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Moises Frias - One of the best experts on this subject based on the ideXlab platform.
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Chemical and mineral transformations that occur in mine waste and washery rejects during pre-utilization calcination
International Journal of Coal Geology, 2014Co-Authors: R. Vigil De La Villa, Moises Frias, Sagrario Martínez-ramírez, Rosario García-giménez, Lucía Fernández-carrascoAbstract:Abstract The mineralogical content of coal mine waste consists primarily of inorganic compounds which can be converted into a metakaolin-based product under controlled activation conditions that is also a highly Pozzolanic material. Activation temperatures ranging from 500 to 900 °C over 2 h retention time affect the mineralogy of coal mine waste, as well as the formation and evolution of the hydrated phases that form during the Pozzolanic reaction. The hydrated phases formed during the Pozzolanic reaction in the activated coal mine waste (ACMW)/Ca(OH) 2 system were C–S–H gels, stratlingite, tetracalcium aluminate hydrate, LDH compounds (phyllosilicate/carbonate) and monosulfoaluminate. Low temperatures (600 °C) favored the formation of LDH compounds and stratlingite; whereas monosulfoaluminate formed during the hydrated phase at higher temperatures (900 °C) during the first day of the Pozzolanic reaction, and tetracalcium aluminate hydrate appeared as the dominant crystalline phase at 7 and 28 days.
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Study on the Pozzolanic properties of a natural Cuban zeolitic rock by conductometric method: Kinetic parameters
Construction and Building Materials, 2011Co-Authors: M. Rosell-lam, E. Villar-cociña, Moises FriasAbstract:Abstract Natural zeolite is a type of mineralogical material containing large quantities of reactive SiO 2 and Al 2 O 3 . These materials have been used in the cement industry as a supplementary cementing material. Like other Pozzolanic materials the zeolite contributes to improve the mortar and concrete performances mainly through the Pozzolanic reaction with calcium hydroxide (CH). The Pozzolanic reactivity of this type of material in comparison with other pozzolans is of great interest. The current paper presents a study about the Pozzolanic activity of a natural Cuban zeolitic rock. The Pozzolanic activity in a zeolitic material/CH solution is investigated by means of electrical conductivity measurements and latter on the kinetic parameters are quantified by applying a kinetic–diffusive model to process. The kinetic parameters that characterize the process (in particular the reaction rate constant) were determined in the fitting process of the model. The index of Pozzolanic activity evaluated according to the obtained values of the reaction rate constant permits to characterize the Pozzolanic activity of these materials in a rigorous way. The results show that this Cuban zeolitic rock is a natural material with high Pozzolanic activity. Also, these results allow corroborating the direct influence of the fineness of zeolitic material on the Pozzolanic and mechanical properties.
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Pozzolanic behavior of bamboo leaf ash characterization and determination of the kinetic parameters
Cement & Concrete Composites, 2011Co-Authors: E Villarcocina, Holmer Savastano, Eduardo Morales, S F Santos, Moises FriasAbstract:Abstract The paper presents a characterization and study of the Pozzolanic behavior between calcium hydroxide (CH) and bamboo leaf ash (BLAsh), which was obtained by calcining bamboo leaves at 600 °C for 2 h in a laboratory electric furnace. To evaluate the Pozzolanic behavior the conductometric method was used, which is based on the measurement of the electrical conductivity in a BLAsh/CH solution with the reaction time. Later, the kinetic parameters are quantified by applying a kinetic-diffusive model. The kinetic parameters that characterize the process (in particular, the reaction rate constant and free energy of activation) were determined with relative accuracy in the fitting process of the model. The Pozzolanic activity is quantitatively evaluated according to the values obtained of the kinetic parameters. Other experimental techniques, such as X-ray diffraction (XRD) and scanning electron microscopy (SEM), were also employed. The results show that this kind of ash is formed by silica with a completely amorphous nature and a high Pozzolanic activity. The correlation between the values of free energy of activation (Δ G # ) and the reaction rate constants ( K ) are in correspondence with the theoretical studies about the rate processes reported in the literature.
