Effect of dynamic load impact of missile on mechanical behavior of ferrocement

International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308
(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME
295
EFFECT OF DYNAMIC LOAD: IMPACT OF MISSILE ON
MECHANICAL BEHAVIOR OF FERROCEMENT –
INFRASTRUCTURE APPLICATION
Mohammed Mansour Kadhum
PhD, Assistant Professor,
College of Engineering, Babylon University,
Iraq / Babylon / 40 Street
ABSTRACT
An investigation into the behavior of ferrocement barriers subjected to impact
load testing and missile impact is reported. This impact test was used to evaluate the
mechanical behavior of cement mortar panels reinforced with one or more of the following
reinforcement types: square steel chicken wire meshes, hexagonal steel chicken wire meshes,
steel fibers and polypropylene fibers randomly distributed in plane. One missile impact
velocity, size and weight was used to investigate the results of the influence of various
mechanical parameters on impact effects due to projectile impact.
This paper describes the first part of a study, which aims to apply of ferrocement
panel in road as a base course to treatments and investigate the wider issues with its
application to road pavements.
The test results showed that the depth of penetration of projectiles decreased
from 23mm for the plain cement mortar panel to 8.7mm for the ferrocement panels with
square steel wire mesh reinforced cement mortar Panels. Whereas, the cement mortar panels
which are reinforced with randomly distributed polypropylene fibers showed no enhancement
to impact resistance when measured by the depth of penetration caused by the projectiles.
Also, the drop load depth can be a reasonable indicator of cumulative damage in the case of
drop impact test
Keywords: Ferrocement; Missile impact; Projectiles; Depth of penetration; barriers
INTERNATIONAL JOURNAL OF CIVIL ENGINEERING AND
TECHNOLOGY (IJCIET)
ISSN 0976 – 6308 (Print)
ISSN 0976 – 6316(Online)
Volume 4, Issue 2, March - April (2013), pp. 295-305
© IAEME: www.iaeme.com/ijciet.asp
Journal Impact Factor (2013): 5.3277 (Calculated by GISI)
www.jifactor.com
IJCIET
© IAEME

296
1. INTRODUCTION
Fiber and mesh reinforced concrete was found to be adequate in sustaining
impact, blast, explosion and other forms of dynamic loads. Although, the toughening
mechanism was well understood in this composite material under statically applied loads,
unfortunately in case of impact and other dynamic loads, our understanding is inadequate
(Banthia et al., 1998).
Several studies such as (Mansur et al.,2000) on punching shear strength of
ferrocement have shown that due to its reinforcement characteristics it has an incredible
mechanical characteristics. However, they used a thin-walled composite comprising closely
spaced layers of fine wire mesh encapsulated in a cement mortar matrix.
Generally, researchers (Ramakrishnan et al., 1980; Swamy and Jojagha 1982)
were used the drop weight test developed by (Schrader, 1981) and published by the (ACI
committee 544-1988) to measure the impact resistance of fiber reinforced cement composites.
The economical and environmental advantages of using reinforcement to
provide thinner road structures, longer life cycles and reduction in maintenance costs and of
course savings in natural resources due to prolonged service intervals.
On the other hand, the projectile impact feature could be more representative. In
general, the projectile impact mass leads to two types of responses which are: Firstly, the load
collision local effects such as surface indentation and local crushing suffered by the target or
penetration of the projectiles. Secondly, the overall dynamic responses of the target which
consist mainly of wave propagation and scabbing.
The depth of penetration is a function of the velocity and mass of the projectile
as well as the stiffness of the targets material. For concrete the latter parameter is normally
related to the compressive strength (Gao 2007).
In the present work, the first type of responses has been investigated which depends on the
following parameters:
- Projectile properties: weight, caliber, shape and strength.
- Target properties: strength, ductility and density.
- Striking velocity: impact velocity and angle of incidence.
2. EXPERIMENTAL PROGRAM
2.1 Testing procedure and instrumentation
The ferrocement specimens which are subjected to test should be cast in rigid
dismountable moulds made of metal. The spacing of steel mesh wires and fiber reinforcement
in the moulds should correspond to the regular reinforcement ratios. The identical spacing
between particular layers of wire mesh in specimens and structure was attained. The details
of the test specimens are shown in Figure 1.

