Paulo Monteiro - Academia.edu (original) (raw)

Papers by Paulo Monteiro

Journal of the American Ceramic Society, 2013

The predominant phase of calcium sulfoaluminate cement, Ca4(Al6O12)SO4, was investigated using hi... more The predominant phase of calcium sulfoaluminate cement, Ca4(Al6O12)SO4, was investigated using high‐pressure synchrotron X‐ray diffraction from ambient pressure to 4.75 GPa. A critical review of the crystal structure of Ca4(Al6O12)SO4 is presented. Rietveld refinements showed the orthorhombic crystal structure to best match the observed peak intensities and positions for pure Ca4(Al6O12)SO4. The compressibility of Ca4(Al6O12)SO4 was studied using cubic, orthorhombic, and tetragonal crystal structures due to the lack of consensus on the actual space group, and all three models provided similar results of 69(6) GPa. With its divalent cage ions, the bulk modulus of Ca4(Al6O12)SO4 is higher than other sodalites with monovalent cage ions, such as Na8(AlSiO4)6Cl2 or Na8(AlSiO4)6(OH)2·H2O. Likewise, comparing this study to previous ones shows the lattice compressibility of aluminate sodalites decreases with increasing size of the caged ions. Ca4(Al6O12)SO4 is more compressible than other c...

Cement & Concrete Composites, Feb 1, 2021

Physical Mesomechanics, 2019

Acta Crystallographica Section A, Aug 8, 1996

Scientific Reports, Nov 9, 2017

Journal of the American Ceramic Society, Dec 7, 2020

IET Microwaves, Antennas & Propagation

In an urban built city environment, the performance of electromagnetic (EM) wave propagation thro... more In an urban built city environment, the performance of electromagnetic (EM) wave propagation through building materials poses a new set of challenges to radio frequency engineers in the prediction of the 5G-network coverage planning. We propose the prospects on the use of composite building materials enhanced with different volumetric fractions of iron (III) oxide (Fe 2 O 3) inclusions as a reddish-brown colouring admixture in modern-day concrete. Using a non-destructive microwave measurement technique, a two-factor 6 � 10 factorial experiment and a randomized controlled statistical study from 3.40 to 3.60 GHz is conducted on 15-cm thick building material prototypes enhanced with 2-wt% to 10-wt% micro-sized Fe 2 O 3 inclusions to evaluate their efficacy on EM wave propagation. Transmission coefficients (S 21) data are analysed statistically between treatment and control groups, yielding up to 2.28 dB mean S 21 improvement in performance and a fractional bandwidth of 100% by the 2-wt% Fe 2 O 3 treatment group. Electromagnetic characterisations of the fabricated mortar samples with different Fe 2 O 3 inclusions are performed using Nicholson-Ross-Weir model followed by the evaluation of dielectric and propagation losses. Our findings support the use of 2-wt% Fe 2 O 3 as the optimal volumetric fraction which improves the microwave transparency, thus creating potential EM benefits for the fifth-generation (5G) wireless communication systems. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Cement and Concrete Research, 2021

Creep of the cement matrix affects the structural stability of concrete. In Portland cements, the... more Creep of the cement matrix affects the structural stability of concrete. In Portland cements, the creep is largely controlled by the binding phase calcium-(aluminum-)silicate-hydrate, or C-(A-)S-H. This phase has a lamellar structure and under deviatoric stress aligns its c-axis with the principal stress. However, the limiting resistance to this reorientation is unknown at the nanocrystalline level. Small-angle X-ray scattering shows that the lamellae thickness decreases under 100's MPa deviatoric stress. Deviatoric stress Raman spectroscopy shows that there are two ways that this break-up can occur. If the material's silicate chains are cross-linked, then strain in Si-O bonds does not increase above certain stresses, indicating a relaxation adjacent to the Si-O bond. If the chains are not cross-linked, then the silicate chains are broken up by rastering against each other, introducing defects. These results show that the plastic deformation of C-(A-)S-H is relevant for Portland cement creep. Table of contents image Material strain Si-O-Ca bond strain Calciumsilicate hydrate Raman laser Turbostratic slip observed! Deviatoric-stress Raman spectroscopy shows how the structure of cement hydrates affects the way they plastically deform.

