La "trasnmutacion" sostenible de los residuos para nuevas materias primas en el ámbito del concreto

[EN] This article collects various options for sustainable reuse of waste in the manufacture of concrete. It details the various options for industrial waste, agricultural waste and construction and demolition waste. The importance of treatments such as milling, air classification and sonication, and preparation of binders in the manufacture of alkali activated systems is emphasized.[ES] En este artículo se recopilan diferentes opciones para la reutilización sostenible de residuos en la fabricación de concreto. Se detallan las diferentes opciones para residuos industriales, residuos agrícolas y residuos de construcción y demolición. Se enfatiza en la importancia de tratamientos como la molienda, clasificación por aire y sonicación, así como en la fabricación de conglomerantes activados alcalinamente.Paya Bernabeu, JJ. (2012). La "trasnmutacion" sostenible de los residuos para nuevas materias primas en el ámbito del concreto. DYNA.Revista de la Facultad de Minas de la Universidad Nacional de Colombia. Sede Medellin. 79(175):38-47. http://hdl.handle.net/10251/50095S38477917

Flipped Accumulative Non-Linear Single Impact Resonance Acoustic Spectroscopy (FANSIRAS): A novel feature extraction algorithm for global damage assessment

[EN] High amplitude non-linear acoustic methods have shown great potential for the identification of micro-damage in inhomogeneous materials such as concrete. Usually, these methods evaluate non-linearity parameters related to the hysteretic behaviour from the dependence of the shifts in both frequency and damping on the amplitude of the strain. A deep understanding of the reverberation phenomena has been obtained in order to introduce a novel signal processing approach called FANSIRAS (Flipped Accumulative Nonlinear Single Impact Resonance Acoustic Spectroscopy). Traditional acoustic spectroscopy techniques, NIRAS (Non-linear Impact Resonance Acoustic Spectroscopy) and NSIRAS (Non-linear Single Impact Acoustic Spectroscopy), have been analyzed and compared with the brand new approach when providing quantitative information related to the degree of micro-cracking in thermal damaged concrete based materials. The new resonance-based algorithm demonstrates that the non-linear non-classical parameters can be determined through a single resonance frequency measurement, obtaining the expected sensitivity to internal damage. Its simplicity and robustness may be important in industrial applications. (C) 2018 Elsevier Ltd. All rights reserved.This work has been supported by the Spanish Administration under grants TEC2011-23403, BES2015-071469, BIA2014-55311-C2-1-P and BIA2014-55311-C2-2-P. The authors are also grateful for FEDER funds.Carrión García, A.; Genovés, V.; Pérez, G.; Paya Bernabeu, JJ.; Gosálbez Castillo, J. (2018). Flipped Accumulative Non-Linear Single Impact Resonance Acoustic Spectroscopy (FANSIRAS): A novel feature extraction algorithm for global damage assessment. Journal of Sound and Vibration. 432:454-469. https://doi.org/10.1016/j.jsv.2018.06.031S45446943

Ultrasonic broadband signal monitoring of Glass-fiber Reinforced Cement (GRC) bending tests

[EN] In this study, complete ultrasonic monitoring of Glass-fiber Reinforced Cement plates under bending tests was addressed. In this kind of experiment, the mechanical properties of the specimen continuously change during the test, thus, the acquisition time of the ultrasonic signals is a critical variable. In order to overcome this drawback, a new ultrasonic procedure based on broadband signals (chirp) has been applied. Following this line of thought, the analysed ultrasonic parameters have been split into the parameters that only depend on time, and those that depend on both time and frequency. In particular,the frequency dependent attenuation parameter allows characterizing the evolution of the plate being damaged over a wide frequency range and significantly detecting the main two events happening during the experiment: the first crack and the maximum stress point. In short, this paper demonstrates the suitability of ultrasonic broadband signals for characterizing fiber-reinforced cementitious composites under bending stress.This work has been supported by the Spanish Administration under grants, BES-2015-071469, TEC2011-23403, BIA2014-55311-C2-1-P and BIA2014-55311-C2-2-P.Genovés, V.; Gosálbez Castillo, J.; Carrión García, A.; Miralles Ricós, R.; Paya Bernabeu, JJ. (2017). Ultrasonic broadband signal monitoring of Glass-fiber Reinforced Cement (GRC) bending tests. Cement and Concrete Composites. 80:55-63. https://doi.org/10.1016/j.cemconcomp.2017.02.009S55638

