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Made available in DSpace on 2021-06-25T10:30:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Pervious concrete is a construction material widely used in pervious pavements. Pozzolanic materials replacing partially Portland cement can improve mechanical and hydraulic issues associated with the use of pervious concrete. This paper reports the use of wastes from the sugar cane industry (sugar cane bagasse ash and sugar cane straw ash) and their influence on the mechanical and hydraulic properties of pervious concrete for different binder:aggregate mass ratio (1:3.5, 1:4.0, 1:4.5, 1:5.0). The assessed pervious concrete achieved a compressive strength in the range 7.4–14.2 MPa, a total porosity between 26.4 and 32.4% and an infiltration rate of 0.6–1.3 cm/s. Grupo de Pesquisa MAC–Materiais Alternativos de Construção Universidade Estadual Paulista (UNESP) Campus de Ilha Solteira ICITECH–GIQUIMA Group–Grupo de Investigación en Química de los Materiales de Construcción Instituto de Ciencia y Tecnología del Hormigón Universitat Politècnica de Valencia Grupo de Pesquisa MAC–Materiais Alternativos de Construção Universidade Estadual Paulista (UNESP) Campus de Ilha Solteira

En los folios finales de los manuscritos que transmiten la Historia de Inglaterra con el fruto de los tiempos (1504 ante quem – 1509), Rodrigo de Cuero añadió al final de la obra un opúsculo sobre el origen de la Orden de la Jarretera, sus divisas y estatutos. En el presente trabajo, se ofrece la edición de la versión castellana, así como una propuesta de filiación textual a los estatutos revisados por Enrique VII, que fueron redactados en francés durante el último cuarto del siglo xv.

The aim of this study was to use the electrical impedance spectroscopy technique (IS) to carry out a systematic study on the mechanism of metakaolin geopolymerization for up to 7 curing days. The study was developed on two batches of metakaolin (MK), and their reaction processes were compared. Interpretative fundamental elements were developed based on the effective electrical conductivity curves regarding the metakaolin geopolymerization. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were previously carried out and used to interpret and validate the electrical behavior of the fresh and hardened MK-based geopolymer pastes. The results highlighted the sensibility of the impedance technique to the identification and description of the MK geopolymerization process, as well as the changes resulting from even slight variations in the metakaolin composition. Furthermore, this indicated that the geopolymerization process in highly alkaline solutions could be divided into seven stages, including the processes of dissolution, nucleation, precipitation and formation of the gel and, eventually, the retraction/microcracks constitution. Late dissolution processes could be observed during the more advanced stages and were attributed to particles not being fully hydrated.

[EN] The possibility of using pozzolanic materials as a partial substitute for Portland cement (PC) to develop mortars and concretes promotes environmental and economic benefits. The present paper includes an in-depth investigation into the characterization of natural pozzolans from Guatemala for the valorization of these materials. An exhaustive physico-chemical characterization of the starting materials was first carried out. Second, an analysis of the pozzolanic reactivity of both pozzolans was performed using an evolution test of the pH and electrical conductivity measurements and a Frattini test. Finally, pastes and mortars were manufactured with pozzolans T and R as a substitute for PC. The results of the pH and electrical conductivity measurements confirmed that natural pozzolans can be classified as low-reactivity. The Frattini test and the thermogravimetric analysis confirmed the pozzolanic behavior of natural pozzolans at 28 curing days. In the cement pastes, lime fixation was positive for a long curing period, which demonstrated that these pozzolans had medium¿long-term pozzolanic activity, similar to fly ash (FA). The results were confirmed by mechanical assays. The mortars with 15%, 25%, and 35% substitutions of cement for pozzolans had strength gain percentages of around 13¿15% at 90 curing days., This research was funded by Adsideo Cooperacion 2012 (Centro de Cooperacion al Desarrollo UPV).

La Demanda del Santo Grial, introducción y edición de José Ramón Trujillo, Alcalá de Henares: Universidad de Alcalá. Servicio de Publicaciones (Los Libros de Rocinante, 33), 2017

Large amounts of waste are derived not only from construction processes, but also the demolition of existing buildings. Such waste occupies large volumes in landfills, which makes its final disposal difficult and expensive. Reusing this waste type is generally limited to being employed as filler material or recycled aggregate in concrete, which limits its valorisation. The present work proposes reusing construction and demolition waste to manufacture alkali-activated cement to improve its sustainability and recovery. Construction and demolition waste (C&DW) from a demolition waste collection plant in Valencia (Spain) was physically and chemically characterised. This residue contained large fractions of concrete, mortar, bricks, and other ceramic materials. X-ray fluorescence (XRF) analysis showed that its chemical composition was mainly CaO, SiO2 and Al2O3. X-ray diffraction (XRD) analysis revealed that it presented some crystalline products, and quartz (SiO2) and calcite (CaCO3) were the main components. Blends of C&DW and blast furnace slag (BFS) were alkali-activated with mixtures of sodium hydroxide and sodium silicate. The corresponding pastes were characterised by techniques such as thermogravimetry and scanning electron microscopy (SEM). The alkali-activated mortars were prepared, and the resulting mortars’ compressive strength was determined, which was as high as 58 MPa with the 50% C&DW-50% BFS mixture. This work concluded that it is possible to make new sustainable binders by the alkali activation of C&DW-BFS without using Portland cement.

