Kinetic and morphological differentiation of Ettringites in plain and blended Portland cements using Metakaolin and the ASTM C 452-68 test. Part I: kinetic differentiation

[EN]In this first part of the study, the results obtained in prior research with XRD and SEM, as well as the Le Chatelier- Ansttet test were confirmed with the ASTM C 452-68 test. To this end, 20%, 30% and 40% metakaolin (MK) was added to ten Portland cements, six OPCs and four SRPCs. Both the ten plain PCs and the 30 metakaolin (MK) blends were tested for two years under ASTM C 452-68 specifications, determining not only the percentage increase in length, ΔL(%), of the specimens, but also the sulphate content in the curing water. Other parameters studied included: chemical analysis of the cementitious materials used and specific properties of some of the cements tested. The experimental results, ΔL(%) versus time, re-confirmed that the formation rate of ettringite from the reactive alumina, Al2O3 r-, present in the pozzolan must be substantially higher than the formation rate of ettringite from the C3A present in the PC. This was verified by the variation of the sulphate content in the specimen curing water throughout the test. In light of those findings, in this article these two types of ettringite are denominated rapid forming ettringite or ett-rf, and slow forming ettringite or ett-lf.[ES]En esta Parte I de la investigación, se han logrado verificar mediante el ensayo ASTM C 452-68, los resultados obtenidos en anteriores investigaciones realizadas con DRX y SEM y el ensayo Le Chatelier-Ansttet. Para ello, a 10 cementos Portland –6 CPO y 4 CPRS– se les añadió 20%, 30% y 40% de metakaolín (MK). Tanto los 10 CP como los 30 de sus mezclas con metakaolín (MK), se ensayaron durante 2 años, mediante dicho método ASTM C 452-68, y a sus probetas no sólo se les determinó su incremento porcentual de longitud, ΔL(%), sino además, el contenido de sulfatos de sus aguas de conservación. Otras determinaciones complementarias fueron: análisis químico de los materiales cementiceos utilizados y propiedades específicas de algunos cementos ensayados. Los resultados experimentales, ΔL(%) frente al tiempo, han confirmado de nuevo que la velocidad de formación de la ettringita de origen alúmina reactiva, Al2O3 r-, de las puzolanas, tiene que ser considerablemente mayor que la velocidad de formación de la ettringita de origen C3A de los CP, lo que ha sido verificado por la evolución durante todo el ensayo, del contenido de sulfatos de las aguas de conservación de las probetas. Debido a ello, se ha propuesto denominar a ambos tipos de ettringitas, ettringita de rápida formación, ett-rf, y ettringita de lenta formación, ett-lf, respectivamente.Peer reviewe

La resistencia a los sulfatos de los cementos portland y su grado de finura de molido: análisis de su relación

This work has demonstrated the great influence that the specific surface of a Portland cement has on its qualification as a high or low resistance to sulfate ion attack - SIA, by means of the accelerated method ASTM C 452. For that purpose two Portland cements have been tested by means of that method. A Portland cement PY (3,83% C3A) (Type V(2)) with 3 different specific surfaces. The experimental results obtained have demonstrated that, according to the ASTM C452-68 method, a Portland Cement Type III(2) can be qualified as from Type V(2), and vice verse, according to its specific surface being adequated, or not, for each objective.Este trabajo ha demostrado la gran influencia que tiene la superficie específica de un cemento portland en su calificación como de alta o baja resistencia al ataque del ion sulfato mediante el método acelerado de ensayo ASTM C 452. Para este objetivo se han ensayado dos cementos portland mediante dicho método de ensayo. Un cemento portland PY (3,83% C3A), Tipo V (2) con 3 diferentes superficies específicas. Los resultados experimentales obtenidos han demostrado que, de acuerdo con el método ASTM C 452, un cemento portland tipo P III (2) puede ser calificado como de Tipo PY Tipo V (2)

