Building Materials, Third Edition

PHR f2w—

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e PH2 IP,S2 PS

PS2 PH2 PS

RH2 PS2 PS

SH2 RH2 PS

f PH2 IP,S2 PS

PS2 PH2 PS

RH2 PS2 SH

g PH2 IP,S2 SH

PS2 PH2 SH

h IP,S2 R,US2 SH

PH2 IP,S2 SH

i IH2 R,US2 SH

IP,S2 IH2 SH

The $2of the test sample depends upon its average specific gravity as given below.

Range of specific Weight of

Gravity Sample (g)

Over 2.80 5500

2.4 to 2.80 5000

2.2 to 2.39 4500

< 2.20 4000

€ ™X2The test sample and the abrasive charge are placed in the Deval abrasion testing
machine and the machine is rotated for 10000 revolutions at a speed of 30 to 33 rev/min. At the
completion of the test, the material is removed from machine and sieved on a 1.70 mm sieve.
The material retained on the sieve is washed, dried and accurately weighed to the nearest
gram.
The loss by abrasion is considered as the difference between the original weight of the
sample and the weight of the material retained on the 1.70 mm sieve, expressed as percentage
of the original weight of the test sample.
In case of crushed gravel, the percentage by weight of crushed fragments is determined, and
the permissible percentage or wear is calculated as:

W =

AL (100 A)L

100

′

Where W = permissible percentage of wear

A = percentage of uncrushed fragments

L = maximum percentage of wear permitted by the specifications for gravel

consisting entirely of uncrushed fragments

100 – A = percentage of crushed fragments

L¢ = maximum percentage of wear permitted by the specifications for gravel

consisting entirely of crushed fragments