agarcia4108@utm.edu.ec
Study of the physical and mechanical behavior of an asphalt-stabilized subgrade of the
Rocafuerte - Tosagua road in the province of Manabí
Estudio del comportamiento físico y mecánico de una sub-rasante estabilizada con asfalto de la vía
Rocafuerte – Tosagua de la provincia de Manabí
Aura Andrea García Cevallos
Master's Degree, Universidad Técnica de Manabí.
Portoviejo, Manabí, Ecuador,
agarcia4108@utm.edu.ec, https://orcid.org/0000-
0001-9637-3140
Jefferson Kelvin Loor Menéndez
Master's Degree, Universidad Técnica de Manabí.
Portoviejo, Manabí, Ecuador, Jloor0557@utm.edu.ec,
https://orcid.org/0000-0002-1308-4536
Lucia Katherine Macias Sanchez
Master's Degree, Universidad Técnica de Manabí.
Portoviejo, Manabí, Ecuador,
lucia.macias@utm.edu.ec, https://orcid.org/0000-
0002-9921-4943
Eduardo Humberto Ortiz Hernández
Master's Degree, Universidad Técnica de Manabí.
Portoviejo, Manabí, Ecuador,
eduardo.ortiz@utm.edu.ec, https://orcid.org/0000-
0002-1885-6005
Abstract
Within the province of Manabí we have different types of soils, among which clays are predominant,
that is why before building any civil work, studies should be carried out where we can know the
properties of the soil, in order to achieve its improvement through its stabilization. In this article we
study the characteristics of a subgrade in its natural state and stabilize it with asphalt to determine the
physical-mechanical behavior of the soil and thus establish differences between them after stabilization.
This research has a quantitative experimental methodology that comprises three stages, the first one is
the extraction of a sample along the Rocafuerte - Tosagua road, where differential changes were
observed in the pavement structure with the presence of cracks of more than 10 centimeters of opening.
In the second stage, the soil samples were tested in the soil laboratory under ASTM standards, including:
moisture test (ASTM D2216), Atterberg Limits (ASTM D4318), Fine Series Granulometry (ASTM
D422), Proctor test (ASTM D 1557-78) and CBR bearing capacity (ASTM D-1883). The tests were
carried out both for the natural soil sample and for the sample stabilized with asphalt, in percentages of
3%, 6%, 9%, 12% and 15%, and finally, in the third stage, comparisons were made between the physical
and mechanical characteristics of the subgrade in its natural state and that stabilized with asphalt,
http://centrosuragraria.com/index.php/revista, Published by: Edwards Deming Institute,
Quito - Ecuador, July - September vol. 1. Num. 14. 2022, This work is licensed under a
Creative Commons License, Attribution-NonCommercial-ShareAlike 4.0 International.
https://creativecommons.org/licenses/by-nc-sa/4.0/deed.es
Received January 09, 2022
Approved: June 30, 2022
Garcia et al 2022
July - September vol. 1. Num. 14 2022
demonstrating that with the addition of asphalt a considerable increase in the maximum dry density and
CBR was obtained in the samples.
Key words: Soil characteristics, clays, soil stabilization, bearing capacity, asphalt.
Resumen
Dentro de la provincia de Manabí tenemos diferentes tipos de suelos entre las que predominan son las
arcillas, es por eso que antes de construir alguna obra civil se deben realizar estudios en donde podamos
saber las propiedades del suelo, con el fin de poder lograr su mejoramiento atreves de estabilización
del mismo. En el presente artículo se estudian las características de una subrasante en estado natural y
estabilizarla con asfalto para determinar el comportamiento físico – mecánico del suelo y así establecer
diferencias entre ellas luego de su estabilización. Esta investigación tiene una metodología
experimental cuantitativa que comprende en tres etapas, la primera es la extracción de muestra a lo
largo de la vía Rocafuerte – Tosagua, donde se observó cambios diferencial en la estructura de
pavimento con presencia de grietas más de 10 centímetros de abertura. En la segunda etapa, la muestra
de suelo fueron realizadas en el laboratorio de suelo bajo normas ASTM entre estos tenemos: ensayo
de humedad (ASTM D2216), Límites de Atterberg (ASTM D4318), Granulometría de serie fina
(ASTM D422), ensayo de Proctor (ASTM D 1557-78) y capacidad Portante CBR (ASTM D-1883).