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Influence of activation temperature of kaolinite-based clay wastes on Pozzolanic activity and kinetic parameters
Advances in Cement Research, 2010Co-Authors: Moises Frias, R Garcia, O. Rodríguez, B. Nebreda, Ernesto Villar CociñaAbstract:It is well known that the transformation of some clay minerals into Pozzolanic materials for the manufacture of Portland cements depends on the activation conditions. In the current paper, a study was carried out to evaluate the effect of activation temperature in the range of 500–700°C on the characteristics of thermally activated clay wastes (ACWs). Different chemical, morphological, mineralogical and Pozzolanic characteristics as well as kinetic parameter determinations were analysed in order to provide a complete study of the activated products and the viability of their use in the manufacture of blended cements. The results obtained showed that activation temperature plays a special role in the mineralogy of ACWs as well as their Pozzolanic behaviour. Mineralogically, the ACWs were essentially formed from calcite and talc; kaolinite and chlorite were also identified depending on activation conditions. The values of the kinetic parameters indicated different Pozzolanic activity of the ACWs, mainly ove...
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use of micro raman spectroscopy to study reaction kinetics in blended white cement pastes containing metakaolin
Journal of Raman Spectroscopy, 2009Co-Authors: Moises Frias, Sergi MartinezramirezAbstract:Curing temperature is known to play an important role in the formation, development, and stability of the hydrated phases appearing during Pozzolanic reactions (chemical reaction between puzzolanic addition, metakaolin (MK), and calcium hydroxide from cement hydration). A typical example of this important reaction is to be found in metakaolin-bearing cement pastes, characterized by hexagonal phases whose thermodynamic stability declines with rising temperature. These phases cannot be exhaustively researched with traditional techniques (such as X-ray diffraction) due to their poor crystallinity. Consequently, micro-Raman spectroscopy was used in the present study to explore the behavior of white cement paste blends containing 0, 10, and 25% MK at two curing temperatures (20 and 60 °C). This led to the identification, for the first time using Raman spectroscopy, of phases C2ASH81 (stratlingite) and C3ASH6, which appear in the MK–white cement reaction. The CSH gel formed was characterized by Q1 dimers and a C/S ratio of 1.3–1.5. Raising the curing temperature favored the formation of C4AH13. Copyright © 2009 John Wiley & Sons, Ltd.
E Villarcocina - One of the best experts on this subject based on the ideXlab platform.
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Pozzolanic behavior of bamboo leaf ash characterization and determination of the kinetic parameters
Cement & Concrete Composites, 2011Co-Authors: E Villarcocina, Holmer Savastano, Eduardo Morales, S F Santos, Moises FriasAbstract:Abstract The paper presents a characterization and study of the Pozzolanic behavior between calcium hydroxide (CH) and bamboo leaf ash (BLAsh), which was obtained by calcining bamboo leaves at 600 °C for 2 h in a laboratory electric furnace. To evaluate the Pozzolanic behavior the conductometric method was used, which is based on the measurement of the electrical conductivity in a BLAsh/CH solution with the reaction time. Later, the kinetic parameters are quantified by applying a kinetic-diffusive model. The kinetic parameters that characterize the process (in particular, the reaction rate constant and free energy of activation) were determined with relative accuracy in the fitting process of the model. The Pozzolanic activity is quantitatively evaluated according to the values obtained of the kinetic parameters. Other experimental techniques, such as X-ray diffraction (XRD) and scanning electron microscopy (SEM), were also employed. The results show that this kind of ash is formed by silica with a completely amorphous nature and a high Pozzolanic activity. The correlation between the values of free energy of activation (Δ G # ) and the reaction rate constants ( K ) are in correspondence with the theoretical studies about the rate processes reported in the literature.
