Estudio del comportamiento de diversos residuos de catalizadores de craqueo catalítico (FCC) en cemento Portland

The fluidized-bed catalytic cracking catalyst (FCC) it is a residue from the industry of the petroleum that shows a high pozzolanic reactivity and, in cementing matrix, it significantly improves their mechanical behaviour as well as durability. In this research a comparative study on residues of catalyst from different sources has been carried out, in order to know if these residues can be used jointly in an indiscriminate way or, on the contrary, it is necessary to classify them according to their characteristics. Thus, a study on five different FCC residues, supplied from different companies, has been carried out, and their physical-chemical characteristics, pozzolanic reactivity by means of thermogravimetric analysis and the evolution of the mechanical strength of mortars were studied. After analyzing all the aspects, it can be concluded that no significant differences among the different tested catalysts were found.El catalizador de craqueo catalítico (FCC) es un residuo de la industria del petróleo que posee una elevada reactividad puzolánica y en matrices cementicias mejora de manera importante los aspectos mecánicos así como de durabilidad. En este trabajo se realiza un estudio comparativo sobre residuos de catalizador de distintos orígenes, para poder conocer si se pueden utilizar conjuntamente de forma indiscriminada o por el contrario hay que catalogarlos según su origen. Para ello, se realizó un estudio sobre cinco residuos de catalizador de craqueo catalítico distintos, suministrados por diferentes empresas y se estudiaron sus características fisicoquímicas, reactividad puzolánica a través de estudios termogravimétricos y la evolución de las resistencias mecánicas en morteros. Tras analizar todos los aspectos se concluye que no existen diferencias significativas entre los distintos catalizadores empleados

Use of residual diatomaceous earth as a silica source in geopolymer production

The use of binders as an alternative to Portland cement has gained importance in recent years. Among them, geopolymeric binders, developed by the reaction between an aluminosilicate precursor and a high alkalinity solution, have become one of the most promising alternatives. The activating solution generally comprises waterglass and sodium hydroxide. Since waterglass is the most expensive material and has a high environmental impact, using alternative silica sources will lead to more sustainable binders. Previous studies have successfully used rice husk ash (RHA) as a silica source. This research aims to assess the possibility of using diatomaceous earth (or diatomite) as an alternative silica source, like the previous studies with RHA. Diatomite is a sedimentary rock with a high amorphous silica content formed by fossilized diatom remains. In this work, the geopolymer was obtained using a fluid cracking catalyst residue as the precursor and six different activating solution types prepared with commercial products, residual diatomite (from beer and wine industries) and RHA. The results open a new possible route for the reuse and recovery of diatomaceous earth residue, although the compressive strength results of the mortars were slightly lower than those for mortars prepared with RHA or commercial reagents

Outstanding aspects on the use of spent FCC catalyst in binders

4 pages, 3 fiures, 7 tables.-- En: 1st Spanish National Conference on Advances in Materials Recycling and Eco – Energy Madrid, 12-13 November 2009.-- Editors: F. A. López, F. Puertas, F. J. Alguacil and A. Guerrero.FCC is a waste material from petrochemical plants which has interesting properties for preparing binders. FCC is lightly grey in color, and white FCC-portland cements with L*≥85 can be prepared. FCC reactivity is enhanced by grinding and it is attributed to pozzolanic reaction towards lime. Stratlingite is the main hydrated product from pozzolanic reaction, and CSH and CAH are also formed. Reactivity of FCC is high, and low curing temperature does not affect this contribution to strength in hardened mixtures. Additionally, high strength concrete can be easily prepared, and compressive strength greater 100MPa can be reached. Mixtures with low w/b ratio showed good behaviour in carbonation tests.Authors thank to Ministerio de Ciencia y Tecnología of Spain and FEDER the financial support of MAT 2001-2694 and BIA 2004-0052 projects.Peer reviewe

