Revista Científica Interdisciplinaria Investigación y Saberes
2024, Vol. 14, No. 1 e-ISSN: 1390-8146
Published by: Universidad Técnica Luis Vargas Torres
How to cite this article (APA):
Vivas, K., Lopez, L., Pico, M., Vega, A. (2024) Use of wood ash as a
substitute for fine aggregate in lightweight concrete production , Revista Científica Interdisciplinaria
Investigación y Saberes, 14(1) 33-.
Use of wood ash as a substitute for fine aggregate in the production of
lightweight concrete
Uso de ceniza de madera como sustituto del agregado fino para elaborar hormigón
liviano
Karol Natalí Vivas Villareal
Ingeniera Civil, Independiente, vivask32@gmail.com, https://orcid.org/0009-0000-1240-6559
Liliana Lizbeth López López
Magister en Ingeniería Civil Mención Estructuras Metálicas, Universidad Técnica de Ambato,
ll.lopez@uta.edu.ec, https://orcid.org/0009-0004-7730-3162
María Fernanda Pico Núñez
Magister en Ingeniería Civil Mención Estructuras Metálicas, Universidad Técnica de Ambato,
mf.pico@uta.edu.ec, https://orcid.org/0000-0002-8468-3026
Alex Santiago Vega Ilaquiche
Ingeniero Civil, Avega Const S.A.S., alexvega2098@gmail.com, https://orcid.org/0009-0002-8952-8030
The present study proposes the use of wood ash as a partial substitute
for fine aggregate, for which a base concrete of 180 kg/cm² and
concretes with 30, 50 and 70% replacement were proposed.
Laboratory tests were carried out on all concrete components such as:
granulometry, real and apparent density, absorption capacity with a
sample of 36 cylindrical specimens evaluated at 7, 14 and 28 days.
Subsequently, an analysis was made of the real hardened density and
compressive strength, the results of which showed the influence of
wood ash on these properties. The densities of 2233.75 kg/m³,
2210.38 kg/m³ and 2176.96 kg/m³ that decrease progressively
according to the replacement percentages do not allow a
classification within the light concretes because the considered limit
of 2000 kg/m³ is exceeded. With respect to the compressive strength,
Abstract
Received 2023-11-12
Revised 2023-12-22
Published 2024-01-05
Corresponding Author
Karol Natalí Vivas Villareal
vivask32@gmail.com
Pages: 1-12
https://creativecommons.org/lice
nses/by-nc-sa/4.0/
Distributed under
Copyright: © The Author(s)
Use of wood ash as a substitute for fine aggregate in lightweight concrete production
Revista Científica Interdisciplinaria Investigación y Saberes , / 2024/ , Vol. 14, No. 1
34
which shows a decrease, it was determined that in order to comply
with the design, the replacement will not exceed 30%. In short, this
concrete could be used in the construction of sidewalks and curbs,
prefabricated masonry constructions used in the division of
environments and for cyclopean concrete.
Keywords:
Lightweight concrete, Fine aggregate, Wood ash,
Construction.
Resumen
El presente estudio plantea el uso de ceniza de madera como
sustituto parcial del agregado fino, para lo cual se planteó un
hormigón base de 180 kg/cm² y hormigones con 30, 50 y 70% de
reemplazo. Se efectuaron ensayos de laboratorio de todos los
componentes del hormigón como: granulometría, densidad real y
aparente, capacidad de absorción con una muestra de 36 probetas
cilíndricas evaluadas a los 7, 14 y 28 días. Posteriormente se hizo un
análisis de la densidad real endurecida y la resistencia a compresión,
cuyos resultados evidenciaron la influencia de la ceniza de madera en
dichas propiedades. Las densidades de 2233.75 kg/m³, 2210.38
kg/m³ y 2176.96 kg/m³ que disminuyen progresivamente de acuerdo
con los porcentajes de reemplazo no permiten una clasificación
dentro de los hormigones livianos pues se sobrepasa el límite
considerado de 2000 kg/m³. Con respecto a la resistencia a
compresión que presenta una disminución se determinó que para
cumplir con el diseño el reemplazo no excederá el 30%. En definitiva,
este hormigón podría ser empleado en la construcción de aceras y
bordillos, construcciones de mampostería prefabricadas usadas en la
división de ambientes y para hormigón ciclópeo.
Palabras clave:
Hormigón liviano, Agregado fino, Ceniza de madera,
Construcción.
