Natural zeolite, a pozzolan for structural concrete

Abstract

Of building materials, concrete is currently one of the most widely used on account of its low cost, appropriate mechanical features and its durability, as well as the ease with which it can adopt different shapes and sizes (Najimi et al., 2012). Because of the importance of the use of concrete as a structural material and its impact on the environment as a consumer of large quantities of natural resources and as a CO2 emitter in the cement industry, it is necessary to develop mixtures from the science of materials to accompany the growth of construction while considering and taking measures to care for the environment, that is, to develop energetically efficient materials.

This article presents the use of a natural zeolite, a material with potential pozzolanic activity, to partially replace Portland cement in different percentages in structural concrete. The physico-chemical characterization of the zeolite material is presented with the results of resistance and durability of concrete to which this addition has been incorporated.

Full text

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Available online at www.sciencedirect.com
Available online at www.sciencedirect.com
ScienceDirect
Structural Integrity Procedia 00 (2016) 000–000
www.elsevier.com/locate/procedia
2452-3216 © 2016 The Authors. Published by Elsevier B.V.
Peer-review under responsibility of the Scientific Committee of PCF 2016.
XV Portuguese Conference on Fracture, PCF 2016, 10-12 February 2016, Paço de Arcos, Portugal
Thermo-mechanical modeling of a high pressure turbine blade of an
airplane gas turbine engine
P. Brandãoa, V. Infanteb, A.M. Deusc*
aDepartment of Mechanical Engineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa,
Portugal
bIDMEC, Department of Mechanical Engineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa,
Portugal
cCeFEMA, Department of Mechanical Engineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa,
Portugal
Abstract
During their operation, modern aircraft engine components are subjected to increasingly demanding operating conditions,
especially the high pressure turbine (HPT) blades. Such conditions cause these parts to undergo different types of time-dependent
degradation, one of which is creep. A model using the finite element method (FEM) was developed, in order to be able to predict
the creep behaviour of HPT blades. Flight data records (FDR) for a specific aircraft, provided by a commercial aviation
company, were used to obtain thermal and mechanical data for three different flight cycles. In order to create the 3D model
needed for the FEM analysis, a HPT blade scrap was scanned, and its chemical composition and material properties were
obtained. The data that was gathered was fed into the FEM model and different simulations were run, first with a simplified 3D
rectangular block shape, in order to better establish the model, and then with the real 3D mesh obtained from the blade scrap. The
overall expected behaviour in terms of displacement was observed, in particular at the trailing edge of the blade. Therefore such a
model can be useful in the goal of predicting turbine blade life, given a set of FDR data.
© 2016 The Authors. Published by Elsevier B.V.
Peer-review under responsibility of the Scientific Committee of PCF 2016.
Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation.
* Corresponding author. Tel.: +351 218419991.
E-mail address: amd@tecnico.ulisboa.pt
Procedia Structural Integrity 11 (2018) 36–43
2452-3216
Copyright  2018 Elsevier B.V. All rights reserved.
Peer-review under responsibility of the CINPAR 2018 organizers
10.1016/j.prostr.2018.11.006
10.1016/j.prostr.2018.11.006 2452-3216
Copyright © 2018 Elsevier B.V. All rights reserved.
Peer-review under responsibility of the CINPAR 2018 organizers
Available online at www.sciencedirect.com
ScienceDirect
Structural Integrity Procedia 00 (2018) 000–000
www.elsevier.com/locate/procedia
2452-3216 Copyright © 2018 Elsevier B.V. All rights reserved.
Peer-review under responsibility of the CINPAR 2018 organizers.
XIV International Conference on Building Pathology and Constructions Repair - CINPAR 2018
Natural zeolite, a pozzolan for structural concrete
Bárbara Belén Raggiottia*, María Josefina Positieria, Ángel Oshiroa
aCINTEMAC, Universidad Tenologia Nacional – Facultad Regional Córdoba, Maestro M. López esq Cruz Roja Argentina, Ciudad
Universitaria, Córdoba (X5016ZAA), Argentina
Abstract
Of building materials, concrete is currently one of the most widely used on account of its low cost, appropriate mechanical features
and its durability, as well as the ease with which it can adopt different shapes and sizes (Najimi et al., 2012). Because of the
importance of the use of concrete as a structural material and its impact on the environment as a consumer of large quantities of
natural resources and as a CO2 emitter in the cement industry, it is necessary to develop mixtures from the science of materials to
accompany the growth of construction while considering and taking measures to care for the environment, that is, to develop
energetically efficient materials.
This article presents the use of a natural zeolite, a material with potential pozzolanic activity, to partially replace Portland cement
in different percentages in structural concrete. The physico-chemical characterization of the zeolite material is presented with the
results of resistance and durability of concrete to which this addition has been incorporated.
Copyright © 2018 Elsevier B.V. All rights reserved.
Peer-review under responsibility of the CINPAR 2018 organizers
Keywords: zeolite; concrete; pozzolan; durability.
1. Introduction
Active mineral admixtures have been used throughout the history of concrete, seeking different purposes, to cover
economic, ecological and technological functions. Economic because they reduce the use of cement, the production
of which consumes high amounts of energy. Ecological because by replacing part of the cement, CO2 emissions are
* Corresponding author. Tel.: +54-3525-482382.
E-mail address: belenraggiotti@gmail.com
Available online at www.sciencedirect.com
ScienceDirect
Structural Integrity Procedia 00 (2018) 000–000
www.elsevier.com/locate/procedia
2452-3216 Copyright © 2018 Elsevier B.V. All rights reserved.
Peer-review under responsibility of the CINPAR 2018 organizers.
XIV International Conference on Building Pathology and Constructions Repair - CINPAR 2018
Natural zeolite, a pozzolan for structural concrete
Bárbara Belén Raggiottia*, María Josefina Positieria, Ángel Oshiroa
aCINTEMAC, Universidad Tenologia Nacional – Facultad Regional Córdoba, Maestro M. López esq Cruz Roja Argentina, Ciudad
Universitaria, Córdoba (X5016ZAA), Argentina
Abstract
Of building materials, concrete is currently one of the most widely used on account of its low cost, appropriate mechanical features
and its durability, as well as the ease with which it can adopt different shapes and sizes (Najimi et al., 2012). Because of the
importance of the use of concrete as a structural material and its impact on the environment as a consumer of large quantities of
natural resources and as a CO2 emitter in the cement industry, it is necessary to develop mixtures from the science of materials to
accompany the growth of construction while considering and taking measures to care for the environment, that is, to develop
energetically efficient materials.
This article presents the use of a natural zeolite, a material with potential pozzolanic activity, to partially replace Portland cement
in different percentages in structural concrete. The physico-chemical characterization of the zeolite material is presented with the
results of resistance and durability of concrete to which this addition has been incorporated.
Copyright © 2018 Elsevier B.V. All rights reserved.
Peer-review under responsibility of the CINPAR 2018 organizers
Keywords: zeolite; concrete; pozzolan; durability.
