International Journal of Civil Engineering and Technology (IJCIET)
Volume 10, Issue 04, April 2019, pp. 1192–1202, Article ID: IJCIET_10_04_125
Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJCIET&VType=10&IType=4
ISSN Print: 0976-6308 and ISSN Online: 0976-6316
© IAEME Publication
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DEVELOPMENT OF A NEW PRODUCT FOR
THE OPTIMIZATION OF THE GEOTECHNIC
CHARACTERISTICS OF THE BASE COURSE IN
THE ROADS CONSTRUCTION IN SOUDANOSAHALIAN AREA: CASE STUDY OF THE
MAROUA AGGLOMERATION
Flavien Guetsa Kamanou*
Ecole Polytechnique, University of Yaoundé I, PO Box 8390 Yaoundé Cameroon
LE COMPETING BET, Centre A. EINSTEIN. PO Box: 7214 Yaoundé.
Denis Ntamack, Thomas Tamo Tatietse
Ecole Polytechnique, University of Yaoundé I, PO Box 8390 Yaoundé Cameroon
*Corresponding Author
ABSTRACT
Road infrastructure is expensive for developing countries. Indeed, on the one hand
the outdated implementation techniques, and the unavailability of standards materials
such as crushed gravels in some project areas, attest to and accentuate this difficulty.
The northern part of Cameroon is part of the Sudano-Sahelian area of the African
continent. Which is characterized by the scarcity and remoteness of rocky deposits as
well as the delicacy of extraction conditions, illustrative of areas where road
construction generates the most prohibitive expenditures. The work carried out, which
is based on the mixture techniques commonly used in soil concretes, aims to
implement locally in abundance available materials, by associating them a minimum
fraction of hydraulic binders, in order to obtain a new constituent for the base course
of road construction, according to the universal standards. After a comprehensive
documentary compilation and experimental approach in the laboratory with samples
taken in the extreme north of Cameroon, the results are convincing: the constituent of
the mixture comprising 70% of sand, 25% of soil and 5% of hydraulic binder, meets
the eligibility criteria prescribed in the implementation of the base course in road
construction, in particular the bearing index or stability (CBR) and the hardness of
skeleton’s (Rc, Rc ‘) product. This mixture would be recommended for road
construction in the Sudano-Sahelian areas, alternating with crushed gravels which is
scarce. Its implementation according to the prescribed optimal conditions, generally
reduce considerably the expenses for an efficient development of road network in the
Sudano-Sahelian area, and precisely in the north of Cameroon .
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Development of a New Product for the Optimization of the Geotechnic Characteristics of the Base
Course in the Roads Construction in Soudano-Sahalian Area: Case Study of the Maroua
Agglomeration
Key words: Aggregates, soil concrete, skeleton, stability, crushed gravels, SudanoSahelian zone, and road construction.
Cite this Article: Flavien GUETSA KAMANOU, Denis NTAMACK, Thomas
TAMO TATIETSE, Development of a New Product for the Optimization of the
Geotechnic Characteristics of the Base Course in the Roads Construction in SoudanoSahalian Area: Case Study of the Maroua Agglomeration, International Journal of
Civil Engineering and Technology 10(4), 2019, pp. 1192–1202.
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1. INTRODUCTION
Road construction is very important in country’s development plans. If the mastering of
concepts and implementation of road construction programs is widespread in industrialized
countries, it is not the case of developing countries [1], where the adoption of stereotyped
model quite often confront to many difficulties among which the scarcity of usual materials
on the site, the problems of implementation and the insufficiencies material, human and
financial resources. In this universe of concerns, where large investments are made often to
achieve poor results, it is necessary to multiply processes likely to reverse the trend, both the
absolute necessity of roads networks and more extensive roads in the cities and the
countryside arises acutely [2]. The subject treated finds its material relevance for the materials
taken of experimentation from a specific area, with the Sudano-Sahelian characteristics
domain, and their implementation which is conform within the normative context, from which
important savings in time and resources could be released. The region of the far north of
Cameroon since it is the case study, is a striking illustration of this constraining environment
from an infrastructural point of view, but conducive to the experimentation of innovative
techniques of improvement of the construction and maintenance of road. The objective in this
Sahelian part of the continent remains to provide constructive solutions adapted to the road
network, prioritizing the materials it abounds in affluence, in order to substantially reduce the
costs of achieving the infrastructure, while remaining in conformity with the requirements,
and respond effectively to the priority needs of the communities that reside there [3]. Road
construction emphasizes, in addition to the sub base course and the surface course, on the base
course which forms the essential structure, and the level at which various technical solutions
more or less conclusive are implemented according to the case, to the ranks of which the
lateritic gravels, crushed gravels, soil concretes, or their respective derivatives stabilized with
cement or bitumen, for the more standard ones [4]. The principle of composition of soil
concretes, which generally results from an input of crushed gravels to a lateritic soil of
insufficient mechanical characteristics, inspires our approach which in the interest region is
implemented with local materials available in quasi unlimited quantities. Namely sand and
soils. If soil concretes are limited to the mixtures techniques of natural materials for the
improvement of the mechanical performances of the pavement layers, the experimentation
carried out within the context of our works associates a minimum fraction of hydraulic binder,
to dope mixtures obtained and bring its characteristics to the values required by the road
construction standards. So we call this approach using the term "outsourcing of concrete soil"
which in its base, on the one hand contextualizes a concept recognized already in a specific
environment, and on the other hand seeks to expand it. This widening consists essentially in
exploring the specific materials of the study area in alternation with those that are usually
used for similar purposes, like 0 / 31.5 crushed gravels, the scarcity of which is established: it
is the neo-productive nature of the environment in which the study takes place.
