portable skid resistance

7/29/2019 Portable Skid Resistance

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Obtain coefficient of friction values ofbituminious and Portland cementconcrete pavements

To measure texture depth

To estimate the vulnerability of an

aggregate to polishing under traffic bydetermining its Polished Stone

Value(PSV)


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Skid resistance is invariant whether wet or dry.

No decrease of the skid resistance with increase inspeed.

No reduction of skid resistance with time. Resistance to wear.

Structural durability.

Low noise generation.

Low cost.


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FACTORS AFFECTING

SKIDDING

PAVEMENT

WATER

TYRE


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Different types of pavements have different skidresistance properties.

Surface with open texture premix carpet have more

skid resistance property than mastic asphalt.The macro texture helps in providing a good drainage

of the surface & the deformation of the tyres.

The macro texture property of the pavements which

brings into play the hysteresis property of friction.Aggregate which polish under traffic into smooth

shape are not desirable for skid resistance


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Danger of skidding is where the pavement iswet.

Contact surface divided into 3 zones

Zone1:Bulk displacement of water.Zone2:Water carries a portion of load.Zone3:Tyre in contact with surface.

At high speed only Zone 1 is present.Providing adequate camber .

Rough surface texture.


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Two components of friction which develop between thetyre and road surface

i)Adhesion component (komponen lekat ) :

Caused by the shear forces at the tyre road interface.

ii)Hysteresis component(komponen histerisis) :

Caused by the deformation of tyres when it comes in

contact with the pavement.

Drainage of surface water is done by the grooves of tyres.


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The thread depth and the pattern of tyres influencethe skid resistance.

Bunga Tayar mengeluarkan air dengan sempurna sekaligus meningkatkan

kesan rintangan gelinciran

Ketebalan Bunga geseran akan berkurangan apabila ketebalan bunga tayar

berkurangan

Kelebaran Tayar kurang lebar memberikan kesan pemecahan filem air tinggi

dan dapat mencecah turapan jalan


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1. Select the spot in which the texture depth has been

measured.


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2. Set the apparatus (Figure 2) on the road so that theslider will swing in the direction of traffic flow and

level the base screws.

3. Raise the swinging arm clear of the road and clamp inthe horizontal position. Release the arm and check

that the pointer reads zero.

4. With the pendulum arm free and hanging vertically,place the spacer, attached to a chain on the base of the

column, under the lifting handle setting screw to raisethe slider. Lower the head of the tester so that theslider just touches the road surface and clamp inposition. Remove the spacer.


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5. Check the sliding length of the rubber slider over theroad surface by gently lowering the pendulum armuntil the slider just touches the surface first on oneside of the vertical and then on the other. Whenpassing the arm through the vertical, use the liftinghandle so that the slider does not touch the road. Thesliding length should be between 125 and 127 mm. If

not, adjust by raising or lowering the head.

6. Place the pendulum arm in the horizontal and clampin position.

7. Wet the road surface and slider with water.8. Bring the pointer to its stop then release the

pendulum by pressing the button. Take care to catchthe arm on its return swing before it hits the ground.


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9. Return the arm and pointer to the release positionkeeping the slider off the road surface by means of thelifting handle. Repeat the test, wetting the surface

between swings. Record the mean of five successivereadings, provided they do not differ by more thanthree units. If the range is greater than this, repeatswings until three successive readings are constant;

record this value.

10.Record the temperature of the water on the roadsurface.


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Measure the apparatus was determined by testing 20 o c.Thus the temperature correction should be done

C20 = 100 + t * Ct

120Di mana :

Ct = Angkali rintangan kegelinciran pada to cC20 = Angkali rintangan kegelinciran pada 20

o c

T = Suhu air permukaan semasa ujikaji


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Jenis Permukaan

JenisPermukaan

Suhu Angkali Rintangan Gelinciran (c)

Ujian PurataCt

Puratadibetul

kan,C20

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Example of table


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portable skid resistance

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