Evaluation of the matrix of plaster with incorporation of rubber of tires for use in construction

[EN] The use of gypsum in the Brazilian construction industry has been growing steadily in recent years, when the drywall system started to be used in the internal seals of all types of buildings. The new use this should be added the traditional use of gypsum as coating material applied directly on walls and ceilings and as casting material. Given the above, this paper studies some physical characteristics of gypsum composites produced with the addition of tire rubber residues. The experimental program included the completion of the following tests: mass density in plastic and hardened state, tensile strength in bending, compressive strength, tensile strength in bending, ultrasound and scanning electron microscopy (SEM). The incorporation of crumb rubber content was 5% and 10% relative to the mass of gypsum. Two different tire rubber particle sizes were used: a thin called (#0.075 mm) and thick (# 2.38 mm). The results provide a reduction in the bulk density value. It was found that the adhesion of the rubber particles in the gypsum matrix does not present satisfactory results in coarse. This adhesion deficiency, found in SEM testing, was responsible for the lower flexural strength, tensile strength in bending and compression in plaster composites with coarse when compared to the results of composites with fine grain. With respect to ultrasound testing, it was found that the rubber delays sound propagation time. Lastly, the technical feasibility of the study was tested by means of test specimens, which proved to be efficient.[PT] O uso do gesso na construção civil brasileira vem crescendo continuamente nos últimos anos, quando o sistema drywall passou a ser utilizado nas vedações internas de todos os tipos de edificações. A essa utilização nova somam-se os usos tradicionais do gesso como material de revestimento e como material de fundição. Diante do exposto, este trabalho estuda algumas características físicas de compósitos de gesso produzidos com a incorporação de resíduos de borracha de pneus. No programa experimental foram realizados os seguintes ensaios: densidade de massa no estado plástico e endurecido, resistência à ruptura na flexão, resistência à compressão, resistência à tração na flexão, ultrassom e microscopia eletrônica de varredura (MEV). O teor de incorporação da borracha de pneus foi de 5% e 10% em relação à massa de gesso. Duas diferentes granulometrias de borracha foram utilizadas: a denominada fina (#0,075 mm) e a grossa (#2,38 mm). Os resultados proporcionaram uma redução no valor da densidade de massa. Identificou-se que a aderência das partículas de borracha na matriz de gesso não apresenta resultados satisfatórios na granulometria grossa. Esta deficiência de aderência, constatada na MEV, foi responsável pela menor resistência à flexão, à tração na flexão e à compressão nos compósitos com a granulometria grossa, quando comparados aos resultados dos compósitos com a granulometria fina. Com relação aos ensaios de ultrassom, constatou-se que a borracha retarda o tempo de propagação do som. Por fim, a viabilidade técnica do estudo foi testada por meio de corpos de prova, onde se mostrou ser eficiente.À agência de fomento FAPESP – Fundação de Amparo à Pesquisa do Estado de São Paulo, pelo auxílio financeiro.Pinto, N.; Fioriti, C.; Paya Bernabeu, JJ.; Akasaki, JL. (2016). Avaliação de matriz de gesso com incorporação de borracha de pneus para utilização na construção civil. Revista Tecnológica. 25(1):103-117. https://doi.org/10.4025/revtecnol.v25i1.29894S10311725

Influence of microwave oven calcination on the pozzolanicity of sugar cane bagasse ashes (SCBA) from the cogeneration industry