1. Introduction
Active mineral admixtures have been used throughout the history of concrete, seeking different purposes, to cover
economic, ecological and technological functions. Economic because they reduce the use of cement, the production
of which consumes high amounts of energy. Ecological because by replacing part of the cement, CO2 emissions are
* Corresponding author. Tel.: +54-3525-482382.
E-mail address: belenraggiotti@gmail.com
2 Raggiotti et al./ Structural Integrity Procedia 00 (2018) 000–000
reduced and this also constitutes a reservoir of many other industrial waste materials. And technological because they
contribute to improving some of the properties of concrete (Rahhal & Eperjeci, 2012).
The use of mineral admixtures in construction came before the use of cement, dating back to the 15th century BC
in Greece, according to Malhotra and Mehta (1996). Nowadays normally used mineral admixtures are waste from
other industries which would normally be disposed of in large quantities in inappropriate places, creating the risk of
contamination of soil and water sources (Dal Molin, 2005). In recent years, care for the environment and the reduction
of manufacturing costs have been a topic of discussion in most industries. The Portland cement industry has undergone
a series of changes, one of which promotes the use of supplementary, natural, residual materials, or industrial by-
products whose production requires less energy.
The term pozzolan was originally associated with natural volcanic ashes and scorched lands. The term has been
currently expanded to all the siliceous and aluminous materials which, eventually ground, in the presence of water,
may react chemically to the calcium hydroxide (CH) to form compounds possessing cementing properties, for which
they are classified as natural and artificial pozzolans.
This work proposes the use of natural zeolite as an active admixture containing reactive SiO2 and Al2O3 in its
composition, contributing to the resistance of the concrete through the pozzolanic reaction to the Ca(OH)2 whereby
this material's pozzolanic reactivity is extremely interesting in the study of sustainable concretes.
1.1. Zeolites
Natural zeolites were discovered by Axel A. F. Cronstedt in 1756. He recognized zeolites as a new class of mineral
consisting of hydrated aluminosilicates containing alkali or alkaline earth species. Clinoptilolite is the most widely
studied type of natural zeolite and is considered to be the most useful on account of its pozzolanic activity in cement
mixes worldwide. In Argentina, however, despite the existence of deposits of this mineral, no research had been
conducted into it.
Natural zeolites are found distributed in deposits around the world. Natural zeolites have generally been considered
low quality material because they are a mineral with a heterogeneous composition with different physical and chemical
properties. They were used in the ancient world, especially as an admixture in building material, but it was later used
mainly in environmental control processes, thus losing protagonism in the building industry.
According to Agosto (2012), the potential disadvantages of applying natural zeolites may be put down to the fact
that they are generally mineral mixtures in which the zeolite phase is often a variable constituent. However, in deposits
with a higher degree of purity, it has been possible to detect the presence of the zeolite phase in a ratio of 80% or
more. In Latin America, zeolites have been found in: Antilles, Argentina, Bolivia, Brazil, Chile, etc. In some cases
these manifestations are recognized as deposits with reserves estimated and approved for industrial exploitation
(Giannetto Pace et al., 2000). The most abundant zeolites in sedimentary rocks are: analcime, clinoptilolite, heulandite,
laumontite and phillipsite.
Today more than 50 natural zeolite minerals and 150 synthetic ones are known and used in different industries. In
the cement industry, natural zeolite is a natural pozzolan popular in some regions of the world. It is used in large
quantities as a kind of natural pozzolanic material in China (Najimi et al, 2012), Iran (Ahmadi & Shekarchi, 2010),
Cuba (Rosell et al., 2006), among others. In China it is widely used as a mixing material for cement. The total amount
consumed for this purpose is approximately 30 million tons a year. (Poon et al., 1999).
According to a survey conducted by Najimi et al. (2012), zeolite tuff has been used as a pozzolanic material in
some cement plants in Russia, Germany, Slovenia, Cuba, Serbia and Spain. It has been researched mostly in countries
with natural zeolite deposits for concrete and mortar containing different amounts of it in properties of resistance,
alkali-silica reaction, and the transportation of substances. Not many studies have been found related to aspects of
durability, particularly in carbonation, freezing, thawing and functions like attacking sulfates and acids, chloride-
induced corrosion in reinforced concrete and contraction from drying.
2. Methodology
The experimental work has been divided into two parts, one in which the physico-chemical characterization of
zeolite is presented, and another which assesses its potential as a pozzolan in structural concrete.

Bárbara Belén Raggiotti et al. / Procedia Structural Integrity 11 (2018) 36–43 37
Available online at www.sciencedirect.com
ScienceDirect
Structural Integrity Procedia 00 (2018) 000–000
www.elsevier.com/locate/procedia
2452-3216 Copyright © 2018 Elsevier B.V. All rights reserved.
Peer-review under responsibility of the CINPAR 2018 organizers.
XIV International Conference on Building Pathology and Constructions Repair - CINPAR 2018
Natural zeolite, a pozzolan for structural concrete
Bárbara Belén Raggiottia*, María Josefina Positieria, Ángel Oshiroa
aCINTEMAC, Universidad Tenologia Nacional – Facultad Regional Córdoba, Maestro M. López esq Cruz Roja Argentina, Ciudad
Universitaria, Córdoba (X5016ZAA), Argentina
Abstract
Of building materials, concrete is currently one of the most widely used on account of its low cost, appropriate mechanical features
and its durability, as well as the ease with which it can adopt different shapes and sizes (Najimi et al., 2012). Because of the
importance of the use of concrete as a structural material and its impact on the environment as a consumer of large quantities of
natural resources and as a CO2 emitter in the cement industry, it is necessary to develop mixtures from the science of materials to
accompany the growth of construction while considering and taking measures to care for the environment, that is, to develop
energetically efficient materials.
This article presents the use of a natural zeolite, a material with potential pozzolanic activity, to partially replace Portland cement
in different percentages in structural concrete. The physico-chemical characterization of the zeolite material is presented with the
results of resistance and durability of concrete to which this addition has been incorporated.
Copyright © 2018 Elsevier B.V. All rights reserved.
Peer-review under responsibility of the CINPAR 2018 organizers
Keywords: zeolite; concrete; pozzolan; durability.
1. Introduction
Active mineral admixtures have been used throughout the history of concrete, seeking different purposes, to cover
economic, ecological and technological functions. Economic because they reduce the use of cement, the production
of which consumes high amounts of energy. Ecological because by replacing part of the cement, CO2 emissions are
* Corresponding author. Tel.: +54-3525-482382.
E-mail address: belenraggiotti@gmail.com
Available online at www.sciencedirect.com
ScienceDirect
Structural Integrity Procedia 00 (2018) 000–000
www.elsevier.com/locate/procedia
2452-3216 Copyright © 2018 Elsevier B.V. All rights reserved.
Peer-review under responsibility of the CINPAR 2018 organizers.
