Javier Castro - Academia.edu (original) (raw)

Papers by Javier Castro

Materiales de Construcción, 1975

Se estudia la hidratacion del clínker en presencia de diferentess aditivos encontrándose que los ... more Se estudia la hidratacion del clínker en presencia de diferentess aditivos encontrándose que los aceleradores, como el cloruro calcico y" el ácido salicílico, producen tobermorita de fibra larga y los inhibidores, como el azúcar, tobermorita de fibra corta. Este mismo efecto se encuentra en la anhidrita, produciéndose cristales de yeso largo, en presencia del sulfato de sodio, y cristales cortos en ausencia del catalizador. La cohesión de un mortero depende luego del largo de sus fibras. Así la cohesión de los morteros de cemento y anhidrita se explican en función del rol de la fibra.

Cement and Concrete Composites, 2018

Reducing the carbon footprint of the cement industry has become one of the main concerns of resea... more Reducing the carbon footprint of the cement industry has become one of the main concerns of researchers in the field. This study explores different strategies to reduce the setting retardation effect of high-SO3 fly ash (HSFA) on cement paste. The SO3 phase was found to correspond to hannebachite (CaSO3•0.5H2O). Chemical (calcium chloride), physical (fine limestone powder), and pre-washing strategies were investigated as means to reduce or eliminate the retardation. Each of these strategies showed some potential to decrease the retardation effect. A combination of fine limestone powder and HSFA pre-washing showed almost the same accelerating power as the calcium chloride, offering a good alternative when chloride incorporation is restricted. The retardation effect can be associated with a combined extension of the induction period and a depression of the initial silicate reactions of the clinker phases. A methodology to assess the hannebachite content based on a thermogravimetric analysis (TGA) technique is proposed, allowing a good alternative control approach for field conditions or for where Xray (XRD or XRF) equipment is not readily available.

Cement and Concrete Composites, 2015

Heteroscorpionate-based [(L10O)MoO 2 Cl] and [(L3S)MoO 2 Cl] complexes containing an interchangea... more Heteroscorpionate-based [(L10O)MoO 2 Cl] and [(L3S)MoO 2 Cl] complexes containing an interchangeable third heteroatom donor have been utilized for the systematic investigation of oxygen atom transfer (OAT) reactivity. The detection of phosphoryl intermediates and products in the reaction pathway were probed by UV-Vis, mass spectrometry, and 31 P NMR spectroscopy. The OAT reactivity of the metal complexes toward PPh 3 were monitored by UV-Vis spectroscopy under pseudo-first order conditions. The sterically encumbered (L10O) ligand gives rise to isolable trans and cis isomers of [(L10O)MoO 2 Cl] allowing investigation into the role of geometry on OAT reactivity. The OAT reactivity of the cis isomer of (L10O)MoO 2 Cl demonstrated a dramatic solvent dependence, in which the reaction proceeded at a measureable rate only in pyridine. However, the trans counterpart reacted in all solvents and at much faster rates. The catalytic oxidation of PPh 3 to OPPh 3 by trans-[(L10O)MoO 2 Cl] and cis-[(L3S)MoO 2 Cl] complexes using DMSO as an oxygen donor was monitored by 31 P NMR in DMF at 30°C with rates, k cat = 4.26 x 10-5 s-1 and 5.28 x 10-5 s-1 , respectively.

Revista ingeniería de construcción, 2009

El trabajo presentado en este estudio muestra la deducción de una ecuación que permite dosificar ... more El trabajo presentado en este estudio muestra la deducción de una ecuación que permite dosificar hormigones porosos en función de la razón agua-cemento y del porcentaje de vacíos interconectados que se requieren en el hormigón endurecido. Usando esta ecuación se analizó el comportamiento de 18 mezclas de hormigón poroso conteniendo razones agua-cemento entre 0,29 y 0,41. Las probetas fueron fabricadas en laboratorio y compactadas con rodillo pesado simulando el proceso constructivo en terreno. Los resultados permiten caracterizas de buena forma el comportamiento estructural e hidráulico de estas mezclas. Relaciones entre el porcentaje de vacíos en el hormigón endurecido y la tasa de infiltración, la resistencia a flexotracción y la densidad en estado fresco son presentadas.