Use of wood ash as a substitute for fine aggregate in lightweight concrete production
Revista Científica Interdisciplinaria Investigación y Saberes , / 2024/ , Vol. 14, No. 1
35
Introduction
Throughout the ages, research has sought to achieve truly novel
qualities in the production of concrete that require and allow changes
to take advantage of its full potential.
Thus, lightweight concretes have been used since ancient times, for
example; the Romans used it in the 2nd century to build the dome of
the Pantheon in Rome using a concrete with pumice stone as
aggregate (Weigler & Sieghart, 1985). (Weigler & Sieghart, 1985)..
The Park Plaza Hotel in St. Louis, the Southwestern Bell Telephone
building in Kansas City, and the upper roadway of the San Francisco
Oakland Bay Suspension Bridge are examples of early uses of
reinforced lightweight concrete in the 1920s and 1930s (Weigler &
Sieghart, 1985). (Weigler & Sieghart, 1985)..
The diffusion of this type of concrete, made with different materials
and the existence of buildings constructed with it, does not mean that
the possibilities for its innovation have ceased.
A study establishes that in the elaboration of low density concrete
with pumice as coarse aggregate, dosages for compressive strength
of 60 kg/cm2 and 45 kg/cm2 were sought. (Medina & Fonseca, 2015)..
For the 60 kg/cm2 concrete, the uncured cylindrical samples reached
a compressive strength equal to 62.94 kg/cm² and the cured
cylindrical samples obtained a compressive strength of 63.66 kg/cm²;
in both cases at 28 days of age. For the 45 kg/cm2 concrete, the
uncured cylindrical samples reached a compressive strength equal to
45.18 kg/cm² and the cured cylindrical samples obtained a
compressive strength of 47.48 kg/cm² for both states at 28 days of
age. This indicates the importance of curing the concrete specimens,
since this directly influences the compressive strength.
Concrete made in materials testing laboratories for a strength of f'c =
60 kg/cm² has an average density of 1649.50 kg/m³; which is within
the limits and is called a lightweight concrete.
Concrete produced in materials testing laboratories for a strength f'c
= 45 kg/cm² has an average density of 1631.17 kg/m³; this is within
the limits and is called a lightweight concrete.
Use of wood ash as a substitute for fine aggregate in lightweight concrete production
Revista Científica Interdisciplinaria Investigación y Saberes , / 2024/ , Vol. 14, No. 1
36
Another study concludes that the compressive strength at 28 days of
normal curing of concrete with wood ash addition decreases as the
wood ash content increases in amounts expressed as a percentage
over a range of 0 to 30 (Sashidhar & Rao, 2010)..
In the results obtained from the samples of 28 and 60 days of age, a
comparison of the percentages of wood ash contained in the mix in
relation to its compressive strength is established, for the case of 0%,
the highest strength values are considered. The appropriate
percentage for replacing cement with wood ash is 20% (Abdullahi,
2006). (Abdullahi, 2006).
In addition, the compression tests of cylindrical samples with a
water/cement ratio of 0.60 executed at 7, 28 and 56 days, manifest
that the mixture with 10% obtained the highest compressive strength
defining it as a recommendable percentage, which indicates an
inversely proportional relationship, i.e.; the higher the wood ash
content the lower the compressive strength (Elahi, Qazi, Yousaf, &
Akmal, 2015).
On the other hand, in the use of wood ash as a partial replacement of
cement content in a mixture with sand as fine aggregate for making
blocks with an age of 7, 14 and 21 days, the optimum compressive
strength is given by 15 % replacement of cement after 21 days of
curing (Subramaniam, Subasinghe, & Fonseka, 2015).
For this reason, the present work starts with the design of a concrete
for a compressive strength of 180 kg/cm2 with the incorporation of
wood ash as a light aggregate in partial substitution of the fine
aggregate, which will be added in percentages from 0, 30, 50 to 70%,
verifying the density as a whole and the compressive strength of the
concrete in hardened state, to establish guidelines on the behavior of
the concrete in relation to the mentioned properties.