Los ensayos fueron realizados tanto para la muestra de suelo natural como para la muestra estabilizada
con asfalto, en porcentaje de 3%, 6%, 9%, 12% y 15% y finalmente en la tercera etapa se obtienen las
comparaciones entre las características físicas y mecánicas de la subrasante en estado natural y la
estabilizada con asfalto, demostrando que con la adición del asfalto se obtiene aumento considerable en
la densidad máxima seca y el CBR en las muestras.
Palabras claves: Características del suelo, Arcillas, estabilización del suelo, capacidad Portante,
Asfalto.
Introduction
Roads are an important source that is closely related to the development and sustainability of a town,
city, country, etc., due to this it is strictly necessary that the materials used in the manufacture of roads
are of high resistance, durability and good quality. A road that is in a state of deterioration can have
consequences of considerable gravity for the society, among which we can point out the lack of
development of the communities or localities, notable problems of mobilization, traffic accidents,
among other problems. (Corradine & Espitia, 2015).
A parameter that must be highly considered is the presence of expansive clays in the soil where the road
project in question will be developed. The mechanisms experienced by expansive clays are the result
of a variation in the moisture content of the soil that alters the internal stress equilibrium in the soil.
Generally, the incidence of the behavior of materials with expansive characteristics is not taken into
account even though it is a fundamental cause of damage experienced in road structures. (Chicaiza &
Oña , 2018).
The subgrade is the initial layer of a pavement structure made up of soils in their natural state or in
certain cases with some improvement process, such as the so-called mechanical stabilization, which is
the application of loads to reduce the voids between particles of the soil structure with the purpose of
increasing its bearing capacity. The quality of this layer influences the thickness of the pavements, even
in the case of third order roads, the wearing course is the same, so it is important that it has a good
quality to avoid problems with traffic due to deformations that may occur on the road. The most
representative properties that are analyzed in a subgrade include drainage, resistance, ease and
preservation of compaction and volumetric stabilization. (Alzate, 2019).
There are several methods to stabilize a soil with the presence of expansive clays, some authors;
(Sanchez, 2014) y (López-Lara, 2010) mention physical procedures consisting of soil mixtures and use
126
of geotextiles; mechanical methods such as compaction, vibro flotation and preloading; and chemical
methods consist of stabilization with lime, portland cement, asphalt products, chlorides and polymers.
The purpose of this project is to study the physical and mechanical behavior of a subgrade stabilized
with asphalt on the Rocafuerte - Tosagua road in the province of Manabí, which presents deformation
problems that can be attributed mainly to the swelling of the clays, this being the predominant material
in this area.
Types of clays
Clays are commonly constituted by three groups of clay minerals, montmorillonites, kaolinites and
illites; being the montmorillonites the cause of the expansion in the clay, while kaolinites and illites are
collapsible, due to this to achieve stabilization of clays it is a priority to first reduce the expansion
caused by the montmorillonites (Jiménez & Zamora, 2017).
According to the qualification work of (Castro, 2017) titled "Stabilization of clayey soils with rice husk
ash for subgrade improvement", the characteristics of the crystalline forms are the most influential
factor on the physical properties of clays, then, the main minerals that constitute clays are presented in
detail: Kaolinites Stable clay because of possessing an inexpandable structure; formed by indefinite
superposition of aluminous and silicic lamellae. The union of the particles is very strong and therefore
opposes the entry of water between them, thus avoiding the effects of swelling when saturated. Illite
presents some internal friction; formed by indefinite superposition of an aluminous layer between two
silicic ones. Its internal constitution is formed by lumps of material that cause a reduction of the area
exposed to water, thus limiting its property to expand. Montmorillonites have a similar structure to
illites, but the union of their particles is much weaker, resulting unstable in the presence of water; the
water molecules enter easily, which causes an increase in the volume of the crystals, thus causing the
expansion of the soil.
The expansion capacity of clay is the cause of serious construction problems because it can absorb a
large amount of water and retain it, which causes an increase in the volume of the material and also a
drastic reduction in volume when the retained water dries up, which leads to a non-uniform increase in
volume, generating settlements that can severely damage the structure of the pavement. (Quezada,
2017). In addition, in the province of Manabí in the city of Calceta, an analysis of the clays was also
carried out, where cohesive soils such as low plasticity clays of medium to very compact compact
compactness and for non-cohesive soils such as sands, silty sands with loose to dense compactness with
the presence of recent deposits with liquefaction susceptibility, in addition, the volumetric changes of
the soil were also studied, qualifying it as a low expansive soil. (Zambrano-Rendón, V. A., Ortiz-
Hernández, E. H., & Alcívar-Moreira, W. S, 2021). Also in the city of Portoviejo, which is 50 km from
Calceta, the expansive behavior was analyzed without any stabilization component and the result was
high to very high, affecting the surface of the structure with presence of deformations. (Hernández, E.
