PAVEMENT MATERIALS PAVEMENT MATERIALS ENGINEERINGENGINEERING

(CE-862) (CE-862) Lec-02 (Lab 2)

Fall Semester 2016 

Dr. Arshad Hussainarshad_nit@yahoo.com , Office Room#111, Tel:

05190854163, Cell: 03419756251

National Institute of Transportation (NIT)

National University of Science and Technology (NUST)

NUST Campus, Sector H-12, Islamabad

AGGREGATE Testing

•Most common tests include:• Crushing value test• Impact value test• Shape test• Los Angeles abrasion• Soundness test• Sand equivalent

AGGREGATE CRUSHING VALUEAGGREGATE CRUSHING VALUE

• Metal measure• Tamping rodBelow mentioned are its specifications:• Three sizes 75mm dia for 1/8 to 1/4 Size aggregate, 150mm dia for 3/8 to 3/4 Size aggregate 300mm dia for 1in to 2in size aggregate

The aggregate crushing value indicates the ability of an aggregate to resist crushing. The lower the figure the stronger the aggregate, i.e. the greater its ability to resist crushing.

AGGREGATE CRUSHING VALUE

Aggregate passing IS sieve 12.5 mm and retained on 10 mm sieve is generally used.

Oven dried aggregates are filled in the measuring cylinder of 11.5cm dia. & 18.0cm height in 3 equal layers, each layer being subjected to 25 tamps with a tamping rod of 16mm dia and 45 to 60mm long.

AGGREGATE CRUSHING VALUE

The crushing test apparatus consist of a 15cm dia open ended heavy steel cylinder, plunger and a base plate.

Compression testing machine a load of 40 tonnes is applied in 10 min. crushed aggregate Sieved through 2.36 mm sieve.

Agg crushing value > 35 weak for pavement.

Agg crushing value < 10 exceptionally strong.

For majority of aggregates the impact value and crushing value are numerically similar.

Rock group Crushing value Impact valueBasalt 14 15 Granite 20 19Lime stone 24 23 Quartzite 16 21

AGGREGATE CRUSHING VALUE

AGGREGATE IMPACT VALUE

A base, which helps in supporting the columns to form a rigid framework around the quick release trigger mechanism for ensuring the effective free fall of the hammer during test. The hammer is offered with locking arrangement and the free fall can be easily adjusted through the 380+ 5mm. cylindrical cup, with the metal measure 75 mm dia x 50 mm high and tamping rod.

Satisfactory resistance to crushing under roller during construction. Adequate resistance to surface abrasion under traffic.

IMPACT VALUE Due to traffic loads the road stones are subjected

to impact. IS sieves 12.5 mm,10 mm & 2.36 mm. Cylindrical steel cup of dia 10.2 cm & depth 5

cm. Metal hammer of weight 13.5 to 14 kg. Height of

fall 38 cm. Cylindrical measure with internal dia 7.5 cm & depth 5 cm.

Metal tamping of 1 cm dia.23 cm long.< 10 % exceptionally strong.10 - 20 % strong.20 - 30 % satisfactory. > 35 % weak.

ELONGATION & FLAKINESS INDEXELONGATION & FLAKINESS INDEX

When the length is more than 1.8 of the mean dimension, then the aggregate particles are considered elongated.The aggregate particles are to be flaky, if the thickness is less than the 0.6 of their mean dimension.

Size of aggregates

Weight of fraction consisting of at least200 pieces,g

Thickness gauge size, mm

Weight of aggregates in each fraction passing thickness gauge,mm

Length gauge size, mm

Weight of aggregates in each fraction retained on length gauge,mm

Passing through IS Sieve, mm

Retained on IS Sieve,mm

1 2 3 4 5 6 763 50 W1 23.90 X1 – –50 40 W2 27.00 X2 81.00 Y1

40 31.5 W3 19.50 X3 58.00 Y2

31.5 25 W4 16.95 X4 – –25 20 W5 13.50 X5 40.5 Y3

20 16 W6 10.80 X6 32.4 Y4

16 12.5 W7 8.55 X7 25.5 Y5

LOS ANGELES ABRASION TESTStart with fraction retained on No. 12

sieve

Sample submerged in magnesium or sodium sulfate—causes salt crystals to form in the aggregate pores

SOUNDNESSSOUNDNESS TESTTEST

SAND EQUIVALENTSAND EQUIVALENT

SE = (Height of Sand/Height of Clay)100

This is a test to determine the amount of clay in fine aggregate.Aggregate passing a No. 4 sieve is agitated in a water-filled transparent cylinder. Liquid is water and flocculating agent. After settling, the sand separates from the flocculated clay. Measure each.

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