XIV International Conference on Building Pathology and Constructions Repair - CINPAR 2018
Natural zeolite, a pozzolan for structural concrete
Bárbara Belén Raggiottia*, María Josefina Positieria, Ángel Oshiroa
aCINTEMAC, Universidad Tenologia Nacional – Facultad Regional Córdoba, Maestro M. López esq Cruz Roja Argentina, Ciudad
Universitaria, Córdoba (X5016ZAA), Argentina
Abstract
Of building materials, concrete is currently one of the most widely used on account of its low cost, appropriate mechanical features
and its durability, as well as the ease with which it can adopt different shapes and sizes (Najimi et al., 2012). Because of the
importance of the use of concrete as a structural material and its impact on the environment as a consumer of large quantities of
natural resources and as a CO2 emitter in the cement industry, it is necessary to develop mixtures from the science of materials to
accompany the growth of construction while considering and taking measures to care for the environment, that is, to develop
energetically efficient materials.
This article presents the use of a natural zeolite, a material with potential pozzolanic activity, to partially replace Portland cement
in different percentages in structural concrete. The physico-chemical characterization of the zeolite material is presented with the
results of resistance and durability of concrete to which this addition has been incorporated.
Copyright © 2018 Elsevier B.V. All rights reserved.
Peer-review under responsibility of the CINPAR 2018 organizers
Keywords: zeolite; concrete; pozzolan; durability.
1. Introduction
Active mineral admixtures have been used throughout the history of concrete, seeking different purposes, to cover
economic, ecological and technological functions. Economic because they reduce the use of cement, the production
of which consumes high amounts of energy. Ecological because by replacing part of the cement, CO2 emissions are
* Corresponding author. Tel.: +54-3525-482382.
E-mail address: belenraggiotti@gmail.com
2 Raggiotti et al./ Structural Integrity Procedia 00 (2018) 000–000
reduced and this also constitutes a reservoir of many other industrial waste materials. And technological because they
contribute to improving some of the properties of concrete (Rahhal & Eperjeci, 2012).
The use of mineral admixtures in construction came before the use of cement, dating back to the 15th century BC
in Greece, according to Malhotra and Mehta (1996). Nowadays normally used mineral admixtures are waste from
other industries which would normally be disposed of in large quantities in inappropriate places, creating the risk of
contamination of soil and water sources (Dal Molin, 2005). In recent years, care for the environment and the reduction
of manufacturing costs have been a topic of discussion in most industries. The Portland cement industry has undergone
a series of changes, one of which promotes the use of supplementary, natural, residual materials, or industrial by-
products whose production requires less energy.
The term pozzolan was originally associated with natural volcanic ashes and scorched lands. The term has been
currently expanded to all the siliceous and aluminous materials which, eventually ground, in the presence of water,
may react chemically to the calcium hydroxide (CH) to form compounds possessing cementing properties, for which
they are classified as natural and artificial pozzolans.
This work proposes the use of natural zeolite as an active admixture containing reactive SiO2 and Al2O3 in its
composition, contributing to the resistance of the concrete through the pozzolanic reaction to the Ca(OH)2 whereby
this material's pozzolanic reactivity is extremely interesting in the study of sustainable concretes.
1.1. Zeolites
Natural zeolites were discovered by Axel A. F. Cronstedt in 1756. He recognized zeolites as a new class of mineral
consisting of hydrated aluminosilicates containing alkali or alkaline earth species. Clinoptilolite is the most widely
studied type of natural zeolite and is considered to be the most useful on account of its pozzolanic activity in cement
mixes worldwide. In Argentina, however, despite the existence of deposits of this mineral, no research had been
conducted into it.
Natural zeolites are found distributed in deposits around the world. Natural zeolites have generally been considered
low quality material because they are a mineral with a heterogeneous composition with different physical and chemical
properties. They were used in the ancient world, especially as an admixture in building material, but it was later used
mainly in environmental control processes, thus losing protagonism in the building industry.
According to Agosto (2012), the potential disadvantages of applying natural zeolites may be put down to the fact
that they are generally mineral mixtures in which the zeolite phase is often a variable constituent. However, in deposits
with a higher degree of purity, it has been possible to detect the presence of the zeolite phase in a ratio of 80% or
more. In Latin America, zeolites have been found in: Antilles, Argentina, Bolivia, Brazil, Chile, etc. In some cases
these manifestations are recognized as deposits with reserves estimated and approved for industrial exploitation
(Giannetto Pace et al., 2000). The most abundant zeolites in sedimentary rocks are: analcime, clinoptilolite, heulandite,
laumontite and phillipsite.
Today more than 50 natural zeolite minerals and 150 synthetic ones are known and used in different industries. In
the cement industry, natural zeolite is a natural pozzolan popular in some regions of the world. It is used in large
quantities as a kind of natural pozzolanic material in China (Najimi et al, 2012), Iran (Ahmadi & Shekarchi, 2010),
Cuba (Rosell et al., 2006), among others. In China it is widely used as a mixing material for cement. The total amount
consumed for this purpose is approximately 30 million tons a year. (Poon et al., 1999).
According to a survey conducted by Najimi et al. (2012), zeolite tuff has been used as a pozzolanic material in
some cement plants in Russia, Germany, Slovenia, Cuba, Serbia and Spain. It has been researched mostly in countries
with natural zeolite deposits for concrete and mortar containing different amounts of it in properties of resistance,
alkali-silica reaction, and the transportation of substances. Not many studies have been found related to aspects of
durability, particularly in carbonation, freezing, thawing and functions like attacking sulfates and acids, chloride-
induced corrosion in reinforced concrete and contraction from drying.
2. Methodology
The experimental work has been divided into two parts, one in which the physico-chemical characterization of
zeolite is presented, and another which assesses its potential as a pozzolan in structural concrete.

38 Bárbara Belén Raggiotti et al. / Procedia Structural Integrity 11 (2018) 36–43
Raggiotti et al./Structural Integrity Procedia 00 (2018) 000–000 3
Resistance assays were conducted, such as axial compression, traction by diameter compression, elastic module,
and assays indicating durability such as absorption, capillary suction, speed of capillary suction and permeability to
air. Concretes were analyzed in which different percentages in weight of cement was gradually replaced by the zeolite
admixture. Ten mixtures were made. Section 6 indicates the dosages.
3. Characterization of the Pozzolanic Material
The zeolite was obtained from a deposit in the Cuenca de Pagancillo area, in the Department of Independencia, in
the center west of the province of La Rioja, Argentina. The work was done using a clinoptilolite of the heulandite
group.
•Density: 2.13 g/cm3. Determined by means of a pycnometer.
•Specific surface: 234 m2/kg. Calculated by fineness test method using dry sifting and by determining the specific
surface by permeability to air (Blaine method)
•Granulometry distribution: The sample is granulometrically heterogeneous (Figure 1) with 40.62% of its particles
larger than 1000 µm (granulometry by sifting) and 59.38% of its particles smaller or equal to 1000 µm
(granulometry by means of an analyzer of distribution of the size of the particles by laser diffraction Partica lA-
950V2, HORIBA).
Figure 1. Granulometry of natural zeolite (NZ) of the fraction > 1000 µm (a) and < 1000 µm (b)
•Spectroscopy by X-ray fluorescence: Table 1 presents the composition of the zeolite material as per FRX using
Rigaku FX2000 equipment.
