Soil Comp Action 2004 Handbook

8/9/2019 Soil Comp Action 2004 Handbook

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a basic handbook


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SOIL COMPACTION HANDBOOK 3

What is soil?

Soil is formed in place or deposited by various forcesof naturesuch as glaciers, wind, lakes and riversresidually or organically. Following are importantelements in soil compaction:

Soil type Soil moisture content Compaction effort required

Why compact?

There are ve principle reasons to compact soil:

Increases load-bearing capacity Prevents soil settlement and frost damage Provides stability Reduces water seepage, swelling and contraction Reduces settling of soil

Types of compaction

There are four types of compaction effort on soil orasphalt: Vibration Impact Kneading Pressure

Soil Compaction

Soil compaction is dened as the method of mechanically increasing the density of soil.

In construction, this is a signicant part of the building process.

If performed improperly,

settlement of the soil

could occur and result in

unnecessary maintenance

costs or structure failure.

Almost all types of

building sites and

construction projects

utilize mechanicalcompaction techniques.

These different types of effort are found in the twoprinciple types of compaction force: static and vibratory.

Static forceis simply the deadweight of the machine,applying downward force on the soil surface, com-pressing the soil particles. The only way to change theeffective compaction force is by adding or subtractingthe weight of the machine. Static compaction is con-ned to upper soil layers and is limited to any appre-ciable depth. Kneading and pressure are two examplesof static compaction.

Vibratory forceuses a mechanism, usually engine-driven, to create a downward force in addition to themachines static weight. The vibrating mechanism isusually a rotating eccentric weight or piston/springcombination (in rammers). The compactors delivera rapid sequence of blows (impacts) to the surface,thereby affecting the top layers as well as deeperlayers. Vibration moves through the material, setting

particles in motion and moving them closer togetherfor the highest density possible. Based on thematerials being compacted, a certain amount of forcemust be used to overcome the cohesive nature of par-ticular particles.

Loose Soil (poor load support)

Compacted Soil (improved load support)

SOIL DENSITY

Figure 1


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Cohesive soils

Cohesive soils have the smallest particles. Clay has aparticle size range of .00004" to .002". Silt ranges from.0002" to .003". Clay is used in embankment lls andretaining pond beds.

Characteristics

Cohesive soils are dense and tightly bound together by molecular attraction. They are plastic when wetand can be molded, but become very hard when dry.Proper water content, evenly distributed, is critical forproper compaction. Cohesive soils usually require aforce such as impact or pressure. Silt has a noticeablylower cohesion than clay. However, silt is still heavilyreliant on water content. [See Figure 4]

Granular soils

Granular soils range in particle size from .003" to.08" (sand) and .08" to 1.0" (ne to medium gravel).Granular soils are known for their water-drainingproperties.

Characteristics

Sand and gravel obtain maximum density in eithera fully dry or saturated state. Testing curves arerelatively at so density can be obtained regardless ofwater content.

The tables on the following pages give a basicindication of soils used in particular constructionapplications. [See Figures 5, 6 & 7]

Figure 3

SIEVE TEST

What to look for

Granular soils, nesands and silts.

Cohesive soils, mixesand clays .

Water movement

When water and soilare shaken in palm ofhand, they mix. Whenshaking is stopped,they separate.

When water and soilare shaken in palm ofhand, they will not mix.

When moist...

Very little or noplasticity.

Plastic and sticky.Can be rolled.

When dry...

Little or no cohe-sive strength whendry. Soil sample willcrumble easily.

Has high strengthwhen dry. Crumbleswith difculty. Slowsaturation in water.

Figure 4 GUIDE TO SOIL TYPES

Appearance/feel

Coarse grains canbe seen. Feels grittywhen rubbed betweenngers.

Grains cannot be seenby naked eye. Feelssmooth and greasywhen rubbed betweenngers.


