Ijciet 06 09_001

http://www.iaeme.com/IJCIET/index.asp 1 editor@iaeme.com
International Journal of Civil Engineering and Technology (IJCIET)
Volume 6, Issue 9, Sep 2015, pp. 01-07, Article ID: IJCIET_06_09_001
Available online at
http://www.iaeme.com/IJCIET/issues.asp?JTypeIJCIET&VType=6&IType=9
ISSN Print: 0976-6308 and ISSN Online: 0976-6316
© IAEME Publication
___________________________________________________________________________
INVESTIGATING THE MARSHALL
STABILITY REQUIREMENTS OF ASPHALT
CONCRETE MIX WITH GROUND SCRAP
TYRES AS AGGREGATE
D.B. Eme and T.C. Nwofor
Department of Civil Engineering, University of Port Harcourt,
P.M.B 5323 Port Harcourt, Rivers State,
Nigeria.
ABSTRACT
Ground scrap tyres can be used in asphalt mixtures either as a binder
modifier (wet process) or as a fine and/or coarse aggregate replacement (dry
process). To evaluate the effect of rubber-bitumen interaction on the dry
processed mixtures, a laboratory investigation was conducted on a range of
dense graded dry process with 4.75mm, 2.36mm and 0.600mm particle size
rubber modified asphalt mixtures containing 0 (control), 2, 4 6, 8 and 10%
ground rubber by aggregate mass. The mixtures were subjected to Marshall
Stability test. The stability, flow, percentage air void, unit weight, voids in
mineral aggregate, and specific gravity were determined. The results
indicated that, in general, as the rubber percentage increase, the stability, unit
weight and specific gravity value decrease. In addition, as the rubber content
increase, the flow of specimen also increases. The result also showed that as
the rubber content increases the percent air voids and VMA increase for
4.75mm RPS and 2.36mm RPS, while for 0.600mm RPS the reverse was the
case. Generally as regards the Marshall Stability tests, the rubber modified
specimens remained intact after failure. Such behavior will be beneficial for a
pavement that requires good impact resistance properties. The use of 10%
4.75mm, 4% 2.36mm or 4% 0.600mm RPS by weight of aggregate mass in
asphaltic concrete is recommended for medium traffic volume pavements.
Cite this Article: D.B. Eme and T.C. Nwofor. Investigating The Marshall
Stability Requirements of Asphalt Concrete Mix with Ground Scrap Tyres as
Aggregate. International Journal of Civil Engineering and Technology, 6(9),
2015, pp. 01-07.
http://www.iaeme.com/IJCIET/issues.asp?JTypeIJCIET&VType=6&IType=9

1. INTRODUCTION
As population grow, so do the volume of waste and by-product materials generated.
Attempts are still been made by various organizations and researchers to find methods
for effectives utilization of waste materials which also includes efforts to the
application of some of the waste products in highway construction. The construction
of highway pavements requires large volume of materials hence highway agencies
have become participants in these recycling efforts. Experience and knowledge
regarding the use of these materials differ from material to material hence to recover
these materials for potential use, engineers and researchers need to be aware of the
properties of the materials, how they can be used and what limitations may be
associated with their use. Every year, an estimated eight hundred and fifty thousand
(850,000) scrap tyres are generated and carelessly discarded in Nigeria, resulting in
serious waste disposal problems, [1].
The introduction of scrap tyre rubber into asphalt concrete production has the
potential to solve this waste problem as has been effectively carried out in the
production of most construction materials, [2-7]. The use of scrap tyre-rubber as an
additive for asphalt concrete has been developing for over thirty years, where it was
generally observed that the benefits outweighs the higher cost of the conventionally
produced asphaltic concrete material, especially on some highways with peculiar
problems, [8-9].
The basic contribution made in this study is to find out the optimum effect of the
substitution of the aggregates for asphalt concrete production with locally available
scrap tyre on the standard strength parameters.
2. MATERIALS AND METHOD
The aggregates were collected from crush rock Nigerian Limited in Rivers State,
Nigeria. This source was chosen because of its proximity. The aggregates supplied
consisted of 9.5mm granite chippings and 0.5mm quarry sand.
The scrap tyres used in this research were collected from a scrap tyre dump along
Anozie street, Diobu, in Port Harcourt, Nigeria. These tyres were cleaned through
washing with water and then dried. The clean tyres were shredded into sections freed
from steel breeds and later the sections were cut into small pieces with aid of knives
and hacksaw. The shredded tyres were also grinded using electric grinding machine
which reduced them into rubber particles and synthetic fibre mixture. The mixture
was then sieved and rubber particles retained on 4.75mm, 2.36mm and 0.600mm
sieves were collected.
Bitumen is a viscous liquid consisting essentially of hydrocarbons and their
derivates. The bitumen used in this research was collected from the building material
market Mile III, Diobu, Port Harcourt.
2.1. Sample Preparation
The following tests were used in the classification and preparation of the samples.
2.1.1 Sieve Analysis
The sieve analysis was carried out in accordance with BS1377:1975 – methods of
tests for soils for Civil Engineering purposes. The gradation requirement used in this

