44 research outputs found
A roadmap for production of cement and concrete with low-CO2 emissions
This review will show that low-CO2 cements can be produced to give superior durability, based on a sound understanding of their microstructure and how it impacts macro-engineering properties. For example, it is essential that aluminium is available in calcium-rich alkali-activated systems to offset the depolymerisation effect of alkali cations on C-(N-)A-S-H gel. The upper limit on alkali cation incorporation into a gel greatly affects mix design and source material selection. A high substitution of cement clinker in low-CO2 cements may result in a reduction of pH buffering capacity, hence susceptibility to carbonation and corrosion of steel reinforcement. With careful mix design, a more refined pore structure and associated lower permeability can still give a highly durable concrete. It is essential to expand thermodynamic databases for current and prospective cementitious materials so that concrete performance and durability can be predicted when using low-CO2 binders. Cationic copolymer and amphoteric plasticisers, when available commercially, will enhance the development of alkali-activated materials. The development of supersonic shockwave reactors will enable the conversion of a wide range of virgin and secondary source materials into cementitious materials, replacing blast furnace slag and coal fly ash that have dwindling supply. A major obstacle to the commercial adoption of low-CO2 concrete is the prescriptive nature of existing standards and design codes, so there is an urgent need to shift towards performance-based standards. The roadmap presented here is not an extension of current cement practice, but a new way of integrating fundamental research, equipment innovation, and commercial opportunity
Structural evolution of synthetic alkali-activated CaO-MgO-Na₂O-Al₂O₃-SiO₂ materials is influenced by Mg content
Stoichiometrically controlled alkali-activated materials within the system CaO-MgO-Na₂O-Al₂O₃-SiO₂ are produced by alkali-activation of high-purity synthetic powders chemically comparable to the glass in ground granulated blast furnace slag, but without additional minor constituents. Mg content controls the formation of hydrotalcite-group and AFm-type phases, which in turn strongly affects C-(N)-A-S-H gel chemistry and nanostructure. Bulk Mg content and the Mg/Al ratio of hydrotalcite-group phases are strongly correlated. With sufficient Ca, increased bulk Mg promotes formation of low-Al C-(A)-S-H and portlandite, due to formation of hydrotalcite-group phases and a reduction in available Al. Hydrotalcite-group phase formation is linked to increased C-(N)-A-S-H gel polymerisation, decreased gel Al uptake and increased formation of the ‘third aluminate hydrate’. These findings highlight the importance of considering available chemical constituents rather than simply bulk composition, so that the desired binder structure for a particular application can be achieved
Alkaline activation of ceramic waste materials
Ceramic materials represent around 45 % of construction and demolition waste, and originate not only from the building process, but also as rejected bricks and tiles from industry. Despite the fact that these wastes are mostly used as road sub-base or construction backfill materials, they can also be employed as supplementary cementitious materials, or even as raw material for alkali-activated binders This research aimed to investigate the properties and microstructure of alkali-activated cement pastes and mortars produced from ceramic waste materials of various origins.
Sodium hydroxide and sodium silicate were used to prepare the activating solution. The compressive strength of the developed mortars ranged between 22 and 41 MPa after 7 days of curing at 65 C, depending on the sodium
concentration in the solution and the water/binder ratio. These results demonstrate the possibility of using alkaliactivated ceramic materials in building applications.The authors are grateful to the Spanish Ministry of Science and Innovation for supporting this study through Project GEOCEDEM BIA 2011-26947, and also to FEDER funding. They also thank Universitat Jaume I for supporting this research through Lucia Reig's granted research stay.Reig Cerdá, L.; Mitsuuchi Tashima, M.; Soriano, L.; Borrachero Rosado, MV.; Monzó Balbuena, JM.; Paya Bernabeu, JJ. (2013). Alkaline activation of ceramic waste materials. Waste and Biomass Valorization. 