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SOIL COMPACTION HANDBOOK6

-- -- 1 1 -- -- 1 1 1 3

-- -- 2 2 -- -- 3 3 3 --

2 4 -- 4 4 1 4 4 9 5

1 1 -- 3 1 2 6 5 5 1

-- -- 3* 6 -- -- 2 2 2 4

-- -- 4* 7* -- -- 5 6 4 --

4 5 -- 8* 5** 3 7 6 10 6

3 2 -- 5 2 4 8 7 6 2

6 6 -- -- 6** 6 9 10 11 --

5 3 -- 9 3 5 10 9 7 7

8 8 -- -- 7** 7 11 11 12 --

9 9 -- -- -- 8 12 12 13 --

7 7 -- 10 8*** 9 13 13 8 --

10 10 -- -- -- 10 14 14 14 --

GW Well-graded gravels, gravel/ sand mixtures, little or no nes

GP Poorly-graded gravels, gravel/sand mixtures, little or no nes

GM Silty gravels, poorly-graded gravel/sand/silt mixtures

GC Clay-like gravels, poorly graded gravel/sand/clay mixtures

SW Well-graded sands, gravelly sands, little or no nes

SP Poorly-graded sands, gravelly sands, little or no nes

SM Silty sands, poorly-graded sand/ silt mixtures

SC Clay-like sands, poorly-graded sand/clay mixtures

ML Inorganic silts and very ne sands, rock our, silty or clay-like ne sands with slight plasticity

CL Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays

OL Organic silts and organic silt-clays of low plasticity

MN Organic silts, micaceous or diatomaceous ne sandy or silty soils, elastic silts

CH Inorganic clays of high plasticity,fat clays

OH Organic clays of medium high plasticity

Group Symbol Soil Type H o m

o g e n e o u s

E m b a n

k m e n t

C o r e

S h e l l

E r o s i o n

R e s

i s -

t a n c e

C o m

p a c t e d

E a r t h

L i n i n g

S e e p a g e

I m p o r t a n t

S e e p a g e

N o t

I m p o r t a n t

F r o s t H e a v e

N o t

P o s s i

b l e

Fills

F r o s t H e a v e

P o s s i

b l e

S u r f a c

i n g

(NAVFAC DM-7.2, MAY 1982)

* if gravelly ** erosion critical

*** volume change critical-- not appropriate for this type of use

Figure 5

S A N D S

L E A N

F A T

C L A Y S & S I L T S

G R A V E L S

Rolled Earth Fill Dams Canal Sections Foundations Roadways

Relative Desirability for Various Uses (1=best; 14=least desirable)

RELATIVE DESIRABILITY OF SOILS AS COMPACTED FILL


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Effect of moisture

The response of soil to moisture is very important,as the soil must carry the load year-round. Rain, forexample, may transform soil into a plastic state or eveninto a liquid. In this state, soil has very little or no load- bearing ability.

Moisture vs soil density

Moisture content of the soil is vital to propercompaction. Moisture acts as a lubricant within soil,sliding the particles together. Too little moisturemeans inadequate compactionthe particles cannot

move past each other to achieve density. Too muchmoisture leaves water-lled voids and subsequentlyweakens the load-bearing ability. The highest densityfor most soils is at a certain water content for agiven compaction effort. The drier the soil, the moreresistant it is to compaction. In a water-saturated statethe voids between particles are partially lled withwater, creating an apparent cohesion that binds themtogether. This cohesion increases as the particle sizedecreases (as in clay-type soils). [See Figure 8]

Figure 6

IMPACT PRESSURE with kneading

VIBRATION KNEADING with pressure

Vibrating Sheepsfoot Rammer

Static Sheepsfoot Grid Roller Scraper

Vibrating Plate Compactor

Vibrating Roller Vibrating Sheepsfoot

Scraper Rubber-tired Roller Loader Grid Roller

GRAVEL 12 + Poor No Good Very Good

SAND 10 + /- Poor No Excellent G

SILT 6 + /- Good Good Poor Exc

CLAY 6 + /- Excellent Very Good No Good

Lift Thickness

Permeability Foundation

Support Pavement Subgrade Expansive

Compaction Difculty

GRAVEL Very High Excellent Excellent No Very Easy

SAND Medium Good Good No Easy

SILT Medium Low Poor Poor Some Some

CLAY None+ Moderate Poor Difcult Very Difcult

ORGANIC Low Very Poor Not Acceptable Some Very Difcult

Figure 7

FILL MATERIALS

MATERIALS


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Soil density tests

To determine if proper soilcompaction is achieved for anyspecic construction application,several methods were developed.The most prominent by far is soildensity.