Table 1. Chemical composition (%) of the pozzolanic material determined by FRX (LOI: loss of ignition)
SiO2TiO2Al2O3Fe2O3MnO MgO CaO Na2O K2O P2O5LOI STotal
59.81
0.19
14.32
1.04
0.01
0.83
5.50
5.76
1.36
0.02
7.47
3.36
99.67
•Characterization by means of X-ray Diffractometry (XRD): This was carried out using a Rigaku D-Max III - C
diffractometer, which works at 35 kV and 15 mA, using Cu Kα1,2 radiation (λ= 1,541840 Å) filtered with a graphite
monochromator in the diffracted ray, between 3 and 60 °2θ, in 0.03 °2θ increments with one-second recounting
intervals per increment. The material corresponds to a mixture of minerals; zeolite is the predominant phase. Based
on the XRD presented in Figure 2, and the determination of semi-quantitative percentage of mineral phases using
the RIR method proposed by Chung (1974), the sample is mainly made up of zeolite of the clinoptilolite-heulandite
series (51%), gypsum (13%), albite (17%), biotite (10%) and quartz (9%).
Figure 2. Diffraction pattern of the pozzolanic material. z: zeolite, g: gypsum, p: plagioclase, b: biotite, q: quartz.
4Raggiotti et al./Structural Integrity Procedia 00 (2018) 000–000
•Semi-quantitative microanalysis by electron probe (SEM -EDS): the zeolite appears as tiny laminar crystals
grouped in the shape of added rosettes. This can be observed in Figure 3. The composition maps (Si, Al, Na, K,
Mg, S, Ca, Fe, Ti) and the SEM images were obtained in gold-laminated dust samples with a Carl Zeiss FE (field
emission)-SEM Zigma high resolution microscope equipped with an EDS. Around 30 mg of sample was used.
Figure 3. SEM image of the laminar crystals of clinoptilolite-Na.
Zeolite is mainly represented by the sum of Si, Al and Na maps with a lower proportion of K, Mg and Ca. Biotite
is represented by the sum of Si, Al, Fe, Mg and a lower measure of Ti. Plagioclase is represented by the sum of Si,
Al, Na and a little more Ca but, as it coincides with the main elements of zeolite, it might not be recognized on the
maps though it was identified by EDS and XRD.
Although the quartz was determined using XRD, it might not be recognized in the compositional maps because the
Si is also part of the clinoptilolite, plagioclase and biotite crystal structures.
With the aim of detecting additional mineral phases not identified by XRD and to assess the origin of the sulfur
different from the gypsum phase, composition maps were obtained by FE-SEM-EDS of the fine fraction (≤ 1,000
m) of the pozzolanic material. Figure 4shows the compositional maps. The gypsum is represented by the sum of
the S and Ca maps. The sulfur is fully bonded to the gypsum phase.
Figure 4. FE-SEM-EDS. a) Image of the secondary electrons of the pozzolanic material (18 kV). b-f) composition maps of Si (b), of Al (c), Na
(d), K (e), Mg (f), S (g), Ca (h), Fe (i)
4. Design of concrete with the addition of zeolite
Two series of concrete were posed, one for each kind of cement used, Normal Portland cement (NPC) and
Compound Portland cement (CPC), to which 5, 10, 15 and 20% of the cement content in weight was replaced by the
addition of zeolite, the main variable in the study. Table 4indicates the dosages.
5. Materials
•Cement: NPC40 from the province of Catamarca, Argentina, was used; and CPC40 from the province of Cordoba,
Argentina, which comply with IRAM standard 50,000 (2014). These two cements were used to analyze the

Bárbara Belén Raggiotti et al. / Procedia Structural Integrity 11 (2018) 36–43 39
Raggiotti et al./Structural Integrity Procedia 00 (2018) 000–000 3
Resistance assays were conducted, such as axial compression, traction by diameter compression, elastic module,
and assays indicating durability such as absorption, capillary suction, speed of capillary suction and permeability to
air. Concretes were analyzed in which different percentages in weight of cement was gradually replaced by the zeolite
admixture. Ten mixtures were made. Section 6 indicates the dosages.
3. Characterization of the Pozzolanic Material
The zeolite was obtained from a deposit in the Cuenca de Pagancillo area, in the Department of Independencia, in
the center west of the province of La Rioja, Argentina. The work was done using a clinoptilolite of the heulandite
group.
•Density: 2.13 g/cm3. Determined by means of a pycnometer.
•Specific surface: 234 m2/kg. Calculated by fineness test method using dry sifting and by determining the specific
surface by permeability to air (Blaine method)
•Granulometry distribution: The sample is granulometrically heterogeneous (Figure 1) with 40.62% of its particles
larger than 1000 µm (granulometry by sifting) and 59.38% of its particles smaller or equal to 1000 µm
(granulometry by means of an analyzer of distribution of the size of the particles by laser diffraction Partica lA-
950V2, HORIBA).
Figure 1. Granulometry of natural zeolite (NZ) of the fraction > 1000 µm (a) and < 1000 µm (b)
•Spectroscopy by X-ray fluorescence: Table 1 presents the composition of the zeolite material as per FRX using
Rigaku FX2000 equipment.
Table 1. Chemical composition (%) of the pozzolanic material determined by FRX (LOI: loss of ignition)
SiO2
TiO2
Al2O3
Fe2O3
MnO
MgO
CaO
Na2O
K2O
P2O5
LOI
S
Total
59.81
0.19
14.32
1.04
0.01
0.83
5.50
5.76
1.36
0.02
7.47
3.36
99.67
•Characterization by means of X-ray Diffractometry (XRD): This was carried out using a Rigaku D-Max III - C
diffractometer, which works at 35 kV and 15 mA, using Cu Kα1,2 radiation (λ= 1,541840 Å) filtered with a graphite
monochromator in the diffracted ray, between 3 and 60 °2θ, in 0.03 °2θ increments with one-second recounting
intervals per increment. The material corresponds to a mixture of minerals; zeolite is the predominant phase. Based
on the XRD presented in Figure 2, and the determination of semi-quantitative percentage of mineral phases using
the RIR method proposed by Chung (1974), the sample is mainly made up of zeolite of the clinoptilolite-heulandite
series (51%), gypsum (13%), albite (17%), biotite (10%) and quartz (9%).
Figure 2. Diffraction pattern of the pozzolanic material. z: zeolite, g: gypsum, p: plagioclase, b: biotite, q: quartz.
4Raggiotti et al./Structural Integrity Procedia 00 (2018) 000–000
•Semi-quantitative microanalysis by electron probe (SEM -EDS): the zeolite appears as tiny laminar crystals
grouped in the shape of added rosettes. This can be observed in Figure 3. The composition maps (Si, Al, Na, K,
Mg, S, Ca, Fe, Ti) and the SEM images were obtained in gold-laminated dust samples with a Carl Zeiss FE (field
emission)-SEM Zigma high resolution microscope equipped with an EDS. Around 30 mg of sample was used.
