of pavement (6 and 10 in.) were placed and compacted. Only a6-in. thickness was compacted with the pneumatic-tired roller. Test

specimens were cut from the pavement and tested in the laboratory after

28 days for the detrmination of density and strength properties.

Test Section

4. The test section (Plate 1) was 105 ft long by 12 ft wide and

consisted of four test items, each 15 ft long. A 15-ft transition was

provided between items 1 and 2 and between items 3 and 4 which was used

for stopping and reversing the different rollers. The subgrade consisted

of a lean clay soil having an in-place CBR of about 10 or a modulus of

soil reaction k of about 185 psi/in.

Concrete mixture

5. The aggregate used in the concrete mixture was a 1-1/2-in.

maximum-size crushed limestone, and the cement was type I portland cement

(Federal Specification SS-C-19 2G). Trial mixes in the laboratory re-

sulted in the following mixture:

Amount perComponent or Ratio cu yd

Cement 517 lbLimestone coarse aggregate 2350 lbLimestone fine aggregate 1250 lbWater-cement ratio 0.33 by weightSand-aggregate ratio 0.35 by volume

The theoretical'unit weight was 161.27 pcf. Twenty 2-cu-yd batches

were mixed in a stationary batch plant at WES and transported in dump

* A table of factors for converting U. S. customary units of measure-

ment to metric (SI) units is presented on page 4.

6

_______________________________

J b °' . °

trucks to the test site, a distance of about I mile.

Placement of ,orncrete

6. Although zero-slump concrete can be placed using a simple base

course spreader and even by end-dumping the concrete and spreading with

a motor patrol, for this study thu concrete mixture was placed on the

subgrade with an available Barber-Green asphalt finisher (Photo h).

Initially a 4-in.-thick lift was placed in the area designed for the

10-in. thickness and was not compacted (Plate 1). An uncompacted lif't

approximately 7 in. thick was then placed over the entire test section

starting at statiun 1+05 and proceeding toward station 0+00. The con-

crete was placed in a continuous 12-ft-wide lane with no transverse

joints.

Compaction of concrete

7. Compaction of the concrete mixture was started on items 4 and

5 with the BW210-A vibratory roller as soon as placement of the 7-in.-

thick loose lift proceeded far enough into the transition area between

items 3 and 4 to permit stopping and reversing the roller in the transi-

tion area. The small capacity of the available mixer plus the long haul

distance resulted in a time lag of about 1 hour from the start of place-

ment of concrete in the initial 4-in. bottom lift until the time of

compaction rolling on the surface of the l-in. uncompacted concrete.

8. The drum width of both the BW210-A and the CC-50A rollers is

84 in., and the same rolling pattern was used for both rollers. The

rolling pattern was as follows: The roller was started with one edge

of the drum extending slightly over the edge of the concrete lane and

traveled in the forward direction into the transition area, where it was

stopped and reversed; it then returned in the same track (Photo 5). The

roller was then shifted laterally to the opposite side of the lane, and

the same procedure was followed. This pattern resulted in two passes

of the roller over the entire width of the paving lane with some over-

laps in the center. The first two passes of the roller were made using

only the static weight of the roller. Six to eight additional passes

were then applied with the drum vibrating. The BW210-A roller was

operated at a maximum frequency of 2000 vibrations per minute (vpm) and

7

AWL~4

at ,ene-half to maximium ampiitude. The CC-5. OA roller wa:; .peratt.,J ;j -i

frequency of ,40() vpm arnd at maximum amplitude. <m.ne w wa. er wa n a[I Ie

to the drums during the rolling operations. In it.em 1, t") C:-LOA

roller was used a, a static rnller (without vibrati ii) fer tw,

of breakdown rol ing, and then six passes )f th, JS-t,,r, :.,mit .

roller with a 90-psi tire pressure were appi ied. Fiil r rg w,:

cmplished by an additional two passes of the CC->jA with r, vibration.

Visual observations

9. The concrete mixture appeared quite st-ibie under the ii'fferen:.

compaction rollers. There was no tendency for shoving or di splac-emtent

of the material except for a slight depression in the tran:sitin ar,-'as

where the rollers stop~ped and reversed. This could b( (iiminated n an

actual job by staggering the location for stopping arid reversing the

roller. There appeared to be good consolidation of the dry concrete mix

under the external vibration of both vibratory rollers. The 7-i'.. un-

,'ompacted thickness conslidated to a compacted thickness -f ab,1t , in.,

and the ll-in. uncompacted lift consolidated to a thickne.;s of r..5 to

9 iii. The vibratory rollers had a tendency to work the fines to the

surface, and the water applied to the vibrating drums re.ulted in a

stlrry which filled the surface voids as indicatul in Photo 6. The

;neumatic-tired roller left a more open textured surface.

10. The compacted pavement was moist-cured for a period of ( iays.

Density and Strength Octerminatiens

ii. Core samples and beam samples were cut from each item of the

pavement and tested for the determination ,.f unit weight, void content,

compressive strength, splitting tensile strength, and fle.,ural strength.

A summary of the test results is shown in Table i. From thesce data, it

can be seen that both vibratory rollers were more effective n compact-

ing the concrete mix than was the static-weight, pneumatic-tired ro'ler.

The densities and strengths developed by the two vibratory rollers were

about equal except for the 10-in, pavement in item 3 which was compacted

with the CC-50A roller. The lower density and strength values for this

8

item are probably due t,) the legree of" drying of the concrete prior to

cmjptt ion (the bottom 4 in. of this item wa:; placed first and therp

was a time Lapse of more than 1 hour prior to compaction roiling,).