H. O., Moncayo, E. H. O., Sánchez, L. K. M., & de Calderero, R. P, 2017).
The important characteristics of clays lie in their properties, according to (Castro, 2017) classifies them
as follows: Plasticity, is the main characteristic of clay type soils, it originates as a consequence of the
presence of water itself which forms a kind of envelope around the lamellar particles causing a
lubricating effect; this property is closely related to the lamellar morphology and particle size, this
property can be measured using the Atterberg limits. The main characteristics of montmorillonites are
hydration and dehydration of the interlamellar space, the swelling of the material originates when water
enters and the lamellae separate causing electrostatic repulsive forces between the lamellae, thus
favoring the swelling process by dispersing some lamellae from others. Thixotropy can be defined as
the loss of resistance when kneaded and the recovery of the same in the course of time, this type of
thixotropic clays can become liquid at the moment of being kneaded, however, when they are left to
rest they recover their cohesion. This phenomenon is present when the water content in the soil is close
to its liquid limit.
Garcia et al 2022
July - September vol. 1. Num. 14 2022
Currently, problems are being presented in pavement structures due to deformations, where it was
necessary to evaluate CBR parameters both in the field and in the laboratory. (Vera, C. A. M., Delgado,
J. R. G., Hernández, E. H. O., & Vínces, J. J. G., 2020).. After obtaining the design CBR value, the
subgrade category to which the sector or section corresponds will be classified as shown in Table 1.
Table 1. Subgrade Category.
Subgrade category
CBR
Inadequate subgrade
CBR < 3% CBR < 3% CBR < 3% CBR < 3%
CBR < 3% CBR < 3%
Poor subgrade
3% ≤ CBR < 6%.
Regular subgrade
6% ≤ CBR < 10%
Good subgrade
10% ≤ CBR < 20%.
Very good subgrade
20% ≤ CBR < 30%.
Excellent subgrade
CBR ≥ 30%.
On occasions when the subgrade is not in optimal conditions to form a pavement structure, either
because of low strength or some other problem, it is necessary to implement a method of improvement
or stabilization of this layer that allows achieving the parameters required in the design. According to
the general specifications for the construction of roads and bridges, stabilization is a treatment applied
to the pavement layer. (Ministry of Public Works and Communications, 2002).stabilization is a
treatment applied to soils through the addition of a binder, be it lime, cement, asphalt or chemical
products, in order to improve their mechanical characteristics and thus obtain a soil capable of
withstanding the stresses caused by traffic loads and resisting the action of atmospheric agents, while
maintaining uniformity. Generally, this type of procedure is used precisely to improve the subgrade and
thus reduce the thickness of the layers above it (sub-base and base) or also for the construction of a base
layer sufficiently capable of supporting a wearing course immediately above it. (Cuadros, 2017).
According to (Demera, M. L. A., Romero, C. M. D., Hernández, E. H. O., & Gutiérrez, D. A. D., 2020).
The term "pavement" refers to the fact that at present there is no single terminology to designate the
different layers that make up a rigid, flexible and articulated pavement.
According to the different studies of the master's work "Stabilization of Macas Clayey Soils with CBR
Values lower than 5% and Liquid Limits higher than 100%, to be used as Subgrade in Roads". (Castillo,
2017) mechanical soil stabilization methods comprise three groups which are: Physical methods,
Mechanical methods, Chemical methods. Stabilization carried out using chemical methods is aimed at
varying the properties of the soil by adding special chemical substances. The purpose of applying a
chemical stabilizer is to give the treated soil properties aimed at improving its behavior during the
construction or service period. In certain cases it is preferable to carry out the stabilization process using
some asphalt type material. The use of these types of products, including cutback asphalts, asphalt
emulsions and asphalt cements, is somewhat restricted to granular or coarse-particle soils. In the case
of clayey materials, stabilization can be difficult because of the lumps that are characteristic of these
types of soils. (Almeida & Sanchez, 2011)..
Stabilization with the use of asphalt products is subject to two purposes:
• Reduction of water absorption in the material, with the use of a slight amount of asphalt.
• Increase in the strength of a material with the use of a considerable amount of asphalt.