The wood ash is obtained by means of a calcination process at an
average temperature of between 580 and 600 ºC (Aramayo, Buncuga,
Cahuapé, Forgione, & Navarrete, 2003). (Aramayo, Buncuga,
Cahuapé, Forgione, & Navarrete, 2003).With the partial use of this
aggregate, a concrete with different characteristics from the
conventional one will be sought, with some special properties that
light concrete has, among which we can highlight the thermal and
Use of wood ash as a substitute for fine aggregate in lightweight concrete production
Revista Científica Interdisciplinaria Investigación y Saberes , / 2024/ , Vol. 14, No. 1
37
acoustic insulation and fire resistance, for which its density should not
exceed 2000 kg/m3 (Short & Kinniburgh, 1977)..
This type of concrete would constitute a great construction alternative
for civil works in general, and for our country an answer to the current
problem of housing costs because of its light weight and the use of
wood waste, it would be more economical and convenient, thus
allowing savings in materials, reduction of section areas, as well as the
possibility of erecting structures on land with low bearing capacity and
in turn contribute to greater innovations in construction works.
Methodology
To meet the parameters of a lightweight concrete made with wood
ash as a partial substitute for fine aggregate, an analysis is required
by means of concrete specimens with different contents of wood ash;
which after being tested in compression at the age of 7, 14 and 28
days, externalize the mechanical behavior of the concrete.
For this purpose, it is necessary to select a representative set of
elements called sample whose purpose within this experimentation
will be to reflect the characteristics of a concrete made with wood ash
as a partial substitute for fine aggregate.
The fine and coarse aggregates come from the Villacrés quarry,
located in the parish of La Península, 5 kilometers east of the city of
Ambato. The wood ash that partially replaces the fine aggregate was
produced in a brick kiln located on the property of the Villacris family,
in the Cevallos canton, Francisco Arias neighborhood, province of
Tungurahua.
Section 5.3.1 of NTE INEN 1576 states that the number of molded
cylinders should be as indicated in the specifications in NTE INEN
1855-2, which indicates that at least two specimens of mixtures should
be prepared for each resistance test. A test will be the result of the
average of the resistances of the specimens tested at the specified
age. (NTE-INEN-1576, 2011).
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Considering the above and for greater reliability, three cylindrical
specimens will be prepared for each age 7, 14 and 28 days, which in
turn correspond to four percentages of partial substitution of fine
aggregate by wood ash, which are 0, 30, 50 and 70 %; that is to say,
the sample totals 36 specimens according to the following table:
Table 1.
Definition of the sample
Age in days
Partial Substitution in %
Partial Substitution in %
0
30
50
70
7
3
3
3
3
14
3
3
3
3
28
3
3
3
3
Subtotal
9
9
9
9
Total
36
Results
Based on the density of conventional concrete, we have a decrease
of 2.66%; 3.68% and 5.13% when replacing the fine aggregate by
30%, 50% and 70% respectively, as can be seen in Figure 1.
Figure 1.
Percentage of Substitution vs. Density in the Hardened
State
Use of wood ash as a substitute for fine aggregate in lightweight concrete production
Revista Científica Interdisciplinaria Investigación y Saberes , / 2024/ , Vol. 14, No. 1
39
The density of wood ash concrete decreases as the percentage of
substitution increases. However, these densities exceed that of a
lightweight concrete, which is 2,000 kg/m³.
According to Figure 2, the compressive strength of the conventional
concrete is found to be within the upper and lower limits defined in
[37] for 7, 14 and 28 days of age. Being the maximum resistance of
186.49 kg/cm² which defines it as a concrete suitable for construction
since it complies with the proposed design.
Figure 2
. Age vs. Compressive Stress / Conventional Concrete
Figure 3 shows that the compressive strength of the concrete with a
30% substitution of fine aggregate is within the upper and lower limits
defined for 7, 14 and 28 days of age. The maximum resistance is
180.06 kg/cm², which defines it as a concrete suitable for construction
since it complies with the proposed design.
Use of wood ash as a substitute for fine aggregate in lightweight concrete production
Revista Científica Interdisciplinaria Investigación y Saberes , / 2024/ , Vol. 14, No. 1
40
Figure 3.
Age vs. Compressive Stress / Replacement at 30%.
Figure 4 shows that the compressive strength of concrete with a 50%
substitution of fine aggregate is below the upper and lower limits
defined for 7 and 14 days of age. However, at 28 days of age it
reaches a maximum strength of 172.85 kg/cm² according to the limits.
Figure 4.