Spent fluid catalytic cracking (FCC) is produced worldwide and has homogeneous chemical, mineralogical, and physical properties, regardless of the petrol refinery source. This good performance facilitates its reuse, especially for making different types of cement or concrete. Spent FCC shows excellent reactivity in pozzolanic behavior terms because of high reactive silica and alumina contents. It has been demonstrated that milling waste represents appropriate conditioning for yielding the highest reactivity, but from the rheological point of view, replacement of Portland cement with spent FCC worsens the workability of the mixes. Spent FCC contains a significant amount of nickel and vanadium, but these heavy metals are strongly bonded to the structure and are not leached when specimens are tested under acidic conditions. The use of this waste has been described in different constructions. In all cases, the performance of the designed materials is very good, so it could be implemented as a new addition to the construction materials industry.

Three-dimensional printed concrete (3DPC) is a relatively recent technology that may be very important in changing the traditional construction industry. The principal advantages of its use are more rapid construction, lower production costs, and less residues, among others. The choice of raw materials to obtain adequate behavior is more critical than for traditional concrete. In the present paper a mixture of cement, silica fume, superplasticizer, setting accelerator, filler materials, and aggregates was studied to obtain a 3DPC with high resistance at short curing times. When the optimal mixture was found, metallic fibers were introduced to enhance the mechanical properties. The fresh and hard properties of the concrete were analyzed, measuring the setting time, workability, and flexural and compressive strength. The results obtained demonstrated that the incorporation of fibers (2% in volume) enhanced the flexural and compressive strength by around 163 and 142%, respectively, compared with the mixture without fibers, at 9 h of curing. At 28 days of curing, the improvement was 79.2 and 34.7% for flexural and compressive strength, respectively.

[EN] Changes caused in the porous microstructure of ordinary Portland cement (OPC) mortars were studied using electrical impedance spectroscopy (EIS) and equivalent circuit (EqC). Two successive processes, at 20 ºC and 50 °C, consisting of several drying-rewetting cycles, were applied to the mortars. After each cycle, the electrical impedance and the amount of water absorbed were measured. The EIS-EqC methodology allowed to find two distributed impedance relaxations, associated to capillary and gel-C-S-H porosities, respectively. At room temperature any microstructural change was not detected. Nevertheless, at 50 °C two microstructural changes were inferred: 1) the volume of accessible porosity increased (pore coarsening) and 2) the surface of the conductive path through C-S-H gel became more conductive (surface smoothing)., The authors would like to thank the Spanish Ministry of Science and Innovation for supporting this research through the project BIA 2011-26947.

Made available in DSpace on 2018-12-11T16:47:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-09-15 This study presents the use of olive-stone biomass ash (OBA) as an alkali source in alkali-activated materials (AAM) based on blast furnace slag (BFS). The OBA was physically and chemically characterized. It presented high K2O and CaO contents, and yielded high alkalinity in water medium. The newly designed OBA + BFS mixes (a 100% waste-based AAM) reached a compressive strength of 30 MPa after 7 days of curing at 65 °C, which was higher than for BFS activated with KOH solution. Thermogravimetric studies showed the formation of C-S-H/(C,K)-A-S-H gels and hydrotalcite. The OBA presented excellent performance as a component in AAM and a good valorisation was achieved. ICITECH – GIQUIMA Instituto de Ciencia y Tecnología del Hormigón Universitat Politècnica de Valencia UNESP – Grupo de Pesquisa MAC – Materiais Alternativos de Construção Universidade Estadual Paulista (UNESP) Faculdade de Engenharia, Ilha Solteira UNESP – Grupo de Pesquisa MAC – Materiais Alternativos de Construção Universidade Estadual Paulista (UNESP) Faculdade de Engenharia, Ilha Solteira

El reinado de Arturo ocupa un lugar destacado en la tradición historiográfica británica desde que en el siglo XIIGeoffrey de Monmouth lo insertara en la genealogía de reyes ingleses. La obra del monje galés devino la fuenteprincipal de la mayoría de narraciones y crónicas medievales y post-medievales que aparecieron hasta bien entradoel siglo XVIII, entre ellas el Brut en prosa o The Chronicles of England. De una impresión de esta última (London:Wynkyn de Worde, 1502) procede la traducción castellana de Rodrigo de Cuero, la Historia de Inglaterra con el fruto delos tiempos (1509), encargada por Catalina de Aragón. El objetivo del artículo es examinar el tratamiento de los episodiosdedicados al reinado del legendario monarca en la versión castellana y las alteraciones que presenta respectode su fuente inglesa.

