transportation engineering lab

1. EXPERIMENT NO. 02
SEMESTER : FALL 2020
PROGRAM : B.SC. CIVIL ENGINEERING
INSTRUCTOR: ENGR. HANIF ULLAH
DEPARTMENT OF CIVIL ENGINEERING
UNIVERSITY OF ENGINEERING & TECHNOLOGY, PESHAWAR
CE – 311L Transportation Engineering – II Lab UET PESHAWAR

2. EXPERIMENT NO. 02
IMPACT TEST
The aim of this laboratory test is to determine:
• Aggregate impact value
APPARATUS
• Impact Testing Machine
i. Having metallic base and a detachable cylindrical steel cup of 10.2 cm dia and 5 cm depth.
ii. Metal hammer of weight 13.5-14 Kg and having lower end of dia 10 cm and depth 5 cm
iii. Arrangement for raising hammer and to allow it to free fall between two vertical guides
from a height of 38 cm on the test sample in the cylinder.
• Cylindrical steel measure having 7.5 cm dia and 5 cm depth for aggregate
measurement.
• Tamping rod having a round end of 1 cm in dia and 23 cm long
• I.S. Sieve of sizes 12.5 mm, 10 mm and 2.36 mm
• Balance of capacity more than 500 gm with 0.1 gm accuracy
CE – 311L Transportation Engineering – II Lab UET PESHAWAR

3. EXPERIMENT NO. 02
Introduction
The value of aggregate impact shows us the toughness of aggregates. As in
highways the aggregates are continuously subjected to repeated impact loads,
which consequently cause breaking of stones in the road.
Toughness represent the capacity of any material to absorb energy. Greater
the energy absorbed by a material, lesser will be the A.I.V and stronger will be
the sample.
Therefore, aggregates must be chosen accordingly for highways construction
by evaluating its impact value using “Aggregate Impact Test”
CE – 311L Transportation Engineering – II Lab UET PESHAWAR

4. EXPERIMENT NO. 02
Principle of the test
The principle of this test is to fall freely a hammer, weighing 13.5-14 kg on the
aggregate sample taken in the steel cylindrical cup.
The aggregate Impact value indicates a relative measure of the resistance of
aggregate to a sudden shock or an Impact.
CE – 311L Transportation Engineering – II Lab UET PESHAWAR

5. EXPERIMENT NO. 02
Procedure
Test sample consist of aggregates passing 12.5 mm sieve and retained on 10
mm sieve. Dry sample kept for 4 hour at 100-110oC.
Fill the cylindrical cup from the aggregates with three layers each tamped with
25 blows by tamping rod.
Remove the extra aggregate from the surface by tamping rod
Measure the entire weight of aggregate in the cup as W1 gm
Now transfer the aggregate into the steel cup fixed at the base of machine
and tamped again for 25 blows in one layer.
Clamp the cylinder at the base of impact testing machine
CE – 311L Transportation Engineering – II Lab UET PESHAWAR

6. EXPERIMENT NO. 02
Procedure
Raise the hammer having 38 cm depth and fall freely on the surface of the
aggregate.
Complete 15 such blows by the hammer being delivered not less than a
second.
Now remove the total sample from the cup and pass through 2.36 mm sieve.
Measure the passing as W2 gm.
A.I.V = W2/W1 *100
Repeat the test and average of the two test is reported as the aggregate
impact value
CE – 311L Transportation Engineering – II Lab UET PESHAWAR

7. EXPERIMENT NO. 02
Procedure
Various agencies have specified the maximum permissible aggregate Impact
values for the different types of pavements. IRC has specified the following
values
Sub-Base coarse 50%
Cement concrete used in base course is 45%
Base course with Bitumen surface should be around 40%.
All the surface courses should possess an A.I.V below 30%.
CE – 311L Transportation Engineering – II Lab UET PESHAWAR

8. EXPERIMENT NO. 02
CE – 311L Transportation Engineering – II Lab UET PESHAWAR

9. LECTURE NO. 02
Thank you
CE – 311L Transportation Engineering – II Lab UET PESHAWAR