The Joint Transportation Research Program serves as a vehicle for INDOT collaboration with higher... more The Joint Transportation Research Program serves as a vehicle for INDOT collaboration with higher education institutions and industry in Indiana to facilitate innovation that results in continuous improvement in the planning, design, construc

these materials to be used and specified more widely in Indiana. It is recommended that a trainin... more these materials to be used and specified more widely in Indiana. It is recommended that a training video be developed that highlights the benefits of this material, describes its use, and discusses important features associated with placement and testing

Cement and Concrete Composites, 2011

This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright

Cement and Concrete Composites, 2012

This paper focuses on testing performed on mixtures that would be consistent with the mortar port... more This paper focuses on testing performed on mixtures that would be consistent with the mortar portion of a concrete bridge deck mixture for many state departments of transportation. In this work a relatively large percentage of cement (40%, 60%, or 80% by volume) is replaced with Class C fly ash. To overcome concerns associated with slow set and early-age strength development that are often expressed with the high volume fly ash mixtures (HVFA), the water-to-cementitious materials ratio (w/cm) by mass has been reduced from a conventional value of 0.42 to 0.30. To overcome potential complications that the low w/cm may cause in terms of self-desiccation, internal curing (IC) with prewetted lightweight aggregate was used to reduce shrinkage and increase hydration. By adopting this approach (lowering the w/c and using IC) IC HVFA mixtures show additional benefits that should permit their broader application.

Cement and Concrete Composites, 2011

Construction and Building Materials, 2012

This paper explores the potential for manufacturing internally cured concretes with lightweight a... more This paper explores the potential for manufacturing internally cured concretes with lightweight aggregate (LWA) that has different initial moisture contents prior to mixing: oven-dry, 24 h pre-wetted, and vacuum saturated. Results show that when LWA is used in an oven-dry condition it can absorb water from the paste prior to set which will be returned to the system as internal curing water. When mixture proportion adjustments are properly made to account for the water absorbed by the aggregate before setting, the mixture can provide internal curing benefits. These beneficial aspects include increased hydration which leads to higher compressive strength, reduced water absorption, and reduced electrical conductivity (permeability). Further, these benefits include reduced autogenous shrinkage and a lower propensity for early-age cracking.

Cement and Concrete Research, 2009

The increased propensity for shrinkage cracking in low w/c concrete has spawned the development o... more The increased propensity for shrinkage cracking in low w/c concrete has spawned the development of new technologies that can reduce the risk of early-age cracking. One of these is internal curing. Internal curing uses saturated lightweight aggregate to supply 'curing water' to low w/c paste as it hydrates. Significant research has been performed to determine the effects of internal curing on shrinkage and stress development; however, relatively little detailed information exists about the effects of internal curing on the fluid transport properties such as water absorption or diffusivity. This study examines the absorption of water into mortar specimens made with saturated lightweight aggregates (SLWA). These results indicate that the inclusion of SLWA can reduce the water absorption of mortar specimens. This observation was reinforced with electrical conductivity measurements that exhibited similar reductions.

Cement and Concrete Composites, 2014

The transport of fluid and ions in concrete mixtures is central to many aspects of concrete deter... more The transport of fluid and ions in concrete mixtures is central to many aspects of concrete deterioration. As a result, transport properties are frequently measured as an indication of the durability that a concrete mixture may be expected to have. This paper is the second in a series investigating the performance of high volume fly ash (HVFA) mixtures with low water-to-cementitious ratios (w/cm) that are internally cured. While the first paper focused on strength and shrinkage, this paper presents the evaluation of the transport properties of these mixtures. Specifically, the paper presents results from: rapid chloride migration (RCM), rapid chloride penetration test (RCPT), apparent chloride diffusion coefficient, surface electrical resistivity, and water absorption. The test matrix consisted of mortar samples with two levels of class C fly ash replacement (40% and 60% by volume) with and without internal curing provided with pre-wetted lightweight fine aggregates (LWA). These mixtures are compared to plain ordinary portland cement (OPC) mortars. The results indicate that HVFA mixtures with and without internal curing provide benefits in terms of reduced transport coefficients compared to the OPC mixtures.