Why test

Soil testing accomplishes thefollowing: Measures density of soil for

comparing the degree ofcompaction vs specs

Measures the effect ofmoisture on soil density vsspecs

Provides a moisture densitycurve identifying optimummoisture

MOISTURE VS SOIL DENSITY

A quick method of determining moisture density is known as the Hand Test.

Pick up a handful of soil. Squeeze it in your hand. Open your hand.

If the soil is powdery and will not retain the shape made by your hand, it is too dry. If it shatters when dropped, it is too dry.

If the soil is moldable and breaks into only a couple of pieces when dropped, it has the right amount of moisture for proper compaction.

If the soil is plastic in your hand, leaves small traces of moisture on your ngers and stays in one piece when dropped, it has too much moisture for compaction.

HAND TEST

Figure 9

Types of tests

Tests to determine optimum moisture content aredone in the laboratory. The most common is theProctor Test, or Modied Proctor Test. A particularsoil needs to have an ideal (or optimum) amountof moisture to achieve maximum density. This isimportant not only for durability, but will save money because less compaction effort is needed to achievethe desired results.

Proctor Test (ASTM D1557-91)The Proctor, or Modied Proctor Test, determines themaximum density of a soil needed for a specic jobsite. The test rst determines the maximum densityachievable for the materials and uses this gure as areference. Secondly, it tests the effects of moisture onsoil density. The soil reference value is expressed as apercentage of density. These values are determined before any compaction takes place to develop thecompaction specications. Modied Proctor values arehigher because they take into account higher densitiesneeded for certain types of construction projects. Testmethods are similar for both tests. [See Figure 10]Field tests

It is important to know and control the soil densityduring compaction. Following are common eld teststo determine on the spot if compaction densities are being reached.

Figure 8


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PROCTOR TEST

Figure 10

Figure 11

Large sample Accurate

Void under plate Sand bulking Sand compacted Soil pumping

Many steps Large area required Slow Halt equipment Tempting to accept ukes

Cost

Disadvantages

Errors

Advantages

Moderate High Low

Large sample Direct reading obtained Open graded material

Fast Deep sample Under pipe haunches

Fast Easy to redo More tests (statistical reliability)

Overdrive Rocks in path Plastic soil

Small sample No gravel Sample not always

retained

Surface not level Soil pumping Void under plate

Slow Balloon breakage Awkward

Miscalibrated Rocks in path Surface prep required Backscatter

No sample Radiation Moisture suspect Encourages amateurs

Sand Cone Balloon Densometer Shelby Tube Nuclear Gauge

FIELD DENSITY TESTING METHODS

Low


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Sand Cone Test (ASTM D1556-90)

A small hole (6 x 6 deep) is dug in the compactedmaterial to be tested. The soil is removed andweighed, then dried and weighed again to determineits moisture content. A soils moisture is guredas a percentage. The specic volume of the hole isdetermined by lling it with calibrated dry sandfrom a jar and cone device. The dry weight of the soil

removed is divided by the volume of sand needed toll the hole. This gives us the density of the compactedsoil in lbs per cubic foot. This density is compared tothe maximum Proctor density obtained earlier, whichgives us the relative density of the soil that was justcompacted. [See Figure 12]

Nuclear Density (ASTM D2922-91)

Nuclear Density meters are a quick and fairly accurateway of determining density and moisture content. Themeter uses a radioactive isotope source (Cesium 137)at the soil surface (backscatter) or from a probe placed

into the soil (direct transmission). The isotope sourcegives off photons (usually Gamma rays) which radiate back to the meters detectors on the bottom of theunit. Dense soil absorbs more radiation than loose soiland the readings reect overall density. Water content(ASTM D3017) can also be read, all within a fewminutes. A relative Proctor Density is obtained aftercomparing maximum density with the compactionresults from the test. [See Figure 13]

Soil Modulus (soil stiffness)This eld-test method is a very recent developmentthat replaces soil density testing. Soil stiffness is theratio of force-to-displacement. Testing is done by amachine that sends vibrations into the soil and thenmeasures the deection of the soil from the vibrations.