4:729-736. https://doi.org/10.1007/s12649-013-9197-zS7297364Puertas, F., GarcÃa-DÃaz, I., Barba, A., Gazulla, M.F., Palacios, M., Gómez, M.P., MartÃnez-RamÃrez, S.: Ceramic wastes as alternative raw materials for Portland cement clinker production. Cement Concrete Comp. 30(9), 798–805 (2008)Ministerio de Fomento de España, Catálogo de Residuos Utilizables en Construcción (2010). http://www.cedexmateriales.vsf.es/view/catalogo.aspx . Retrieved on 6 Dec 2012Stock, D.: World production and consumption of ceramic tiles. Tile Today 73, 50–58 (2011)Medina, C., Juan, A., FrÃas, M., Sánchez-de-Rojas, M.I., Morán, J.M., Guerra, M.I.: Characterization of concrete made with recycled aggregate from ceramic sanitary ware. Mater. Construcc. 61(304), 533–546 (2011)Pacheco-Torgal, F., Jalali, S.: Reusing ceramic wastes in concrete. Constr. Build. Mater. 24(5), 832–838 (2010)Lavat, A.E., Trezza, M.A., Poggi, M.: Characterization of ceramic roof tile wastes as pozzolanic admixture. Waste Manage. 29(5), 1666–1674 (2009)Nuran, A., Mevlut, U.: The use of waste ceramic tile in cement production. Cement Concrete Res. 30, 497–499 (2000)Pereira-de-Oliveira, L.A., Castro-Gomes, J.P., Santos, P.M.S.: The potential pozzolanic activity of glass and red-clay ceramic waste as cement mortars components. Constr. Build. Mater. 31, 197–203 (2012)Van Deventer, J.S.J., Provis, J.L., Duxson, P., Brice, D.G.: Chemical research and climate change as drivers in the commercial adoption of alkali activated materials. Waste Biomass Valor. 1, 145–155 (2010)van Deventer, J.S.J., Provis, J.L., Duxson, P., Lukey, G.C.: Reaction mechanisms in the geopolymeric conversion of inorganic waste to useful products. J. Hazard. Mater. A139, 506–513 (2007)Duxson, P., Fernández-Jiménez, A., Provis, J.L., Lukey, G.C., Palomo, A., van Deventer, J.S.J.: Geopolymer technology: the current state of the art. J. Mater. Sci. 42(9), 2917–2993 (2007)Bernal, S.A., RodrÃguez, E.D., de Gutiérrez, R.M., Provis, J.L., Delvasto, S.: Activation of metakaolin/slag blends using alkaline solutions based on chemically modified silica fume and rice husk ash. Waste Biomass Valor. 3, 99–108 (2012)Fernández-Jiménez, A., Palomo, A., Criado, M.: Microstructure development of alkali-activated fly ash cement: a descriptive model. Cement Concrete Res 35, 1204–1209 (2005)Payá, J., Borrachero, M.V., Monzó, J., Soriano, L., Tashima, M.M.: A new geopolymeric binder from hydrated-carbonated cement. Mater. Lett. 74, 223–225 (2012)Kourti, I., Amutha-Rani, D., Deegan, D., Boccaccini, A.R., Cheeseman, C.R.: Production of geopolymers using glass produced from DC plasma treatment of air pollution control (APC) residues. J. Hazard. Mater. 176, 704–709 (2010)Puertas, F., Barba, A., Gazulla, M.F., Gómez, M.P., Palacios, M., MartÃnez-RamÃrez, S.: Residuos cerámicos para su posible uso como materia prima en la fabricación de clÃnker de cemento Portland: caracterización y activación alcalina. Mater. Construcc. 56(281), 73–84 (2006)Reig, L., Tashima, M.M., Borrachero, M.V., Monzó, J., Payá, J.: Nuevas matrices cementantes generadas por Activación Alcalina de residuos cerámicos. II Simposio Aprovechamiento de residuos agro-industriales como fuente sostenible de materiales de construcción, November 8–9, Valencia, Spain, pp. 199–207 (2010)L. Reig, M.M. Tashima, M.V. Borrachero, J. Monzó, J. Payá: Residuos de ladrillos cerámicos en la producción de conglomerantes activados alcalinamente, I Pro-Africa Conference: Non-conventional Building Materials Based on Agroindustrial Wastes, October 18–19, Pirassununga, SP, Brazil, pp. 18–21 (2010)GarcÃa Ten F.J. Descomposición durante la cocción del carbonato cálcico contenido en el soporte crudo de los azulejos. Tesis de doctorado, Departamento de IngenierÃa quÃmica, UJI (2005)Baronio, G., Binda, L.: Study of the pozzolanicity of some bricks and clays. Constr. Build. Mater. 11(1), 41–46 (1997)Zanelli, C., Raimondo, M., Guarini, G., Dondi, M.: The vitreous phase of porcelain stoneware: composition, evolution during sintering and physical properties. J. Non-Cryst. Solids 357, 3251–3260 (2011)Carty, W.M., Senapati, U.: Porcelain-raw materials, processing, phase evolution, and mechanical behaviour. J. Am. Ceram. Soc. 81(1), 3–20 (1998)ASCER, COACV, COPUT, ITC-AICE, WEBER ET BROUTIN – CEMARKSA: GuÃa Baldosa GuÃa de la baldosa cerámica. IVE: Conselleria d’Obres Públiques, Urbanisme i Transports, 4ª Ed. Valencia (2003)Khater, H.M.: Effect of calcium on geopolimerization of aluminosilicate wastes. J. Mater. Civ. Eng. 24, 92–101 (2012)Bondar, D., Lynsdale, C.J., Milestone, N.B., Hassani, N., Ramezanianpour, A.A.: Effect of adding mineral additives to alkali-activated natural pozzolan paste. Constr. Build. Mater. 