[EN] The use of almond-shell biomass ash (ABA) as an alternative component to the commercial reagents used in the activation of blast furnace slag (BFS) systems is investigated. The presence in its chemical composition of a high content of K2O indicate s that it can alkalinize the medium. 100% waste-based mixtures ABA/BFS were studied by micro- and macrostructural tests. A compressive strength of 44 MPa was achieved by the mortar with 25% ABA addition cured for 7 days at 65 °C. The microstructural analysis showed the formation of slightly different C(K)-A-S-H gels to those formed when using KOH. The use of ABA in BFS mortars is shown as a greener alternative for onstruction materials because the replace- ment of synthetic chemical reagents that produced around a 75¿80% of reduction in the values of kgCO2eq/m3 material, We wish to thank the Spanish Government for project support (MINECO/FEDER-Project RTI2018-09612-B-C21). The authors would like to thank Borges Agricultural & Industrial Nuts for supplying the biomass ash and the Electronic Microscopy Service at the UPV.

[EN] Use of lime as construction material is limited mainly by low initial strength. These properties can be improved by adding pozzolanic materials, but the evolution of the reaction usually needs older ages than 7 days. Alkali-activated materials, or geopolymers, are good-performance materials that can be produced with residual waste. The combination of traditional and new materials can lead to new uses of lime mortars. This paper studies a lime/pozzolan and geopolymer mixture. The chosen pozzolan is fluid catalytic cracking catalyst residue (FCC), a material employed as a precursor in alkali-activated material. FCC is activated by two activators: a mixture of NaOH and waterglass; a mixture of NaOH and rice husk ash (RHA). The new materials were studied in microstructure and mechanical behaviour terms. The results demonstrated that lime/pozzolan/geopolymer obtained superior compressive strengths after 1 curing day to that obtained for the corresponding lime/pozzolan mortar after 90 days. An improvement in compressive strength of around 145% was achieved for the mortar with 40% geopolymer compared to the mortar with only lime/pozzolan at 28 curing days., This research was supported by Centro de Cooperacion al Desarrollo (CCD) of the Universitat Politecnica de Valencia, ADSIDEO-COOPERACION 2017 Program "Reutilizacion de residuos agricolas e industriales para la fabricacion de conglomerantes sostenibles en paises en desarrollo (AD1708)". The investigation is framed within the ECOSOST (RTI2018-097612-B-C21-AR) project supported by MINECO and FEDER funds. The authors are grateful to the Electron Microscopy Service of the Universitat Politecnica de Valencia, Dacsa Group S.A., Cales Pascual S.L. and BP Oil Espana S.A.U.

The present work aims to obtain an optimal Portland cement, gypsum and fly ash (OPC-G-FA) ternary binder matrix and assess both the addition of paper pulp-by means of mechanical dispersion in aqueous suspension-for cementitious composites reinforcement and the fiber properties over time. To evaluate microfibers preservation from pulp in low-alkaline environments, ternary binder matrices OPC-G-FA are optimized to achieve lower pH values. For that purpose, pH and electrical conductivity over time were analyzed. Only samples with the lowest content in Portland cement (15 20%) offered low alkalinity for short-term. The use of ternary binder systems enhances microfibers conservation compared with control samples (matrices 100% Ordinary Portland Cement) by using FA that, as expected, reduces the presence of Ca(OH)2 in the matrix. Mechanical results prove that obtained matrices yield to a mechanical properties maintenance unlike samples with OPC matrices where toughness is reduced by 95%, Financial support for this research project was provided by Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq - Brazil) by means of a grant [351196/2014-5].