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Flavien GUETSA KAMANOU, Denis NTAMACK, Thomas TAMO TATIETSE
The use as a base course of 0 / 31.5 crushed gravels recommended in road projects carried
out generally in the Sudano-Sahelian zone and precisely in Far-North Cameroon in particular
generates very high costs, in view of the origin of this material and the conditions of its
implementation, hence the need to seek for economic solutions integrating the use of local
materials. The abundance of sand in this region and particularly in the Maroua’s town and its
neighbouring localities, precisely in the beds of Mayo (rivers) militate in favor of the usage of
this material in the pavement layers design.
The objective is to find the proportion of the constituents of a sand-soil mixture stabilized
with cement and according to the criteria of eligibility of materials use as base course for
pavement with moderate traffic in zones according to the characteristics described above:
2. MATERIAL AND METHODOLOGICAL APPROACH
In practice, the design of the structure of a road is based on the knowledge of its essential
components such as the formation layer, the sub base, the base course and the Surface course
(Figure 1).
Figure 1 Drawing of the concept of pavement structure
Of these different parameters, the base course is one of the most constraining, due to the
severity of its mechanical characteristics, its key role in the durability of the road structure,
and the costs it generates.
The methodological approach developed to achieve the goal is to vary the percentage of
sand and soil by maintaining the percentage of cement at 5% and appreciate the geotechnical
characteristics of the mixture.
The geotechnical characteristics evaluated are the simple compressive strength after 7
days exposure to the air (Rc), the simple compressive strength after 3 days exposure to the air
and 4 days of immersion (Rc'), the CBR (California Bearing Ratio) index after 3 days
exposure to the air and 4 days of immersion.
2.1. Materials and Equipment
The experimental material is divided into two main classes, described below:
The specimen making equipment: It includes the CBR mold, rammer and the normal and
modified Proctor compaction equipment with the set of accessories (extension collar , annular
surcharge disc, spatula or palette knife, small tools), and the material of common use
comprising a balance, trays, an oven and a hot plate.
A cylindrical metal plunger, the lower end of which shall be of hardened steel and have a
nominal cross-sectional area of 19.35 cm², corresponding to a specified diameter of 60 mm. A
convenient size would be approximately 20 cm long.
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Development of a New Product for the Optimization of the Geotechnic Characteristics of the Base
Course in the Roads Construction in Soudano-Sahalian Area: Case Study of the Maroua
Agglomeration
A machine for applying the test force through the plunger, having a means for applying
the force at a controlled rate. The machine shall be capable of applying at least 50 kN at a rate
of penetration of the plunger of 1.27 mm/min to and a dynamometric device for measuring the
punching forces.
2.2. The Constituents of the Mixture
The materials used in this study all come from the Maroua’s city, whose location map is
illustrated in figure 2. We estimated the quantities of soil available in the site of Wourndé II,
from where the analysis samples were taken. This calculation shows that the exploitable
quantities are considerable. The minimum volume measured is estimated at nearly 2,800,000
m3, according to the identification map, shown in Figure 3.
Figure 2: Site experiment: a portion of the Sudano-Sahelian influencing zone, part of Cameroon
Figure 3 The city seat of experiment (Maroua) and its availability in sand and soil materials
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Flavien GUETSA KAMANOU, Denis NTAMACK, Thomas TAMO TATIETSE
The table below shows the origin of materials exploited in this formulation
Table 1 Origin of collected materials
Material
Origin
The Mayos bed
Borrow of Wourndé II
Figuil
Sand
Soil
Cement
2.3. Composition of the Mixtures
In reference to experiments conducted by researchers in the field of material stabilization [4],
we selected three compositions by varying only the percentage of sand and clay. In each
composition, the percentage of cement is maintained at 5%.
