Revista Investigación e Innovación en Ingenierias, vol. 6, n°. 2, pp.16-29, Julio-Diciembre, 2018. DOI: 10.17081/invinno.6.2.3109
Physical and mechanic characterization
of the sterile part of coal, searching for
an environmental alternative in civil
infrastructure works
Caracterización físico-mecánica del
estéril de carbón, en busca de una al-
ternativa ambiental para las obras de
infraestructura civil
Andrés Gutiérrez Bayona, Carlos Javier Obando Gamboa,
Cristian Jair Moreno Moreno
Fundación Universitaria Agraria de Colombia
12 julio de 2017
22 noviembre de 2017
Objetivo: La presente investigación se enfocó en caracterizar física y mecánicamente
múltiples Samples del estéril de carbón perteneciente al municipio de Lenguazaque (Cun-
dinamarca), con el propósito de identicar el posible uso de este material en la ingeniería,
en especial en obras de infraestructura vial.
Metodología: Se utilizaron fundamentos normativos, técnicas que generaron resultados e
información suministrada por el Ministerio de Minas quienes indican que la contribución de
la minería al crecimiento de la economía del país ha presentado un elevado crecimien-
to en los últimos años lo cual hace contraste con el efecto negativo que esta práctica
acarrea sobre el medio ambiente, teniendo en cuenta que en la extracción de carbón
existen residuos sólidos producto de la explotación de este mineral, a estos residuos se les
denomina “estéril de carbón”, los cuales en su mayoría se retiran del carbón para no afec-
tar el potencial energético del producto.
Resultados y conclusiones: Los resultados de la investigación son esperanzadores ya que
sus características lo ubican como un material alternativo para la construcción de estruc-
turas viales de bajo tráco.
Palabras clave: Carbon, residuo, estéril de carbon, caracterización, infraestructura vial,
uso alternativo.
Open Access:
Copyright: Gutiérrez et al
Objective: The present investigation is focused on physically and mechanically characterizing
multiple Samples of the coal waste belonging to the municipality of Lenguazaque (Cundinamar-
ca), with the purpose of identifying the possible use of this material in engineering, especially in
road infrastructure works.
Methodology: Normative foundations were used, techniques that generated results and infor-
mation provided by the Ministry of Mines who indicate that the contribution of mining to the
growth of the country’s economy has shown high growth in recent years, which contrasts with
the negative effect that this practice entails on the environment, taking into account that in the
extraction of coal there are solid residues resulting from the exploitation of this mineral, these
residues are called “sterile coal”, which are mostly removed from the carbon so as not to affect
the energy potential of the product.
Results and conclusions: The results of the research are encouraging since its characteristics
place the material as an alternative for the construction of low trafc road structures.
Keywords: Oal, residue, sterile of coal, characterizing, road infrastructure, alternative usage.
Como citar este articulo (IEEE) A. Gutiérrez - Bayona, y C. Obando- Gamboa,
C. Moreno- Moreno, “Physical and mechanic characterization of sterile of coal, searching for an en-vironmental
alternative in civil infrastructure”, Revista Investigación e Innovación en Ingenierias, vol. 6, n°. 2, 2018. DOI: 10.17081/
Revista Investigación e Innovación en Ingenierias, vol. 6, n°. 2, pp.16-29, Julio-Diciembre, 2018. DOI: 10.17081/invinno.6.2.3109
Colombia is known as a major producer of coal in the region and because
it has large reserves of it, this makes it an attractive country for investment in
mining. According to data from the Ministry of Mines between 2002 and 2009,
coal production grew 84.61%, generating a large contribution to the GDP; For
the year 2014 the contribution of mineral coal represented a growth of 3.56%,
this was a result of the investment made in different projects in the north of the
country. It is known that the coal mineral is of sedimentary origin and organic,
constituted by vegetal remains and transformed by the metamorphism [2],
and according to its characteristics can have different classications as they
are: thermal coal, implemented for the generation of energy; coal coke and
semi-coke also called metallurgical coal, used for the manufacture of steel
and cement
As a result of the exploration and exploitation of the coal mineral, residues
arise as are the semisolids and solids. The semi-solid residues occur due to the
washing of the coal because it has ash or sulfur [3]. Lace rocks are dened as
solid wastes [4], also known as coal sterile; this sterile is mostly removed from
the coal miner because it affects the energy potential of the nal product.