High pozzolanic activity of the residue spent catalytic cracking catalyst (FCC) has been reported by various authors in recent years. However, no report on the lime fixation of this residue when dosed together with other pozzolan has been developed, such material partially replacing Portland cement in the manufacture of hydraulic binders. One of the possibilities is to mixture it with fly ash (FA). This joint replacement provides several advantages in that: 1) Generation of FCC is low compared to other pozzolans including fly ash (FA); 2) The FCC tends to react to short curing times, while the FA does at longer times; 3) The FCC is demanding water, while the FA tends to improve the fluidity of the binder. This paper studies on cement pastes by thermogravimetric analysis of various mixed substitutions FCC:FA, varying the replacing percentage for FCC in the 0-15% range and for FA in the 0-30% range. Evolution of pastes was monitored by means of thermogravimetric analysis on pastes cured for 3-365 days. Products of the pozzolanic reaction were identified by SEM, being some of them cubic crystals (C3AH6 and/or hydrogarnet). By TGA analysis it was observed that when the %FCC is increased in the system, the amount of the calcium aluminate hydrates (C-A-H) and calcium aluminosilicate hydrates (C-A-S-H) also increased. Negative values of fixed lime were obtained due to an acceleration of the hydration of OPC, since the FA particles acted as nucleation sites for the precipitation of hydrated compounds. Fixed rates up to 90% of hydrated lime with substitutions as high as 45% in Portland cement system at one year of curing were reached. (C) 2016 Elsevier B.V. All rights reserved., This work was supported by Ministerio de Ciencia y Tecnologia, Spain (Project MAT 2001-2694).

The use of ternary systems composed of ordinary Portland cement (OPC) and two pozzolanic mineral admixtures could supply several advantages in terms of the properties in both fresh and hardened states. Fly ash (FA) and spent fluid catalytic cracking catalyst (FCC) were combined to produce high strength mortars due to a synergic effect. OPC/FA systems (70%/30%) and OPC/FA/FCC systems (70%/20%/10%) were analyzed by thermogravimetric and SEM techniques. Mortars with different binder/sand ratios were prepared in order to yield high compressive strength values. On the one hand, fly ash particles act as nucleation sites that favour the hydration of Portland cement particles: at early stages (7 days), the calculated fixed hydrated lime values were negative, suggestive of a nucleating effect. For a longer curing period (90 days), the pozzolanic effect develops, as can be noted in terms of its compressive strength behaviour. The 90-days curing strength for OPC/FA mortars ranged between 96 and 98 MPa. In ternary mixtures (OPC/FA/FCC), FCC act as pozzolan during the initial 7 days period; the presence of fly ash particles favoured the presence of more portlandite by means of the nucleation effect. For longer curing times, fly ash particles also contribute to strength development, producing a synergic effect with FCC. The 90 days curing strength for OPC/FA/FCC mortars ranged between 103 and 106 MPa. Binary and ternary mortars reached strength activity index values equal or igher to the unit. Contributions to the strength (i.e. hydration of cement, the nucleation effect, and early and long term pozzolanic effects) have been calculated for 7 and 90 curing days pozzolan-containing mortars., This work was supported by Ministerio de Ciencia y Tecnologia, Spain (Project MAT 2001-2694). Thanks are given to the Electron Microscopy Service of the Universitat Politecnica de Valencia.

[EN] Reusing ceramic waste as a pozzolanic admixture may offer environmental benefits as it allows the reduction in the consumption of natural resources and energy, and the reduction of CO2 emissions associated with Portland cement (PC) production, while valorising waste materials with a long biodegradation period. This paper assessed the pozzolanic activity of three different ceramic waste types: red clay bricks (RCB), ceramic tiles (TCW) and ceramic sanitary-ware (CSW). After adapting their particle size by crushing and milling, each was used to replace 0 to 50 wt% PC (CEM I 42.5 R type). The milled powders were characterised by laser diffraction, field emission scanning electron microscopy (FESEM), X-ray fluorescence (XRF) and X-ray diffraction (XRD), and consistency and setting time tests were used to investigate the fresh behaviour of the ceramic waste/PC blended pastes. A basic sustainability analysis was performed, and the pozzolanic activity of RCB, TCW and CSW was assessed by compressive strength tests (performed in mortars cured at room temperature from 3 to 365 days) and microstructural analyses (thermogravimetry, XRD and FESEM performed in the pastes cured at 20 °C for 28 and 90 days). The pozzolanic reaction of these waste materials improved with curing time, and all the mortars prepared with up to 25 wt% RCB, TCW or CSW met the mechanical requirements set out for coal fly ashes, whatever the ceramic waste type used. Among them, these results open up the possibility of partially replacing PC with the closest available ceramic waste, which would reduce the CO2 emissions and economic cost deriving from transporting waste., The authors are grateful to the Spanish Ceramic Tile Manufacturers' Association (ASCER) for supporting this study through the collaboration agreement with Universitat Jaume I (Aula Ceramica). They also thank the Electron Microscopy Service of the Universitat Politecnica de Valencia and the Central Service for Scientific Instrumentation of the Universitat Jaume I of Castellon for helping with the microstructural characterisation tests.