Diferenciación cinética y morfológica de Ettringitas mediante Metakaolín, cementos Portland y el ensayo ASTM C 452-68. Parte I: diferenciación cinética

In this first part of the study, the results obtained in prior research with XRD and SEM, as well as the Le Chatelier-Ansttet test were confirmed with the ASTM C 452-68 test. To this end, 20%, 30% and 40% metakaolin (MK) was added to ten Portland cements, six OPCs and four SRPCs. Both the ten plain PCs and the 30 metakaolin (MK) blends were tested for two years under ASTM C 452-68 specifications, determining not only the percentage increase in length, ΔL(%), of the specimens, but also the sulphate content in the curing water. Other parameters studied included: chemical analysis of the cementitious materials used and specific properties of some of the cements tested.The experimental results, ΔL(%) versus time, re-confirmed that the formation rate of ettringite from the reactive alumina, Al2O3r-, present in the pozzolan must be substantially higher than the formation rate of ettringite from the C3A present in the PC. This was verified by the variation of the sulphate content in the specimen curing water throughout the test. In light of those findings, in this article these two types of ettringite are denominated rapid forming ettringite or ett-rf, and slow forming ettringite or ett-lf.En esta Parte I de la investigación, se han logrado verificar mediante el ensayo ASTM C 452-68, los resultados obtenidos en anteriores investigaciones realizadas con DRX y SEM y el ensayo Le Chatelier-Ansttet. Para ello, a 10 cementos Portland –6 CPO y 4 CPRS– se les añadió 20%, 30% y 40% de metakaolín (MK). Tanto los 10 CP como los 30 de sus mezclas con metakaolín (MK), se ensayaron durante 2 años, mediante dicho método ASTM C 452-68, y a sus probetas no sólo se les determinó su incremento porcentual de longitud, ΔL(%), sino además, el contenido de sulfatos de sus aguas de conservación. Otras determinaciones complementarias fueron: análisis químico de los materiales cementiceos utilizados y propiedades específicas de algunos cementos ensayados.Los resultados experimentales, ΔL(%) frente al tiempo, han confirmado de nuevo que la velocidad de formación de la ettringita de origen alúmina reactiva, Al2O3r-, de las puzolanas, tiene que ser considerablemente mayor que la velocidad de formación de la ettringita de origen C3A de los CP, lo que ha sido verificado por la evolución durante todo el ensayo, del contenido de sulfatos de las aguas de conservación de las probetas. Debido a ello, se ha propuesto denominar a ambos tipos de ettringitas, ettringita de rápida formación, ett-rf, y ettringita de lenta formación, ett-lf, respectivamente

Estado del conocimiento sobre la sal de Friedel

A vast bibliography revision is done about the Friedel's salt. The structure, more possible mechanisms of formation and stability intervals in presence of other salts and temperature effect and by pH are pointed out.Se ha realizado un extenso estudio bibliográfico sobre la sal de Friedel. Se indica su estructura, sus probables mecanismos de formación e intervalos de estabilidad en presencia de otras sales, así como también el efecto de la temperatura y el pH

Preparación de morteros y hormigones no tradicionales a base de cemento portland, metacaolín y yeso (15,05%)