[EN] This study evaluates the effects of microwave oven calcining conditions on the pozzolanicity of sugar cane bagasse ashes (SCBA) generated by the electric power cogeneration industry. The calcining temperatures varied between 600 ºC and 800 ºC, and the permanence times were 60 min in an electric oven and 30, 45 and 60 min in a microwave oven. To evaluate the behaviour of the ashes according to different calcining conditions, we carried out the following analyses: granulometric distribution (laser diffraction), oxide percentages (XRF), loss on ignition (LOI), powder X-ray diffraction (XRD), pozzolanic reactivity, determination of amorphous silica content and thermogravimetry of hydrated lime pastes (DTG). The results show that SCBA calcination in a microwave oven results in ashes with greater pozzolanic reactivity and a significantly more efficient burning process than in an electric oven.The authors would like to thank the CNPq-Brazil (Project: 200133/2017-9) for financial support.Rossignolo, J.; Borrachero Rosado, MV.; Soriano Martinez, L.; Paya Bernabeu, JJ. (2018). Influence of microwave oven calcination on the pozzolanicity of sugar cane bagasse ashes (SCBA) from the cogeneration industry. Construction and Building Materials. 187:892-902. https://doi.org/10.1016/j.conbuildmat.2018.08.016S89290218

Optimized ultrasonic attenuation measures for non-homogeneous materials

In this paper the study of frequency-dependent ultrasonic attenuation in strongly heterogeneous materials is addressed. To determine the attenuation accurately over a wide frequency range, it is necessary to have suitable excitation techniques. Three kinds of transmitted signals have been analysed, grouped according to their bandwidth: narrowband and broadband signals. The mathematical formulation has revealed the relation between the distribution of energy in their spectra and their immunity to noise. Sinusoidal and burst signals have higher signal-to-noise ratios (SNRs) but need many measurements to cover their frequency range. However, linear swept-frequency signals (chirp) improve the effective bandwidth covering a wide frequency range with a single measurement and equivalent accuracy, at the expense of a lower SNR. In the case of highly attenuating materials, it is proposed to use different configurations of chirp signals, enabling injecting more energy, and therefore, improving the sensitivity of the technique without a high time cost. Thus, if the attenuation of the material and the sensitivity of the measuring equipment allows the use of broadband signals, the combination of this kind of signal and suitable signal processing results in an optimal estimate of frequency-dependent attenuation with a minimum measurement time.This work has been supported by the Spanish Administration under grant BIA2014-55311-C2-2-P.Genovés Gómez, V.; Gosálbez Castillo, J.; Carrión García, A.; Miralles Ricós, R.; Paya Bernabeu, JJ. (2016). Optimized ultrasonic attenuation measures for non-homogeneous materials. Ultrasonics. 65:345-352. https://doi.org/10.1016/j.ultras.2015.09.007S3453526