297
Figure 1. Dimension and detail of the specimen
The mould is supplied by separating combs that stabilize the horizontal position of wire
mesh and distance sheets that determine the stable vertical position of the wire mesh layers. The strips
of particular wire mesh layers passing through the separating combs and separated by distance sheets
are rigidly fixed in each opposite two ends of the mould.
In this experimental investigation, a spherical head of non-deformable type projectile
with a mass of about 0.2kg and diameter of 25mm was used. The small balls projectile were shoot
from a shooting gun as shown in Figure 2. The head and body of the projectiles were made from steel
and aluminum respectively. These projectiles were ejected by air pressure at velocity of about 218
m/sec; this speed is sufficient to model collision by an aircraft. Also, a high speed camera, which
capable of recording about 5350 frames per second was poisoned beside the specimen to record
collision behavior when the missile projectile approach to the tested panel specimen.
The panel specimen was suspended vertically in front of the gun by two steel slings to
allow free movement after impact. Also, the impact direction of the steel ball projectiles was mounted
normally to the ferrocement panel as can seen in Figure 2. After being impacted by the projectile
missiles, the panel specimens were examined visually. Various measurements, such as penetration
depth, dimension of damage area of both front and rear faces and weight of flying concrete were
determined. The shooting distance of the gun was kept at 5.0 meters away from the panel target.
Point of collision
gun
Steel and aluminum ball projectiles
Ferrocement panel barrier
Specimen
Stopper
Figure 2. Dimension of the missile projectile an schematic impact test apparatus arrangement
B) Test Setup
A) Missile Projectile
Head
Body
45 20 10
45
400m
m
400m
m
Thickness of panel= 50mm
Steel wire mesh fixed
in place by rivets

298
For the ferrocement panel specimens which were subjected under impact load,
the conducted impact test was the drop-weight test. In this work, a testing apparatus
manufactured locally is presented. The details of this apparatus were presented by earlier
work of (Barr and Baghli 1989). The impact apparatus consists of three main components:
i. The supporting frame,
ii. The drop weight guide system, and
iii. The impact masses or strikers.
A special supporting frame was manufactured and used. This supporting frame
was made using four steel beams of the type W-shape (W4×13) welded and arranged to form a
square shape. Steel bars of (25mm) diameter welded on top faces of each four steel beams to
provide a simply support for the ferrocement panel specimen edge as shown in Figure 3.
The specimens simply supported and the impacting mass was dropped freely through the
guiding system at the center of the specimen by a line contact between the impacting mass
and the specimen surface. The front end of the impact masses has a rounded surface in order
to create a line contact between the impact mass and the test specimens. The numbers of
blows which cause ferrocement fracture were calculated as impact resistance. The energy
produced by each blow is given by the product of the drop height and weight of the striker,
and then the total impact energy is determined by multiplying the energy per blow by the
number of blows.
2.2 Casting and curing the panel specimens
After the mould preparation, cement mortar mixture was mixed using a small
rotating mixer. Then the mixture is casted in the prepared mould in layers each of 5mm. For
the ferrocement panels a layer of chicken wire mesh was fixed in place each 10mm of depth;
i.e. 4 layers for each panel. While for the fiber reinforced cement mortar plates, the specified
Figure 3. Schematic diagram showing impact apparatus

299
quantity of (crimped steel or polypropylene) fibers was randomly dispersed in plane each
5mm depth layer.
The fresh panels with the mould were covered with polyethylene sheets
immediately after casting to prevent dryness and plastic shrinkage cracks. Two days later the
mould was dismantled carefully and the panels were moist cured by immersing in a water
curing basin for 28 days. After this period of curing the panels were taken off the curing
basin, dried for about two hours before conducting the experimental tests.
2.3 Materials
Ordinary Portland cement and natural sand passing through sieve 2.38mm were
used in the ratio of (cement : fine aggregate was 1:1) by weight. The water-cement ratio used
kept was 0.5. To improve workability, a superplastisizers was added at 0.065% by weight of
cement. Galvanized welded wire meshes were used throughout the test program.
2.4 Types of ferrocement panel specimens
The ferrocement panel specimens were reinforced with the following types of
reinforcement:
1- Steel chicken wire meshes.
2- Steel fibers.
3- Polypropylene fibers.
4- Steel chicken wire meshes and steel fibers.
5- Steel chicken wire meshes and polypropylene fibers.
In the present study, the impact resistance of these five types of ferrocement
panel specimens was determined. The panel designation, mix proportions and reinforcement
details are given in Table 1. The properties of crimped steel fibers and polypropylene fibers
which were used as reinforcing fibers are given in Table 2. Also, the properties of the square
steel wire meshes and hexagonal steel wire meshes which were used as reinforcing wire
meshes are given in Table 3.
Table 1. Specimens designation and reinforcement details.
Specimen
s
Type of Reinforcement
Fibers
Volume
Fraction %
Steel Wire meshes
% by Volume
RP Plain cement mortar ---- ----
FS1 Steel fibers 0.9 -----
FS2 Steel fibers 0.8 -----
FP1 Polypropylene fibers 0.9 -----
FP2 Polypropylene fibers 0.8 ----
FM Square steel wire mesh ---- 0.9
FH Hexagonal steel wire mesh ---- 0.8
FMS Square steel wire mesh + steel fibers 0.45 0.45
FMP
Square steel wire mesh + polypropylene
fibers
0.45 0.45
FHS Hexagonal steel wire mesh + steel fibers 0.4 0.4
FHP
Hexagonal steel wire mesh + polypropylene
fibers
0.4 0.4