Figure 3. SEM image of the laminar crystals of clinoptilolite-Na.
Zeolite is mainly represented by the sum of Si, Al and Na maps with a lower proportion of K, Mg and Ca. Biotite
is represented by the sum of Si, Al, Fe, Mg and a lower measure of Ti. Plagioclase is represented by the sum of Si,
Al, Na and a little more Ca but, as it coincides with the main elements of zeolite, it might not be recognized on the
maps though it was identified by EDS and XRD.
Although the quartz was determined using XRD, it might not be recognized in the compositional maps because the
Si is also part of the clinoptilolite, plagioclase and biotite crystal structures.
With the aim of detecting additional mineral phases not identified by XRD and to assess the origin of the sulfur
different from the gypsum phase, composition maps were obtained by FE-SEM-EDS of the fine fraction (≤ 1,000
m) of the pozzolanic material. Figure 4shows the compositional maps. The gypsum is represented by the sum of
the S and Ca maps. The sulfur is fully bonded to the gypsum phase.
Figure 4. FE-SEM-EDS. a) Image of the secondary electrons of the pozzolanic material (18 kV). b-f) composition maps of Si (b), of Al (c), Na
(d), K (e), Mg (f), S (g), Ca (h), Fe (i)
4. Design of concrete with the addition of zeolite
Two series of concrete were posed, one for each kind of cement used, Normal Portland cement (NPC) and
Compound Portland cement (CPC), to which 5, 10, 15 and 20% of the cement content in weight was replaced by the
addition of zeolite, the main variable in the study. Table 4indicates the dosages.
5. Materials
•Cement: NPC40 from the province of Catamarca, Argentina, was used; and CPC40 from the province of Cordoba,
Argentina, which comply with IRAM standard 50,000 (2014). These two cements were used to analyze the

40 Bárbara Belén Raggiotti et al. / Procedia Structural Integrity 11 (2018) 36–43
Raggiotti et al./ Structural Integrity Procedia 00 (2018) 000–000 5
behavior of zeolite with a normal cement and one compound that is allowed by the standard to have two or more
admixtures in its composition, such as pozzolan, slag, and calcareous filler up to 35%. Table 2 shows the
characteristics of the cements.
Table 2. Characteristics of the cements
Designation NPC CPC
IRAM 50,000 denomination NPC40 CPC40
Density [g/cm3] 3.15 3.10
Specific surface [cm2/g] 3869 4008
Retained in Sieve #200 [%] 0.0 0.6
Loss from calcination [%] 3.74 4.00
Insoluble waste [%] 2.00 2.50
SO3 [%] 1.65 2.64
MgO [%] 2.43 5.50
• Coarse aggregate: Crushed coarse aggregate of local origin was used (Córdoba, Argentina).
• Fine aggregate: Sand from the Suquía River paleochannel in Córdoba, Argentina, was used.
Coarse and fine aggregates found within the limit curves of IRAM 1627 (1997) Standard. Table 3 shows the
characteristics of the aggregates.
Table 3. Characteristics of the aggregates
Type of
aggregate
Maximum size [mm]
IRAM 1505:2003
Fineness module
IRAM 505:2003
Apparent relative density of the
saturated aggregate and dry surface
IRAM 1533:2002
Absorption
[%]
IRAM 533:2002
Coarse
19
-
2.73
1.15
Fine
-
3.15
2.66
0.86
• Additive: A plastifying additive for concrete was used based on chemical lignosulfonates. The density of the
additive is 1.2 Kg/l.
• Zeolite: The zeolite used is a porous aluminosilicate corresponding to class F pozzolan as per the chemical
composition compared to that expressed in ASTM C618 Standard (2015). The main characteristics have been
described in Section 3.
• Water: The water employed was from the water supply network which fulfills the requirements established by
CIRSOC 201 Regulation (2005) and IRAM 1601 Standard (2012).
6. Dosages
The criteria and concepts of CIRSOC 201 Regulation (2005) were used in the design of the mixtures as relates to
the levels of resistance to compression and the concepts of granular packing.
Table 4 shows the dosages used. Each mixture was designated by two letters and a number. The first letter is "Z"
and corresponds to zeolite; the second letter refers to the type of cement, "N" for normal cement and "C" for compound
cement. The number indicates the percentage of weight of cement replaced by zeolite. Concrete designated as ZC15
means it has compound cement and that 15% of the cement has been replaced by zeolite. Additive was used with a
dosage of 0.35% of the weight of the binder material, that is, cement plus zeolite. The w/bm (water - binder material)
ratio remained constant at 0.41.
6 Raggiotti et al./ Structural Integrity Procedia 00 (2018) 000–000
Table 4. Dosage in kg. for one m3 of concrete.
Material/concrete
ZN0
ZN5
ZN10
ZN15
ZN20
ZC0
ZC5
ZC10
ZC15
ZC20
NCP40 Cement
450.0
427.5
405.0
382.5
360.0
-
-
-
-
-
CPC40 Cement
-
-
-
-
-
450.0
427.5
405.0
382.5
360.0
Water
185.0
185.0
185.0
185.0
185.0
185.0
185.0
185.0
185.0
185.0
Addition (Zeolite)
-
22.5
45.0
67.5
90.0
-
22.5
45.0
67.5
90.0
Coarse aggregate
972.5
967.6
962.6
957.7
952.7
972.5
967.6
962.6
957.7
952.7
Fine aggregate
840.3
836.0
831.8
827.5
823.2
840.3
836.0
831.8
827.5
823.2
Plastifying additive
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
Ratio w/c
0.41
0.43
0.46
0.48
0.51
0.41
0.43
0.46
0.48
0.51
Ratio of w/bm
0.41
0.41
0.41
0.41
0.41
0.41
0.41
0.41
0.41
0.41
7. Assays and Result Analysis
Fresh state: The consistency was determined by means of Abrams Cone (IRAM 1536 Standard, 1978). Figure 5
shows the results reached.
Figure 5. Settling measured using Abrams Cone
In fresh state, the use of the admixture, from the rheological point of view, improved cohesion; zeolite's lower
density makes the volume of the cement paste plus the zeolite greater than the volume of the cement paste of the
reference concrete; this situation increases the contact between solid particles giving the mixture greater cohesion. On
the other hand, as can be observed in Figure 5, the mixtures lost consistency as the incorporation of zeolite increased.
The phenomenon can partly be put down to the fact that this mineral is a good cation exchanger and to its porous
structure which retains water. The difference in behavior between the mixtures with NPC and CPC can be put down
to the composition of the cement. The only mixture with no type of admixture included, either in the concrete or the
cement, is ZN0, and it was the one that settled the best, evidencing the influence of workability in the incorporation
of the admixtures in the mixes.
• Hardened state: Resistance to compression was defined at 7, 28, 90 and 180 days as per IRAM 1546 Standard
(2013); resistance to traction by diameter compression (IRAM 1658, 1995), elastic module at 28 days (ASTM
C469, 2014), absorption (ASTM C642, 2013), suction and speed of capillary suction (IRAM 1871, 2004) and
permeability to air (Swiss Standard SIA 262/1-E, 2003). Figure 6 shows resistance to compression at different
ages.