Effect of different high surface area silicas on the rheology of cement paste

[ES] Efecto de diferentes sílices de alta área superficial sobre la reología de pastas de cemento. Este tra¬bajo estudia el efecto de la nanosílice (NS) sobre la reología de pastas de cemento por comparación con sílices de alta área superficial: humo de sílice (SF) y pirosílice (PS). Las pastas fueron fabricadas con diferentes rela¬ciones agua-material cementante y sustituciones sólidas de sílice. Fueron ejecutados ensayos de demanda de agua, tiempo de fraguado y reología. Se encontró que la NS y SF disminuyen la viscosidad plástica, mientras que la PS la aumenta. Solo la PS tuvo efecto sobre el límite elástico. La NS presentó mayor disminución de la viscosidad, independientemente de su alta demanda de agua. Se concluyó que el comportamiento de las pastas con NS y SF es gobernado por el efecto de ¿rodamiento¿ de la sílice, por su grado de aglomeración y por su impacto en la fracción de sólidos. El comportamiento de las pastas con PS es gobernado por su capacidad de absorber agua.[EN] This work studies the effect of nanosilica (NS) on the rheology of cement paste by comparing it with two high specific surface area silicas: silica fume (SF) and pyrogenic silica (PS). Portland cement pastes were produced with different water-to-cementing material ratios and different solid substitutions of cement by silica. Water demand, setting time, and rheology tests were performed. Results showed that NS and SF decreased plastic viscosity, while PS increased it. Only PS was found to have an effect on yield stress. NS showed the most decreasing effect on viscosity, regardless of its higher water demand. It was concluded that the behavior of pastes containing NS and SF is governed by the "ball-bearing" effect from silica particles, by their agglomeration degree, and their impact on the solid volume fraction. The behavior of pastes containing PS is governed by its ability to absorb a portion of the mixing water.Tobón, J.; Mendoza, O.; Restrepo, O.; Borrachero Rosado, MV.; Paya Bernabeu, JJ. (2020). Effect of different high surface area silicas on the rheology of cement paste. Materiales de Construcción. 70(340):1-9. https://doi.org/10.3989/mc.2020.15719S19703401. Kwan, A.K.H.; Li, Y. (2013) Effects of fly ash microsphere on rheology, adhesiveness and strength of mortar. Constr. Build. Mater. 42, 137-145.2. Jal, P.K.; Sudarshan, M.; Saha, A.; Patel, S.; Mishra, B.K. (2004) Synthesis and characterization of nanosilica prepared by precipitation method. Coll. Surf. A Physicochem. Eng. Asp. 240 [1-3], 173-178.3. El Sokkary, T. M.; Assal, H. H.; Kandeel, A. M. (2004) Effect of silica fume or granulated slag on sulphate attack of ordinary portland and alumina cement blend. Ceram. Int. 30 [2], 133-138.4. Gutsch, A.; Krämer, M.; Michael, G.; Mühlenweg, H.; Pridöhl, M.; Zimmermann, G. (2002) Gas-Phase production of nanoparticles. KONA Powder Part. J. 20, 24-37.5. Singh, L.P.; Karade, S.R.; Bhattacharyya, S.K.; Yousuf, M.M.; Ahalawat, S. (2013) Beneficial role of nanosilica in cement based materials - A review. Constr. Build. Mater. 47, 1069-1077.6. Björnström, J.; Martinelli, A.; Börjesson, L.; Panas, I.; (2004) Accelerating effects of colloidal nano-silica for beneficial calcium-silicate-hydrate formation in cement. Chem. Phys. Lett. 392 [1-3], 242-248.7. Mendoza Reales, O.A.; Silva, E.C.C.M.; Paiva, M.D.M.; M.; Duda, P.; Toledo Filho, R.D. (2017) The role of surface area and compacity of nanoparticles on the rheology of cement paste 25.3. ACI Symp. Pub. 320, 25.1-25.14. https://www.concrete.org/publications/internationalconcreteabstractsportal/m/details/id/51701063.8. Tobón, J. I.; Mendoza Reales, O.; Retrepo, O.J.; Borrachero, M.V. (2018) Effect of pyrogenic silica and nanosilica on Portland cement matrices. J. Mater. Civ. Eng. 30 [10], 1-10.9. Mehdipour, I.; Khayat, K.H. (2018) Understanding the role of particle packing characteristics in rheo-physical properties of cementitious suspensions: A literature review. Constr. Build. Mater. 161, 340-353.10. Boukendakdji, O.; Kadri, E.H.; Kenai, S. (2012) Effects of granulated blast furnace slag and superplasticizer type on the fresh properties and compressive strength of selfcompacting concrete. Cem. Concr. Compos. 34 [4], 583-590.11. Park, C.K.; Noh, M.H.; Park, T.H. (2005) Rheological properties of cementitious materials containing mineral admixtures. Cem. Concr. Res. 35 [5], 842-849.12. Deng, H.; Li, H. (2018) Assessment of self-sensing capability of carbon black engineered cementitious composites. Constr. Build. Mater. 173, 1-9.13. Mendoza-Reales, O.A.; Arias Jaramillo, Y.P.; Ochoa Botero, J.C.; Delgado, C.A.; Quintero, J.H.; Toledo Filho, R.D. (2018) Influence of MWCNT/surfactant dispersions on the rheology of Portland cement pastes. Cem. Concr. Res. 107, 101-109.14. Quercia, G.; Hüsken, G.; Brouwers, H.J.H. (2012) Water demand of amorphous nano silica and its impact on the workability of cement paste. Cem. Concr. Res. 42 [2], 344-357.15. Norhasri, M.S.M.; Hamidah, M.S.; Fadzil, A.M. (2017) Applications of using nano material in concrete: A review. Constr. Build. Mater. 133, 91-97.16. Bowen, P. (2002). Particle size distribution measurement from millimeters to nanometers and from rods to platelets. J. Dispers. Sci. Technol. 23 [5], 631-662.17. Staiger, M.; Bowen, P.; Ketterer, J.; Bohonek, J. (2002) Particle size distribution measurement and assessment of agglomeration of commercial nanosized ceramic particles. J. Dispers. Sci. Technol. 23 [5], 619-630.18. Hidalgo, A.; Petit, S.; Domingo, C.; Alonso, C.; Andrade, C. (2007) Microstructural characterization of leaching effects in cement pastes due to neutralisation of their alkaline nature. Part I: Portland cement pastes. Cem. Concr. Res. 37 [1], 63-70.19. Srinivasan, S.; Barbhuiya, S.A.; Charan, D.; Pandey, S.P. (2010) Characterising cement-superplasticiser interaction using zeta potential measurements. Constr. Build. Mater. 24 [12], 2517-2521.20. de Larrard, F. (1999) Concrete mixture proportioning a scientific approach, E. & F.N. Spon, London.21. Banfill, P.F.G. (2006) Rheology of fresh cement and concrete. Rheol. Reviews 2006. 61-130.22. Burneau, A.; Barres, O.; Gallas, J.P.; Lavalley, J.C. (1990) Comparative Study of the Surface Hydroxyl Groups of Fumed and Precipitated Silicas. 2. Chatracterization by infrared spectroscopy of the interacctions with water. Langmuir. 6 [8], 1364-1372.23. Xie, X-L.; Liu, Q-X.; Li, R.K-Y.; Zhou, X-P.; Zhang, Q-X.; Yu, Z-Z.; Mai, Y-W. (2004) Rheological and mechanical properties of PVC/CaCO3 nanocomposites prepared by in situ polymerization. Polymer. 45 [19], 6665-6673.24. Asavapisit, S.; Fowler, G.; Cheeseman, C.R. (1997) Solution chemistry during cement hydration in the presence of metal hydroxide wastes. Cem. Concr. Res. 27 [8], 1249-1260