L'. The average void content produced by the two vibratory rollers

wis ".. percent, which is s.lightly higher than would be expected in

.n,,-air-entrained concrete consolidated by internal vibration.

i.,ww,:r, the spiitting tensile arid flexural strengths are c',mparable to

r-ngths obtained on conventional 5000-psi concrete; i.e., I0 and

L" pe.rcetnt of the compressive strength, respectively.

I i. It is estimated that, to obtain a strength comparable to that

',ttiinf.d with Ihe dry mix used in this study, a conventional concrete

with a 1- to .)-in. slump would have required one additional bag of ce-

ment per cubic yard. This would require a water-cement ratio of about

0. 45. Full optimization of mixture proportions could conceivably result

in preater ;avings in cement. However, even greater savings could be

realised throjuwh the labor and construction costs associated with zero-

s ivsnl ,.n ret .

Performance

14. As previously stated, the zero-slump concrete was placed as

cntinuous slab 1? ft wide by 105 ft long. No shrinkage crack,,; le-

veloped in the pavement during a 28 -day curing period. Beam samples

wt_,ru f'ror. the- pavement for 2'i-day strength tests, and consaquently

thr- lenVh I the: slabs was reduced to about I0 to 50 ft since, tw& of

the te.;t bean.-Lis were cut across the pavement fur the full I -ft wilth.

, treriche..f whre bens were removed were bakfill ed with fresh port-

mad cement concrete. Subsequently, the pavement was sub,'' ed to ve-

hi(_ular t raff'ic for 4 m ths and no visual cracks or otier del'ects

develope,l. The fact that nu, cracks developed in the l05-ft-long slab

dtr ing e ir;t days of the curing period or in the pavement after

-,itting bums, due to expansion, cotraction, or load, may be signifi-

,'ar1. It appears that airy (zero-slump) portland cement concrete mix

is les!; suscept ible to volume change and cracking than a conventional

wot , mix with a slump in excess of 1 in.

9

(olc I usions

i' . viised on thet test results presented herein, the foil . wi r

colc is '.~.:are believed warranted.

a. iry-mix (zero-slump) portland cement concrete- can beadequatel y compacted by rol ling with heavy vibratoryCompact ion rollers.

b. :'atisfactury placement of zero-:Ilimp oncrete carl beaccumplished with a 'onvent i015,1 base s'ourse spreaderir az'j-hait finisher.

c. Comparable strcngths, ani be 'ibtained in a properly de-signe,i zero-slump conic rete mixture usirig less cementthan that required fo(r a conventional wet mix with ai- to , -in. :slunI.

d. L',atisfactry surface texture, smoothness, and ridingqual ity '" zer -slamup concrete pavements can be obtain(for wearing surfaces of secondary roads and streets -)rfor base courses in any pavement construction using ,'on-vertional base course or asphalt spreading equipment fr(rlaydown and vibratury rollers for compaction. Althoughnot tested, it is Le ,ieved that satisfactory surfacescan be obtained u.;in, erd-dumped concrete spread with amotor patrol an c,,mpacted usint- ibratory rollers.

e. A considerable reduction in construction cost of purtlandcement 'oricrete can be realized by use of a dry ccuncretemixture 'ompact,_:d with heavy vibratory rollers.

'. The amount of cracking from irying, shrinkage, and subse-(luent expansioi ',rd c-:ntraction can be reduced using thedry concrete mixtur, .

. More study i. ne,:ca ',, l'termine requirements f'," expan-sion arid J , ,tcti , ,], i nt.- an . 0 1nnstru-tio r tochniqueL;for i( ug i tud i na I ', i nt s where lit.eded.

h. The sub.'ect of durability should be investigated sinceroad surfaces may be tsusceptible to scailing and, illcolie. c imates, to freeze-thaw deterioration.

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Ihioto 1. Buffalo-Bonag EW210-A vibratory roller

I'loto 2. Dynapac CC-50A vibratory roller

I Fiotc, 3 -ton, self-propelled, pneumt c -tired rnllf-r

l-jioto 4. Barber-Green anphalt finisher

lhotn 5. Roling pattern with vibratory rollers

Photo 6. Surface texture of zero-sluw concretecompacted by vibratory roller

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In accordance with IR 70-2-3, paragraph 6c(l)(b),dated 15 February 1973, a race1alle catalog cardin Library of Congress tormt in reproduced below.

Burns, Cec il DawsonCoimpact ion st udy of zero-si imp conc(ret e, by ceci 1I ).

Burns. Vicksburg, 11. S. Army Engineer WaterwaysExperiment Station, 1976.

10 p. illus. 27 cm. (U. S. Waterways ExperimentStation. Miscellaneoius paper S-76-16)Prepared for Office, Chief of Engineers, V. S. Army,

Washington, D). C., under Project No). 4K078012A061.

1Compact ion. 2. Concrete compact inn. 3. Concreteconstruction. 4. Concrete pavements. 5. Dry-mix co)n-crete. 6. Pavements. 7. Portland cement. B. Zero-slump coincrete. 1. U. S. Army. Coirps of Engineers.(Series: Ii. S. Waterways Experiment Station, Vlckshurg,

Miss. Miscellaneoius paper S-76-16)TA7.W34m no.S-76-16