Table 2 below shows the different mixtures studied.
Table 2 Proportion of materials content in each mixture
Mixture
Materials
Proportion
Sand
60%
Soil
35%
Cement
5%
Sand
65%
Soil
30%
Cement
5%
Sand
70%
Soil
25%
Cement
5%
N°1
N°2
N°3
3. RESULTS AND DISCUSSION
3.1. Identification of materials before mixing
The sand of Mayo Kaliao, a river running through the city of Maroua from west to east, and
the soil of Wournde II quarry located in the northern peripheral districts of the same city are
tested before mixing. The main results obtained are as follows:
Table 3: Particle Size Analysis of the Wourndé II and Mayo kaliao Samples
Boring
Depth of
sampling (m)
P1
0,40 - 1,50
P4
On surface
Nature of the
materials
Sandy-Clay
(soil)
Coarse sand
Sieve analysis
(sieve opening in mm)
25
20
Atterberg’s
limits
LL LP IP
0,5 0,08
( %) (%) (%)
10
5
2
1
100 98,8 96
94
86
78
68 55,8
62
100 100
90
58
28
10
Not necessary
97
0,4
34
28
Observation: The plasticity index of the Wournde II soil material is greater than 25 and the
percentage of fine elements greater than 50. The coarse sand of Mayo Kaliao has a fineness
modulus of 3.87.
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Development of a New Product for the Optimization of the Geotechnic Characteristics of the Base
Course in the Roads Construction in Soudano-Sahalian Area: Case Study of the Maroua
Agglomeration
3.2. Results
The characteristics of the different mixtures are given in the following table.
Table 4 Characteristics of the different mixtures
Sieve analysis
(Sieve opening in mm)
Mixture Composition
25
1
2
3
60% Sand
35% Soil
5% Cement
65% Sand
30% Soil
5% Cement
70% Sand
25% Soil
5% Cement
20
10
5
2
1
0,5
Atterberg’ Modified
s limits
Proctor
LL LP Ɣd
w
3
0,08 (%) (%) (T/m ( % )
)
100 100 97,8 93,9 74,2 52,4 34,6 17,7
26
18
2,15
7,3
100 100 97,8 90,8 66,1 42,9 26,6 11,4
28
19
1,99
10,5
100 100 98,6 93,6 59,8 41,6 21,3
30
20
2,105
8,9
5,2
Thus, the experiment carried out on the samples of mixtures 1 and 2 gave the following
graphical representations:
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Development of a New Product for the Optimization of the Geotechnic Characteristics of the Base
Course in the Roads Construction in Soudano-Sahalian Area: Case Study of the Maroua
Agglomeration
On the samples compacted at 95% of the OPM density, the values of the CBR index and
the simple compressive strength obtained are summarized in the table below.
Table 5 Value of the CBR index, résistance to simple compression
Mixture
1
2
3
𝑹𝒄 (bar)
18,7
19,3
21,4
CBR
162
193
215
𝑹𝒄′ (bar)
7,4
9,1
10,7
Observation: The bearing capacity index CBR (after 3 days of air treatment and 4 days of
immersion) of the Sand-Soil-Cement mixture is greater than 160 which is the value required
for an improved material intended for the base course implementation.
3.3. Discussion of Results
Eligibility criteria of the materials : The principal criteria retained for the eligibility of
materials at the base course are as follows : The stability or bearing index (CBR) and the
hardness of the skeleton ( Rc, Rc’) : To meets these criteria, the bearing capacity index CBR
must be at least equal to 80 for a dry density corresponding to 95% of the OPM. If the natural
material does not reach this bearing capacity, a stabilization is necessary before its usage at
the base course. Borrow materials from the city of Maroua (Soil from the mountains of
Woundé II) have a bearing capacity Index CBR including between 25 and 35, sufficient to be
used at the sub base course, but not at the base course.
Interpretations of the results obtained: The bearing capacity index CBR increases
progressively when the percentage of soil decreases in the mixture, until it reaches an
empirical point of the composition. As a result, the mixture containing 25% of soil against
70% of sand and 5% of cement present the best CBR. Indeed, the increase in soil’s
percentages aims at ameliorating the cohesion of the whole. The sand used has a fineness
modulus in the order of 3.8 describing the poverty of this soil in fine elements.