RSC Adv., 2017

Calcium (alumino)silicate hydrate (C–(A–)S–H) is the critical binding phase in modern Portland ce... more Calcium (alumino)silicate hydrate (C–(A–)S–H) is the critical binding phase in modern Portland cement-based concrete, yet the relationship between its structure and stoichiometry is not completely understood.

Composites Part B: Engineering, 2018

This paper presents an experimental study that investigates the influence of the low fiber conten... more This paper presents an experimental study that investigates the influence of the low fiber content of polypropylene and hooked-end steel fibers on the properties of high-strength concrete. The study variables include fiber types and fiber contents. The effect of combining both fibers with a total fiber content of 1.0% was also studied in some mixtures. Silica fume, as a supplementary cementitious material, was used at 10% of the cement weight in all fiber-reinforced concrete mixtures. Compressive strength, modulus of elasticity, longitudinal resonant frequency, rapid chloride migration and free drying shrinkage tests were performed for different curing ages. The results show that replacement of the cement weight with 10% silica fume improved all of the characteristics of the concrete evaluated in this research study. It was observed that the inclusion of fibers, particularly steel fibers, enhanced the mechanical properties of concrete. It was found that the incorporation of polypropylene fibers resulted in a reduction of chloride diffusivity, while introducing steel fibers significantly increased the chloride diffusivity of concrete. Finally, the results showed that hybridization of two types of fibers was an effective way to improve the properties of concrete and specifically reduce the drying shrinkage compared with that of the plain concrete.

ACS applied materials & interfaces, Jan 27, 2017

Properties of organic/inorganic composites can be highly dependent on the interfacial connections... more Properties of organic/inorganic composites can be highly dependent on the interfacial connections. In this work, molecular dynamics, using pair potential based force fields, was employed to investigate the structure, dynamics and stability of interfacial connections between calcium silicate hydrates (C-S-H) and organic functional groups of three different polymer species. The calculation results suggest that the affinity between C-S-H and polymers is influenced by the polarity of the functional groups, the diffusivity and aggregation tendency of polymers. In the interfaces, the calcium counter-ions from C-S-H act as the coordination atoms in bridging the double-bonded oxygen atoms in the carboxyl groups (-COOH), and the Ca-O connection plays a dominant role in binding poly acrylic acid (PAA) due to the strong bond strength defined by time correlated function. The defective calcium silicate chains provide significant number of non-bridging oxygen sites to accept H-bonds from -COOH gr...

American Mineralogist, 2017

Tricalcium aluminate (cement clinker phase), gypsum, katoite, ettringite, and calcium monosulfoal... more Tricalcium aluminate (cement clinker phase), gypsum, katoite, ettringite, and calcium monosulfoaluminate hydrate (abbreviated as kuzelite) are the major minerals in the hydration reaction of tricalcium aluminate in the presence of gypsum and have critical impacts on the kinetics and thermodynamics of early-age cement hydration mechanisms. Here, spectroscopic analysis of these minerals is conducted using scanning transmission X-ray microscopy (STXM). Their Ca L 2,3-edge near edge X-ray absorption fine structure (NEXAFS) spectra are measured and correlated to the known Ca coordination environments. The results indicate that these minerals have unique Ca environments that can be differentiated from one another based on the intensities and positions of the absorption peaks at 346.5-348.5 and 350.5-351.5 eV. It is concluded that Ca in tricalcium aluminate (cubic and orthorhombic polymorphs) and katoite is in cubic-like coordination with negative 10Dq, whereas Ca is in an octahedral-like coordination with positive 10Dq in ettringite, gypsum, and kuzelite. For tricalcium aluminate, the Ca atoms in both polymorphs are in similar chemical environments with slightly more distortion in the orthorhombic polymorph. As a common issue in STXM experiments, absorption saturation of NEXAFS spectra is also investigated. It is demonstrated that the optical density difference between pre-and post-edge absorption levels provides a reliable indication of the sample thickness in the systems studied. The present work provides a reference for the STXM study of the calcium (sulfo)aluminate reactions in cement hydration and natural aqueous environments, and in the former case, provides a more complete understanding of a system that may serve as a low-C alternative to Portland cement.