Investigating The Marshall Stability Requirements of Asphalt Concrete Mix with Ground
Scrap Tyres as Aggregate
research was for Asphalt Institute Mix No. IV(a), in order to meet the specification
requirement of 49% granite chippings and 51% of quarry sand.
2.1.2 Specific Gravity
The specific gravity test was carried out in accordance with BS1377:1975 methods of
test for soils for Civil Engineering purposes. Close values 2.66 and 2.57 were
obtained for granite chippings and Quarry sand respectively, while the ground scrap
tyre specimens gave specific gravity values of 1.11, 1.16 and 0.96 for rubber particle
sizes of 4.75, 2.36 and 0.6mm respectively which also indicates their light weight.
2.1.3 LOS Angles Abrasion and Aggregate Crushing Test
This test is used for measuring the abrasion resistance of aggregates. The top layer of
a pavement gets abraded due to the movement of tyres. A material which has high
abrasion resistance has a long life. The LOS Angles Abrasion test was carried out in
accordance with AASHTO-T96. Also one of the modes in which a pavement material
can fail is by crushing under severe stresses. A test devised to express the crushing
strength is the aggregate crushing test. The test consists of subjecting the aggregate
specimen in a standard mould to a compression test under standard loading
conditions. The aggregate crushing test was carried out in accordance with BS1377
:(1975). The granite chippings gave a Los Angeles abrasion value of 31.19% and
aggregate crushing value of 36.80%. From the specification recommended in
Emesiobi [10], the granite chipping is adequate for use in asphalt concrete mix.
2.1.4. Penetration Test
The penetration of bitumen is defined as the distance in tenths of a millimeter that
a standard needle will penetrate into the bitumen under a load of 100g applied in five
seconds at 250
C. The higher the penetration, the softer is the bitumen. It is used for
classifying bitumen into standard grade. The bitumen test was carried out in
accordance with AASHTO-T49. The bitumen gave a penetration of 63pen. The result
indicates that the bitumen used is a 60/70 grade bitumen which is adequate for use in
hot mix asphaltic concrete in tropical climate.
2.2. Mix Design
The mix was designed as dense graded with 100% passing the 12.5mm sieve using
the Asphalt institute IV (a) specification. The aggregates were blended using the
Rothfuch’s method. The control mix with no chunk or crumb rubber was designed
and the amount of rubber used in the mixes varied from 2% to 10% by weight of the
granite chippings for scrap tyre rubber particles retained on sieves 4.75mm and
2.36mm and quarry sand for rubber particles retained on 0.600mm sieve.
2.3. Specimen Preparation and Testing Method
The method adopted in preparing the test specimens was the same as that
recommended for Marshall test specimens by Emesiobi [10] in accordance with
ASTMD 1559. The basic test carried out in the laboratory was the Marshall Stability
test. Marshall Stability values which are maximum load at failure and their
corresponding flows were recorded. Also values of stability flow air void, unit weight
and aggregate voids filled with binder (VMA) against bitumen content were also
obtained. During the test procedure an optimum bitumen content of 6.22%
(corresponding to the average of the maximum stability, average air voids of 3-5%

