This document describes the procedure to test the impact value of aggregates according to ASTM C125. The test involves compacting a sample of aggregates passing a 14mm sieve and retained on a 10mm sieve in a cup. The cup is dropped 15 times from a height, after which the material passing a 2.36mm sieve is weighed. The impact value is calculated as the percentage of material passing the 2.36mm sieve relative to the total sample weight. A value between 10-20% is considered very strong and suitable for use in concrete and road construction. The results of testing three samples are reported, with an average impact value of 13.42% indicating very strong aggregates.

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

3.  Awais Sikandar
 Contact Number: 0342-9205376
 Email:
awaissikandar932@gmail.com

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.

7. Apparatus

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

14. Results
 The impact value of aggregate is……….

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.