Cement and Concrete Composites, 2017

Cenosphere particles are hollow, but due to their hard shells, they can be used in cementitious c... more Cenosphere particles are hollow, but due to their hard shells, they can be used in cementitious composites to produce ultra-lightweight cement composites (ULCC) with high strength and low thermal conductivity. This study integrates thermal conductivity with mechanical experimental research, microscopic investigation, and numerical simulations to provide new insights into the behavior of these advanced composites. The microstructure of ULCC samples was characterized using synchrotron high-resolution microtomography, transmission electron microscopy and scanning electron microscopy. Composite models were used to predict the thermal conductivity of the cenospheres based on the experimental results of ULCC thermal conductivity and the porosity of the samples.

Cement and Concrete Research, 2016

This paper reports an investigation of the recycled concrete (RC) microstructure using synchrotro... more This paper reports an investigation of the recycled concrete (RC) microstructure using synchrotron microtomography (μCT) at the Advanced Light Source combined with Scanning Electron Microscopy analysis. The study evaluated the influence of 50% of recycled concrete aggregate (RCA) and its water absorption compensation on the RC microstructure. The following variables were studied: a) the compressive strength of the original concrete used to obtain the RCA (40 and 80MPa) and b) the initial moisture condition of the RCA (Saturated Surface Dry and Oven Dry). The microtomographic images showed the mixtures cast with RCA in the dry condition developed an evident macropore network surrounding the RCA particle that was not observed in the mixtures using RCA in the SSD condition. SEM images confirmed the initial findings from CT and showed that the thickness of the interfacial transition zone in RC is in the same order of magnitude as the reference concrete.

Journal of Applied Crystallography, 2009

Sulfate attack and the accompanying crystallization of fibrous ettringite [Ca6Al2(OH)12(SO4)3·26H... more Sulfate attack and the accompanying crystallization of fibrous ettringite [Ca6Al2(OH)12(SO4)3·26H2O] cause cracking and loss of strength in concrete structures. Hard synchrotron X-ray microdiffraction is used to quantify the orientation distribution of ettringite crystals. Diffraction images are analyzed using the Rietveld method to obtain information on textures. The analysis reveals that thecaxes of the trigonal crystallites are preferentially oriented perpendicular to the fracture surfaces. By averaging single-crystal elastic properties over the orientation distribution, it is possible to estimate the elastic anisotropy of ettringite aggregates.

Cement and Concrete Research, 2021

Abstract Polycarboxylate ether (PCE), a commonly used superplasticizer, is known to influence the... more Abstract Polycarboxylate ether (PCE), a commonly used superplasticizer, is known to influence the morphology of ettringite during the early hydration of C3A- and ye'elimite-containing cements. According to existing theories, such morphological changes may be crucial to the expansive behavior of these cements. This paper studied the expansion of ye'elimite-anhydrite pastes and found the use of PCE to reduce expansion after 4 days of curing. Hydration studies were conducted by calorimetry, X-ray diffractometry, scanning electron microscopy, mercury intrusion porosimetry, inductively coupled plasma–optical emission spectrometry, and X-ray microtomography. The results show that the influences of PCE on the morphology of ettringite and the hydration of ye'elimite were quite small after 2 days. Based on the crystal growth theory, the range of pores in which ettringite can grow was calculated to explain the observed expansive behaviors. The presence of ettringite nano-crystals in aluminum hydroxide was also revealed and considered as a possible expansion mechanism.

The Journal of Physical Chemistry C, 2012

Cement and Concrete Composites, 2014

ABSTRACT The present work studies the hydration process and microstructural features of five calc... more ABSTRACT The present work studies the hydration process and microstructural features of five calcium sulfoaluminate (CSA) cements and a ternary mixture including also ordinary Portland cement (OPC). The pastes were studied with simultaneous differential thermal-thermogravimetric (DTA-TG) analysis, mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), and expansion/shrinkage tests. The DTA-TG analysis confirmed the role of the hydration reactions involving the main CSA clinker constituent, tetracalcium trialuminate sulfate, which produced (i) ettringite when combined with lime and calcium sulfate, (ii) ettringite and aluminum hydroxide in the presence of calcium sulfate alone, and (iii) monosulfate and aluminum hydroxide in the absence of both lime and calcium sulfate. The MIP and SEM were able to discriminate between expansive (ternary mixture and CSA cement containing 50% gypsum) and non-expansive cements. Expansive cement pastes had (i) a nearly unimodal pore size distribution shifted toward higher radii and (ii) ettringite crystals smaller in size during the first day of curing. In a SEM image of a hardened paste of the CSA cement containing 50% gypsum, a stellate ettringite cluster was observed.