Figure 6. Resistance to compression at different ages
0
5
10
15
20
ZN0 ZN5 ZN10 ZN15 ZN20 ZC0 ZC5 ZC10 ZC15 ZC20
Slump [cm]
0
10
20
30
40
50
60
70
ZN0 ZN5 ZN10 ZN15 ZN20 ZC0 ZC5 ZC10 ZC15 ZC20
Strenght [MPa]
728 90 180

Bárbara Belén Raggiotti et al. / Procedia Structural Integrity 11 (2018) 36–43 41
Raggiotti et al./ Structural Integrity Procedia 00 (2018) 000–000 5
behavior of zeolite with a normal cement and one compound that is allowed by the standard to have two or more
admixtures in its composition, such as pozzolan, slag, and calcareous filler up to 35%. Table 2 shows the
characteristics of the cements.
Table 2. Characteristics of the cements
Designation
NPC
CPC
IRAM 50,000 denomination
NPC40
CPC40
Density [g/cm3]
3.15
3.10
Specific surface [cm2/g]
3869
4008
Retained in Sieve #200 [%]
0.0
0.6
Loss from calcination [%]
3.74
4.00
Insoluble waste [%]
2.00
2.50
SO3 [%]
1.65
2.64
MgO [%]
2.43
5.50
• Coarse aggregate: Crushed coarse aggregate of local origin was used (Córdoba, Argentina).
• Fine aggregate: Sand from the Suquía River paleochannel in Córdoba, Argentina, was used.
Coarse and fine aggregates found within the limit curves of IRAM 1627 (1997) Standard. Table 3 shows the
characteristics of the aggregates.
Table 3. Characteristics of the aggregates
Type of
aggregate
Maximum size [mm]
IRAM 1505:2003
Fineness module
IRAM 505:2003
Apparent relative density of the
saturated aggregate and dry surface
IRAM 1533:2002
Absorption [%]
IRAM 533:2002
Coarse
19
-
2.73
1.15
Fine
-
3.15
2.66
0.86
• Additive: A plastifying additive for concrete was used based on chemical lignosulfonates. The density of the
additive is 1.2 Kg/l.
• Zeolite: The zeolite used is a porous aluminosilicate corresponding to class F pozzolan as per the chemical
composition compared to that expressed in ASTM C618 Standard (2015). The main characteristics have been
described in Section 3.
• Water: The water employed was from the water supply network which fulfills the requirements established by
CIRSOC 201 Regulation (2005) and IRAM 1601 Standard (2012).
6. Dosages
The criteria and concepts of CIRSOC 201 Regulation (2005) were used in the design of the mixtures as relates to
the levels of resistance to compression and the concepts of granular packing.
Table 4 shows the dosages used. Each mixture was designated by two letters and a number. The first letter is "Z"
and corresponds to zeolite; the second letter refers to the type of cement, "N" for normal cement and "C" for compound
cement. The number indicates the percentage of weight of cement replaced by zeolite. Concrete designated as ZC15
means it has compound cement and that 15% of the cement has been replaced by zeolite. Additive was used with a
dosage of 0.35% of the weight of the binder material, that is, cement plus zeolite. The w/bm (water - binder material)
ratio remained constant at 0.41.
6 Raggiotti et al./ Structural Integrity Procedia 00 (2018) 000–000
Table 4. Dosage in kg. for one m3 of concrete.
Material/concrete
ZN0
ZN5
ZN10
ZN15
ZN20
ZC0
ZC5
ZC10
ZC15
ZC20
NCP40 Cement
450.0
427.5
405.0
382.5
360.0
-
-
-
-
-
CPC40 Cement
-
-
-
-
-
450.0
427.5
405.0
382.5
360.0
Water
185.0
185.0
185.0
185.0
185.0
185.0
185.0
185.0
185.0
185.0
Addition (Zeolite)
-
22.5
45.0
67.5
90.0
-
22.5
45.0
67.5
90.0
Coarse aggregate
972.5
967.6
962.6
957.7
952.7
972.5
967.6
962.6
957.7
952.7
Fine aggregate
840.3
836.0
831.8
827.5
823.2
840.3
836.0
831.8
827.5
823.2
Plastifying additive
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
Ratio w/c
0.41
0.43
0.46
0.48
0.51
0.41
0.43
0.46
0.48
0.51
Ratio of w/bm
0.41
0.41
0.41
0.41
0.41
0.41
0.41
0.41
0.41
0.41
7. Assays and Result Analysis
Fresh state: The consistency was determined by means of Abrams Cone (IRAM 1536 Standard, 1978). Figure 5
shows the results reached.
Figure 5. Settling measured using Abrams Cone
In fresh state, the use of the admixture, from the rheological point of view, improved cohesion; zeolite's lower
density makes the volume of the cement paste plus the zeolite greater than the volume of the cement paste of the
reference concrete; this situation increases the contact between solid particles giving the mixture greater cohesion. On
the other hand, as can be observed in Figure 5, the mixtures lost consistency as the incorporation of zeolite increased.
The phenomenon can partly be put down to the fact that this mineral is a good cation exchanger and to its porous
structure which retains water. The difference in behavior between the mixtures with NPC and CPC can be put down
to the composition of the cement. The only mixture with no type of admixture included, either in the concrete or the
cement, is ZN0, and it was the one that settled the best, evidencing the influence of workability in the incorporation
of the admixtures in the mixes.
• Hardened state: Resistance to compression was defined at 7, 28, 90 and 180 days as per IRAM 1546 Standard
(2013); resistance to traction by diameter compression (IRAM 1658, 1995), elastic module at 28 days (ASTM
C469, 2014), absorption (ASTM C642, 2013), suction and speed of capillary suction (IRAM 1871, 2004) and
permeability to air (Swiss Standard SIA 262/1-E, 2003). Figure 6 shows resistance to compression at different
ages.
Figure 6. Resistance to compression at different ages
0
5
10
15
20
ZN0 ZN5 ZN10 ZN15 ZN20 ZC0 ZC5 ZC10 ZC15 ZC20
Slump [cm]
0
10
20
30
40
50
60
70
ZN0 ZN5 ZN10 ZN15 ZN20 ZC0 ZC5 ZC10 ZC15 ZC20
Strenght [MPa]
728 90 180

42 Bárbara Belén Raggiotti et al. / Procedia Structural Integrity 11 (2018) 36–43
Raggiotti et al./ Structural Integrity Procedia 00 (2018) 000–000 7
Resistance to compression of concretes containing zeolite was lower than the resistance reached by reference
mixtures at virtually all ages, particularly at early ages (7 and 28 days). However, the reduction percentages were
lower or even nil at higher ages of the concrete (90 and 180 days). This may be attributed to the zeolite's pozzolanic
activity. The development of resistance in the master mixture ZN0 depends mainly on the speed of hydration of the
clinker, while in the other mixtures, it depends on the combination of the hydration of the clinker and the pozzolanic
activity of the zeolite (Perraki et al., 2010).