and average maximum unit weight) was obtained. Thereafter the bitumen content
(optimum bitumen content) was fixed while the effect of other parameters was
investigated. The parameters such as scrap tyre rubber particle sizes and rubber
content of the hot-mix asphaltic concrete were varied. The mix parameter chosen
were rubber particle sizes retained on 4.75mm, 2.36mm and 0.600mm sieves and
rubber content of mix from 2 to 10 percent by weight of granite chippings.
3. RESULTS AND DISCUSSION
A total of 103 laboratory prepared Marshall specimens were made and tested. All of
the testing was conducted at the Civil Engineering laboratory of the Rivers State
University of Science and Technology and in accordance with AASHTO and/or
ASTM procedure. Table 1 contains Marshall Test results from this study as a function
of rubber content and rubber particle size.
Table 1: Values of Marshall Stability test properties of asphaltic concrete.
Rubber
Content
(%)
Rubber
Particle
Size (mm)
Marshal
Stability
(kN)
Flow
(mm)
Air voids by
Total
Mixtures (%)
Unit
Weight
(kg/m3
)
Voids filled
with Bitumen
(VMA) (%)
Specific
Gravity
0 7.24 4.04 3.23 2.354 81.19 2.385
2
4.75 4.63 3.68 3.09 2.275 81.11 2.355
2.36 5.47 3.71 3.05 2.288 81.92 2.360
0.600 6.20 3.74 3.02 2.300 81.79 2.316
4
4.75 3.61 3.25 3.40 2.230 80.16 2.332
2.36 4.95 4.05 3.53 2.276 79.45 2.335
0.600 4.97 4.22 2.28 2.246 85.52 2.316
6
4.75 3.49 3.61 4.30 2.206 75.19 2.306
2.36 4.90 4.52 4.46 2.268 74.56 2.311
0.600 4.33 4.48 2.13 2.231 86.70 2.283
8
4.75 3.14 4.21 4.34 2.191 75.43 2.267
2.36 4.85 4.97 4.76 2.177 73.63 2.289
0.600 3.84 4.69 2.04 2.205 86.72 2.251
10
4.75 2.69 4.52 4.37 2.158 75.51 2.255
2.36 4.28 5.54 4.89 2.164 72.89 2.265
0.600 3.61 5.43 1.35 2.190 90.74 2.220
3.1. The Effect of Rubber Content on Marshall Stability
A study of Table 1 shows that at 0% rubber content, the stability was 7.24kN for
4.75mm rubber particle size. At 2% rubber content, the stability reduced to 4.63kN
while at 4% rubber content, the stability is 3.61 KN. When the rubber content was
increased from 6 to 10%, the stability reduced from 3.49kN to 2.69kN. With these
results it can be seen that Marshall stability decreases with increasing rubber content
of 4.75mm rubber particle size (RPS). This follows the normal trend when using the
dry process in mixing aggregates and ground scrap tyre rubber where similar trend
has also been reported that the Marshall stability of an asphalt aggregate-chunk rubber
mix would be lower than that of the control mix, [11-12]. Since rubber is not as hard
as the crushed stone aggregates, the rubber chunks tend to absorb some of the energy