The objective of this project was to evaluate the transport properties of concrete pavement in th... more The objective of this project was to evaluate the transport properties of concrete pavement in the state of Indiana using common testing procedures. Specifically this work evaluated the absorption of water, the absorption of deicing solutions, and electrical conductivity. A series of concrete paving mixtures were tested to provide a range of values that were typical for the state of Indiana. While similar mixture proportions were used for the mixtures in Indiana differences in the magnitude of water absorbed occurred. A series of mortars were tested to illustrate the effect of curing conditions, water to cement ratio, and paste volume. It was observed that a long duration of drying was needed to obtain equilibrium. Samples dried to a lower relative humidity showed a greater volume of water absorbed. It was observed that drying at 105C resulted in substantial anomalies in water absorption, as such this method is not recommended. It was observed that when samples were tested using deicing solutions or samples were tested that were previously exposed to deicing solutions the water absorption could be influenced. The electrical conductivity work was performed as a potential method to develop the understanding of rapid test techniques for quality control. The research used a modified parallel law to relate the electrical conductivity to the pore volume, pore solution conductivity and the tortuosity through the pore network. The influence water addition was able to be determined using electrical conductivity. In addition, the pore solution was observed to be approximately linearly related to the degree of hydration. It is critical that a correction be applied to samples tested at different temperatures. An activation energy of conduction was observed that was approximately 10 kL/mol irrespective of water to cement ratio. In addition to the measurement of transport properties, the relative humidity was assessed for concrete exposed to different exposure conditions. The samples considered in this investigation included a sample stored at 50% relative humidity, covered concrete, a concrete with an exposed vertical surface, a concrete on a drainable base, a concrete on a non-drainable base, and concrete that was submerged. The samples showed that for practical field samples the relative humidity in the concrete was always above 80% for the samples tested. The samples that were exposed to precipitation events demonstrated higher relative humidities.

The experiments reported in this paper were conducted as part of a multi-state collaborative eval... more The experiments reported in this paper were conducted as part of a multi-state collaborative evaluation sponsored by the Pooled Fund Program and the American Association of American Highway and Transportation Officials Technology Implementation Group and organized by the Florida Department of Transportation. This document was published in collaboration with the Joint Transportation Research Program at Purdue University. The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the data presented herein. The contents do

Aging Health, 2009

The median age of diagnosis of colorectal cancer is during the seventh decade and the incidence o... more The median age of diagnosis of colorectal cancer is during the seventh decade and the incidence of the disease increases continuously with age. However, as a patient ages, the likelihood of receiving adequate cancer treatment diminishes and mortality rises. The geriatric population is a very heterogeneous group in which patients with an excellent health status coexist with both comorbidities and functional dependency. Therefore, there is a great need to redefine treatment strategies in elderly patients with colorectal carcinoma, personalizing the treatment according to the degree of vulnerability of the elderly patient. It is essential to perform a multidimensional geriatric assessment in order to consider the cancer and the stage of the cancer as well as to identify features that could modify the survival or interfere with therapy. The aim of this review is to discuss the factors that are relevant for the therapeutic management of colorectal cancer in elderly patients.

Proceedings of SPIE, 2003

Under a contract with the GRANTECAN, the Commissioning Instrument is a project developed by a tea... more Under a contract with the GRANTECAN, the Commissioning Instrument is a project developed by a team of Mexican scientists and engineers from the Instrumentation Department of the Astronomy Institute at the UNAM and the CIDESI Engineering Center. ...