This is a very fast, safe method of testing soil stiffness.Soil stiffness is the desired engineering property, not just dry density and water content. This method iscurrently being researched and tested by the FederalHighway Administration.

NUCLEAR TEST

Figure 13

SAND CONE TEST

Figure 12


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Compaction Equipment

ApplicationsThe desired level of compaction is best achieved bymatching the soil type with its proper compactionmethod. Other factors must be considered as well,such as compaction specs and job site conditions. Cohesive soilsclay is cohesive; its particles stick

together.* Therefore, a machine with a high impactforce is required to ram the soil and force the airout, arranging the particles. A rammer is the bestchoice, or a pad-foot vibratory roller if higher produc-tion is needed. [See Figure 14]*The particles must be sheared to compact.

Granular soilssince granular soils are not cohe-sive and the particles require a shaking or vibra-tory action to move them, vibratory plates (forwardtravel) are the best choice.

Figure 14

COHESIVE SOILS

MT-65H Rammer

Reversible platesand smooth drum vibratory rollers are appropriate for production work. Granular soilparticles respond to different frequencies (vibra-tions) depending on particle size. The smaller theparticle, the higher the frequency necessary tomove it. As you compact soils with larger particles,move up to larger equipment to obtain lower fre-quencies and higher compaction forces.[See Figure 15]

MVC-88 Vibratory Plate

GRANULAR SOILS

Figure 15

AR-13H Ride-on Vibratory Roller

P33/24 HHMR Roller

P33 HHMR-BD Roller

MVH-306 Reversible Plate


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Soil can also be over-compacted if the compactormakes too many passes (a pass is the machine goingacross a lift in one direction). Over-compaction is likeconstantly hitting concrete with a sledgehammer.Cracks will eventually appear, reducing density. Thisis a waste of man-hours and adds unnecessary wear tothe machine.

Compaction specications

A word about meeting job site specications.Generally, compaction performance parameters aregiven on a construction project in one of two ways: Method Specicationdetailed instructions

specify machine type, lift depths, number ofpasses, machine speed and moisture content.A recipe is given as part of the job specs toaccomplish the compaction needed. This method isoutdated, as machine technology has far outpacedcommon method specication requirements.

End-Result Specicationengineers indicate

nal compaction requirements, thus giving thecontractor much more exibility in determiningthe best, most economical method of meetingthe required specs. Fortunately, this is the trend,allowing the contractor to take advantage of thelatest technology available.

Normally, soils are mixtures of clay and granularmaterials, making the selection of compactionequipment more difcult. It is a good idea to choosethe machine appropriate for the larger percentage ofthe mixture. Equipment testing may be required tomatch the best machine to the job.

Asphalt is considered granular due to its base of mixedaggregate sizes (crushed stone, gravel, sand and

nes) mixed with bitumen binder (asphalt cement).Consequently, asphalt must be compacted withpressure (static) or vibration.

Compaction machine characteristics

Two factors are important in determining the type offorce a compaction machine produces: frequencyandamplitude.Frequency is the speed at which an eccentric shaftrotates or the machine jumps. Each compactionmachine is designed to operate at an optimumfrequency to supply the maximum force. Frequency isusually given in terms of vibrations per minute (vpm). Amplitude (or nominal amplitude) is the maximummovement of a vibrating body from its axis in onedirection. Double amplitude is the maximum distancea vibrating body moves in both directions from itsaxis. The apparent amplitude varies for each machineunder different job site conditions. The apparentamplitude increases as the material becomes moredense and compacted.