Journal of the American Ceramic Society, 2013

The predominant phase of calcium sulfoaluminate cement, Ca4(Al6O12)SO4, was investigated using hi... more The predominant phase of calcium sulfoaluminate cement, Ca4(Al6O12)SO4, was investigated using high‐pressure synchrotron X‐ray diffraction from ambient pressure to 4.75 GPa. A critical review of the crystal structure of Ca4(Al6O12)SO4 is presented. Rietveld refinements showed the orthorhombic crystal structure to best match the observed peak intensities and positions for pure Ca4(Al6O12)SO4. The compressibility of Ca4(Al6O12)SO4 was studied using cubic, orthorhombic, and tetragonal crystal structures due to the lack of consensus on the actual space group, and all three models provided similar results of 69(6) GPa. With its divalent cage ions, the bulk modulus of Ca4(Al6O12)SO4 is higher than other sodalites with monovalent cage ions, such as Na8(AlSiO4)6Cl2 or Na8(AlSiO4)6(OH)2·H2O. Likewise, comparing this study to previous ones shows the lattice compressibility of aluminate sodalites decreases with increasing size of the caged ions. Ca4(Al6O12)SO4 is more compressible than other c...

Cement & Concrete Composites, Feb 1, 2021

Physical Mesomechanics, 2019

Acta Crystallographica Section A, Aug 8, 1996

Scientific Reports, Nov 9, 2017

Journal of the American Ceramic Society, Dec 7, 2020

IET Microwaves, Antennas & Propagation

In an urban built city environment, the performance of electromagnetic (EM) wave propagation thro... more In an urban built city environment, the performance of electromagnetic (EM) wave propagation through building materials poses a new set of challenges to radio frequency engineers in the prediction of the 5G-network coverage planning. We propose the prospects on the use of composite building materials enhanced with different volumetric fractions of iron (III) oxide (Fe 2 O 3) inclusions as a reddish-brown colouring admixture in modern-day concrete. Using a non-destructive microwave measurement technique, a two-factor 6 � 10 factorial experiment and a randomized controlled statistical study from 3.40 to 3.60 GHz is conducted on 15-cm thick building material prototypes enhanced with 2-wt% to 10-wt% micro-sized Fe 2 O 3 inclusions to evaluate their efficacy on EM wave propagation. Transmission coefficients (S 21) data are analysed statistically between treatment and control groups, yielding up to 2.28 dB mean S 21 improvement in performance and a fractional bandwidth of 100% by the 2-wt% Fe 2 O 3 treatment group. Electromagnetic characterisations of the fabricated mortar samples with different Fe 2 O 3 inclusions are performed using Nicholson-Ross-Weir model followed by the evaluation of dielectric and propagation losses. Our findings support the use of 2-wt% Fe 2 O 3 as the optimal volumetric fraction which improves the microwave transparency, thus creating potential EM benefits for the fifth-generation (5G) wireless communication systems. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Cement and Concrete Research, 2021

Creep of the cement matrix affects the structural stability of concrete. In Portland cements, the... more Creep of the cement matrix affects the structural stability of concrete. In Portland cements, the creep is largely controlled by the binding phase calcium-(aluminum-)silicate-hydrate, or C-(A-)S-H. This phase has a lamellar structure and under deviatoric stress aligns its c-axis with the principal stress. However, the limiting resistance to this reorientation is unknown at the nanocrystalline level. Small-angle X-ray scattering shows that the lamellae thickness decreases under 100's MPa deviatoric stress. Deviatoric stress Raman spectroscopy shows that there are two ways that this break-up can occur. If the material's silicate chains are cross-linked, then strain in Si-O bonds does not increase above certain stresses, indicating a relaxation adjacent to the Si-O bond. If the chains are not cross-linked, then the silicate chains are broken up by rastering against each other, introducing defects. These results show that the plastic deformation of C-(A-)S-H is relevant for Portland cement creep. Table of contents image Material strain Si-O-Ca bond strain Calciumsilicate hydrate Raman laser Turbostratic slip observed! Deviatoric-stress Raman spectroscopy shows how the structure of cement hydrates affects the way they plastically deform.