Materiales de Construcción, 1975

Se estudia la hidratacion del clínker en presencia de diferentess aditivos encontrándose que los ... more Se estudia la hidratacion del clínker en presencia de diferentess aditivos encontrándose que los aceleradores, como el cloruro calcico y" el ácido salicílico, producen tobermorita de fibra larga y los inhibidores, como el azúcar, tobermorita de fibra corta. Este mismo efecto se encuentra en la anhidrita, produciéndose cristales de yeso largo, en presencia del sulfato de sodio, y cristales cortos en ausencia del catalizador. La cohesión de un mortero depende luego del largo de sus fibras. Así la cohesión de los morteros de cemento y anhidrita se explican en función del rol de la fibra.

Cement and Concrete Composites, 2018

Reducing the carbon footprint of the cement industry has become one of the main concerns of resea... more Reducing the carbon footprint of the cement industry has become one of the main concerns of researchers in the field. This study explores different strategies to reduce the setting retardation effect of high-SO3 fly ash (HSFA) on cement paste. The SO3 phase was found to correspond to hannebachite (CaSO3•0.5H2O). Chemical (calcium chloride), physical (fine limestone powder), and pre-washing strategies were investigated as means to reduce or eliminate the retardation. Each of these strategies showed some potential to decrease the retardation effect. A combination of fine limestone powder and HSFA pre-washing showed almost the same accelerating power as the calcium chloride, offering a good alternative when chloride incorporation is restricted. The retardation effect can be associated with a combined extension of the induction period and a depression of the initial silicate reactions of the clinker phases. A methodology to assess the hannebachite content based on a thermogravimetric analysis (TGA) technique is proposed, allowing a good alternative control approach for field conditions or for where Xray (XRD or XRF) equipment is not readily available.

Cement and Concrete Composites, 2015

Heteroscorpionate-based [(L10O)MoO 2 Cl] and [(L3S)MoO 2 Cl] complexes containing an interchangea... more Heteroscorpionate-based [(L10O)MoO 2 Cl] and [(L3S)MoO 2 Cl] complexes containing an interchangeable third heteroatom donor have been utilized for the systematic investigation of oxygen atom transfer (OAT) reactivity. The detection of phosphoryl intermediates and products in the reaction pathway were probed by UV-Vis, mass spectrometry, and 31 P NMR spectroscopy. The OAT reactivity of the metal complexes toward PPh 3 were monitored by UV-Vis spectroscopy under pseudo-first order conditions. The sterically encumbered (L10O) ligand gives rise to isolable trans and cis isomers of [(L10O)MoO 2 Cl] allowing investigation into the role of geometry on OAT reactivity. The OAT reactivity of the cis isomer of (L10O)MoO 2 Cl demonstrated a dramatic solvent dependence, in which the reaction proceeded at a measureable rate only in pyridine. However, the trans counterpart reacted in all solvents and at much faster rates. The catalytic oxidation of PPh 3 to OPPh 3 by trans-[(L10O)MoO 2 Cl] and cis-[(L3S)MoO 2 Cl] complexes using DMSO as an oxygen donor was monitored by 31 P NMR in DMF at 30°C with rates, k cat = 4.26 x 10-5 s-1 and 5.28 x 10-5 s-1 , respectively.

Revista ingeniería de construcción, 2009

El trabajo presentado en este estudio muestra la deducción de una ecuación que permite dosificar ... more El trabajo presentado en este estudio muestra la deducción de una ecuación que permite dosificar hormigones porosos en función de la razón agua-cemento y del porcentaje de vacíos interconectados que se requieren en el hormigón endurecido. Usando esta ecuación se analizó el comportamiento de 18 mezclas de hormigón poroso conteniendo razones agua-cemento entre 0,29 y 0,41. Las probetas fueron fabricadas en laboratorio y compactadas con rodillo pesado simulando el proceso constructivo en terreno. Los resultados permiten caracterizas de buena forma el comportamiento estructural e hidráulico de estas mezclas. Relaciones entre el porcentaje de vacíos en el hormigón endurecido y la tasa de infiltración, la resistencia a flexotracción y la densidad en estado fresco son presentadas.