Lift height and machine performance

Lift height (depth of the soil layer) is an importantfactor that affects machine performance andcompaction cost. Vibratory and rammer-typeequipment compact soil in the same direction: fromtop to bottom and bottom to top. As the machine hitsthe soil, the impact travels to the hard surface belowand then returns upward. This sets all particles inmotion and compaction takes place.As the soil becomes compacted, the impact has ashorter distance to travel. More force returns to themachine, making it lift off the ground higher in itsstroke cycle. If the lift is too deep, the machine will

take longer to compact the soil and a layer within thelift will not be compacted.[See Figure 16]

Proper Lift Improper Lift

Figure 16

LIFT HEIGHT


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Equipment types

Rammers

Rammers deliver a high impact force (high ampli-tude) making them an excellent choice for cohesiveand semi-cohesive soils. Frequency range is 500 to750 blows per minute. Rammers get compaction forcefrom a small gasoline or diesel engine powering alarge piston set with two sets of springs. The rammeris inclined at a forward angle to allow forward travelas the machine jumps. Rammers cover three types ofcompaction: impact, vibration and kneading.[See Figure 17]

Vibratory plates

Vibratory plates are low amplitude and high frequen-cy, designed to compact granular soils and asphalt.Gasoline or diesel engines drive one or two eccentricweights at a high speed to develop compaction force.The resulting vibrations cause forward motion. The en-gine and handle are vibration-isolated from the vibrat-ing plate. The heavier the plate, the more compactionforce it generates. Frequency range is usually 2500 vpmto 6000 vpm. Plates used for asphalt have a water tank and sprinkler system to prevent asphalt from stickingto the bottom of the baseplate. Vibration is the oneprincipal compaction effect. [See Figure 17]

Reversible vibratory plates

In addition to some of the standard vibratory platefeatures, reversible plates have two eccentric weightsthat allow smooth transition for forward or reversetravel, plus increased compaction force as the result of

dual weights. Due to their weight and force, reversibleplates are ideal for semi-cohesive soils.

A reversible is possibly the best compaction buy dol-lar for dollar. Unlike standard plates, the reversiblesforward travel may be stopped and the machine willmaintain its force for spot compaction.[See Figure 17]

Granular Soils Sand and Clay Cohesive Clay Asphalt

Rammers Not recommended Testing recommended Best application Not recommended

Vibratory Plates Best application Testing recommended Not recommended Best application

Reversible Plates Testing recommended Best application Best application Not recommended

Vibratory Rollers Not recommended Best application Testing recommended Best application

Rammax Rollers Testing recommended Best application Best application Not recommended

Figure 18 EQUIPMENT APPLICATIONS

EQUIPMENT TYPES

MT-76D Diesel-Powered Rammer

MVC-88 Vibratory Plate

Figure 17

MVH-402DS Reversible Plate


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Walk-behindSmoothA popular design for many years, smooth-drummachines are ideal for both soil and asphalt. Dual steeldrums are mounted on a rigid frame and powered by gasoline or diesel engines. Steering is done bymanually turning the machine handle.

ROLLER TYPES

Figure 19

Frequency is around 4000 vpm and amplitudes rangefrom .018 to .020. Vibration is provided by eccentricshafts placed in the drums or mounted on the frame.

RollersRollers are available in several categories: walk-behind and ride-on, which are available as smooth drum,padded drum and rubber-tired models; and are further divided into static and vibratory sub-categories.[See Figure 18]

P48 Ride-on Roller

AR-13H Ride-on Vibratory Roller

MRH-800GS Vibratory Roller

V30-3E Vibratory Roller

P33/24 HHMR Roller


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Safety and General Guidelines

As with all construction equipment, there are manysafety practices that should be followed while usingcompaction equipment. While this handbook is notdesigned to cover all aspects of job site safety, wewish to mention some of the more obvious items inregard to compaction equipment. Ideally, equipmentoperators should familiarize themselves with all oftheir companys safety regulations, as well as anyOSHA, state agency or local agency regulationspertaining to job safety. Basic personal protection,consisting of durable work gloves, eye protection,ear protection, approved hard hat and work clothes,should be standard issue on any job and available forimmediate use.In the case of walk-behind compaction equipment,additional toe protection devices should be available,

depending on applicable regulations. All personneloperating powered compaction equipment shouldread all operating and safety instructions for eachpiece of equipment. Additionally, training should beprovided so that the operator is aware of all aspects ofoperation.