El reinado de Arturo ocupa un lugar destacado en la tradición historiográfica británica desde que en el siglo XIIGeoffrey de Monmouth lo insertara en la genealogía de reyes ingleses. La obra del monje galés devino la fuenteprincipal de la mayoría de narraciones y crónicas medievales y post-medievales que aparecieron hasta bien entradoel siglo XVIII, entre ellas el Brut en prosa o The Chronicles of England. De una impresión de esta última (London:Wynkyn de Worde, 1502) procede la traducción castellana de Rodrigo de Cuero, la Historia de Inglaterra con el fruto delos tiempos (1509), encargada por Catalina de Aragón. El objetivo del artículo es examinar el tratamiento de los episodiosdedicados al reinado del legendario monarca en la versión castellana y las alteraciones que presenta respectode su fuente inglesa.

[EN] The use of almond-shell biomass ash (ABA) as an alkali source in one-part blast furnace slag (BFS) mortars activation was investigated for the first time. The chemical composition of ABA revealed high alkalinity ash to be composed mainly of K2O and CaO. The one-part 100% waste-based mortars and pastes were studied by mechanical and thermogravimetric tests. The compressive strength values of the newly designed materials were higher than the mortars fabricated with commercial products (36.4 versus 21.2 MPa). The formation of C-S-H/(C,K)-A-S-H gels took place in the thermogravimetric studies. The use of ABA in mortars proved an interesting alternative to chemical reagents in alkali activated cements., We wish to thank Borges Agricultural & Industrial Nuts for supplying ash and the Electronic Microscopy Service at the UPV. This research was supported by Spanish governerment MINECO/FEDER (Project RTI2018-097612-B-C21).

The necessity of cleaning wastewater because of environmental concerns produces a huge amount of sewage sludge (SS). The calcination of SS removes organic matter and reduces 90% of the original volume. The remaining material of inorganic nature is referred to as SS ash (SSA). SSA is a powdered material that contains high percentages of SiO2, Al2O3, Fe2O3, CaO, P2O5 and SO3, and has shown moderate reactivity in terms of pozzolanicity. This behaviour makes it viable as a cement replacement material in mortar and concrete, or in new alkali-activated binders. This approach will assist in achieving zero waste in relation to urban wastewater. Several aspects must be taken into account in this valorisation context: the origin of the wastewater and chemical and mineralogical nature of the SSA, calcination process, treatment of the ash and the dosage in mortar of concrete (SSA acting as filler or pozzolan), among others.

[EN] Alkali-activated binders (AABs) are a material obtained from the combination of a solid precursor and an alkaline activating solution. In this study, one solid precursor used was blast-furnace slag (BFS) and the other was an agro waste: sugar cane straw ash (SCSA). Sodium hydroxide was used for preparing activating solutions. In order to reach the potential reactivity of the SCSA, a study varying the BFS/SCSA mass ratio and H2O=Na2O molar ratio was carried out. The BFS/SCSA ratio varied from 100=0 to 70=30, and H2O=Na2O was studied in the range of 11.1¿18.5. To fulfill this objective, specimens were assessed by their compressive strength of mortars and microstructural studies of pastes [X-ray diffraction (XRD); thermogravimetric analysis (TGA); Fourier transform infrared spectroscopy (FTIR); and field emission scanning electron microscopy (FESEM)] in the curing time range of 3¿90 days at 25°C. Results from these tests showed that the best BFS/SCSA and H2O=Na2O ratios were 70=30 and 18.5, respectively. This study revealed an interesting valorization of the SCSA as a complementary precursor in BFS-based AABs because of the improvement of mechanical properties and the reduction in the consumption of BFS in AAB, The authors would like to thank CNPq processo n° 401724/2013-1, CNPq processo n° 140779/2015-0, and the Ministerio de Educación, Cultura y Deporte of Spain ( Cooperación Interuniversitaria program with Brazil PHB-2011-0016-PC). Thanks are also given to the Electron Microscopy Service of the Universitat Politècnica de València.

In this paper, the effect of calcium aluminate cement (CAC) additions on the alkali activation of red clay brick waste (RCBW) was studied at room temperature and at 65 C. RCBW was partially replaced with CAC (0e50 wt.%) and blends were activated with NaOH and sodium silicate solutions. The compressive strength evolution was tested on mortars and the nature of the reaction products was analysed by infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, microscopic studies and pH measurements. The results show that the use of CAC accelerates the activation process of RCBW so that 50 MPa were obtained in the blended mortars containing 40 wt.% CAC cured for 3 days at room temperature. CAC did not undergo normal hydration and only the C3AH6 phase was identified in the pastes blended with more than 30 wt.% CAC and cured at 65 C, while the main reaction product was a cementitious gel containing Ca and Al from CAC., The authors are grateful to the Spanish Ministry of Science and Innovation for supporting this study through Project GEOCEDEM BIA 2011-26947, and to FEDER funding.