Use of ancient copper slags in portalnd cement and alkali activated cement matrices

Some Chilean copper slag dumps from the nineteenth century still remain, without a proposed use that encourages recycling and reduces environmental impact. In this paper, the copper slag abandoned in landfills is proposed as a new building material. The slags studied were taken from Playa Negra and Púquios dumps, both located in the region of Atacama in northern Chile. Pozzolanic activity in lime and Portland cement systems, as well as the alkali activation in pastes with copper slag cured at different temperatures, was studied. The reactivity of the slag was measured using thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), electrical conductivity and pH in aqueous suspension and Fourier Transform Infrared Spectroscopy (FTIR). Furthermore, copper slag-Portland cement mortars with the substitution of 25% (by weight) of cement by copper slag and alkali-activated slag mortars cured at 20 and 65 C were made, to determine the compressive strength. The results indicate that the ancient copper slags studied have interesting binding properties for the construction sector.Nazer, A.; Paya Bernabeu, JJ.; Borrachero Rosado, MV.; Monzó Balbuena, JM. (2016). Use of ancient copper slags in portalnd cement and alkali activated cement matrices. Journal of Environmental Management. 167:115-123. doi:10.1016/j.jenvman.2015.11.024S11512316

Concrete for precast blocks: binary and ternary combination of sewage sludge ash with diverse mineral residue