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study of the Pozzolanic reaction kinetics in sugar cane bagasse clay ash calcium hydroxide system kinetic parameters and Pozzolanic activity
Advances in Cement Research, 2009Co-Authors: E Villarcocina, Frias M Rojas, Valencia E Morales, Holmer SavastanoAbstract:This paper presents a study of the Pozzolanic reaction kinetics between calcium hydroxide and a mixture of sugar cane bagasse with 20 and 30% of clay, burned at 800 and 1000°C (SCBCA) by electrical conductivity measurements. A kinetic–diffusive model produced in previous studies by some of the authors was used. The model was fitted to the experimental data, which allowed the computation of the kinetic parameters of the Pozzolanic reaction (reaction rate constant and free energy of activation) that rigorously characterised the Pozzolanic activity of the materials. The results show that SCBCA demonstrated reactivity and good Pozzolanic qualities in the range 800–1000°C.
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characterisation of sugar cane straw waste as Pozzolanic material for construction calcining temperature and kinetic parameters
Waste Management, 2007Co-Authors: Moises Frias, E Villarcocina, E ValenciamoralesAbstract:Abstract This paper reports on the influence of calcining temperature (800 and 1000 °C) on the Pozzolanic activation of sugar cane straw (SCS). The reaction kinetics of SCS ash–lime mixtures were inferred from physicochemical characteristics (X-ray diffraction patterns and thermogravimetry analysis. The fitting of a kinetic–diffusive model to the experimental data (fixed lime versus time) allowed the computing of the kinetic parameters (reaction rate constant) of the Pozzolanic reaction. Results obtained confirm that the sugar cane straw ash (SCSA) calcined at 800 and 1000 °C have properties indicative of very high Pozzolanic activity. No influence of calcining temperature on the Pozzolanic activity was observed. Also, no crystalline compounds during the Pozzolanic reaction were identified up to 90 days of reaction. Environmental durability and strength of the consequential mortars remain to be assessed.
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characterisation of sugar cane straw waste as Pozzolanic material for construction calcining temperature and kinetic parameters
Waste Management, 2007Co-Authors: Moises Frias, E Villarcocina, E ValenciamoralesAbstract:This paper reports on the influence of calcining temperature (800 and 1000 degrees C) on the Pozzolanic activation of sugar cane straw (SCS). The reaction kinetics of SCS ash-lime mixtures were inferred from physicochemical characteristics (X-ray diffraction patterns and thermogravimetry analysis. The fitting of a kinetic-diffusive model to the experimental data (fixed lime versus time) allowed the computing of the kinetic parameters (reaction rate constant) of the Pozzolanic reaction. Results obtained confirm that the sugar cane straw ash (SCSA) calcined at 800 and 1000 degrees C have properties indicative of very high Pozzolanic activity. No influence of calcining temperature on the Pozzolanic activity was observed. Also, no crystalline compounds during the Pozzolanic reaction were identified up to 90 days of reaction. Environmental durability and strength of the consequential mortars remain to be assessed.
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the effect that different Pozzolanic activity methods has on the kinetic constants of the Pozzolanic reaction in sugar cane straw clay ash lime systems application of a kinetic diffusive model
Cement and Concrete Research, 2005Co-Authors: Moises Frias, M Sanchez I De Rojas, E Villarcocina, E ValenciamoralesAbstract:The reaction kinetics of a mixture of sugar cane straw with 20% and 30% of clay burned at 800 and 1000 °C and lime (calcium hydroxide) is studied. A direct method (accelerated chemical method) based on the measurement of the amount of lime reacted as the reaction proceeds is applied. A kinetic–diffusive model published in a previous paper by some authors of this research is used. The fitting of the model by computerized methods allows determining the kinetic coefficients that characterize the process: in particular, the reaction rate constant. The index of Pozzolanic activity evaluated according to the obtained values of the reaction rate constant permits to characterize the Pozzolanic activity of these materials in a rigorous way. The results are compared with the results obtained applying an indirect method (conductometric method). The kinetic results obtained in the current paper allow affirming that the kinetic–diffuse model used in order to evaluate the Pozzolanic reaction is valid, independently of the method used for the evaluation of the Pozzolanic activity.