novel geopolymeric material cured at room temperature

[EN] Alkali activated binders are a new class of binding material with comparable or enhanced performance to Portland cement. These binding materials are obtained by a chemical reaction between an aluminosilicate material and a highly alkaline solution. In most cases, the setting hardening process of this binder is performed at high curing temperatures. In this paper, alkali activated mortars based on vitreous calcium aluminosilicate (VCAS) cured at room temperature are evaluated. Mechanical strength development and microstructural analysis (scanning electron microscopy, thermogravimetric analysis, X-ray diffraction and mercury intrusion porosimetry) of these materials are performed. Mortars yielded compressive strength ¡-89 MPa after 360 days. This is the first time that VCAS is used as aluminosilicate source material in the production of alkali activated mortars cured at room temperature.The authors acknowledge the Ministerio de Ciencia e Innovacio´ n of the Spanish Government (projecto. BIA2011-26947) and the Vitrominerals company for supplying VCAS samples.Mitsuuchi Tashima, M.; Soriano Martínez, L.; Monzó Balbuena, JM.; Borrachero Rosado, MV.; Paya Bernabeu, JJ. (2013). novel geopolymeric material cured at room temperature. Advances in Applied Ceramics. 112:179-183. https://doi.org/10.1179/1743676112Y.0000000056S17918311

Properties of Ca–(Y)–Si–Al–O–N–F Glasses: Independent and Additive Effects of Fluorine and Nitrogen

Thirty glasses of composition (in equivalent percent) 20-xCa:xY:50Si:30Al:(100-y-z)O:yN:zF, with x = 0, 10; y = 0, 10, 20, and z = 0, 1, 3, 5, 7 were prepared by melting and casting. All glasses were X-ray amorphous. Glass molar volumes (MV) decreased with nitrogen substitution for oxygen for all fluorine contents and, correspondingly, glass fractional compactness increased. Fluorine substitution of oxygen had virtually no effect on molar volume or fractional glass compactness for the three nitrogen contents tested. Young's modulus and microhardness were virtually unaffected by fluorine substitution for oxygen while nitrogen substitution for oxygen caused increases in these two properties. Glass-transition temperature and dilatometric-softening point values all decreased with increasing fluorine substitution levels, while increasing nitrogen substitution caused values for these thermal properties to increase. Correspondingly, the thermal expansion coefficient increased with fluorine and decreased with nitrogen substitution levels. Using property value differences between glasses containing fluorine and the corresponding glass containing 0 eq.% F enabled 24 data points to be used to determine the effect of fluorine on Tg,dil and TDS. The trends were linear with a gradient for both properties of the order of −22°C (eq.% F)−1. For the nitrogen effect, 20 data points were analyzed for trend effects. As expected from earlier work, all trends had good linearity. Gradients were for Tg,dil and TDS +2.5°C (eq.% N)−1, which are fairly similar to previous results in oxynitride systems. All of the data collected and its analysis clearly shows that the substitution effects of fluorine for oxygen and nitrogen for oxygen are independent and additive with the fluorine substitution. The property trends of the glasses are discussed in terms of their implications for glass structure.The authors wish to acknowledge Science Foundation Ireland and Valencian Small and Medium Enterprise Institute for financial support of this research and to thank colleagues in Materials Ireland and the Materials and Surface Science Institute for their help and advice

Factors Controlling Properties of Ca-Mg, Ca-Er, Ca-Nd, or Ca-Y-Modified Aluminosilicate Glasses Containing Nitrogen and Fluorine

Glasses with composition (in eq.%) (30 − x)Ca:xM:55Si:15Al:80O:15N:5F have been prepared with different levels of substitution of Ca2+ cations by Mg2+, Y3+, Er3+, or Nd3+. The properties of these glasses are examined in detail and changes observed in molar volume (MV), free volume, fractional glass compactness, Young's modulus, microhardness, glass transition temperature, and thermal expansion as a function of M content are presented. Using linear regression analysis, evidence is presented which clearly shows that these glass properties are either solely dependent on the effective cation field strength, if modifier cation valency is the same (e.g., Mg substitution for Ca), or dependent on the effective cation field strength and the number of (Si, Al) (O, N, F) tetrahedra associated with each modifier when Ca is replaced by the trivalent modifiers. Combining these correlations with those observed previously relating glass properties to N and F substitution for O, it becomes apparent that glass properties for Ca–M–Si–Al–O–N–F glasses can be described by correlations which involve independent, but additive contributions by N and F substitution levels, effective cation field strength, and the number of tetrahedra associated with each modifier ion