Nowadays, scientific community is looking for alternatives to reduce the problem of CO2emissions, making more sustainable binders and reusing wastes from other industries.In this line, the technology of geopolymers was born, in which, binders based on alkali-activation can be produced entirely or almost entirely from waste materials. In alkali-activation a source of aluminosilicate is dissolved by a highly alkaline solution previous to precipitation reactions that form a gel binder.The use of alumino-silicate minerals such as metakaolin, blast furnace slag and fly ash to produce alkali-activated cements has been extensively studied and it’s increasing the interest in investigating the suitability of using other materials. Different wastes containing silica and alumina, such as hydrated-carbonated cement, glass, fluid catalytic cracking catalyst residues (FCC) have been activated.The aim of this study is to verify if the use of geopolymers is compatible with the manufacturing technology of typical building elements, in this case roof tiles.Mechanical properties of mortars and roof tiles using as source of aluminosilicates FCC have been studied, with different mixtures and variating the proportions of NaOH and waterglass.Compressive strength development was evaluated in mortars cured at 20oC for 7 and 28 days and flexural strength, impermeability and impact resistance were evaluated in roof tiles. The results obtained demonstrated the feasibility on the use of geopolymers in the design of new products with less CO2emissions and then the contribution to the sustainability in the construction sector.

Thermogravimetric analysis is one of the most common instrumental techniques used for the characterization of pastes, mortars and concretes based on both calcium hydroxide and Portland cement. Important information about pozzolanic materials can be assessed concerning calcium hydroxide consumption and the formation of new hydrated products. Nevertheless, in some cases, problems associated with the overlapped decomposition processes for hydrates make the analysis of obtained data difficult. In this paper, the use of high-resolution thermogravimetric analysis, a powerful technique that allows separating decomposition processes in analysis of hydrated binders, was performed for spent FCC catalyst Portland cement pastes. These pastes were monitored for 1, 4, 8 h and 1, 2, 3, 7 and 28 curing days. In order to study the influence of the pozzolanic material (spent FCC catalyst), Portland cement replacements of 5, 15 and 30 % by mass were carried out. The presence of spent FCC catalyst in blended pastes modified the amount and the nature of the formed hydrates, mainly ettringite and stratlingite., This work was supported by the Ministry of Science and Technology, Spain (Project MAT 2001-2694).

The scope of this paper is to study the sulphate attack on concrete with new testing methods based on vibrational spectroscopy with mechanical waves. These are based on Non-linear Impact Resonance Acoustic Spectroscopy (NIRAS) that allows detecting the frequency shift of its resonant modes. Both, signal quality factor and alpha, are measured to monitor the increase of the non-linearity of the material due to the stiffness change on the matrix after being attacked. Different Portland cement matrices were assessed and results between vibrational tests and the traditional expansion ASTM method were compared. Two types of cement with different C3A content were tested for external sulphate attack and one cement with high C3A content with different amount of addition of SO3 on the original mix was tested for internal attack. NIRAS was suitable for monitoring external sulphate attack process. A microstructual analysis was carried out with thermogravimetry (TG), scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques in order to detect harmful products on damaged series., The authors acknowledge the financial support of the Ministerio de Ciencia e Innovacion MICINN, Spain, and FEDER funding (Ondacem Project: BIA 2010-19933).

Many agrowastes are being used for energy production by combustion in power plants. This process generates huge amounts of ash, which has a potential pozzolanic activity for blending with Portland cement or hydrated lime. In this paper, the ash obtained from elephant grass (Pennisetum purpureum Schum var. purple) leaves (EGLs) was studied, including the silicon content and its distribution, the presence of other compounds, and in addition, the presence of silica bodies (phytoliths). Combustion temperatures of 450 and 650°C produced an unaltered inorganic skeleton (spodogram), whereas at 850°C, there is a sintering process because of high potassium content in the ash. Phytoliths and different types of hairs were identified, and they contained high percentages of silica. Magnesium (mainly as periclase) was distributed in the most porous parts in the interior of the leaves. The silica can react with calcium hydroxide (pozzolanic reaction) forming calcium silicate hydrates (observed by field-emission scanning electron microscopy and thermogravimetric analysis). Fixed lime percentages at 28 curing days (63%) indicated the high reactivity of EGL ashes in calcium hydroxide pastes due to the pozzolanic reaction. This study demonstrates the possibility of the reuse of ashes from EGLs for the production of environmental-friendly cements.