E Valenciamorales - One of the best experts on this subject based on the ideXlab platform.
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characterisation of sugar cane straw waste as Pozzolanic material for construction calcining temperature and kinetic parameters
Waste Management, 2007Co-Authors: Moises Frias, E Villarcocina, E ValenciamoralesAbstract:This paper reports on the influence of calcining temperature (800 and 1000 degrees C) on the Pozzolanic activation of sugar cane straw (SCS). The reaction kinetics of SCS ash-lime mixtures were inferred from physicochemical characteristics (X-ray diffraction patterns and thermogravimetry analysis. The fitting of a kinetic-diffusive model to the experimental data (fixed lime versus time) allowed the computing of the kinetic parameters (reaction rate constant) of the Pozzolanic reaction. Results obtained confirm that the sugar cane straw ash (SCSA) calcined at 800 and 1000 degrees C have properties indicative of very high Pozzolanic activity. No influence of calcining temperature on the Pozzolanic activity was observed. Also, no crystalline compounds during the Pozzolanic reaction were identified up to 90 days of reaction. Environmental durability and strength of the consequential mortars remain to be assessed.
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characterisation of sugar cane straw waste as Pozzolanic material for construction calcining temperature and kinetic parameters
Waste Management, 2007Co-Authors: Moises Frias, E Villarcocina, E ValenciamoralesAbstract:Abstract This paper reports on the influence of calcining temperature (800 and 1000 °C) on the Pozzolanic activation of sugar cane straw (SCS). The reaction kinetics of SCS ash–lime mixtures were inferred from physicochemical characteristics (X-ray diffraction patterns and thermogravimetry analysis. The fitting of a kinetic–diffusive model to the experimental data (fixed lime versus time) allowed the computing of the kinetic parameters (reaction rate constant) of the Pozzolanic reaction. Results obtained confirm that the sugar cane straw ash (SCSA) calcined at 800 and 1000 °C have properties indicative of very high Pozzolanic activity. No influence of calcining temperature on the Pozzolanic activity was observed. Also, no crystalline compounds during the Pozzolanic reaction were identified up to 90 days of reaction. Environmental durability and strength of the consequential mortars remain to be assessed.
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the effect that different Pozzolanic activity methods has on the kinetic constants of the Pozzolanic reaction in sugar cane straw clay ash lime systems application of a kinetic diffusive model
Cement and Concrete Research, 2005Co-Authors: Moises Frias, M Sanchez I De Rojas, E Villarcocina, E ValenciamoralesAbstract:The reaction kinetics of a mixture of sugar cane straw with 20% and 30% of clay burned at 800 and 1000 °C and lime (calcium hydroxide) is studied. A direct method (accelerated chemical method) based on the measurement of the amount of lime reacted as the reaction proceeds is applied. A kinetic–diffusive model published in a previous paper by some authors of this research is used. The fitting of the model by computerized methods allows determining the kinetic coefficients that characterize the process: in particular, the reaction rate constant. The index of Pozzolanic activity evaluated according to the obtained values of the reaction rate constant permits to characterize the Pozzolanic activity of these materials in a rigorous way. The results are compared with the results obtained applying an indirect method (conductometric method). The kinetic results obtained in the current paper allow affirming that the kinetic–diffuse model used in order to evaluate the Pozzolanic reaction is valid, independently of the method used for the evaluation of the Pozzolanic activity.
Guilherme Chagas Cordeiro - One of the best experts on this subject based on the ideXlab platform.