In a thorough previous research (1), it appeared that creation, evolution and development of the values of compressive mechanical strength (CS) and flexural strength (FS), measured in specimens 1x1x6cm of mortar type ASTM C 452-68 (2), manufactured by ordinary Portland cement P-1 (14.11% C3A) or PY-6 (0.00% C3A), metakaolin and gypsum (CaSO4∙2H2O) -or ternary cements, CT-, were similar to the ones commonly developed in mortars and concretes of OPC. This paper sets up the experimental results obtained from non-traditional mortars and concretes prepared with such ternary cements -TC-, being the portland cement/metakaolin mass ratio, as follows: 80/20, 70/30 and 60/40. Finally, the behaviour of these cements against gypsum attack, has been also determined, using the following parameters: increase in length (ΔL%), compressive, CS, and flexural, FS, strengths, and ultrasound energy, UE. Experimental results obtained from these non-traditional mortars and concretes, show an increase in length (ΔL), in CS and FS, and in UE values, when there is addition of metakaolin.En una exhaustiva investigación anterior (1), se pudo comprobar que la creación, evolución y desarrollo de los valores de resistencias mecánicas a compresión, RMC, y flexotracción, RMF, proporcionados por probetas de 1x1x6 cm, de mortero 1:2,75, selenitoso tipo ASTM C 452-68 (2) -que habían sido preparadas con arena de Ottawa, cemento portland, P-1 (14,11% C3A) o PY- 6 (0,00% C3A), metacaolín y yeso (CaSO4∙2H2O)-, fue semejante a la que, comúnmente, desarrollan los morteros y hormigones tradicionales de cemento portland. En el presente trabajo se exponen los resultados experimentales obtenidos de morteros y hormigones no tradicionales, preparados con dichos cementos ternarios, CT, siendo las proporciones porcentuales en masa ensayadas, cemento portland/metacaolín, las siguientes: 80/20, 70/30 y 60/40. Finalmente, el comportamiento de estos cementos frente el ataque del yeso, se ha determinado mediante los siguientes parámetros: incremento de longitud (ΔL%), resistencias mecánicas a compresión, RMC, y flexotracción, RMF, y energía de ultrasonido, EU. Los resultados experimentales obtenidos con tales morteros y hormigones no tradicionales, han dado un aumento de los valores de ΔL, RM y EU, con la cantidad de metacaolín añadida

Preparación de la dosificación de un hormigón con humo de sílice, cuya RMC sea > 40 kp/cm2, a edades iniciales (5-10 horas)

Silica fume (SF) or microsilica is related mainly with preparation of High Resistance Concrete. This has justified its use -together with portland cement (I-42'5/SR,MR) and an superfiuidifying additive- in the preparation of a concrete whose value for compressive mechanical resistance at early ages (only 5 to 10 hours) is higher than 40 kp/cm2, instead of preparing it with the portland cement plus a setting accelerator or "model" dosage. The experimental techniques used to reach that objective have been: ultrasound energy and a press for breaking 30 x 15 mm specimens, and a maximum load of 2001. With the first technique, in only 25 days, 13 different dossages were prepared, which were compared to the "model" dosage, and two more that did not contain neither setting accelerator nor SF, this means that they had been prepared with the same portland cement, same fine and coarse aggregates and the same consistency, and that they would act as "reference" for all previous ones. In such a way the dosage was found: E, in this case, that was the same as the "model" as for the amount of fine and coarse aggregates, but not as for the amount of the portland cement used which this time was 360 kg/m3 instead of 400kg/m3 SF content 40 kg/m3 and water 144 l/m3Al humo de sílice(HSE) o microsílice, se le relaciona, principalmente, con la preparación de hormigones de alta resistencia. Esta peculiar característica, ha justificado su utilización -junto a cemento portland (un I-42,5/SR,MR) y un aditivo superfluidificante- en la preparación de un hormigón cuyo valor de resistencia mecánica a compresión a edades iniciales (5 a 10 horas, solamente) fuera superior a 40 kp/cm2, en lugar de prepararlo con dicho cemento portland y un acelerador de fraguado o dosificación "patrón”. Las técnicas experimentales utilizadas para alcanzar dicho objetivo han sido: la energía de ultrasonido y una prensa para la rotura de probetas de 30x15 cm, de 200 t de carga máxima. Mediante la primera de las técnicas, el sistema de tanteo y en tan sólo 25 días, se logró preparar hasta un total de 13 dosificaciones diferentes, las cuales fueron comparadas con dicha dosificación "patrón" y otras dos que no poseían ni acelerador de fraguado, ni HSE; es decir, que habían sido preparadas con el mismo cemento portland, los mismos áridos gruesos y finos y la misma consistencia plástica, las cuales actuarían como "referencia " de todas las anteriores. De esta manera se logró la dosificación buscada, la E, en este caso, que fue la misma que la "patrón" en cuanto a la cantidad de áridos-gruesos y finos(arena), que no, en cambio, en cuanto a la cantidad de cemento portland utilizado, la cual pasaría a ser de 360 kg/m3 en lugar de 400 kg/m3 de HSE, que fue de 40 kg/m3 y de agua de amasado, que fue de 144 l/m3