Made available in DSpace on 2020-12-12T00:55:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-10 Universitat Politècnica de València Alkali-activated cements (AACs) technology is being widely investigated as a replacement for ordinary Portland cement (OPC) for environmental benefits. Blast furnace slag (BFS) is one of the most well known precursors used in AACs, having comparable properties to those of traditional OPC-based materials. AACs require alkali solutions, which are commonly based on a combination of sodium or potassium hydroxides with sodium or potassium silicates in high concentration. These alkali solutions represent the use of chemical reagents, and thus can have major environmental, health and economic impacts. Olive-stone (also known as olive pits) biomass ash (OBA) is a residue mainly composed of calcium and potassium oxides. Rice husk ash (RHA) is a rich silica residue from the combustion of rice husk. The combination of both residues can produce a good activating reagent for BFS-based AACs. In the present work, 100% waste-based ternary alkali-activated mortars (TAAM) based on BFS activated by OBA and RHA were developed. The mortars were assessed in terms of their dosage, curing treatment and time evolution. Finally an eco-friendly 100% waste-based TAAM with 67.39 ± 0.44 MPa after 90 days of curing at 20 °C is obtained and a complete microstructural characterization shows a dense and compact matrix with binding gel products labelled as C(K)–S(A)-H and C(K)–S–H. ICITECH – GIQUIMA Group – Grupo de Investigación en Química de los Materiales de Construcción Instituto de Ciencia y Tecnología del Hormigón Universitat Politècnica de Valencia UFES - Federal University of Espírito Santo Department of Civil Engineering Universidade Estadual Paulista (UNESP) Faculdade de Engenharia de Ilha Solteira. MAC – Grupo de Pesquisa em Materiais Alternativos de Construção Universidade Estadual Paulista (UNESP) Faculdade de Engenharia de Ilha Solteira. MAC – Grupo de Pesquisa em Materiais Alternativos de Construção

This investigation presents an important contribution to the understanding of the “zero discharge in the aluminium cycle” goal. The salt slag recycled by-product was reused as alternative aerating agent in the manufacture of cellular concretes: fluid catalytic cracking catalyst (FCC) – based geopolymer (GCC) and blast furnace (BFS) – based alkali-activated (AACC). The hydrogen emission test was used to evaluate the gas releasing properties because of the presence of metallic aluminium in the salt slag. Density (kg/cm3), compressive strength (MPa) and thermal conductivity (W/mK) for GCC were 75, 6.9 and 0.31 and for AACC were 602, 7.5 and 0.16.

The reduction in Portland cement consumption means lower CO 2 emissions. Partial replacement of Portland cement by pozzolans such as fly ash has its limitations due to the quantity of calcium hydroxide generated in the mix. In this work we have studied the contribution of the addition of hydrated lime to Portland cement + fly ash systems. We have also studied several levels of cement replacement, ranging from 15% to 75%. The best mechanical results were obtained replacing 50% of Portland cement by the same amount of fly ash plus the addition of hydrated lime (20% respect to the amount of fly ash). In these systems, an acid-base self-neutralization of the matrix has occurred through a pozzolanic reaction of fly ash with portlandite liberated in the hydration of Portland cement and the added hydrated lime. It has been identified for these mixtures a significant amount of hydrated gehlenite, typical reaction product from rich-alumina pozzolans.

Objective The aim of this research was to investigate the influence of the alkali activator concentration and calcium dosage on the fresh behavior, compressive strength and microstructure of the binder produced by the alkali activation of porcelain stoneware waste, using NaOH and sodium silicate solution as activators. Materials Porcelain stoneware waste, NaOH and sodium silicate. Method Tested properties of mortars were the compressive strength and the setting times. Thermogravimetric analyses, microscopic studies, pH measurements, XRD and FTIR tests were used to assess the evolution of the microstructure developed. Results The results show that the activator concentration and calcium to sodium molar ratio strongly influence the fresh behavior and the hardening process of mortars. A linear evolution of compressive strength with sodium addition was observed when keeping the SiO2 concentration constant. Mortar samples with up to 36 MPa under compression were obtained after curing for 7 days at 65 °C., The authors are grateful to the Spanish Ministry of Science and Innovation for supporting this study through Project GEOCEDEM BIA 2011-26947, and to FEDER funding.

Spent FCC catalyst is a waste from the petrochemical industry which has excellent pozzolanic properties, containing more than 90% silica and alumina. Its similarity to metakaolin creates interesting prospects for its use in the production of alkali-activated binders. In this study, the alkali activation of this residue, spent FCC catalyst, through mixtures with alkali hydroxide and silicate solutions (both sodium and potassium) has been carried out. The alkali cation had an important role in the nature of AA-FCC pastes: some differences in the mass loss in the thermogravimetric tests and in the X-ray mineral characterization were found. No significant differences in compressive strength were observed for mortars cured for 3 days in several conditions: room temperature and 65oC. Prepared AA-FCC mortars had a compressive strength of about 65-70 MPa. Microstructural studies showed that an amorphous, dense and compact microstructure was obtained, independent of the activating solution and curing condition.