The percentages of barren of coal are very variable because they depend
on the site from which the mineral is extracted.
Since this coal sterile is coupled in different sites as a waste material and con-
taminant, this research proposes the possibility of using it as an element and/
or material of benet within the construction of infrastructure, for this, different
laboratory tests have been carried out in order to arrive at comparisons that
allow to establish their possible performance in road construc-tion.
Methods and materials
In this section the normative foundations, technical concepts, tests and re-
sults, location, characteristics of the area of material supply and protocols are
The regulations used are national regulations, and are related to the techni-
cal specications of materials for construction of road infrastructure projects
and standards of testing of materials in road infrastructure, which govern in
Technical specications of materials and construction: The quality control re-
quirements are established under standards and pro-cedures of execution
and control, in which are framed general aspects of dirt road material, granu-
lar base material and granular subbase material, asphalt pavement and va-
rious civil works. The standards used in this researching were version 2007 and
2013 [5] of General Road Construction Specications of the National Road
Institute known as INVIAS [6].
Testing standards for road materials: Sampling procedures and la-
boratory tests adopted for road materials at the National level are
taken as standard. The standards used in this researching were ver-
sion 2007 and 2013 of the National Road Institute – INVIAS [6].
Technical Concepts
The concepts presented below are directly related to the devel-opment of
the research:
Stone material: They are denominated in this way the materials used for the
construction coming from rocks or stones, are classied according to their
origin in natural and articial. Natural materials have this name because they
are in a natural state in the Earth’s crust and come from rocks that have for-
med over many years, are classied in igneous rocks, sedimentary rocks and
metamorphic rocks. Articial materials are man-made materials, either be-
cause of a combination of natural materials or a transformation of natural
Phisycal and mechanic characterization of sterile of coal, shearching for an environmental alternative in civil infrastructuture
Revista Investigación e Innovación en Ingenierias, vol. 6, n°. 2, pp.16-29, Julio-Diciembre, 2018. DOI: 10.17081/invinno.6.2.3109
materials such as glass, ceramics or brick.
Coal Sterile Commonly Selected: The common coal sterile is an inorganic soil
mixed with coal residues considered as solid waste product from coal mining.
Because coal is located at great depths, it is necessary that the extraction
is carried out in an industrialized way by implementing explosives, hydraulic
drills, backhoes or with pickaxes and shovels, it is necessary to extract the coal
next to its lace rocks, which are named like Inter-mantle or interburden [8].
Selected Coal Sterile: It is an inorganic soil (between-mantles or iterburde)
[8], selected from the solid residue (barren of com-mon coal), product of the
exploitation of the coal mineral that is at great depths, this differs from the
common coal sterile since the visible particles that do not have coal residues.
Physical and Mechanical Characteristics: These characteristics indicate the
properties of the materials. These characteristics are very important because
based on them can dene the best use and implementation of any material.
Tests and calculations
The tests presented below were performed in order to physically and mecha-
nically characterize the coal sterile, all calculations and processes are based
on testing standards for road materials in Colombia.
The laboratory tests performed were: Density, Standard I.N.V.E. 222 and 223,
Particle Size, Standard I.N.V.E. 213, Humidity, Standard I.N.V.E. 122, Absorp-
tion, Standard I.N.V.E. 222 and 223, California Bearing Ratio (CBR), Standard
I.N.V.E. 148, Resistance to the degradation of aggregates by means of the
Los Angeles machine, Standard I.N.V.E. 218, and Organic Matter, Standard
I.N.V.E. 121, all of the National Insitute of Routes of Colombia, INVIAS [6 - 7].
The material was supplied by the industrialized plant belonging to C.I. CAR-
BOCOQUE S.A.S, producer and exporter of coal coke located at kilometer 1
route to Lenguazaque, at a distance of 116 km from Bogota - Cundinamar-
ca. The plant is located in the left margin of the road that communicates
Cucunuba with Lenguazaque, passing through the municipality of Ubaté.
Because of the location of the industrialized coal plant, neighboring coal pro-
ducing regions supply raw material to this coal, it is also important to mention
that this washing and screening plant is the only one in operation in the Cun-
dinamarca region.
The economy of Lenguazaque is based on activities such as min-ing for coal
mineral, potato farming and, to a lesser extent, willow, maize, barley and
wheat [9].