300
Table 2. Properties of the reinforcing fibers
Fiber Type
Density
kg/m3
Tensile
Strength (MPa)
Equivalent Diameter
(mm)
Length
(mm)
Aspect Ratio
Crimped steel 7700 1080 0.4 40 100
Polypropylene 925 330 0.42 50 119.05
Table 3. Properties of the steel chicken wire meshes.
2.5 Compressive strength test
The specimens which will be tested finally for compressive strength were
obtained by cutting six cubes of dimensions 50mm × 50mm × 50mm from each plain mortar,
fiber reinforced mortar and ferrocement panel.
Practically, the best direction of cutting the cubes is obtained by putting the
panel in the same position at which it was cast with mortar; as the upper surface is weaker
than the molded surfaces. Such method of cutting ensures that the strength of concrete is
justifiable because there is no significant amount of splinters and fragmentation and hence the
quality of planes and dimensional tolerances are attained to be in the best manner.
3. TEST RESULTS AND DISCUSSION
3.1 General
All panels were conducted with identical projectile velocities of 218 m/sec. The
results of the projectile penetration test, the compressive strength, impact resistance test; and
density tests are given in Table 5. Additionally, Figure 4 and 5 demonstrate the values of
projectile penetration into each type of panel with the designated reinforcement.
From Figure 4 and 5, the effect of the type of reinforcement on the depth of
penetration can be clearly detected. However, it can be seen obviously from Figure 4 that the
ferrocement panel which was reinforced with square steel chicken wire mesh (FM) with
(0.9%) volume fraction of steel reinforcement has shown the lowest value of depth of
penetration (8.7mm). This proves that it has superior characteristic in impact resistance than
the other panels. Whereas, the panel which was reinforced with the polypropylene fiber (FP1)
has the highest value of depth of penetration (23.3mm), which means that it acquires the
lowest impact resistance compared with the other panels even the non reinforced one
(23.0mm). Also, it can be seen that the cement mortar panel which was reinforced with
(0.9%) volume fraction of crimped steel fibers randomly distributed in plane possessed a low
value of projectile penetration (9.0mm) which indicates remarkable impact resistance.
On the other hand, the ferrocement panel which was reinforced with (0.8%)
volume fraction of hexagonal steel chicken wire mesh (FH) has shown a low value of depth
of penetration (8.9mm). While, the panel which was reinforced with the polypropylene fiber
Wire Meshes
Wire
Diameter
(mm)
Density
kg /m3 Tensile Strength (MPa)
Weight per Unit
Area
kg /m2
Square Meshes 0.20 7720 980 0.2765
Hexagonal
Meshes
0.29 7680 938 0.2474