The inclusion of asphalt in the mix increases the shear strength and on the other hand decreases the
susceptibility to damage due to the presence of moisture, as a result of the dispersion of the asphalt
among the finer particles of the aggregate. When asphalt emulsions are used, they are conveniently
dispersed among the finer particles, but not only in them, but also some coarse particles are partially
coated. However, when asphalt of the foamed type is used, it does disperse only among the fine
particles, producing what are known as "spot welds" between the mastic of the asphalt droplets and the
fine particles of the aggregate. (Asphalt Institute, 2001). In addition, modifications are also made with
additives in the conventional asphalt, which makes a great contribution to improve all its physical-
128
mechanical properties to extend its useful life once practiced in the road field, since it works in an ideal
way to have roads in better conditions and satisfy the needs of road users. (Ortiz Hernández, E. H., &
Macías Sánchez, L. K., 2018).
According to the guide "Design guide for asphalt-stabilized materials", granular materials that are
stabilized with asphalt differ from other materials in the following ways (Ulloa Calderón & Múnera
Miranda, 2020). granular materials that are stabilized with asphalt differ from other materials by the
following elements: The behavior is very similar to that of granular materials that are not stabilized,
however, a considerable increase in cohesion is notable, with the angle of internal friction remaining
practically constant, which is evident with the increase in the mechanical capacity of the material. In
addition, greater resistance to damage caused by humidity is also achieved, as well as greater durability
and resistance to bending due to the viscoelastic properties of the asphalt.
The properties of the soil that make up the subgrade are the most determining parameters when
designing a pavement structure, whether it is rigid, flexible or paved. To determine the physical and
mechanical characteristics of the material that makes up the subgrade, it is necessary to take samples
along the entire length of the road, taking a minimum depth of 1.5m, to be subsequently taken to the
laboratory and carry out the corresponding tests. (Cuadros, 2017)
Materials and methods
The methodology applied is quantitative experimental, where numerical values corresponding to each
laboratory test were obtained and with them it was possible to determine the physical and mechanical
characteristics of the sample to determine its behavior.
The research work was carried out in three stages: The first was the work done in the field taking soil
samples on the Rocafuerte - Tosagua road, three calicatas were made in the most critical places, where
the deterioration of the road could be appreciated as illustrated in the (Figure 1). The second stage was
the laboratory work, which included tests such as natural moisture, Atterberg limits, granulometry,
Proctor and CBR, the latter two were done for both natural soil and soil stabilized with asphalt, in
percentages of 3%, 6%, 9%, 12% and 15%. The laboratory tests were performed in accordance with
ASTM (American Society for Testing and Materials) standards. The third stage consisted of calculating
and interpreting the results of the laboratory tests to determine the physical-mechanical properties of
the asphalt-stabilized subgrade.
Result
The following are the results of laboratory soil mechanics tests such as: moisture, liquid limit, plastic
limit, granulometry, Proctor and CBR for subsequent stabilization with asphalt in percentages of 3%,
6%, 9%, 12% and 15%.
NATURAL MOISTURE TEST
This physical property of the soil is very useful in civil construction and is obtained in a simple way,
since the behavior and resistance of soils in construction are governed by the amount of water they
contain. The moisture content of a soil is the ratio of the quotient of the weight of the solid particles and
the weight of the water it holds, expressed in terms of percentages. (Bedoya Peña, E. R., & Molina Real,
A. E., 2010).. The results are illustrated below in bar graphs.
Garcia et al 2022
July - September vol. 1. Num. 14 2022
Graph 1 Natural moisture (ASTM D2216)
Graph 1 shows the percentages of natural moisture of the soil sample in its natural state, values between
12.58% and 25.98% are observed, which could clearly indicate that it is a soil sample that is moderately
moistened and even contains a considerable amount of moisture, since being a clay soil sample, it tends
to present an expansive behavior.
ATTEBERG LIMIT TEST
For the determination of the liquid limit, it was obtained following the following standard. (ASTM D
4318-00)For this, a soil sample is taken to which water is added, it is mixed and placed in the
Casagrande cup, a groove is made in the center of the sample and the crank is turned to perform the
process of lifting the cup and letting it fall from a height of approximately 10 mm with a frequency of
one stroke per second. It is continued until the groove of the sample closes in an approximate length of
13 mm, this should be achieved after 25 blows with the cup. (CANDELARIA, J., BERNAL, M.,
FLORES, O., GUZMAN, A., & HERNANDEZ, S, 2018). The water content, in percent, in the soil
specimen when the groove is closed at 25 blows, as indicated above, is defined as the liquid limit.