Following the Practical Guide of Dimensioning road of tropical areas, the stabilized
materials are satisfactory when they respond to the criteria presented in the following table:
Table 6: Eligibility criteria of the materials
Criteria
CBR at 95% of OPM after 3 days air treatment and 4
days of immersion
The simple compressive strength after 7 days of air
treatment Rc
The simple compressive strength after 3 days of air
treatment and 4 days of immersion Rc’.
Required value
>160
>18 bars
>5 bars
The three mixtures submitted to the study are all satisfactory, each meeting the eligibility
criteria presented in the table above. One of the objectives of this study being encouraging the
use of sand which will allow to eradicate the stream of the Mayo Kaliao, we recommend the
adoption of mixture 3 which integrates the use of 70% of sand.
4. CONCLUSIONS
This study aims at adapting roads structures in Soudano-Salelian areas, case of the region of
the far North Cameroun, according to local materials available. At the end of this experiment,
to meet the needs of the implementation of the base course in the roads construction in areas
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described above: Mixture III made up of 70% of sand, 25% of soil and 5% of cement could be
definitely adopted for the construction of base course of roads in substitution to standard
methods that appeals to the use of lateritic gravels or crushed gravels, almost inexistent in the
interest region. This mixture has the advantage of incorporation up to 70% of sand, which is
present in abundance in this part of the territory, and could also contribute in curing the
Mayos’stream, which is full, and can reduce the hydraulic power. We can easily realize that
the adoption of this new technic helps on the one hand in ameliorating the development of
road’s insfrastructures in the Far Nord of Cameroon at reduced cost on one hand, and on the
other hand limit flooding sites exposed to the overflow of Mayos by curing their stream.
REFERENCES
[1]
Organisation des Nations Unies pour l’éducation, la science et la culture. Routes dans les
pays en voie de développement – Construction et entretien – Conditions économiques et
techniques (2009) p.2.
[2]
MINEPAT. Vision Cameroun 2035. 2009 p.v.
[3]
Direction de la statistique et de la comptabilité nationale. Conditions de vie des ménages
et profil de pauvreté à l’extrême-nord Cameroun
(Décembre 2002) p.18.
[4]
LCPC/SETRA. Traitement des sols à la chaux et/ou aux liants hydrauliques Application à
la réalisation des remblais et des couches de forme, Guide technique (janvier 2000).
[5]
Modou Diop (2002), Conception des structures routières sur Marnes et argiles gonflantes.
Projet de fin d’étude en vue de l’obtention du diplôme d’ingénieur de conception,
Thiès.133P
[6]
Tidiane Ibrahim Doucoure et Mamadou Doudou Ndiaye (2009), Etude de matériaux de
substitution à la latérite en couche de base : Sable –bitume et Banco-coquillage. Projet de
fin d’études en vue de l’obtention du diplôme de conception, Thiès 168P.
[7]
Bakaiyang Lemankreo (2013), Contribution à l’entretien des routes revêtues en zone
tropicale : cas des régions du Grand-Nord Cameroun. Mémoire de fin d’études en vue de
l’obtention du diplôme d’ingénieur de conception, ENSP Yaoundé.
[8]
Symkiewicz Fabien, Evaluation des propriétés mécaniques d’un sol traité au ciment.
Thèse de doctorat en vue de l’obtention du diplôme de docteur de l’université de ParisEst. Option Géotechnique.245P
[9]
BCEOM-CEBTP (1984), Guide pratique de dimensionnement des chaussées pour les
zones tropicales, 155p.
[10]
MINDHU (Août 2014), Etude Technique en vue de la protection des berges du Mayos
Kaliao-Maroua, Rapport d’APD –LE COMPETING-BET.142P
[11]
NB: The laboratory LE COMPETING-MAT, approved category B, served within the
context of all the tests carried out, as part of the experiment conducted. May he find here
the expression of our sincere gratitude.
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Development of a New Product for the Optimization of the Geotechnic Characteristics of the Base
Course in the Roads Construction in Soudano-Sahalian Area: Case Study of the Maroua
Agglomeration
ANNEX
A1-Summary sheet of geotechnic test ;
A2- Some graphical illustrations
ANNEX A1 : SUMMARY SHEET OF GEOTECHNIC TEST
Result of the Sieve Size analysis Curve of the material Sand and Soil
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ANNEX A2 : SOME GRAPHICAL ILLUSTRATIONS
Soil sampling at the bottom of Mount Wourndé
…
Avaibility of soil materials (Mountain range)
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