As can be seen in Figure 6, the concrete made with NPC40 shows better performance to compression, at all ages,
than that made with CPC40. The composition of the cement is an important variable in the performance to resistance
of concrete.
The lower resistances reached by the CPC40 can be put down to the lower content of non hydrated calcium silicates
capable of reacting to the admixture forming new hydrated calcium silicates. The silicates, that made up about 75%
of the common Portland cement, lead a dominant role in determining the hardening characteristics (rate of resistance
development). Table 5 shows the results of the assays of traction by diameter compression and elastic module.
Table 5. Resistance to traction by diameter compression and elastic module
Concretes ZN0 ZN5 ZN10 ZN15 ZN20 ZC0 ZC5 ZC10 ZC15 ZC20
Traction [MPa] 4.5 3.8 3.8 4.2 4.5 3.9 3.9 3.2 3.8 3.8
Elastic module [GPa] 38.2 37.2 35.8 39.2 37.2 38.7 37.9 38.1 35.6 34.1
The mixtures showed variable behavior to traction by diameter compression, but with a common point between the
two series of cements. The mixtures with 10% zeolite were those that presented the least resistance to traction. With
a content of admixture greater than 10% the resistance increased gradually.
The results of the elastic module show a dispersion of 1.26 and 1.94 corresponding to a mean of 37.5 and 36.9 GPa
for NPC and CPC respectively. For the CPC series, as the zeolite increases, the material becomes more deformable,
that is to say, the effort required to achieve the same deformation is lower. Table 6 shows the results of the durability
indicators.
Table 6. Results of absorption, suction and speed of capillary suction and permeability to air
Concretes
ZN0
ZN5
ZN10
ZN15
ZN20
ZC0
ZC5
ZC10
ZC15
ZC20
Absorption [%]
3.9
3.4
4.3
3.8
3.9
6.5
6.8
7.3
7.6
8.3
Capillary suction [gr/m2]
4133.8
4145.1
4549.7
4224.3
3491.5
7039.6
7444.2
7888.4
8143.1
8626.9
Suction speed [gr/m2.s1/2]
8.4
8.7
9.9
8.5
6.7
15.9
14.1
17.5
18.4
19.5
Permeability to air [kT]
0.33
1.37
2.58
0.33
0.16
3.40
3.55
3.75
3.48
5.88
The permeability to air was determined with Permea-TORR (Swiss Standard SIA 262/1-E, 2003) equipment. The
classes of permeability to air according to this standard are: PK1: very low (kT < 0.01), PK2: low (0.01< kT< 0.1),
PK3: moderate (0.1< kT< 1.0), PK4: high (1.0< kT< 10.0), PK5: very high (kT>10.0).
Analyzing the results shown in Table 6, there is an improvement in this property as from a 15% replacement of
cement with zeolite in the NPC series; in the CPC series there is no decrease of permeability at a greater content of
the admixture and the permeability of all the concretes remains within the same PK4 class, classified as "high."
NPC concretes showed better behavior than CPC concretes in view of the transportation of water through the
capillary suction mechanism. This may be correlated with the absorption results presented in Table 6. The
phenomenon finds its explanation in the composition of NPC concretes, as the porous structure of the paste depends
only on the interaction of the normal cement with the zeolite, while other admixtures are present in the CPC series.
The properties analyzed improve in NPC concrete with replacements greater than 10%; while CPCs show an increase
in the capacity for water absorption at a greater replacement of cement by the admixture, with a greater capacity for
capillary suction and greater speed for capillary suction.
8 Raggiotti et al./ Structural Integrity Procedia 00 (2018) 000–000
8. Conclusions
The physico-chemical characterization performed for natural zeolite makes it possible to classify this material as
zeolite clinoptilolite-Na; although it does not adjust exactly to the maximum limit of SO3 as per the type of pozzolan
described in ASTM C618 Standard (2015), it can be used as a material with pozzolanic characteristics in Portland
cement mixtures. This was confirmed by the results obtained in the second experimental stage of the mechanical
resistance and durability assays of the concretes.
Zeolite's rough and porous structure, as well as its large surface area, create a structure of the mixture pastes with
zeolite that contain more complex forms and vacuums than the master mixture caused by the growth of the crystalline
structure in all directions (Yılmaz et al., 2007); a phenomenon that manifests itself in a loss of consistency of the
mixtures as the incorporation of zeolite is increased, as could be observed in the Abrams Cone assay.
In the mechanical assays, the use of zeolite contributes to the development of resistance in concretes over longer
periods of time, showing its activity at ages of over 28 days.
The difference in behavior between concretes with different cements stands out, mainly when durability indicators
are analyzed. In this case we find more porous mixtures with compound Portland cement. The importance of the
composition of the cement becomes evident, and the way it interacts and reacts to the zeolite added.
The durability properties were generally achieved satisfactorily. The greatest effectiveness of applying zeolite was
observed in mixtures with normal Portland cement.
Lastly, it should be clarified that natural zeolites have different chemical properties, because of which it is necessary
to carefully characterize them before using them as admixtures in cement mixes. The zeolite studied herein,
Clinoptilolite-Na, fulfilled the three functions for which admixtures are used in Portland cement mixes. An economic
function, as the amount of cement used in the mix was reduced, an ecological function, as an available material was
used which has no use in the market and would otherwise have accumulated and become waste from the mining
industry, and a technological function, as it improved properties of concretes. Therefore the zeolite proposed may be
applied as a pozzolan in structural concretes improving its properties (Raggiotti, 2015).
References
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y contralor ambiental. Tesis Doctoral. Universidad nacional de La Plata. Facultad de ciencias exactas. Departamento de química. 185 pp.
Ahmadi, B, & Shekarchi, M., 2010. Use of natural zeolite as a supplementary cementitious materials. Cement & Concrete Composites, 32: 34 –
141.
Chung, F.H., 1974. Quantitative interpretation of x-ray diffraction patterns of mixtures I. Matrix-flushing method for quantitative multicomponent
analysis. J. Appl Crystallogr, 7(6):519–25.
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Giannetto Pace G., Montes Rendón A. & Rodriguez Fuentes, G., 2000. Zeolitas: Características, Propiedades y Aplicaciones Industriales,
Innovación Tecnológica. Pp 187-205. Caracas. Editorial.
Malhotra, V.M. & Mehta, P.K., 1996. Pozzolanic and cementitious materials. Advances in Concrete Technology, Vol 1, Gorgon and Breach
Publishers.
Najimi, M., Sobhani, J., Ahmadi, B. & Shekarchi, M., 2012. An experimental study on durability properties of concrete containing zeolite as a
highly reactive pozzolan. Construction and Building Materials, 35: 1023–1033.
Perraki, T., Kontori, E., Tsivilis, S. & Kakali, G., 2010. The effect of zeolite on the properties and hydration of blended cements. Cement and
Concrete Composites, 32. doi: 10.1016/j.cemconcomp.2009.10.004.