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influence of particle size and specific surface area on the Pozzolanic activity of residual rice husk ash
Cement & Concrete Composites, 2011Co-Authors: Guilherme Chagas Cordeiro, Romildo Dias Toledo Filho, Luis Marcelo Tavares, Eduardo De Moraes Rego Fairbairn, Simone HempelAbstract:Abstract The effect of the particle size distribution and specific surface area on the Pozzolanic activity of a residual rice husk ash (RHA) was investigated in this work. Different samples of RHA obtained from ultrafine grinding were characterized with respect to particle size analyses by laser granulometry, BET and Blaine specific surface areas, pore volume distribution by mercury intrusion porosimetry, surface texture by scanning electron microscopy, Pozzolanic activity using the cement mortar method and activity with lime using the Chapelle method. From the results, it was concluded that a good correlation exists between the ‘external’ specific surface area, that is, the surface area associated with the measured particle size distribution, and the Pozzolanic activity of the residual RHA. On the other hand, nearly no correlation was identified between the Pozzolanic activity and the specific surface area measured using the BET method, an observation that is particularly related to the cellular nature of the internal structure of this RHA.
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influence of particle size and specific surface area on the Pozzolanic activity of residual rice husk ash
Cement & Concrete Composites, 2011Co-Authors: Guilherme Chagas Cordeiro, Romildo Dias Toledo Filho, Luis Marcelo Tavares, Eduardo De Moraes Rego Fairbairn, Simone HempelAbstract:Abstract The effect of the particle size distribution and specific surface area on the Pozzolanic activity of a residual rice husk ash (RHA) was investigated in this work. Different samples of RHA obtained from ultrafine grinding were characterized with respect to particle size analyses by laser granulometry, BET and Blaine specific surface areas, pore volume distribution by mercury intrusion porosimetry, surface texture by scanning electron microscopy, Pozzolanic activity using the cement mortar method and activity with lime using the Chapelle method. From the results, it was concluded that a good correlation exists between the ‘external’ specific surface area, that is, the surface area associated with the measured particle size distribution, and the Pozzolanic activity of the residual RHA. On the other hand, nearly no correlation was identified between the Pozzolanic activity and the specific surface area measured using the BET method, an observation that is particularly related to the cellular nature of the internal structure of this RHA.
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Influence of ultrafine wet grinding on Pozzolanic activity of submicrometre sugar cane bagasse ash
Advances in Applied Ceramics, 2011Co-Authors: Guilherme Chagas Cordeiro, Romildo Dias Toledo Filho, Rs De AlmeidaAbstract:Abstract Sugar cane bagasse ash is an important byproduct of sugar and alcohol production. This residual material requires only grinding and classification in order to achieve adequate fineness and homogeneity to be used as Pozzolanic admixture in concrete. In this study, submicrometre ashes were produced from wet grinding using a planetary ball mill. Measurements of the Pozzolanic activity of the ashes with cement and lime were carried using mechanical methods based on the compressive strength of mortars. It was observed that the Pozzolanic activity of submicrometre ashes is inversely correlated to its particle size. Moreover, it was demonstrated that the grinding intensity clearly increased the sugar cane bagasse ash reactivity.
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ultrafine grinding of sugar cane bagasse ash for application as Pozzolanic admixture in concrete
Cement and Concrete Research, 2009Co-Authors: Guilherme Chagas Cordeiro, Romildo Dias Toledo Filho, Lua Marcelo S Tavares, Eduardo De Moraes Rego FairbairnAbstract:Abstract Sugar cane bagasse ash, a byproduct of sugar and alcohol production, is a potential Pozzolanic material. However, its effective application in mortar and concrete requires first the controlled use of grinding and classification processes to allow it to achieve the fineness and homogeneity that are required to meet industry standards. The present paper investigates the role of mill type and grinding circuit configuration in grinding in laboratory- and pilot plant-scale on the particle size, specific surface area and Pozzolanic activity of the produced ashes. It was observed that, although different size distributions were produced by the different mills and milling configurations, the Pozzolanic activity of the ground ash was directly correlated to its fineness, characterized by its 80% passing size or Blaine specific surface area. From a low Pozzolanic activity of less than 50% of the as-received ash, values above 100% could be reached after prolonged grinding times. Electric power requirements to reach the minimum Pozzolanic activity were estimated to be in the order of 42 kWh/t in an industrial ball mill. Incorporation of an ultrafinely-ground ash in a high-performance concrete in partial replacement of Portland cement (10, 15 and 20% by mass) resulted in no measurable change in mechanical behavior, but improved rheology and resistance to penetration of chloride ions.
