earth compaction techniques

8/9/2019 Earth Compaction Techniques

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EARTH COMPACTION TECHNIQUES

(VIBRATING ROLLERS, SMOOTH WHEELED ROLLERS)


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Earth Compaction Techniques

(dead weight roller,!i"rati#g roller,$ooth wheeled roller)

Objectives of compaction

Compaction can be applied to improve the properties of an existing soil or in the processof placing fill. The main objectives are to:

increase shear strength and therefore bearing capacity

increase stiffness and therefore reduce future settlement

decrease voids ratio and so permeability, thus reducing potential frost heave

Factors affectin compaction

A number of factors will affect the degree of compaction that can be achieved:

Nature and type of soil, i.e. sand or clay, grading, plasticity

ater content at the time of compaction

!ite conditions, e.g. weather, type of site, layer thic"ness

Compactive effort: type of plant #weight, vibration, number of passes$

Roa! Ro""er

A roa! ro""er#sometimes called a roller%&o$'a&tor, or just roller$ isa compactortype engineering vehicleused to compact soil, gravel, concrete, or asphaltinthe constructionof roadsand foundations, similar rollers are used also at landfills or inagriculture.

%n some parts of the world, road rollers are still "nown collo&uially as steam rollers,

regardless of their method of propulsion. This typically only applies to the largest examples#used for road'ma"ing$
http://en.wikipedia.org/wiki/Compactorhttp://en.wikipedia.org/wiki/Engineering_vehiclehttp://en.wikipedia.org/wiki/Soil_compactionhttp://en.wikipedia.org/wiki/Gravelhttp://en.wikipedia.org/wiki/Concretehttp://en.wikipedia.org/wiki/Asphalthttp://en.wikipedia.org/wiki/Constructionhttp://en.wikipedia.org/wiki/Roadhttp://en.wikipedia.org/wiki/Roadhttp://en.wikipedia.org/wiki/Foundation_(architecture)http://en.wikipedia.org/wiki/Steamrollerhttp://en.wikipedia.org/wiki/Engineering_vehiclehttp://en.wikipedia.org/wiki/Soil_compactionhttp://en.wikipedia.org/wiki/Gravelhttp://en.wikipedia.org/wiki/Concretehttp://en.wikipedia.org/wiki/Asphalthttp://en.wikipedia.org/wiki/Constructionhttp://en.wikipedia.org/wiki/Roadhttp://en.wikipedia.org/wiki/Foundation_(architecture)http://en.wikipedia.org/wiki/Steamrollerhttp://en.wikipedia.org/wiki/Compactor


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The first road rollers were horse'drawn, and were probably just borrowed farmimplements (ee roller (agri&ltral tool)).

!ince the effectiveness of a roller depends to a large extent on its weight, self'poweredvehicles replaced horse'drawn rollers from the mid'()th century. The first such vehicleswere steam rollers. !ingle'cylinder steam rollers were generally used for base compactionand run with high engine revs in a low gear to promote bounce and vibration from thecran"shaft through to the rolls in much the same way as a vibrating roller. The doublecylinder or compound steam rollers became popular from around ()(* onwards and wereused mainly for the rolling of hot'laid surfaces due to their smoother running engines,however both cylinder types are capable of rolling the finished surface. !team rollers wereoften dedicated to a tas" by their gearing as the slower engines were for base compactionwhereas the higher geared models were often referred to as +chip chasers+ which followedbehind the hot tar and chipping laying machines. !ome road companies in the nited!tates used steamrollers through the ()-*s, and in the , some remained in commercialservice until the early ()/*s.

As internal combustion engine technology improved during the 0*thcentury, "erosene', gasoline' #petrol$, and diesel'powered rollers gradually replacedtheir steam'powered counterparts. The first internal'combustion powered road rollers werevery similar to the steam rollers they replaced. They used similar mechanisms to transmitpower from the engine to the wheels, typically large, exposed spur gears. !ome users didnot li"e them in their infancy, as the engines of the era were typically difficult to start,particularly the "erosene'powered ones.

1irtually all road rollers in commercial use now use diesel power.

ses on a road: !tart'to'finish

2oad rollers use the weight of the vehicle to compress the surface being rolled #static$ oruse mechanical advantage #vibrating$. %nitial compactionof the substrate on a road projectis done using a padfoot drum roller, which achieves higher compaction density due to thepads having less surface area. 3n large freeways a four wheel compactor with padfootdrum and a blade, such as a Caterpillar 4(-540- series machine, would be used due to itshigh weight, speed and the powerful pushing force to spread bul" material. 3n regionalroads a smaller single padfoot drum machine may be used. The next machine is usually asingle smooth drum compactor that compacts the high spots down until the soil is smooth,and this is usually done in combination with a motor grader to get a level surface.!ometimes at this stage a pneumatic tyre roller would be used. These rollers feature two