Analysis of noise temperature sensitivity for the design of a broadband thermal noise primary standard

A broadband primary standard for thermal noise measurements is presented and its thermal and electromagnetic behaviour is analysed by means of a novel hybrid analytical?numerical simulation methodology. The standard consists of a broadband termination connected to a 3.5mm coaxial airline partially immersed in liquid nitrogen and is designed in order to obtain a low reflectivity and a low uncertainty in the noise temperature. A detailed sensitivity analysis is made in order to highlight the critical characteristics that mostly affect the uncertainty in the noise temperature, and also to determine the manufacturing and operation tolerances for a proper performance in the range 10MHz to 26.5 GHz. Aspects such as the thermal bead design, the level of liquid nitrogen or the uncertainties associated with the temperatures, the physical properties of the materials in the standard and the simulation techniques are discussed

Identification by Real-time PCR of 13 mature microRNAs differentially expressed in colorectal cancer and non-tumoral tissues

MicroRNAs (miRNAs) are short non-coding RNA molecules playing regulatory roles by repressing translation or cleaving RNA transcripts. Although the number of verified human miRNA is still expanding, only few have been functionally described. However, emerging evidences suggest the potential involvement of altered regulation of miRNA in pathogenesis of cancers and these genes are thought to function as both tumours suppressor and oncogenes. In our study, we examined by Real-Time PCR the expression of 156 mature miRNA in colorectal cancer. The analysis by several bioinformatics algorithms of colorectal tumours and adjacent non-neoplastic tissues from patients and colorectal cancer cell lines allowed identifying a group of 13 miRNA whose expression is significantly altered in this tumor. The most significantly deregulated miRNA being miR-31, miR-96, miR-133b, miR-135b, miR-145, and miR-183. In addition, the expression level of miR-31 was correlated with the stage of CRC tumor. Our results suggest that miRNA expression profile could have relevance to the biological and clinical behavior of colorectal neoplasia

New method to assess teh pozzolanic reactivity of mineral admixtures by measn of pH and electrical conductivity measurements in lime: pozzolan suspensions