301
randomly distributed in plane (FP2) has a depth of penetration of (22.9mm). Actually it is
equal to that of the non reinforced panel as can be seen in Figure 5.
However, the preceded experimental results clearly indicate that the ferrocement
panels reinforced with steel wire meshes or the steel fibers are possess appreciable impact
resistance and can successfully used as barriers against impact loads.
Effect of volume fraction and different types of fibers (steel and polypropylene)
on the characteristics of impact test is presented in Figures 6 and 7. From the results, it is
clear that the impact resistance of the ferrocement was improved with higher ratio of volume
fraction and type of fiber. Also, it can be seen from these results that the energy input
required to initiate first crack and to produce failure in fiber reinforced panel specimens is
very much greater than that for plain cement mortar.
Table 5. Results of the conducted tests.
Specim
en
Failure Mode
Weight
of
Flying
Concret
e (kg)
Density
kg/m3
Compress
ive
Strength
(MPa)
No. of
Blows
Total
Absorb
ed
Energy
(N.m)
Mean
Depth of
Penetrati
on (mm)
Perforati
on
Scabbin
g
at
First
Crac
k
at
Fail
ure
RP 2.60 2120.00 40.0 3 19 745.6 23.0
F S1 2.15 2160.00 46.4 6 77 3021.5 9.0
FS2 2.05 2159.50 45.0 5 68 2668.3 9.1
FP1 3.10 2104.24 37.0 4 23 902.5 23.3
FP2 2.92 2105.46 39.0 3 21 824.0 22.9
FM 1.95 2166.20 49.0 6 73 2864.5 8.7
FH 2.18 2165.06 47.0 5 71 2786.0 8.9
FMS 1.90 2165.70 48.0 9 93 3649.3 8.8
FMP 1.74 2134.50 40.4 5 52 2040.5 9.2
FHS 1.90 2160.03 46.2 8 86 3374.6 9.0
FHP 2.00 2132.46 40.2 5 48 1883.5 9.3
Figure 4. Effect type of fiber and square steel wire
mesh
reinforcement on depth of projectile penetration
Figure 5. Effect type of fiber and hexagonal steel
wire mesh
reinforcement on depth of projectile penetration
Specimens Designation
8
10
12
14
16
18
20
22
24
DepthofPentration(mm)
FP1 RP FMP FS1 FMS FM
Specimens Designation
8
10
12
14
16
18
20
22
24
RP FHP FS2 FHS FHFP2

302
In addition and depending on the obtained results of both projectile penetration depth
and the compressive strength of the panels, it was found that there is a negative relationship
between the mean depth of projectile penetration on one side and the compressive strength on
the other side as shown in Figure 8.
Furthermore, it was found that while the non reinforced (plain) cement mortar panel
possessed 23.0mm depth of projectile penetration with 40MPa compressive strength, the
ferrocement panel which was reinforced with square steel wire mesh possessed 8.7mm depth
of projectile penetration with 49MPa compressive strength. However, from the preceded
results it can be concluded that the inclusion of steel wire mesh reinforcement which is
decrease the depth of projectile penetration by about (37.8%) can correspondingly result an
increase in the compressive strength by about (22.5%).
Figure 8. Depth of projectile penetration versus compressive strength of the ferrocement panels
36 38 40 42 44 46 48 50
Compressive Strength (MPa)
8
10
12
14
16
18
20
22
24
Figure 6. Absorbed energy by different types
of specimens
Figure 7. Impact resistance of various
specimens

303
3.2 Modes of failure
After a carefully examination of the type of cracking and crushing of concrete, two
modes of damages were identified for the specimens in the present test program. As shown in
Figure 9, and also indicated in Table 5, these two modes of failure are: perforation and
scabbing. It can be observed from the said figure that the depth of crater depends on the type
of reinforcement.
As expected and regardless of the type and amount of reinforcement employed, it was
observed that the panel specimens (RP, FS1, FS2 and FH) failed in perforation mode.
Meanwhile, the panel specimens (FP1, FP2, FM, FMS, FMP and FHP) failed in scabbing.
Results found from impact resistance tests that all specimens broke into pieces once the no. of
impact blows causes the first crack, which indicate their brittle nature. The fractures of the
specimens are clean with little debris, thus emphasizing the tensile nature of the actual failure
process, as shown in Figure 10.
The economical and environmental advantages of using reinforcement to provide
thinner road structures, longer life cycles and reduction in maintenance costs and of course
savings in natural resources due to prolonged service intervals.
B) Rear Face DamageB) Rear Face DamageB) Rear Face DamageB) Rear Face Damage
FHPFHPFHPFHP
FMPFMPFMPFMP
A) Typical Front Face DaA) Typical Front Face DaA) Typical Front Face DaA) Typical Front Face Damagemagemagemage
FMSFMSFMSFMSRPRPRPRP
Figure 9. Mode of failure of the tested specimens
FS1FS1FS1FS1 FHFHFHFH