rows #front and bac"$ of pneumatic tyres that overlap, and the flexibility of the tyresprovides a "neading action that seals the surface and with some vertical movement of the
http://en.wikipedia.org/wiki/Horsehttp://en.wikipedia.org/wiki/Roller_(agricultural_tool)http://en.wikipedia.org/wiki/Steam_rollerhttp://en.wikipedia.org/wiki/Kerosenehttp://en.wikipedia.org/wiki/Gasolinehttp://en.wikipedia.org/wiki/Diesel_enginehttp://en.wikipedia.org/wiki/Steamhttp://en.wikipedia.org/wiki/Soil_compactionhttp://en.wikipedia.org/wiki/Horsehttp://en.wikipedia.org/wiki/Roller_(agricultural_tool)http://en.wikipedia.org/wiki/Steam_rollerhttp://en.wikipedia.org/wiki/Kerosenehttp://en.wikipedia.org/wiki/Gasolinehttp://en.wikipedia.org/wiki/Diesel_enginehttp://en.wikipedia.org/wiki/Steamhttp://en.wikipedia.org/wiki/Soil_compaction


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wheels, enables the roller to operate effectively on uneven ground. 3nce the soil base isflat the pad drum compactor is no longer used on the road surface. The next course #roadbase$ would be compacted using a smooth single drum, smooth tandem roller orpneumatic tyre roller in combination with a grader, and a water truc" to achieve the desiredflat surface with the right moisture content for optimum compaction. 3nce the road base is

compacted, the smooth single drum compactor is no longer used on the road surface#There is however an exception, if the single drum has special flat'wide'base tyres on themachine$. The final wear course of asphalt concrete#a.".a. asphalt or blac"top in NorthAmerica, or macadam in 6ngland$ is laid using a paver and compacted using a tandemsmooth drum roller, a three'point roller or a pneumatic tyre roller. Three point rollers onasphalt were very common once and are still used, but tandem vibrating rollers are theusual choice now, with the pneumatic tyre roller+s "neading action being the last roller toseal off the surface.

2ollers are also used in landfillcompaction. !uch compactors typically have padfoot or7sheep+s'foot7 drums, and do not achieve a smooth surface. The pads aid in compression,

due to the smaller area contacting the ground.Confi#rations

The roller can be a simple drum with a handle that is operated by one person, and weighs(** pounds, or as large as a ride'on road roller weighing 0( short tons#88,*** lb or0* tonnes$ and costing more than !9(-*,***. A landfill unit may weigh -) short tons #-8tonnes$.

Ro""er t$pesPe!estrian operate!

2ammer #bounce up and down$

al"'behind plate compactor5light

al"'behind plate compactor5heavy #with reverse$

Trench roller #manual unit or radio'fre&uency remote control$

al"'behind roller5light #single drum$

al"'behind roller5heavy #double drum$Ri!e%on smoot& finis&

Tandem drum #static$

Tandem drum #vibrating$

!ingle drum roller #smooth$

neumatic'tyre, a.".a. rubber tyre or multi'wheel

Combination roller #single row of tyres and a steel drum$
http://en.wikipedia.org/wiki/Asphalt_concretehttp://en.wikipedia.org/wiki/Landfillhttp://en.wikipedia.org/wiki/Short_tonhttp://en.wikipedia.org/wiki/Metric_tonhttp://en.wikipedia.org/wiki/United_States_dollarhttp://en.wikipedia.org/wiki/Asphalt_concretehttp://en.wikipedia.org/wiki/Landfillhttp://en.wikipedia.org/wiki/Short_tonhttp://en.wikipedia.org/wiki/Metric_tonhttp://en.wikipedia.org/wiki/United_States_dollar


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Three point roller #steam rollers are usually three'point$

Ri!e%on soi"'"an!fi"" compactor (it& pa!s'feet'spi)es

!ingle drum roller #soil$

8'wheel #soil5landfill$

;'point #soil5landfill$

Tandem drum #soil5landfill$

Ot&er

Tractor'mounted and tractor'powered (&o#!erio# ee galler* 'i&tre "elow)


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1ibratory tandem rollers

Normally with small to medium amplitude #used on soil and asphalt$

!afety distance in metres (.* x drum module weight.


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Smoot& Ro""er 0&ee"e!

!mooth heel 2ollers or !mooth


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weight of the drum to rearrange the soil particles into a dense soil mass. 1ibratorycompaction, when properly controlled, can be one of the most effective and economicalmeans of attaining the desired density for cohesionless materials. This roller is veryeffective in compacting noncohesive5nonplastic sands and gravels, which are often usedin subbase and base'course applications. ?ecause this roller is relatively light, the

recommended maximum loose'lift depth #the fill material measured before compaction$ is) inches.

earth compaction techniques

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