imparted, resulting in a weaker aggregate structure. The Marshall stability result
shows the same trend with the other two rubber particle size, see Table 1. It can also
be seen that as the rubber content increases from 2 to 10%, the Marshall stability
decreases from 6.20kN to 3.5lkN which is higher than 2.0KN which the minimum
stability for medium volume traffic roads, Emesiobi [10].
3.2. The Effect of Rubber Content on Flow
Observing Table 1 for the flow characteristic of the rubber modified asphaltic
concrete, it can be seen that as the rubber content is increased, the flow also increased.
The flow value for the control mix (0% rubber content) which was 4.04mm, reduced
to 3.68mm flow for 2% 4.75mm, rubber particle size (RPS) content. It starts to
increase to 3.71mm for 4% rubber content and as the rubber content increased from 6-
10 percent, the flow also increased to 4.52mm from 3.61mm. The results show trend
that would be expected for flow property and it is reported by Hossain et al (1996)
and Amirkhanian et al (1996). The same trend is noticed for 2.36mm RPS modified
asphaltic concrete because the flow value increased from 3.71mm to 5.54mm when
the rubber content was increased from 2 to 10 percent. Also the flow value increased
from 3.74mm to 5.43mm when 0.600mm RPS rubber content was increased from 2 to
10 percent. From the results gotten, it can be deduced that the addition of ground
scrap tyre rubber into asphaltic concrete using the dry process method generally
increase the flow value no matter the size of rubber used. Specimen produced with the
three different rubber particle sizes, within the range of rubber content tested have
their resulting flows falling within 5mm maximum specification for wearing courses
Emesiobi (2000) except 10% rubber content of 2.36mm and 0.600mm RPS.
3.3. The Effect of Rubber Content on Percentage Air Void
Table 1 gives the results of the effect of rubber on air voids of the mix. The control
mix (0% rubber content) gave an air void of 3.23% which meets the requirement for
medium volume traffic pavement as given by Asphalt institute. At 2%, 4.75mm RPS
content, the air void was 3.09%, at 4% rubber content the air void increased to 3.40%.
On further increase of rubber content from 6 to 10%, the air void increased also from
4.30 to 4.37 percent. The same trend was noticed for 2 36mm RPS , where 2% rubber
content gave an air void of 3.05% and it increased to 3.40% at 4% rubber content.
When the rubber content increased from 4-10 percent, the air void increased from
3.40-4.89%. The reverse was the case for 0.600mm RPS where at 2% rubber content,
the air void was 3.02% and when the rubber content increased to 10%, the air void
reduced to 1.35%. This follows the normal trend when using the wet process method
in asphalt concrete mix as was also reported by Roque etal., [13]. Referencing the
recommendation that percentage air voids for medium volume roads should range
between 3-5% Emesiobi [10], only specimens produced with 4 75mm, 2.36mm and
2% of 0.600mm RPS meet these specification.
3.4. The Effect of Rubber Content on Unit Weight
From Table 1, it can be seen that at 0% rubber content, the unit weight was
2.354kg/rn3
. When the rubber content increases from 2 to 10%, the unit weight
reduced from 2.275 to 2.158kg/m3
for 4.75mm RPS mix. The same trend was noticed
for 2.36mm RPS whose unit weight reduced from 2.288kg/rn3
to 2.164kg/rn3
when
the rubber content increased from 2 to 10% and also 0.600mm RPS mix whose unit
weight decreased from 2.300kg/rn3
to 2.190kg/m3
for the same increased rate in

rubber content. The results show the trend that would be expected for the three
different rubber particle sizes and is also in agreement with Roque etal., [13].
3.5. The Effect of Rubber Content on Voids in Mineral Aggregate
The control mix gave a VMA value of 81.19% which meets the specification given by
Asphalt Institute. As ground rubber was added, the VMA generally decreased. At 2%
rubber content, the VMA was 81.11% for 4.75mm RPS which decreased to 75.43% at
8% rubber content. The same trend is noticed for 2.36mm RPS. While for the
0.600mm RPS the reverse was the case in which at 2% rubber content, VMA was
81.79% which increased to 90.74% as the rubber content increased to 10%. The result
of VMA for 4.75mm RPS and 2.36mm RPS follows the normal trend and is in
agreement with Hossain etal., [11].
3.6. The Effect of Rubber Content on Specific Gravity
It is generally expected that the specific gravity of the specimen will decreases as the
rubber content increases. From Table 1, at 0% rubber content, the specific gravity was
2.385 and decreased to 2.255, 2.265 and 2.220 for 4.75, 2.36 and 0.600mm RPS
respectively as the rubber content increased to 10%. This trend is as result of the
lightweight and low specific gravity of ground scrap tyre rubber as compared to the
conventional aggregates used.
4. CONCLUSION AND RECOMMEDATIONS
4.1. CONCLUSON
The following conclusion was drawn in this study:
1. The control specimen (i.e. 0% rubber content) produced higher stability value
compared to specimens containing various percentages of rubber. The stability
generally decreases as the rubber content increases and the lower the RPS, the
higher the stability.
2. The flow increases as the rubber content increases for the various RPS and there
is no set pattern between RPS and flow.
3. The percent air voids increases as rubber content increases for 4.75mm RPS and
2.36mm RPS. However, the same trend is not true for 0.600mm RPS.
4. As the rubber percentage increases, the unit weight decreases and there is no set
pattern for RPS.
5. The VMA decreases as the rubber content increases for 4.75mm RPS and
2.36mm RPS but for 0.600mm RPS where the VMA increases as the rubber
content increases. In general, the VMA increases as the RPS increases from
2.36mm to 4.75mm.
6. As the rubber percentage increases, the specific gravity decreases and there is no
set pattern for RPS.
4.2. RECOMMENDATIONS
1. The upper limit of 10% of 4.75mm RPS and 4% of 2.36mm and 0.600mm RPS
meets the design criteria for medium volume pavement surface. .
2. Other alternatives uses of scrap tyre rubber, not related to asphaltic concrete
should be studied, for example, use of rubber in producing lightweight concrete.