RSC Adv., 2017

Calcium (alumino)silicate hydrate (C–(A–)S–H) is the critical binding phase in modern Portland ce... more Calcium (alumino)silicate hydrate (C–(A–)S–H) is the critical binding phase in modern Portland cement-based concrete, yet the relationship between its structure and stoichiometry is not completely understood.

Composites Part B: Engineering, 2018

This paper presents an experimental study that investigates the influence of the low fiber conten... more This paper presents an experimental study that investigates the influence of the low fiber content of polypropylene and hooked-end steel fibers on the properties of high-strength concrete. The study variables include fiber types and fiber contents. The effect of combining both fibers with a total fiber content of 1.0% was also studied in some mixtures. Silica fume, as a supplementary cementitious material, was used at 10% of the cement weight in all fiber-reinforced concrete mixtures. Compressive strength, modulus of elasticity, longitudinal resonant frequency, rapid chloride migration and free drying shrinkage tests were performed for different curing ages. The results show that replacement of the cement weight with 10% silica fume improved all of the characteristics of the concrete evaluated in this research study. It was observed that the inclusion of fibers, particularly steel fibers, enhanced the mechanical properties of concrete. It was found that the incorporation of polypropylene fibers resulted in a reduction of chloride diffusivity, while introducing steel fibers significantly increased the chloride diffusivity of concrete. Finally, the results showed that hybridization of two types of fibers was an effective way to improve the properties of concrete and specifically reduce the drying shrinkage compared with that of the plain concrete.

ACS applied materials & interfaces, Jan 27, 2017

Properties of organic/inorganic composites can be highly dependent on the interfacial connections... more Properties of organic/inorganic composites can be highly dependent on the interfacial connections. In this work, molecular dynamics, using pair potential based force fields, was employed to investigate the structure, dynamics and stability of interfacial connections between calcium silicate hydrates (C-S-H) and organic functional groups of three different polymer species. The calculation results suggest that the affinity between C-S-H and polymers is influenced by the polarity of the functional groups, the diffusivity and aggregation tendency of polymers. In the interfaces, the calcium counter-ions from C-S-H act as the coordination atoms in bridging the double-bonded oxygen atoms in the carboxyl groups (-COOH), and the Ca-O connection plays a dominant role in binding poly acrylic acid (PAA) due to the strong bond strength defined by time correlated function. The defective calcium silicate chains provide significant number of non-bridging oxygen sites to accept H-bonds from -COOH gr...

American Mineralogist, 2017

Tricalcium aluminate (cement clinker phase), gypsum, katoite, ettringite, and calcium monosulfoal... more Tricalcium aluminate (cement clinker phase), gypsum, katoite, ettringite, and calcium monosulfoaluminate hydrate (abbreviated as kuzelite) are the major minerals in the hydration reaction of tricalcium aluminate in the presence of gypsum and have critical impacts on the kinetics and thermodynamics of early-age cement hydration mechanisms. Here, spectroscopic analysis of these minerals is conducted using scanning transmission X-ray microscopy (STXM). Their Ca L 2,3-edge near edge X-ray absorption fine structure (NEXAFS) spectra are measured and correlated to the known Ca coordination environments. The results indicate that these minerals have unique Ca environments that can be differentiated from one another based on the intensities and positions of the absorption peaks at 346.5-348.5 and 350.5-351.5 eV. It is concluded that Ca in tricalcium aluminate (cubic and orthorhombic polymorphs) and katoite is in cubic-like coordination with negative 10Dq, whereas Ca is in an octahedral-like coordination with positive 10Dq in ettringite, gypsum, and kuzelite. For tricalcium aluminate, the Ca atoms in both polymorphs are in similar chemical environments with slightly more distortion in the orthorhombic polymorph. As a common issue in STXM experiments, absorption saturation of NEXAFS spectra is also investigated. It is demonstrated that the optical density difference between pre-and post-edge absorption levels provides a reliable indication of the sample thickness in the systems studied. The present work provides a reference for the STXM study of the calcium (sulfo)aluminate reactions in cement hydration and natural aqueous environments, and in the former case, provides a more complete understanding of a system that may serve as a low-C alternative to Portland cement.