25, 2906–2910 (2011)Provis, J.L., Harrex, R.M., Bernal, A.S., Duxson, P., van Deventer, J.S.J.: Dilatometry of geopolymers as a means of selecting desirable fly ash sources. J. Non-Cryst. Solids 358, 1930–1937 (2012)Duxson, P., Provis, J.L., Lukey, G.C., Mallicoat, S.W., Kriven, W.M., van Deventer, J.S.J.: Understanding the relationship between geopolymer composition, microstructure and mechanical properties. Colloid Surf. A 269, 47–58 (2005)Tashima, M.M., Akasaki, J.L., Castaldelli, V.N., Soriano, L., Monzó, J., Payá, J., Borrachero, M.V.: New geopolymeric binder based on fluid catalytic cracking catalyst residue (FCC). Mater. Lett. 80, 50–52 (2012)Komnitsas, K., Zaharaki, D., Perdikatsis, V.: Geopolymerisation of low calcium ferronickel slags. J. Mater. Sci. 42, 3073–3082 (2007)Bernal, S.A., Gutierrez, R.M., Provis, J.L., Rose, V.: Effect of silicate modulus and metakaolin incorporation on the carbonation of alkali silicate-activated slags. Cement Concrete Res. 40, 898–907 (2010)Tashima, M.M. Produccion y caracterizacion de materiales cementantes a partir del silicoaluminato calcico vitreo (VCAS). Tesis de doctorado, Departamento de IngenierÃa de la construcción y de proyectos de ingenierÃa civil, UPV (2012)Provis, J.L., van Deventer, J.S.J.: Geopolymerisation kinetics. 2. Reaction kinetic modelling. Chem. Eng. Sci. 62, 2318–2329 (2007
Development of Alkali-Activated Binders froRecycled Mixed Masonry-originated Waste
YesIn this study, the main emphasis is placed on the development and characterization of alkali-activated binders completely produced by the use of mixed construction and demolition waste (CDW)-based masonry units as aluminosilicate precursors. Combined usage of precursors was aimed to better simulate the real-life cases since in the incident of construction and demolition, these wastes are anticipated to be generated collectively. As different masonry units, red clay brick (RCB), hollow brick (HB) and roof tile (RT) were used in binary combinations by 75-25%, 50-50% and 25-75% of the total weight of the binder. Mixtures were produced with different curing temperature/periods and molarities of NaOH solution as the alkaline activator. Characterization was made by the compressive strength measurements supported by microstructural investigations which included the analyses of X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDX). Results clearly showed that completely CDW-based masonry units can be effectively used collectively in producing alkali-activated binders having up to 80 MPa compressive strength provided that the mixture design parameters are optimized. Among different precursors utilized, HB seems to contribute more to the compressive strength. Irrespective of their composition, main reaction products of alkali-activated binders from CDW-based masonry units are sodium aluminosilicate hydrate (N-A-S-H) gels containing different zeolitic polytypes with structure ranging from amorphous to polycrystalline
Examination of alkali-activated material nanostructure during thermal treatment
The key nanostructural changes occurring in a series of alkali-activated materials (AAM) based on blends of slag and fly ash precursors during exposure to temperatures up to 1000 °C are investigated. The main reaction product in each AAM is a crosslinked sodium- and aluminium-substituted calcium silicate hydrate (C-(N)-A-S-H)-type gel. Increased alkali content promotes the formation of an additional sodium aluminosilicate hydrate (N-A-S-(H)) gel reaction product due to the structural limitations on Al substitution within the C-(N)-A-S-H gel. Heating each AAM to 1000 °C results in the crystallisation of the disordered gels and formation of sodalite, nepheline and wollastonite. Increased formation of N-A-S-(H) reduces binder structural water content after thermal treatment and correlates closely with previous observations of improved strength retention and reduced microcracking in these AAM after heating to 1000 °C. This provides new insight into thermally induced changes to gel atomic structure and thermal durability of C-(N)-A-S-H/N-A-S-H gel blends which are fundamental for the development of new fire-resistant construction materials
Dissolution behaviour of source materials for synthesis of geopolymer binders: A kinetic approach
The Durability of Fly ash based Geopolymers as Construction Material.
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