(CANDELARIA, J., BERNAL, M., FLORES, O., GUZMÁN, A., & HERNÁNDEZ, S, 2018). The
results are illustrated below by bar graphs.
Graph 2 Plasticity index.
22,79
22,50
22,90
17,41
19,96
24,69
14,00
25,98
12,58
10,00
12,00
14,00
16,00
18,00
20,00
22,00
24,00
26,00
28,00
0,5 1 1,5
Humidity (%)
Depth (m)
Natural Moisture
CALICATA 1 CALICATA 2 CALICATA 3
130
Once the liquid and plastic limits have been calculated, the plasticity index [PI] can be determined,
which is defined as. (CANDELARIA, J., BERNAL, M., FLORES, O., GUZMÁN, A., &
HERNÁNDEZ, S, 2018).:
IP = wL - wP (1)
Graph 2 shows the plasticity indexes of each test pit in the state of natural soil, and as can be observed,
the values of plasticity index, for each test pit is in a range of values between 10.74% and 28.21%,
which could be considered as a medium plasticity for the case of test pit 1, and even low as is the case
of test pit 2 and 3; and it is precisely because in the area prevails pavement damage with the presence
of settlement in the pavement structure. When referring to WL and IP (Casagrande, 1932)proposed the
plasticity chart, in which the liquid limit is plotted on the abscissa axis and the plasticity index on the
ordinate axis, as illustrated in Figure 2. (CANDELARIA, J., BERNAL, M., FLORES, O., GUZMÁN,
A., & HERNÁNDEZ, S, 2018) Within the plasticity chart we distinguish line A, which is the division
between silty (ML and MH) and clayey (CL and CH) soils, while line U is approximately the upper
limit of the ratio of the plasticity index with respect to the plastic limit for any soil found by Casagrande.
(Das, B. M., 2001)..
Graph 3 Plasticity chart proposed by Arthur Casagrande in 1932.
FINE SERIES PARTICLE SIZE TEST
Graph 4 Grain size analysis of test pit 1 (ASTM D422).
After performing the fine granulometry according to the standard (ASTM D422) of the natural soil, the
percentages passing each of the sieves of the fine material are illustrated. Graph 3 shows the results of
test pit 1, Graph 4 shows the results of test pit 2 and Graph 5 shows the results of test pit 3.
Granulometric analysis (ASTM D422) of test pit 2.
70,00
75,00
80,00
85,00
90,00
95,00
100,00
105,00
0,010,1110100
Passing percentage (%)
Sieves in mm
CALICATA
1: 0.50m
CALICATA
1: 1.00m
CALICATA
1: 1.50m
Garcia et al 2022
July - September vol. 1. Num. 14 2022
Graph 5. Fine grain size series (ASTM D422) of test pit 3.
PROCTOR TEST
From this test, the maximum dry density and optimum soil moisture are determined, its importance lies
in increasing the resistance and the reduction of voids in the soil, in addition to reducing the
deformations that may occur in the soil. That is why in the study methodology the soil density was
evaluated in a 500 m section in the Rocafuerte Tosagua El Junco sector, obtaining very similar results
between the three test pits as shown in graph 6,7,8 in natural state. In addition, the Proctor tests
stabilized with Asphalt have a slight increase in density and a decrease in optimum soil moisture as
shown in the Proctor test graphs. In Graph 6 belonging to test pit 1, a maximum dry density of the
stabilized soil of 1616 kg/m3 is observed, which is greater than that of the soil in its natural state, which
is 1506 kg/m3, while the values of optimum moisture decrease, this is due to the fact that when
stabilized with asphalt, this material becomes more compact and does not allow the material to become
wet.
In Graph 7 corresponding to test pit 2, the same behavior is observed, a maximum dry density of the
stabilized soil of 1637 kg/m
3
, this is higher than that of the soil in its natural state, which is 1567 kg/m
3
, while the values of optimum humidity decrease, when stabilized with asphalt, this material becomes
more compact and does not allow the material to become wet. Graph 8 corresponding to test pit 3 shows
the same behavior with asphalt stabilization, a maximum dry density of the stabilized soil of 1607 kg/m
3
, which is greater than that of the soil in its natural state, which is 1529 kg/m
3
, while the values of
optimum moisture decrease when stabilized with asphalt, this material becomes more compact and does
not allow the material to become wet.