Eduardo De Moraes Rego Fairbairn - One of the best experts on this subject based on the ideXlab platform.
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influence of particle size and specific surface area on the Pozzolanic activity of residual rice husk ash
Cement & Concrete Composites, 2011Co-Authors: Guilherme Chagas Cordeiro, Romildo Dias Toledo Filho, Luis Marcelo Tavares, Eduardo De Moraes Rego Fairbairn, Simone HempelAbstract:Abstract The effect of the particle size distribution and specific surface area on the Pozzolanic activity of a residual rice husk ash (RHA) was investigated in this work. Different samples of RHA obtained from ultrafine grinding were characterized with respect to particle size analyses by laser granulometry, BET and Blaine specific surface areas, pore volume distribution by mercury intrusion porosimetry, surface texture by scanning electron microscopy, Pozzolanic activity using the cement mortar method and activity with lime using the Chapelle method. From the results, it was concluded that a good correlation exists between the ‘external’ specific surface area, that is, the surface area associated with the measured particle size distribution, and the Pozzolanic activity of the residual RHA. On the other hand, nearly no correlation was identified between the Pozzolanic activity and the specific surface area measured using the BET method, an observation that is particularly related to the cellular nature of the internal structure of this RHA.
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influence of particle size and specific surface area on the Pozzolanic activity of residual rice husk ash
Cement & Concrete Composites, 2011Co-Authors: Guilherme Chagas Cordeiro, Romildo Dias Toledo Filho, Luis Marcelo Tavares, Eduardo De Moraes Rego Fairbairn, Simone HempelAbstract:Abstract The effect of the particle size distribution and specific surface area on the Pozzolanic activity of a residual rice husk ash (RHA) was investigated in this work. Different samples of RHA obtained from ultrafine grinding were characterized with respect to particle size analyses by laser granulometry, BET and Blaine specific surface areas, pore volume distribution by mercury intrusion porosimetry, surface texture by scanning electron microscopy, Pozzolanic activity using the cement mortar method and activity with lime using the Chapelle method. From the results, it was concluded that a good correlation exists between the ‘external’ specific surface area, that is, the surface area associated with the measured particle size distribution, and the Pozzolanic activity of the residual RHA. On the other hand, nearly no correlation was identified between the Pozzolanic activity and the specific surface area measured using the BET method, an observation that is particularly related to the cellular nature of the internal structure of this RHA.
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ultrafine grinding of sugar cane bagasse ash for application as Pozzolanic admixture in concrete
Cement and Concrete Research, 2009Co-Authors: Guilherme Chagas Cordeiro, Romildo Dias Toledo Filho, Lua Marcelo S Tavares, Eduardo De Moraes Rego FairbairnAbstract:Abstract Sugar cane bagasse ash, a byproduct of sugar and alcohol production, is a potential Pozzolanic material. However, its effective application in mortar and concrete requires first the controlled use of grinding and classification processes to allow it to achieve the fineness and homogeneity that are required to meet industry standards. The present paper investigates the role of mill type and grinding circuit configuration in grinding in laboratory- and pilot plant-scale on the particle size, specific surface area and Pozzolanic activity of the produced ashes. It was observed that, although different size distributions were produced by the different mills and milling configurations, the Pozzolanic activity of the ground ash was directly correlated to its fineness, characterized by its 80% passing size or Blaine specific surface area. From a low Pozzolanic activity of less than 50% of the as-received ash, values above 100% could be reached after prolonged grinding times. Electric power requirements to reach the minimum Pozzolanic activity were estimated to be in the order of 42 kWh/t in an industrial ball mill. Incorporation of an ultrafinely-ground ash in a high-performance concrete in partial replacement of Portland cement (10, 15 and 20% by mass) resulted in no measurable change in mechanical behavior, but improved rheology and resistance to penetration of chloride ions.