A very simple method based on electrical conductivity and pH measurements was proposed for assessing reactivity of pozzolans. Calcium hydroxide:pozzolan water suspensions were monitored by means of measurements of electrical conductivity and pH values. In these suspensions, Ca(OH)2 in solid state was initially present, being them, thus, saturated in this reagent. Three testing temperatures were selected (40, 50 and 60 °C). In the experiments carried out, calcium hydroxide was suspended in deionized water for yielding a lime saturated suspension. The addition of siliceous pozzolan (two types of rice husk ash RHA and two types of densified silica fume DSF were tested) to the saturated lime suspension can produce the unsaturation of the system, depending on the testing time, testing temperature and reactivity of pozzolan. When unsaturation was reached, the loss of electrical conductivity was higher than 30% and the variation of pH was higher than 0.15 units. These threshold values were selected for characterizing the reactivity of pozzolans by means of a proposed template, classifying the pozzolan in three different reactivity levels.Mitsuuchi Tashima, M.; Soriano Martinez, L.; Monzó Balbuena, JM.; Borrachero Rosado, MV.; Akasaki, JL.; Paya Bernabeu, JJ. (2014). New method to assess teh pozzolanic reactivity of mineral admixtures by measn of pH and electrical conductivity measurements in lime: pozzolan suspensions. Materiales de Construcción. 64(316):32-44. doi:10.3989/mc.2014.00914S324464316Schneider, M., Romer, M., Tschudin, M., & Bolio, H. (2011). Sustainable cement production—present and future. Cement and Concrete Research, 41(7), 642-650. doi:10.1016/j.cemconres.2011.03.019Altmann, F., & Mechtcherine, V. (2013). Durability design strategies for new cementitious materials. Cement and Concrete Research, 54, 114-125. doi:10.1016/j.cemconres.2013.08.008Shi, C., Jiménez, A. F., & Palomo, A. (2011). New cements for the 21st century: The pursuit of an alternative to Portland cement. Cement and Concrete Research, 41(7), 750-763. doi:10.1016/j.cemconres.2011.03.0164. Payá, J. (2012) La "transmutación" sostenible de los residuos para nuevas materias primas en el ámbito del concreto. Dyna 79, 38–47.Donatello, S., Freeman-Pask, A., Tyrer, M., & Cheeseman, C. R. (2010). Effect of milling and acid washing on the pozzolanic activity of incinerator sewage sludge ash. Cement and Concrete Composites, 32(1), 54-61. doi:10.1016/j.cemconcomp.2009.09.002Soriano, L., Monzó, J., Bonilla, M., Tashima, M. M., Payá, J., & Borrachero, M. V. (2013). Effect of pozzolans on the hydration process of Portland cement cured at low temperatures. Cement and Concrete Composites, 42, 41-48. doi:10.1016/j.cemconcomp.2013.05.0077. Villar-Coci-a, E.; Frías, M.; Valencia-Morales, E.; Rojas, M.I.S. (2005) Validation of a kinetic-diffusive model to characterize pozzolanic reaction kinetics in sugar cane straw-clay ash/lime systems. Mater. Construcc. 55 [278], 29–40.8. Cruz, J.M.; Payá, J.; Lalinde, L.F.; Fita, I.C. (2011) Evaluation of electric properties of cement mortars containing pozzolans. Mater. Construcc. 61 [301], 7–26.Luxán, M. P., Madruga, F., & Saavedra, J. (1989). Rapid evaluation of pozzolanic activity of natural products by conductivity measurement. Cement and Concrete Research, 19(1), 63-68. doi:10.1016/0008-8846(89)90066-5Payá, J., Borrachero, M. ., Monzó, J., Peris-Mora, E., & Amahjour, F. (2001). Enhanced conductivity measurement techniques for evaluation of fly ash pozzolanic activity. Cement and Concrete Research, 31(1), 41-49. doi:10.1016/s0008-8846(00)00434-8Villar-Cociña, E., Valencia-Morales, E., González-Rodrı́guez, R., & Hernández-Ruı́z, J. (2003). Kinetics of the pozzolanic reaction between lime and sugar cane straw ash by electrical conductivity measurement: A kinetic–diffusive model. Cement and Concrete Research, 33(4), 517-524. doi:10.1016/s0008-8846(02)00998-5Frías, M., Villar-Cociña, E., Sánchez de Rojas, M. I., & Valencia-Morales, E. (2005). 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, 35(11), 2137-2142. doi:10.1016/j.cemconres.2005.07.005Sinthaworn, S., & Nimityongskul, P. (2009). Quick monitoring of pozzolanic reactivity of waste ashes. Waste Management, 29(5), 1526-1531. doi:10.1016/j.wasman.2008.11.010Payá, J., Monzó, J., Borrachero, M. ., Mellado, A., & Ordoñez, L. . (2001). Determination of amorphous silica in rice husk ash by a rapid analytical method. Cement and Concrete Research, 31(2), 227-231. doi:10.1016/s0008-8846(00)00466-xMartínez-Velandia, D., Payá, J., Monzó, J., & Borrachero, M. V. (2011). Effect of sonication on the reactivity of silica fume in Portland cement mortars. Advances in Cement Research, 23(1), 23-31. doi:10.1680/adcr.8.00027Tashima, M. M., Fioriti, C. F., Akasaki, J. L., Bernabeu, J. P., Sousa, L. C., & Melges, J. L. P. (2012). Cinza de casca de arroz (CCA) altamente reativa: método de produção e atividade pozolânica. Ambiente Construído, 12(2), 151-163. doi:10.1590/s1678-86212012000200010Payá, J., Monzó, J., Borrachero, M. V., Peris-Mora, E., & Amahjour, F. (2000). Mechanical treatment of fly ashes. Cement and Concrete Research, 30(4), 543-551. doi:10.1016/s0008-8846(00)00218-