70,00
75,00
80,00
85,00
90,00
95,00
100,00
105,00
0,010,1110100
Passing percentage (%)
Sieves in mm
CALICATA
2: 0.50m
CALICATA
2: 1.00m
SQUID 2:
1.50m
65,00
75,00
85,00
95,00
105,00
0,010,1110100
Passing percentage (%)
Sieves in mm
CALICATA 1: 0.50m
CALICATA 1: 1.00m
CALICATA 1: 1.50m
132
Graph 6 Determination of the Soil Moisture-Density Ratio of test pit 1.
Graph 7. Determination of the Soil Moisture-Density Ratio of test pit 2.
Determination of the Soil Moisture-Density Ratio of test pit 3.
CBR TESTING
As can be seen in Graph 9 of the CBR test, it shows the values for the soil stabilized with asphalt, which
provides greater bearing capacity than the natural soil because the stabilized soil reaches a higher
maximum dry density, generating a substantial increase in the bearing capacity of the soil. Subsequently
qualifying the stabilized subgrade and the natural subgrade from a poor to fair subgrade.
1452,44
1506,16
1494,80
1402,83
1477,95
1580,11
1616,69
1579,26
1469,17
1350
1400
1450
1500
1550
1600
1650
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34
MAXIMUM DENSITY DRY
(kg/m3)
OPTIMUM HUMIDITY (%)
CALICATA PROCTOR 1
NATURAL SOIL STABILIZED SOIL
1509,29
1566,65
1539,94
1464,89
1557,19
1620,53
1637,02
1613,63
1545,66
1450
1500
1550
1600
1650
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
MAXIMUM DENSITY DRY
(kg/cm3)
OPTIMUM HUMIDITY (%)
CALICATA PROCTOR 2
NATURAL SOIL STABILIZED SOIL
1445,63
1495,74
1528,55
1517,22
1452,53
1423,58
1535,77
1595,03
1606,91
1561,39
1488,77
1400
1450
1500
1550
1600
1650
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
MAXIMUM DENSITY DRY
(kg/cm3)
OPTIMUM HUMIDITY (%)
CALICATA PROCTOR 3
NATURAL SOIL STABILIZED SOIL
Garcia et al 2022
July - September vol. 1. Num. 14 2022
Graph 8 Determination of the bearing capacity (CBR) of the soil.
Conclusions
The ideal percentage of asphalt to stabilize the natural soil is approximately 12%, determined by the
Proctor test graph. When comparing the physical and mechanical characteristics of the soil, it is shown
that with stabilization using the optimum percentage, its maximum dry density improves, providing a
decrease in natural moisture, making the soil more compact and consequently decreasing sponging.
References
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Alzate, A. (2019). Subgrade improvement in third order roads. Retrieved from Repositorio
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Asphalt Institute (2001). Basic Handbook of Asphalt Emulsions. Asphalt Institute.
ASTM D 4318-00. (n.d.). Liquid Limit, Plastic Limit, and Plasticity Index of Soils. ASTM, USA.
Bedoya Peña, E. R., & Molina Real, A. E. (2010). Determinations of correlations of the compressibility
index as a function of natural moisture and void ratio for the calculation of settlements in soft
soils in the canton of Puerto Quito. Bachelor's thesis. QUITO/PUCE.
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Geotechnical Engineering. León, Guanajuato, Mexico: Sociedad Mexicana de Ingeniería
Geotécnica, AC.
Castillo, B. F. (2017). Stabilization of Macas Clayey Soils with CBR Values lower than 5% and Liquid
Limits higher than 100%, for use as Subgrade in Roads [Master's Thesis, Universidad de
Cuenca] . Retrieved from Institutional Repository:
http://dspace.ucuenca.edu.ec/handle/123456789/26917
Castro, A. F. (2017). Stabilization of clayey soils with rice husk ash for subgrade improvement [Degree
thesis, Universidad Nacional de Ingeniería]. Retrieved from Institutional Repository:
http://cybertesis.uni.edu.pe/handle/uni/10054
2,05%
3,75%
3,00%
5,10%
7,20%
7,60%
0,0%
1,0%
2,0%
3,0%
4,0%
5,0%
6,0%
7,0%
8,0%
9,0%
1
CBR (%)
CALICATA (#)
CBR
CALICATA 1. NATURAL SOIL CALICATA 2. NATURAL SOIL
CALICATA 3. NATURAL SOIL CALICATA 1. STABILIZED SOIL
CALICATA 2. STABILIZED SOIL CALICATA 3. STABILIZED SOIL
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