2. Highway and Traffic Engineering
CE-442
BSc Civil Engineering
Semester 7th
Wah Engineering College
University of Wah
To Perform test of Impact Value of
Aggregates
4. Introduction
Aggregates: Combination of sand, gravel,
crushed stone or other materials.
Natural Aggregates
Manufactured aggregates
Aggregates Classification (ASTM C125)
Fine Aggregates
Passing No. 4 (4.75 mm) sieve
Retained on No. 2 00 (75_micron Sieve
Coarse Aggregates
Retained on no. 4(4.75mm) Sieve
5. Test Significance
Aggregates Strong enough to resist crushing
under traffic.
Toughness is property of material to resist impact.
Traffic loads, roads stones subjected to pounding
action.
Possibility of breaking stone into smaller pieces.
Road aggregates should be tough enough to
resist fracture under impact.
6. Apparatus
Impact Testing machine
Sample Cup
A Cylindrical measure
Tamping rod
BS sieves; size (14mm, 10mm, 2.36mm)
Balance, oven, rubber mallet, metal tray and
brush etc.
8. Procedure
Sample consists of aggregates passing 14 mm
and retained on 10 mm sieve
Wash sample and dry at 100 degree C to 110
degree C. for 4 hours and cool to room
temperature.
Fill cylindrical measures with aggregate sample
and tamp 25 blows.
Weight and record mass of sample (M1).
Transfer sample to machine cup and compact it
by applying 25 strokes of tamping rod.
Raise hammer and allow it fall freely. Sample
subjected to 15 such blows each delivered at an
interval of not less than 1 sec.
9. Procedure
Remove crush aggregates from cup and sieve
using #8 sieve.
Fraction passing sieve is weighed M2.
Friction retained on sieve is weighed M3
If M2+M3 differ from M1 by more than 1 g discard
the Results and repeat the test.
10. Formula Used
Aggregate Impact value is expressed as
percentage of fineness formed w.r.t total weight of
sample.
Aggregate Impact Value (AIV) = (M2/M1)*100.
Where
M1= Mass of test specimen.
M2= Mass of test specimen passing 2.36 mm test sieve.
I.V.A = M2/M1 x100
OR
I.V.A = C/A x100
M1 = Total weight
M2 = Weight of sample pass
11. Observation and Calculations
Dia of cup= 4”
Depth of cup= 2.5”
Weight of hammer = 14 lb
No of blows= 15
Sr.
No
Total weight
of sample
(gm)
Sample
retained of
sieve#8 (gm)
Sample
pass
from
sieve #8
(gm)
AIV =C/A
x100
Remarks
1 591.02 499.8 89.6 15 Very
strong
2 591.6 512.2 79.4 13.42 Very
strong
3 565 472.6 91.8 16.2 Very
Strong
12. Precautions
Sieve sample carefully.
Aggregate must not fall from the cup.
Be Extra cautions of your foot when hammer is
falling.
Weight the sample carefully.
13. Aggregate Impact Values
A.I.V =< 10% Exceptionally strong
A.I.V = 10-20% Very strong/ Tough
A.I.V= 20 -30% Good for pavement surfacing
A.I.V=>35% Weak for pavement surfacing
15. Conclusion
Value of AIV for sample is 13.42 which is in
between 10-20% so it is very tough aggregate
Best considered for building concrete and road
concrete
16. Report
Standard Reference
Objective
Introduction
Test Significance
Apparatus
Procedure
Formula used
Observation and Calculations
Aggregate impact value
Precautions
Result
Conclusion
17. Instruction(Report writing)
Do not copy.
Write in your own words
Attach pic where possible with proper title.
Make report according to the pattern given.
At least write 3 to 4 line against each topic.
Submit it before next session.