304
4. CONCLUSIONS
From the results of the experimental investigations reported herein, the following conclusions
can be drawn:
1- The advantages of employing steel wire mesh or steel fiber reinforcement appreciably
decreases depth of projectile penetration and correspondingly increases the
compressive strength of the cement mortar panels.
2- In this study, it is observed that the value of compressive strength decrease with
addition of polypropylene fiber.
3- Another objective of this study was that will provide recommendations as to best
practice use of ferrocement panel in road as a base course and improvements that
could be made to the specification.
4- Within the scope of this experimental investigation reported two mode of failure are
observed: perforation, and scabbing.
5- The drop load depth can be a reasonable indicator of cumulative damage in the case
of drop impact test.
6- The impact resistance of the ferrocement was improved with higher ratio of volume
fraction and type of fibers.
7- It was found that the ferrocement panel which was reinforced with square steel wire
meshes has the lowest depth of projectile penetration (8.7 mm) i.e. possessed superior
impact resistance, while the ferrocement panel which was reinforced with hexagonal
steel wire meshes comes next with a depth of projectile penetration (8.9 mm).
8- The cement mortar panel which was reinforced with crimped steel fibers (FS1)
reveals a low depth of projectile penetration close to that of the ferrocement panels
(9.0 mm) i.e. comparable impact resistance.
9- The cement mortar panel which was reinforced with polypropylene fibers (FP1) has
the highest depth of penetration (23.3mm) which indicates that such polymeric fiber
reinforcement does not enhance impact resistance if measured by the present
projectile penetration depth method.
Figure 10. Damages of specimens under impact load
FHSFHSFHSFHSRPRPRPRP

305
REFERENCES
1. ACI Committee 544, 1988, "Measurement of Properties of Fiber Reinforced Concrete",
ACI Materials Journal, Vol.85, No.6, Nov.-Dec., pp.583-593.
2. Banthia, N.; Yan, C. and Sakai, K., 1998, "Impact Resistance of Fiber Reinforced Concrete
at Subnormal Temperatures", Cement and Concrete Composites, Vol.20, pp.393-404.
3. Barr, B. and Baghli, A., 1989, "A repeated Drop-weight Impact Testing Apparatus for
Concrete", Magazine of Concrete Research, Vol.40, No.144.
4. Mansur, M. A., Ahmed, I., and Paramasivam, P., 2000, "Punching Shear Behavior of
Reinforced Ferrocement Slabs", ACI Structural Journal, Vol.97, No.5, Sep.-Oct.
5. Ramakrishnan, V.; Brand Shaug, T.; Coyle, W.V. and Schrader, E.K., 1980, "A
Comparative Evaluation of Concrete Reinforced with Straight Steel Fibers and Fibers with
Deformed Ends Glued Together into Bundles", ACI Journal, Vol.77, No.3, May-June,
pp.135-143.
6. Schrader, E.K., 1981, "Impact Resistance and Test Procedure for Concrete", ACI Journal,
Vol.78, No.2, March-April, pp.141-146.
7. Swamy, R.N. and Jojagha, A.H., 1982, "Impact Resistance of Steel Fiber Reinforced
Lightweight Concrete", Journal of Cement Composites and Lightweight Concrete, Vol.4,
No.4, November, pp.209-220.
8. Gao, X. 2007, "Mix Design and Impact Response of Fibre Reinforced and Plain Reactive
Powder Concrete", M.Sc. Thesis, RMIT University, Melbourne, Australia.
9. K. Sasiekalaa and R. Malathy, “Flexural Performance of Ferrocement Laminates
Containing Silicafume and Fly Ash Reinforced with Chicken Mesh”, International Journal of
Civil Engineering & Technology (IJCIET), Volume 3, Issue 2, 2012, pp. 130 - 143, ISSN
Print: 0976 – 6308, ISSN Online: 0976 – 6316.
10. Dr. Prahallada. M.C, Dr. Prakash. K.B and Dr. Shanthappa B.C, “Effect of Redmud on
the Properties of Waste Plastic Fibre Reinforced Concrete an Experimental Investigation”,
International Journal of Civil Engineering & Technology (IJCIET), Volume 2, Issue 1, 2011,
pp. 25 - 34, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316.
11. P.A. Ganeshwaran, Suji and S. Deepashri, “Evaluation of Mechanical Properties of Self
Compacting Concrete with Manufactured Sand and Fly Ash”, International Journal of Civil
Engineering & Technology (IJCIET), Volume 3, Issue 2, 2012, pp. 60 - 69, ISSN Print:
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