No minors should be allowed to operate constructionequipment. No operator should run constructionequipment when under the inuence of medication,illegal drugs or alcohol. Serious injury or death could

occur as a result of improper use or neglect of safetypractices and attitudes. This applies to both the newworker as well as the seasoned professional.

Shoring

Trench work brings a new set of safety practices andregulations for the compaction equipment operator.This section does not intend to cover the regulationspertaining to trench safety (OSHA Part 1926, SubpartP). The operator should have knowledge of what isrequired beforecompacting in a trench or connedarea. Be certain a competent person (as dened by OSHA in Part 1926.650 revised July 1, 1998) hasinspected the trench and follows the OSHA guidelinesfor inspection during the duration of the job. Besidesthe obvious danger of a trench cave-in, the workermust also be protected from falling objects. Unshored(or shored) trenches can be compacted with the use ofremote control compaction equipment. This allows theoperator to stay outside the trench while operating theequipment.Safety rst!

PaddedPadded rollers are also known as trench rollers due totheir effective use in trenches and excavations. Thesemachines feature hydraulic or hydrostatic steeringand operation. Powered by diesel engines, trenchrollers are built to withstand the rigors of connedcompaction. Trench rollers are either skid-steer orequipped with articulated steering. Operation can be by manual or remote control. Large eccentric unitsprovide high impact force and high amplitude (forrollers) that are appropriate for cohesive soils. Thedrum pads provide a kneading action on soil. Usethese machines for high productivity.

Ride-onCongured as static steel-wheel rollers, ride-ons areused primarily for asphalt surface sealing and nishingwork in the larger (8 to 15 ton) range. Small ride-onunits are used for patch jobs with thin lifts.The trend is toward vibratory rollers. Tandemvibratory rollers are usually found with drum widthsof 30 up to 110, with the most common being 48.

Suitable for soil, sub-base and asphalt compaction,tandem rollers use the dynamic force of eccentricvibrator assemblies for high production work. Single-drum machines feature a single vibrating drum withpneumatic drive wheels. The drum is available assmooth for sub-base or rock ll, or padded for soilcompaction. Additionally, a ride-on version of the padfoot trench roller is available for very high productivityin conned areas, with either manual or remotecontrol operation.

Rubber-tire

These rollers are equipped with 7 to 11 pneumatictires with the front and rear tires overlapping. A staticroller by nature, compaction force is altered by theaddition or removal of weight added as ballast inthe form of water or sand. Weight ranges vary from10 to 35 tons. The compaction effort is pressure andkneading, primarily with asphalt nish rolling. Tirepressures on some machines can be decreased whilerolling to adjust ground contact pressure for different job conditions.


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Glossary

AASHO American Association of State HighwayOfcials.

Adhesion a property of soil which causes the par-ticles to stick together.

Aggregate stone or gravel that was crushed andscreened to various sizes for use in concrete, asphaltor road surfaces.

Amplitude the total vertical distance the vibratingdrum or plate is displaced from a resting or neutralposition from the eccentric moment.

ASTM American Society for Testing Materials.

Backll materials used in relling a cut or otherexcavation, or the act of such relling.

Ballast heavy material, such as water, sand ormetal which has no function in a machine except toincrease its weight.

Bank a mass of soil rising above an average level.Generally, any soil which is to be dug from its natu-ral position.

Bank Gravel a natural mixture of cobbles, gravel,sand and nes.

Bank Yards soil or rock measured in its originalposition before digging.

Base the course or layer of materials in a roadwaysection on which the actual pavement is placed. Itmay be of different types of materials ranging fromselected soils to crushed stone or gravel.

Berm an articial ridge of earth, generally side-slopes of a roadbed.

Binder nes which ll voids or hold gravel togetherwhen dry.

Borrow Pit an excavation from which ll material istaken.

BPR U.S. Bureau of Public Roads. BUREC U.S. Bureau of Reclamation.

Capillary a phenomenon of soil which allows waterto be absorbed either upward or laterally.

Centrifugal Force the force generated from theunbalanced condition of eccentric shaft rotation at agiven speed.

Clay material composed and derived from thedecomposition of rock which consists of microscopicparticles.