The Joint Transportation Research Program serves as a vehicle for INDOT collaboration with higher... more The Joint Transportation Research Program serves as a vehicle for INDOT collaboration with higher education institutions and industry in Indiana to facilitate innovation that results in continuous improvement in the planning, design, construc

these materials to be used and specified more widely in Indiana. It is recommended that a trainin... more these materials to be used and specified more widely in Indiana. It is recommended that a training video be developed that highlights the benefits of this material, describes its use, and discusses important features associated with placement and testing

Cement and Concrete Composites, 2011

This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright

Cement and Concrete Composites, 2012

This paper focuses on testing performed on mixtures that would be consistent with the mortar port... more This paper focuses on testing performed on mixtures that would be consistent with the mortar portion of a concrete bridge deck mixture for many state departments of transportation. In this work a relatively large percentage of cement (40%, 60%, or 80% by volume) is replaced with Class C fly ash. To overcome concerns associated with slow set and early-age strength development that are often expressed with the high volume fly ash mixtures (HVFA), the water-to-cementitious materials ratio (w/cm) by mass has been reduced from a conventional value of 0.42 to 0.30. To overcome potential complications that the low w/cm may cause in terms of self-desiccation, internal curing (IC) with prewetted lightweight aggregate was used to reduce shrinkage and increase hydration. By adopting this approach (lowering the w/c and using IC) IC HVFA mixtures show additional benefits that should permit their broader application.

Cement and Concrete Composites, 2011

Construction and Building Materials, 2012

This paper explores the potential for manufacturing internally cured concretes with lightweight a... more This paper explores the potential for manufacturing internally cured concretes with lightweight aggregate (LWA) that has different initial moisture contents prior to mixing: oven-dry, 24 h pre-wetted, and vacuum saturated. Results show that when LWA is used in an oven-dry condition it can absorb water from the paste prior to set which will be returned to the system as internal curing water. When mixture proportion adjustments are properly made to account for the water absorbed by the aggregate before setting, the mixture can provide internal curing benefits. These beneficial aspects include increased hydration which leads to higher compressive strength, reduced water absorption, and reduced electrical conductivity (permeability). Further, these benefits include reduced autogenous shrinkage and a lower propensity for early-age cracking.

Cement and Concrete Research, 2009

The increased propensity for shrinkage cracking in low w/c concrete has spawned the development o... more The increased propensity for shrinkage cracking in low w/c concrete has spawned the development of new technologies that can reduce the risk of early-age cracking. One of these is internal curing. Internal curing uses saturated lightweight aggregate to supply 'curing water' to low w/c paste as it hydrates. Significant research has been performed to determine the effects of internal curing on shrinkage and stress development; however, relatively little detailed information exists about the effects of internal curing on the fluid transport properties such as water absorption or diffusivity. This study examines the absorption of water into mortar specimens made with saturated lightweight aggregates (SLWA). These results indicate that the inclusion of SLWA can reduce the water absorption of mortar specimens. This observation was reinforced with electrical conductivity measurements that exhibited similar reductions.

Cement and Concrete Composites, 2014

The transport of fluid and ions in concrete mixtures is central to many aspects of concrete deter... more The transport of fluid and ions in concrete mixtures is central to many aspects of concrete deterioration. As a result, transport properties are frequently measured as an indication of the durability that a concrete mixture may be expected to have. This paper is the second in a series investigating the performance of high volume fly ash (HVFA) mixtures with low water-to-cementitious ratios (w/cm) that are internally cured. While the first paper focused on strength and shrinkage, this paper presents the evaluation of the transport properties of these mixtures. Specifically, the paper presents results from: rapid chloride migration (RCM), rapid chloride penetration test (RCPT), apparent chloride diffusion coefficient, surface electrical resistivity, and water absorption. The test matrix consisted of mortar samples with two levels of class C fly ash replacement (40% and 60% by volume) with and without internal curing provided with pre-wetted lightweight fine aggregates (LWA). These mixtures are compared to plain ordinary portland cement (OPC) mortars. The results indicate that HVFA mixtures with and without internal curing provide benefits in terms of reduced transport coefficients compared to the OPC mixtures.