Up-Regulation of the Nrf2/HO-1 Antioxidant Pathway in Macrophages by an Extract from a New Halophilic Archaea Isolated in Odiel Saltworks

The production of reactive oxygen species (ROS) plays an important role in the progression of many inflammatory diseases. The search for antioxidants with the ability for scavenging free radicals from the body cells that reduce oxidative damage is essential to prevent and treat these pathologies. Haloarchaea are extremely halophilic microorganisms that inhabit hypersaline environments, such as saltworks or salt lakes, where they have to tolerate high salinity, and elevated ultraviolet (UV) and infrared radiations. To cope with these extreme conditions, haloarchaea have developed singular mechanisms to maintain an osmotic balance with the medium, and are endowed with unique compounds, not found in other species, with bioactive properties that have not been fully explored. This study aims to assess the potential of haloarchaea as a new source of natural antioxidant and anti-inflammatory agents. A carotenoid-producing haloarchaea was isolated from Odiel Saltworks (OS) and identified on the basis of its 16S rRNA coding gene sequence as a new strain belonging to the genus Haloarcula. The Haloarcula sp. OS acetone extract (HAE) obtained from the biomass contained bacterioruberin and mainly C18 fatty acids, and showed potent antioxidant capacity using ABTS assay. This study further demonstrates, for the first time, that pretreatment with HAE of lipopolysaccharide (LPS)-stimulated macrophages results in a reduction in ROS production, a decrease in the pro-inflammatory cytokines TNF-α and IL-6 levels, and up-regulation of the factor Nrf2 and its target gene heme oxygenase-1 (HO-1), supporting the potential of the HAE as a therapeutic agent in the treatment of oxidative stress-related inflammatory diseases.This research was funded by the Operative FEDER Program-Andalucía 2014-2020 (US-1380844 and UHU-1257518), Spanish Agencia Estatal de Investigación (PID2019-110438RBC22-AEI/FEDER), the Andalusian government (I+D+i-JA-PAIDI-Retos projects 2020-PY20) and the “VII Plan Propio de Investigación y Transferencia” of The University of Seville. The work was partially funded by national funds from Fundação para a Ciência e a Tecnologia (FCT, Portugal) in the scope of the projects UIDB/04565/2020 and UIDP/04565/2020 of the Research Unit iBB-Institute for Bioengineering and Biosciences, and of the project LA/P/0140/2020 of the i4HB-Associate Laboratory Institute for Health and Bioeconomy. P.G.-V acknowledges financial support from the “Margarita Salas” grant for the training of young doctors, University of Huelva

Clinical and laboratory features of anti-MAG neuropathy without monoclonal gammopathy

Antibodies against myelin-associated glycoprotein (MAG) almost invariably appear in the context of an IgM monoclonal gammopathy associated neuropathy. Very few cases of anti-MAG neuropathy lacking IgM-monoclonal gammopathy have been reported. We investigated the presence of anti-MAG antibodies in 69 patients fulfilling diagnostic criteria for CIDP. Anti-MAG antibodies were tested by ELISA and confirmed by immunohistochemistry. We identified four (5.8%) anti-MAG positive patients without detectable IgM-monoclonal gammopathy. In two of them, IgM-monoclonal gammopathy was detected at 3 and 4-year follow-up coinciding with an increase in anti-MAG antibodies titers. In conclusion, anti-MAG antibody testing should be considered in chronic demyelinating neuropathies, even if IgM-monoclonal gammopathy is not detectable