The aim of this paper is to study hydration processes in cement pastes and mortars, blended with either metakaolin (MK) or a catalyst used in catalytic cracking (FCC), and cured at low temperature. The amounts of hydrates and portlandite in pastes have been determined for 3–28 days curing at 5–20 °C. Microstructural study, using thermogravimetric analysis of the pastes, has shown that FCC acts mainly as a pozzolan at low temperatures (5–10 °C), whereas MK also accelerates Portland cement hydration. Mechanical strengths of a control mortar, and mortars made with 15% replacement of cement by these two pozzolans, have been measured. Both mortars containing pozzolans exhibited a relative increase in compressive strength when cured at 5 °C. A limestone filler (LF) has been used to compare the effects of adding inert or pozzolanic materials. Finally, mortars were prepared by partially replacing aggregates with either MK, FCC or LF. The MK and FCC are effective materials even for low curing temperatures, especially when they are used to replace a fraction of the aggregates in mortars.

In this paper, mortars and pastes containing large replacement of pozzolan were studied by mechanical strength, thermogravimetric analysis (TGA), scanning electronic microscopy (SEM), mercury intrusion porosimetry (MIP) and electrical impedance spectroscopy (EIS). The effect of metakaolin (35%) and fly ash (60%) was evaluated and compared with an inert mineral addition (andalusite). The portlandite content was measured, finding that the pozzolanic reaction produced cementing systems with all portlandite fixed. The EIS measurements were analyzed by the equivalent electrical circuit (EEC) method. An EEC with three branches in parallel was applied. The dc resistance was related to the degree of hydration and allowed us to characterize plain and blended mortars. A constant phase element (CPE) quantified the electrical properties of the hydration products located in the solid¿solution interface and was useful to distinguish the role of inert and pozzolanic admixtures present in the cement matrix., The authors thank the Universitat Politecnica de Valencia (UPV, Vicerrectorado de Investigacion) for its support (project PAID-05-09 ref 4302) and Debra Westall (UPV) for revising the manuscript.

Reuse of industrial and agricultural wastes as supplementary cementitious materials (SCMs) in concrete and mortar productions contribute to sustainable development. In this context, fluid catalytic cracking catalyst residue (spent FCC), a byproduct from the petroleum industry and petrol refineries, have been studied as SCM in blended Portland cement in the last years. Nevertheless, another environmental friendly alternative has been conducted in order to produce alternative binders with low CO2 emissions. The use of aluminosilicate materials in the production of alkali-activated materials (AAMs) is an on going research topic which can present low CO2 emissions associated. Hence, this paper studies some variables that can influence the production of AAM based on spent FCC. Specifically, the influence of SiO2/Na2O molar ratio and the H2O/spent FCC mass ratio on the mechanical strength and microstructure are assessed. Some instrumental techniques, such as SEM, XRD, pH and electrical conductivity measurements, and MIP are performed in order to assess the microstructure of formed alkali-activated binder. Alkali activated mortars with compressive strength up to 80 MPa can be formed after curing for 3 days at 65 C. The research demonstrates the potential of spent FCC to produce alkali-activated cements and the importance of SiO2/Na2O molar ratio and the H2O/spent FCC mass ratio in optimising properties and microstructure., Authors would like to thank to the Ministerio de Ciencia e Innovacion (MICINN) of the Spanish Government (BIA2011-26947) and to FEDER for funding, and also to the PROPG - UNESP "Universidade Estadual Paulista Julio de Mesquita Filho'', Brazil.

The using of wastes in the design of new binders for construction is the key for the success of new developments regarding environmental, technical, and economic issues. Biomass ashes usually contain reactive compounds for creating binding matrices by means of alkali activation and by blending with hydrated lime. These ashes are available in many countries, especially developing countries, and their using in new binders could be a feasible option for communities with few resources. Additionally, with the using of these biomass waste-derived ashes a reduction in the CO2 emissions from the preparation of the binder could be achieved. In this chapter, different uses of biomass ashes in the preparation of binders are described. Many examples have been reported, most of them involving the use of rice husk ash (RHA), sugarcane bagasse ash (SCBA), palm oil fuel ash (POFA), and wood ash (WA). In general, for alkali-activated systems, most reported results involve the use of mixtures of biomass ashes and other mineral admixtures (blast furnace slag (BFS), metakaolin, fly ash). Interestingly, the use of RHA as a component of the alkali activating solution shows excellent potential for replacing sodium silicate solution, which mitigates the economic and environmental issues associated with this chemical reagent. Hydrated lime-based binders containing biomass ashes were described and studied many years ago; however, in recent years this has become an active field in terms of new applications and new mixtures, because of the availability of biomass ashes and the interest in the design of low-CO2 binders.