The objective of this project was to evaluate the transport properties of concrete pavement in th... more The objective of this project was to evaluate the transport properties of concrete pavement in the state of Indiana using common testing procedures. Specifically this work evaluated the absorption of water, the absorption of deicing solutions, and electrical conductivity. A series of concrete paving mixtures were tested to provide a range of values that were typical for the state of Indiana. While similar mixture proportions were used for the mixtures in Indiana differences in the magnitude of water absorbed occurred. A series of mortars were tested to illustrate the effect of curing conditions, water to cement ratio, and paste volume. It was observed that a long duration of drying was needed to obtain equilibrium. Samples dried to a lower relative humidity showed a greater volume of water absorbed. It was observed that drying at 105C resulted in substantial anomalies in water absorption, as such this method is not recommended. It was observed that when samples were tested using deicing solutions or samples were tested that were previously exposed to deicing solutions the water absorption could be influenced. The electrical conductivity work was performed as a potential method to develop the understanding of rapid test techniques for quality control. The research used a modified parallel law to relate the electrical conductivity to the pore volume, pore solution conductivity and the tortuosity through the pore network. The influence water addition was able to be determined using electrical conductivity. In addition, the pore solution was observed to be approximately linearly related to the degree of hydration. It is critical that a correction be applied to samples tested at different temperatures. An activation energy of conduction was observed that was approximately 10 kL/mol irrespective of water to cement ratio. In addition to the measurement of transport properties, the relative humidity was assessed for concrete exposed to different exposure conditions. The samples considered in this investigation included a sample stored at 50% relative humidity, covered concrete, a concrete with an exposed vertical surface, a concrete on a drainable base, a concrete on a non-drainable base, and concrete that was submerged. The samples showed that for practical field samples the relative humidity in the concrete was always above 80% for the samples tested. The samples that were exposed to precipitation events demonstrated higher relative humidities.

The experiments reported in this paper were conducted as part of a multi-state collaborative eval... more The experiments reported in this paper were conducted as part of a multi-state collaborative evaluation sponsored by the Pooled Fund Program and the American Association of American Highway and Transportation Officials Technology Implementation Group and organized by the Florida Department of Transportation. This document was published in collaboration with the Joint Transportation Research Program at Purdue University. The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the data presented herein. The contents do

Aging Health, 2009

The median age of diagnosis of colorectal cancer is during the seventh decade and the incidence o... more The median age of diagnosis of colorectal cancer is during the seventh decade and the incidence of the disease increases continuously with age. However, as a patient ages, the likelihood of receiving adequate cancer treatment diminishes and mortality rises. The geriatric population is a very heterogeneous group in which patients with an excellent health status coexist with both comorbidities and functional dependency. Therefore, there is a great need to redefine treatment strategies in elderly patients with colorectal carcinoma, personalizing the treatment according to the degree of vulnerability of the elderly patient. It is essential to perform a multidimensional geriatric assessment in order to consider the cancer and the stage of the cancer as well as to identify features that could modify the survival or interfere with therapy. The aim of this review is to discuss the factors that are relevant for the therapeutic management of colorectal cancer in elderly patients.

Proceedings of SPIE, 2003

Under a contract with the GRANTECAN, the Commissioning Instrument is a project developed by a tea... more Under a contract with the GRANTECAN, the Commissioning Instrument is a project developed by a team of Mexican scientists and engineers from the Instrumentation Department of the Astronomy Institute at the UNAM and the CIDESI Engineering Center. ...