Cement and Concrete Composites, 2017

Cenosphere particles are hollow, but due to their hard shells, they can be used in cementitious c... more Cenosphere particles are hollow, but due to their hard shells, they can be used in cementitious composites to produce ultra-lightweight cement composites (ULCC) with high strength and low thermal conductivity. This study integrates thermal conductivity with mechanical experimental research, microscopic investigation, and numerical simulations to provide new insights into the behavior of these advanced composites. The microstructure of ULCC samples was characterized using synchrotron high-resolution microtomography, transmission electron microscopy and scanning electron microscopy. Composite models were used to predict the thermal conductivity of the cenospheres based on the experimental results of ULCC thermal conductivity and the porosity of the samples.

Cement and Concrete Research, 2016

This paper reports an investigation of the recycled concrete (RC) microstructure using synchrotro... more This paper reports an investigation of the recycled concrete (RC) microstructure using synchrotron microtomography (μCT) at the Advanced Light Source combined with Scanning Electron Microscopy analysis. The study evaluated the influence of 50% of recycled concrete aggregate (RCA) and its water absorption compensation on the RC microstructure. The following variables were studied: a) the compressive strength of the original concrete used to obtain the RCA (40 and 80MPa) and b) the initial moisture condition of the RCA (Saturated Surface Dry and Oven Dry). The microtomographic images showed the mixtures cast with RCA in the dry condition developed an evident macropore network surrounding the RCA particle that was not observed in the mixtures using RCA in the SSD condition. SEM images confirmed the initial findings from CT and showed that the thickness of the interfacial transition zone in RC is in the same order of magnitude as the reference concrete.

Journal of Applied Crystallography, 2009

Sulfate attack and the accompanying crystallization of fibrous ettringite [Ca6Al2(OH)12(SO4)3·26H... more Sulfate attack and the accompanying crystallization of fibrous ettringite [Ca6Al2(OH)12(SO4)3·26H2O] cause cracking and loss of strength in concrete structures. Hard synchrotron X-ray microdiffraction is used to quantify the orientation distribution of ettringite crystals. Diffraction images are analyzed using the Rietveld method to obtain information on textures. The analysis reveals that thecaxes of the trigonal crystallites are preferentially oriented perpendicular to the fracture surfaces. By averaging single-crystal elastic properties over the orientation distribution, it is possible to estimate the elastic anisotropy of ettringite aggregates.

Cement and Concrete Research, 2021

Abstract Polycarboxylate ether (PCE), a commonly used superplasticizer, is known to influence the... more Abstract Polycarboxylate ether (PCE), a commonly used superplasticizer, is known to influence the morphology of ettringite during the early hydration of C3A- and ye'elimite-containing cements. According to existing theories, such morphological changes may be crucial to the expansive behavior of these cements. This paper studied the expansion of ye'elimite-anhydrite pastes and found the use of PCE to reduce expansion after 4 days of curing. Hydration studies were conducted by calorimetry, X-ray diffractometry, scanning electron microscopy, mercury intrusion porosimetry, inductively coupled plasma–optical emission spectrometry, and X-ray microtomography. The results show that the influences of PCE on the morphology of ettringite and the hydration of ye'elimite were quite small after 2 days. Based on the crystal growth theory, the range of pores in which ettringite can grow was calculated to explain the observed expansive behaviors. The presence of ettringite nano-crystals in aluminum hydroxide was also revealed and considered as a possible expansion mechanism.

The Journal of Physical Chemistry C, 2012

Cement and Concrete Composites, 2014

ABSTRACT The present work studies the hydration process and microstructural features of five calc... more ABSTRACT The present work studies the hydration process and microstructural features of five calcium sulfoaluminate (CSA) cements and a ternary mixture including also ordinary Portland cement (OPC). The pastes were studied with simultaneous differential thermal-thermogravimetric (DTA-TG) analysis, mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), and expansion/shrinkage tests. The DTA-TG analysis confirmed the role of the hydration reactions involving the main CSA clinker constituent, tetracalcium trialuminate sulfate, which produced (i) ettringite when combined with lime and calcium sulfate, (ii) ettringite and aluminum hydroxide in the presence of calcium sulfate alone, and (iii) monosulfate and aluminum hydroxide in the absence of both lime and calcium sulfate. The MIP and SEM were able to discriminate between expansive (ternary mixture and CSA cement containing 50% gypsum) and non-expansive cements. Expansive cement pastes had (i) a nearly unimodal pore size distribution shifted toward higher radii and (ii) ettringite crystals smaller in size during the first day of curing. In a SEM image of a hardened paste of the CSA cement containing 50% gypsum, a stellate ettringite cluster was observed.