Clean free of foreign material; in reference to sandor gravel, lack of a binder.Cohesion a property of soil which holds theparticlestogether by sticking. Also, the soils ability to resistshear is determined by its degree of cohesiveness.

Cohesive Material a soil having properties of cohe-sion.

Compacted Yards measurement of soil or rock afterit is placed and compacted in a ll.

Compressibility a property of soil which permitsdeformation when subjected to a load.

Core a cylindrical piece of an underground forma-tion, cut and raised by a rotary drill with a hollow bit. The impervious center of an earthll dam.

Crown the elevation of a road surface at its edges,to encourage drainage.

Datum any level surface taken as a plane of refer-ence from which to measure elevations.

Density the ratio of the weight of a substance to itsvolume.

Embankment a ll with a top higher than the ad- joining natural surface.

Elasticity a characteristic of soil which allowsdeformation during a subjected load, but returnsalmost to its original conguration after removal ofthe force.

Fines clay or silt particles in soil.

Finish Grade the nal grade required by specica-tions.

Foot in tamping rollers, one of a number ofprojections from a cylindrical drum. Frequency referring to rotational speed of the ec-centric shaftusually rated in Vibrations Per Min-utewhich is equal to the RPM of the shaft.

Frost Line the greatest depth to which ground isexpected to freeze in a given location.


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Grade usually the surface elevation of the ground atpoints where it meets a structure. Also, surface slope.

Grain Size Curve a soil graph analysis showing thepercentage size variations by weight.

Granular Material a sandy type of soil withparticles that are coarser than cohesive material anddo not stick to each other.

Gravel a cohesionless aggregate of rock fragmentswith varying dimensions of 3.0 to .08 inches.

Gumbo material in the plastic state identied by asoapy or waxy appearance.

Humus organic material formed by the decomposi-tion of vegetation.

Impervious

resistant to movement of water. In Situ natural undisturbed soil in place.

Lift a layer of ll as spread or compacted.

Liquid Limit the water content at which soil passesfrom a plastic to a liquid state.

Loam a soft, easily worked soil containing sand, silt,clay and decayed vegetation.

Optimum Moisture Content that percent of moistureat which the greatest density of a soil can beobtained through compaction.

Pass a working trip or passage of an excavating,grading or compaction machine from point A topoint B. (One direction only.)

Permeability a characteristic of soil which allowswater to ow through it because of gravity.

Plastic the ability of a soil to be rolled into a nethread at a certain moisture content.

Plastic Limit the lowest moisture content at whicha soil can be rolled into a 1/8 diameter thread with-

out breaking. Proctor a method developed by R.R. Proctor fordetermining the density/moisture relationship insoils. It is almost universally used to determine themaximum density of any soil so that specicationsmay be properly prepared for eld constructionrequirements.

Proctor, Modied a moisture density test of morerigid specication than Proctor. The basic differenceis the use of heavier weight dropped from a greaterdistance in laboratory tests.

Quicksand ne sand or silt that is prevented fromsettling rmly together by upward movement ofunderground water.

Sand a cohesiveless aggregate of round and angularfragments of rock with a particle size between 2.0and .05mm.

Shearing Resistance a soils ability to resist slidingagainst neighboring soil grains when force isapplied. Internal friction and cohesion determineshear resistance.

Shrinkage

soil volume which is reduced when subjected to moisture; usually occurs in ne grain soils.

Silt soil material composed of particles between .005and .05mm in diameter.

Soil the loose surface material of the earths crust.

Stabilize to make soil rm and prevent it from mov-ing.

Sub-base the layer of material placed to furnishstrength to the base of a road.

Subgrade the surface produced by grading nativeearth, or cheap imported materials which serve as a base for more expensive paving.

Acknowledgements: Budinger & Associates, Geotechnical &Material Engineers, for their assistance with some material.


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Notes


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blank page


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MULTIQUIP INC.POST OFFICE BOX 6254 CARSON, CA 90749 310-537-3700 800-421-1244 FAX:310-537-3927

email: [email protected] www.multiquip.com

COPYRIGHT 2004, MULTIQUIP INC.Rev. 3 (08-04)

Soil Comp Action 2004 Handbook

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