Age vs. Compressive Stress / 50% Replacement
Figure 5 shows that the compressive strength of concrete with a 70%
substitution of fine aggregate is below the upper and lower limits
defined for 7, 14 and 28 days of age. The maximum resistance is
Use of wood ash as a substitute for fine aggregate in lightweight concrete production
Revista Científica Interdisciplinaria Investigación y Saberes , / 2024/ , Vol. 14, No. 1
41
155.40 kg/cm², which shows a decrease of 16.67% with respect to the
design.
Figure 5
. Age vs. Compressive Stress / Replacement at 70%.
According to Figure 6, there is an inversely proportional behavior due
to the decrease in compressive stress at 28 days, produced by the
increase in the percentage of fine aggregate substitution.
Figure 6.
28-day compressive stress vs. percentage of substitution
Both conventional and 30% substitution concrete meet the design
specification with stresses equivalent to 104% and 100% respectively.
However, the 50 and 70 % substitution concretes do not meet the
Use of wood ash as a substitute for fine aggregate in lightweight concrete production
Revista Científica Interdisciplinaria Investigación y Saberes , / 2024/ , Vol. 14, No. 1
42
design specification as they represent stresses of 96 and 86 %
respectively.
Conclusions
The concrete obtained by partially replacing the fine aggregate with
wood ash does not reach the classification of lightweight concrete
because its density is not in the range of 1200 to 2000 kg/m³. The
concrete with 30% substitution presents a decrease in its real density
of 2.66% with reference to conventional concrete (from 2294.73
kg/m³ to 2233.75 kg/m³).
The concrete with 50% substitution shows a decrease in its real
density of 3.68% with reference to conventional concrete (from
2294.73 kg/m³ to 2210.38 kg/m³). The concrete with 70% substitution
shows a decrease in its real density of 5.13% with reference to
conventional concrete (from 2294.73 kg/m³ to 2176.92 kg/m³). The
inclusion of wood ash maintains the homogeneity of the concrete in
view of its correct distribution with the components of the mix.
The concrete with 30% substitution shows a decrease in compressive
strength of 3.45% with respect to conventional concrete (from 186.49
kg/cm² to 180.06 kg/cm²). The concrete with 50% substitution shows
a decrease in compressive strength of 7.31% with respect to
conventional concrete (from 186.49 kg/cm² to 172.85 kg/cm²).
Concrete with 70% substitution shows a decrease in compressive
strength of 16.67% with respect to conventional concrete (from
186.49 kg/cm² to 155.40 kg/cm²).
The concrete resulting from this research could be used mainly in the
construction of prefabricated masonry used in the division of rooms.
Initially; if there is availability of wood ash indicated as kiln waste, the
concrete with a substitution of 30% of fine aggregate has a cost of
96.89 USD/m³, resulting more economical than the conventional one;
in a percentage equivalent to 1.88.
In the opposite case, the alternative of producing ash using low-cost
waste wood is proposed, so the processed concrete is priced at
113.94 USD/m³, being 13.33% more expensive than conventional
concrete; then the economic benefit becomes functional when the
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Revista Científica Interdisciplinaria Investigación y Saberes , / 2024/ , Vol. 14, No. 1
43
fine aggregate (sand) is scarce at the construction site or its value is
high due to transportation issues.
Based on compliance with the design strength of 180 kg/cm², the
suggested percentage of substitution will be that which does not
exceed 30%. The fineness of the wood ash generates a greater
demand for water in the concrete, therefore, a correction for humidity
should be made and if necessary, a superplasticizing additive should
be added to maintain a slump between 6 and 9 centimeters.
In addition to partially replacing the fine aggregate, it is possible to
opt for partial or total replacement of the coarse aggregate with
lightweight aggregates, given that in weight and volume it is the
component with the greatest presence in the concrete.
To accelerate the combustion process, use wood that is superficially
dry. Use an industrial kiln, since it allows temperature control and
uniform calcination of the wood. Sieve the ash obtained in order to
eliminate charcoal residues and obtain a material of homogeneous
granulometry. To store the produced ash in double plastic bags, as
well as in a dry and fresh environment.
Work with a dosage by volume so that the wood ash content does not
hinder the workability of the mix. Use a content ratio: maximum
percentage of coarse aggregate/maximum percentage of fine
aggregate of 50/50, which implies a greater quantity of wood ash in
replacement of the fine aggregate and therefore a reduction in the
real density of the concrete. Carefully handle the specimens in fresh
state to avoid surface irregularities that hinder the transmission of
loads during the compression test.
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