Poon, C.S., Lam, L., Kou, S.C. & Lin, Z.S., 1999. A study on the hydration rate of natural zeolite blended cement paste. Construction and Building
Materials, 13: 427 – 432.
Raggiotti, B.B., 2015. Hormigones con adiciones activas: diseño, optimización y caracterización con criterio de sustentabilidad. Tesis de doctorado.
Universidad Tecnológica Nacional. Córdoba, Argentina.
Rahhal, V. & Eperjeci, L., 2012. Ese material llamado hormigón. Cap 3: Adiciones minerles. Pp 79. ISBN: 978-987-21660-5-2
Rosell, M., Galloso, R. & Calvo, B., 2006. Zeolita como aditivo mineral activo en hormigones de altas prestaciones. Boletín Geológico y Minero
117 (4): 783-792. ISSN: 0366-0176.
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Bárbara Belén Raggiotti et al. / Procedia Structural Integrity 11 (2018) 36–43 43
Raggiotti et al./ Structural Integrity Procedia 00 (2018) 000–000 7
Resistance to compression of concretes containing zeolite was lower than the resistance reached by reference
mixtures at virtually all ages, particularly at early ages (7 and 28 days). However, the reduction percentages were
lower or even nil at higher ages of the concrete (90 and 180 days). This may be attributed to the zeolite's pozzolanic
activity. The development of resistance in the master mixture ZN0 depends mainly on the speed of hydration of the
clinker, while in the other mixtures, it depends on the combination of the hydration of the clinker and the pozzolanic
activity of the zeolite (Perraki et al., 2010).
As can be seen in Figure 6, the concrete made with NPC40 shows better performance to compression, at all ages,
than that made with CPC40. The composition of the cement is an important variable in the performance to resistance
of concrete.
The lower resistances reached by the CPC40 can be put down to the lower content of non hydrated calcium silicates
capable of reacting to the admixture forming new hydrated calcium silicates. The silicates, that made up about 75%
of the common Portland cement, lead a dominant role in determining the hardening characteristics (rate of resistance
development). Table 5 shows the results of the assays of traction by diameter compression and elastic module.
Table 5. Resistance to traction by diameter compression and elastic module
Concretes
ZN0
ZN5
ZN10
ZN15
ZN20
ZC0
ZC5
ZC10
ZC15
ZC20
Traction [MPa]
4.5
3.8
3.8
4.2
4.5
3.9
3.9
3.2
3.8
3.8
Elastic module [GPa]
38.2
37.2
35.8
39.2
37.2
38.7
37.9
38.1
35.6
34.1
The mixtures showed variable behavior to traction by diameter compression, but with a common point between the
two series of cements. The mixtures with 10% zeolite were those that presented the least resistance to traction. With
a content of admixture greater than 10% the resistance increased gradually.
The results of the elastic module show a dispersion of 1.26 and 1.94 corresponding to a mean of 37.5 and 36.9 GPa
for NPC and CPC respectively. For the CPC series, as the zeolite increases, the material becomes more deformable,
that is to say, the effort required to achieve the same deformation is lower. Table 6 shows the results of the durability
indicators.
Table 6. Results of absorption, suction and speed of capillary suction and permeability to air
Concretes
ZN0
ZN5
ZN10
ZN15
ZN20
ZC0
ZC5
ZC10
ZC15
ZC20
Absorption [%]
3.9
3.4
4.3
3.8
3.9
6.5
6.8
7.3
7.6
8.3
Capillary suction [gr/m2]
4133.8
4145.1
4549.7
4224.3
3491.5
7039.6
7444.2
7888.4
8143.1
8626.9
Suction speed [gr/m2.s1/2]
8.4
8.7
9.9
8.5
6.7
15.9
14.1
17.5
18.4
19.5
Permeability to air [kT]
0.33
1.37
2.58
0.33
0.16
3.40
3.55
3.75
3.48
5.88
The permeability to air was determined with Permea-TORR (Swiss Standard SIA 262/1-E, 2003) equipment. The
classes of permeability to air according to this standard are: PK1: very low (kT < 0.01), PK2: low (0.01< kT< 0.1),
PK3: moderate (0.1< kT< 1.0), PK4: high (1.0< kT< 10.0), PK5: very high (kT>10.0).
Analyzing the results shown in Table 6, there is an improvement in this property as from a 15% replacement of
cement with zeolite in the NPC series; in the CPC series there is no decrease of permeability at a greater content of
the admixture and the permeability of all the concretes remains within the same PK4 class, classified as "high."
NPC concretes showed better behavior than CPC concretes in view of the transportation of water through the
capillary suction mechanism. This may be correlated with the absorption results presented in Table 6. The
phenomenon finds its explanation in the composition of NPC concretes, as the porous structure of the paste depends
only on the interaction of the normal cement with the zeolite, while other admixtures are present in the CPC series.
The properties analyzed improve in NPC concrete with replacements greater than 10%; while CPCs show an increase
in the capacity for water absorption at a greater replacement of cement by the admixture, with a greater capacity for
capillary suction and greater speed for capillary suction.
8 Raggiotti et al./ Structural Integrity Procedia 00 (2018) 000–000
8. Conclusions
The physico-chemical characterization performed for natural zeolite makes it possible to classify this material as
zeolite clinoptilolite-Na; although it does not adjust exactly to the maximum limit of SO3 as per the type of pozzolan
described in ASTM C618 Standard (2015), it can be used as a material with pozzolanic characteristics in Portland
cement mixtures. This was confirmed by the results obtained in the second experimental stage of the mechanical
resistance and durability assays of the concretes.
Zeolite's rough and porous structure, as well as its large surface area, create a structure of the mixture pastes with
zeolite that contain more complex forms and vacuums than the master mixture caused by the growth of the crystalline
structure in all directions (Yılmaz et al., 2007); a phenomenon that manifests itself in a loss of consistency of the
mixtures as the incorporation of zeolite is increased, as could be observed in the Abrams Cone assay.
In the mechanical assays, the use of zeolite contributes to the development of resistance in concretes over longer
periods of time, showing its activity at ages of over 28 days.
The difference in behavior between concretes with different cements stands out, mainly when durability indicators
are analyzed. In this case we find more porous mixtures with compound Portland cement. The importance of the
composition of the cement becomes evident, and the way it interacts and reacts to the zeolite added.
The durability properties were generally achieved satisfactorily. The greatest effectiveness of applying zeolite was
observed in mixtures with normal Portland cement.
Lastly, it should be clarified that natural zeolites have different chemical properties, because of which it is necessary
to carefully characterize them before using them as admixtures in cement mixes. The zeolite studied herein,
Clinoptilolite-Na, fulfilled the three functions for which admixtures are used in Portland cement mixes. An economic
function, as the amount of cement used in the mix was reduced, an ecological function, as an available material was
used which has no use in the market and would otherwise have accumulated and become waste from the mining
industry, and a technological function, as it improved properties of concretes. Therefore the zeolite proposed may be
applied as a pozzolan in structural concretes improving its properties (Raggiotti, 2015).
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