Collection of Samples
Five samples of coal sterile from the discarded material were collected, and
collected from different collection sites, each composed of 25kg taken from
the base, the middle and the crown of the collection to have representative
samples, all the material was stored in tarpaulins outside the affectation of the
rain or the sun.
It is believed that the material collected belongs to a series of formations from
the Oligocene period which is about 33.7 mil-lion years old, the Eocene which
is 53 million years old and the Late Superior that has 96 million years belonging
to the Cenozoic period and Cretaceous. The lithological characteristics pre-
sented for the Oligocene zone (E1-Sc) are conglomerates interspersed with
medium-to-thick laurel sandstones and coal aceous lodolites, for the Eocene
(e6e9-Sct) are ne-grained to conglomeratic sandstones with arcillolites and
limolites , which occasionally exhibit lenses of iron and coal, and nally for the
late upper (k6-Stm) are gray and black arcillolites, variegated with interca-
lations of ne-grained to coarse-grained quartzites and frequent mantles of
coal [10].
Andrés Gutiérrez Bayona, Carlos Javier Obando Gamboa, Cristian Jair Moreno Moreno
Revista Investigación e Innovación en Ingenierias, vol. 6, n°. 2, pp.16-29, Julio-Diciembre, 2018. DOI: 10.17081/invinno.6.2.3109
Some protocols were implemented when specied in the Material Testing
Standard adopted did not t the reality of the samples and their conditions.
Temperature: High temperature is one of the factors that al-
ter the samples, since some tests made that the material is dry
with a constant mass, it was necessary to change the temperatu-
re to 60 ± 5°c, extending the time the moisture content, density, re-
lative density (specic gravity), absorption of the ne aggregate,
and resistance were determined in the samples. To the degrada-tion of the
aggregates of sizes smaller than 37.5mm (1 1/2 “), by means of the machi-
ne of the angels.
CBR (California Bearing Ratio): To adjust the granulometry re-quired in the
test standard I.N.V E-148, it was necessary to reduce the size by impact. A
compressive energy of 56 strokes and humidities of 7% and 4% was imple-
mented for the realization of the tests. A combination of coal sterile and
granular Base 400 was performed.
Organic matter: This test was performed with 10 sub-samples taken from
the 5 original samples. The material tested was ne material passed sieve
# 4, thick material product of the Machine of the Angels and passed sieve
# 4.
Densities and Absorption: This laboratory test was performed 7 times in or-
der to obtain the density of the 5 samples, a test for selected coal sterile
and a test to determine the density of the coal, the latter two would serve
as points of comparison.
Results and discussion
Next, the results obtained in the physical-mechanical characteri-zation of
the coal sterile are shown. These results will show results such as humidity,
particle size, density and absorption, wear resistance at the Los Angeles
Machine and support capacity (CBR).
Moisture content
The moisture content of the collected samples of sterile of coal are be-
tween 7.85% and 18.88%, with an average of 13.65%.
Phisycal and mechanic characterization of sterile of coal, shearching for an environmental alternative in civil infrastructuture
Revista Investigación e Innovación en Ingenierias, vol. 6, n°. 2, pp.16-29, Julio-Diciembre, 2018. DOI: 10.17081/invinno.6.2.3109
Sample Moisture Content (%)
1 13,66
2 14,73
3 13,15
4 18,88
5 7,85
Average 13,65
Table 1. Moisture content.
Table 2. Percentage of content according to particle size, for common
coal sterile.
For the physical characterization of the coal sterile, several granulometries
were realized, that is, for each one of the 5 samples in order to determine the
classication of the material based on the particle size. The results are com-
pared with the INVIAS grades of Granular Base material, Sub-base granular
material, dirt road material, and Embankment material. Greater agreement
is found with the granulometric range of granular subbase material (SBG-50),
and with embankment
material with selected soil, as shown below:
Sample Content of Stones (%) Sand Content (%) Fine Soil Content (%)
1 52,11 44,72 3,17
2 44,93 54,64 0,43
3 49,87 46,6 3,53
4 66,57 33,04 0,4
5 70,86 28,25 0,89
Average 52,11 44,72 3,17
Figure 1. Granulometric curves of the 5 analyzed samples.
Andrés Gutiérrez Bayona, Carlos Javier Obando Gamboa, Cristian Jair Moreno Moreno