roller and compactors
TRANSCRIPT
-
7/27/2019 Roller and Compactors
1/23
Mansoor Azam Qureshi
NUST
Islamabad
-
7/27/2019 Roller and Compactors
2/23
-
7/27/2019 Roller and Compactors
3/23
-
7/27/2019 Roller and Compactors
4/23
Compactor
Compaction equipment ranges from handheldvibratory tampers (suitable for small or confinedareas) to large, self-propelled rollers and high speedcompactors (ideally suited for large, horizontalconstruction projects).
Types of Rollers
Tamping rollers and Sheepsfoot rollers Smooth-drum vibratory soil compactors
Pad-drum vibratory soil compactors
Pneumatic-tired rollers
15 January 2014 Mansoor Azam Qureshi 4
-
7/27/2019 Roller and Compactors
5/23
-
7/27/2019 Roller and Compactors
6/23
Smooth wheel Rollers
Widely used simple rollers
Work on static weight.
Used for compactinggranular bases, bituminouspavements
15 January 2014 Mansoor Azam Qureshi 6
-
7/27/2019 Roller and Compactors
7/23
Smooth-Drum Vibratory Soil
Compactors The smooth-drum vibratory
roller uses a vibratory action inconjunction with the ballast
weight of the drum to rearrangethe soil particles into a dense soilmass.
Vibratory compaction is veryeffective means of attaining thedesired density for cohesionless
materials. Because this roller is relatively
light, the recommendedmaximum loose-lift depth is 9inches.
15 January 2014 Mansoor Azam Qureshi 7
-
7/27/2019 Roller and Compactors
8/23
Pad-drum Vibratory Soil Compactor
These rollers are effective onsoils with up to 50% of thematerial having a PI of 5 orgreater.
The edges of the pads arerolled inward enabling them to
walk out of the lift withoutfluffing the soil.
The typical lift thickness forpadded-drum units oncohesive soil is 12 to 18 in.
These units are sometimesequipped with a leveling blade.
15 January 2014 Mansoor Azam Qureshi 8
-
7/27/2019 Roller and Compactors
9/23
-
7/27/2019 Roller and Compactors
10/23
Pneumatic Tired Rollers
These rollers apply the principle of kneadingaction to affect compaction below the surface.
They may be self-propelled or towed.
Pneumatics are used on small-to medium-sizesoil compaction jobs, primarily on bladedgranular base materials.
Small pneumatics are not suited for high-production, thick lift embankment compaction
projects. Pneumatic tired rollers are also used in
compacting asphalt, chip seals, recycledpavement, and base and subbase materials.
15 January 2014 Mansoor Azam Qureshi 10
-
7/27/2019 Roller and Compactors
11/23
The flexible tire surface permits conformance of the tire toslightly irregular surfaces to maintain uniform density andbearing capacity.
The rear tires are spaced to track over the uncompactedsurface left by the passage of the front tires.
The wheels may be mounted slightly out of line with theaxle, giving them a weaving action (the name "wobby
wheel") to increase the kneading action of the soil. Four parameters must be known to determine the
compacting ability of pneumatic rollers: Wheel load Tire size Tire ply Inflation pressure
15 January 2014 Mansoor Azam Qureshi 11
Pneumatic Tired Rollers
-
7/27/2019 Roller and Compactors
12/23
-
7/27/2019 Roller and Compactors
13/23
15 January 2014 Mansoor Azam Qureshi 13
Vibratory PlateCompactors
Self-propelled vibratory-plate compactorsare used for compacting granular soils,
crushed aggregate, and asphalt concrete inlocations where large compactors could notoperate.
These gasoline or diesel powered units arerated by centrifugal force, exciter revolutions
per minute, depth of vibration penetration(lift), foot-per-minute travel, and area ofcoverage per hour.
Many of these compactors can be operatedeither manually as a walk-behind unit or by
remote control
Special Compactors
-
7/27/2019 Roller and Compactors
14/23
Manually OperatedRammers
Gasoline-engine-driven rammers are usedfor compacting cohesive or mixed soils in
confined areas. These units range in impact from 300 to
900 foot-pounds (ft-lb) per sec at animpact rate up to 850 per min, dependingon the specific model.
Performance criteria include pounds perblow, area covered per hour, and depth ofcompaction (lift) in inches.
Rammers are self propelled in that eachblow moves them ahead slightly to contact
a new area.15 January 2014 Mansoor Azam Qureshi 14
Special Compactors
Special compactor provide
adequate output if
Lift thickness is minimal(usually 3 to 4 in.),
Moisture content iscarefully controlled, and
Coverage are sufficient.
-
7/27/2019 Roller and Compactors
15/23
Type of Soils
To select the most appropriate type of compactionequipment, a project officer must know the characteristics,capabilities, and limitations of the different types of rollers.
Generally, tamping-foot compactors that produce high unitpressures are best for predominantly fine-grained cohesivematerials such as clays and sandy clays.
Large, steel-drum rollers are best for larger particle materials
such as gravel or cobble. Vibratory rollers are ideal for well-graded or gap-graded
materials because the shaking action causes the smallerparticles to fill voids around the larger grains.
15 January 2014 Mansoor Azam Qureshi 15
-
7/27/2019 Roller and Compactors
16/23
Suitability of Soils
Suitability ofdifferent roller for
varying soil type isshown on chart;
15 January 2014 Mansoor Azam Qureshi 16
-
7/27/2019 Roller and Compactors
17/23
Desired Soil Density
15 January 2014 Mansoor Azam Qureshi 17
-
7/27/2019 Roller and Compactors
18/23
Lift Thickness
The lift thickness to achieve required density will varywith soil and compacter characteristics.
For tamping foot rollers lift thickness should not exceedroller feet.( 2 in)
For smooth wheel rollers lift should be limited to 6 in.
For Pneumatic tired rollers lift should not be greater
than 6 in. Heavy rollers may compact lift upto 12in.
15 January 2014 Mansoor Azam Qureshi 18
-
7/27/2019 Roller and Compactors
19/23
Compaction Equipment
Equipment must suit thesite.
Must provide optimumcompaction density andproduction
Enough speed
15 January 2014 Mansoor Azam Qureshi 19
-
7/27/2019 Roller and Compactors
20/23
-
7/27/2019 Roller and Compactors
21/23
-
7/27/2019 Roller and Compactors
22/23
Example What is the estimated production rate (CCY per hour) for a tamping-
foot roller with a compaction width of 5 feet? The followinginformation was obtained from a test strip at the project:
Compacted lift thickness = 6 inches
Average speed = 6 mph
Number of passes = 5
Efficiency factor = 0.83
15 January 2014 Mansoor Azam Qureshi 22
-
7/27/2019 Roller and Compactors
23/23
Example A self-propelled tamping foot compactor will be used to compact a fill
being constructed of clay material. Field tests have shown that therequired density can be achieved with four passes of the rolleroperating at an average speed of 3 mph. The compacted lift will have athickness of 6 in. The compacting width of this machine is 7 ft. One
bank cubic yard equals 0.83 ccy. The scraper production, estimated forthe project, is 510 bcy/hr. How many rollers will be required tomaintain this production? Assume a 50-min hour efficiency.
16,3 X 7 X 3 X 6 X 50/60
Compacted cubic yards per hour = ----------------------------= 428 ccy/hr
4
428/0.83=516 bcy/hr
No of compactor = 510/516=0.99 One compactor is sufficient
15 January 2014 Mansoor Azam Qureshi 23