3. 0.600mm RPS modified asphaltic concrete is highly recommended for
intersections (high volume, slow moving traffic)
REFERENCES
[1] Aisien, F.A. & Anyata B.U. Comparative study of the effect of conditioning
environment on the mechanical properties of asphaltic concrete. Nigerian Journal
of Industrial and Systems Studies, 1, 2004, pp. 12-17
[2] Nwofor, T.C. & Eme, D.B. Stability of concrete work with partial substitute of
rice husk ash (RHA) for cement in Nigeria. Journal of Chemical, Mechanical and
Engineering Practice, 1(2&3), pp.42-47, 2010
[3] Sule, S. & Nwofor, T.C. Analytical models for prediction of mechanical
properties of rice husk ash concrete. International Journal of Current Research,
3(11), 2011, pp. 368-370,
[4] Nwofor, T.C. & Sule, S. Stability of groundnut shell ash (GSA)/ordinary Portland
cement (OPC) concrete in Nigeria. Advances in Applied Science Research, 3(4),
2012, pp.2283-2287.
[5] Nwofor, T.C. & Sule, S. Investigating geometric characteristics of cement
concrete materials. International Journal of Innovative Research in Advanced
Engineering, 1(9), 2014, pp.74-82.
[6] Eme, D.B., Nwofor, T.C. & Umukoro, E.S. Stability of asphalt cement concrete
produced from waste plastics as replacement for aggregate. International Journal
of Civil Engineering and Technology, 6(5), 2015, pp 65-75.
[7] Robin, L.S. The use of recycled materials in highway construction. Journal of
Public Roads, 58(2), pp.1-4. 1994
[8] Heitzman, M. An overview of design and construction of asphalt paving material
with crumb rubber additives. Proceedings of Transportation Research Board,
Washington D.C., 71, 1992, pp. 2-7.
[9] Robert, N., Flexible pavement rehabilitation using asphalt rubber combinations.
Proceedings of Transportation Research Board, Washington D.C., pp. 213-223,
1988
[10] Emesiobi, F.C. Testing and quality control of materials in civil and highway
engineering. The Blueprint Publishers Limited, Nigeria, pp. 18-24, 2000
[11] Hossain, M., Sadeq, M., Funk, L. & Maag, R. A study of chunk rubber from
recycled tyres as a road construction material. Proceeding of Semi
sesquicentennial Transport Conference, pp.7-11, 1996
[12] Rahman, M.M., Airey, G.D. & Collop, A.C. The mechanical properties of the dry
process CRM asphalt mixtures following short-term and long-term ageing.
International Journal of Pavement Engineering, 14(4), pp. 344-354. 2003
[13] Roque, R., Birgisson, B., Drakos, C. & Sholar, G. Guildelines for use of modified
binders. Department of Civil and Coastal Engineering, University of Florida, 365
Weil Hall, Florida, pp.8-44, 2005

Ijciet 06 09_001

Recommended

Recommended

More Related Content

What's hot

What's hot (19)

Viewers also liked

Viewers also liked (14)

Similar to Ijciet 06 09_001

Similar to Ijciet 06 09_001 (20)

More from IAEME Publication

More from IAEME Publication (20)

Recently uploaded

Recently uploaded (20)

Ijciet 06 09_001