[EN] This paper proposes binary and ternary combinations of sewage sludge ash (SSA) with fly ash (FA), marble dust (MD) and rice husk ash (RHA) as partial replacements of Portland cement in concretes with a similar dosage to that used in precast blocks, with very dry consistency. Several physical-mechanical tests were carried out on concrete specimens with curing ages of 28 and 90 days: density, water absorption, capillary water absorption, ultrasonic pulse velocity and compressive strength. The combinations of residues significantly improve the properties of the cementitious systems: 30% replacement of Portland cement provides strength values similar to the reference sample, showing the synergetic effects of the combination of the mineral additions. The significance of this research relies on the combined use of the mineral additions as well as the use of them for the precast block industry. The results show synergies among the additions and even that some of them showed relevant improvements when they are used in combination, performing better than when used individually.Baeza-Brotons, F.; Paya Bernabeu, JJ.; Galao, O.; Alberti, MG.; Garcés, P. (2020). Concrete for precast blocks: binary and ternary combination of sewage sludge ash with diverse mineral residue. Materials. 13(20):1-19. https://doi.org/10.3390/ma13204634S1191320Zabalza Bribián, I., Valero Capilla, A., & Aranda Usón, A. (2011). Life cycle assessment of building materials: Comparative analysis of energy and environmental impacts and evaluation of the eco-efficiency improvement potential. Building and Environment, 46(5), 1133-1140. doi:10.1016/j.buildenv.2010.12.002Lothenbach, B., Scrivener, K., & Hooton, R. D. (2011). Supplementary cementitious materials. Cement and Concrete Research, 41(12), 1244-1256. doi:10.1016/j.cemconres.2010.12.001Ministerio de Agricultura Alimentación y Medio Ambiente http://www.magrama.gob.es/es/calidad-y-evaluacion-ambiental/temas/prevencion-y-gestion-residuos/flujos/lodos-depCyr, M., Coutand, M., & Clastres, P. (2007). Technological and environmental behavior of sewage sludge ash (SSA) in cement-based materials. Cement and Concrete Research, 37(8), 1278-1289. doi:10.1016/j.cemconres.2007.04.003Donatello, S., & Cheeseman, C. R. (2013). Recycling and recovery routes for incinerated sewage sludge ash (ISSA): A review. Waste Management, 33(11), 2328-2340. doi:10.1016/j.wasman.2013.05.024Marble Association of Alicante http://www.marmoldealicante.esChen, M., Blanc, D., Gautier, M., Mehu, J., & Gourdon, R. (2013). Environmental and technical assessments of the potential utilization of sewage sludge ashes (SSAs) as secondary raw materials in construction. Waste Management, 33(5), 1268-1275. doi:10.1016/j.wasman.2013.01.004Monzó, J., Payá, J., Borrachero, M. V., & Córcoles, A. (1996). Use of sewage sludge ash(SSA)-cement admixtures in mortars. Cement and Concrete Research, 26(9), 1389-1398. doi:10.1016/0008-8846(96)00119-6Payá, J., Monzó, J., Borrachero, M. V., Amahjour, F., Girbés, I., Velázquez, S., & Ordóñez, L. M. (2002). Advantages in the use of fly ashes in cements containing pozzolanic combustion residues: silica fume, sewage sludge ash, spent fluidized bed catalyst and rice husk ash. Journal of Chemical Technology & Biotechnology, 77(3), 331-335. doi:10.1002/jctb.583Tay, J.-H., & Show, K.-Y. (1994). Municipal wastewater sludge as cementitious and blended cement materials. Cement and Concrete Composites, 16(1), 39-48. doi:10.1016/0958-9465(94)90029-9Donatello, S., Tyrer, M., & Cheeseman, C. R. (2010). Comparison of test methods to assess pozzolanic activity. Cement and Concrete Composites, 32(2), 121-127. doi:10.1016/j.cemconcomp.2009.10.008Research Group in Chemistry Building Materials—Universitat Politècnica de València. Proyecto PEL-CEN http://epsar.cop.gva.es/depuradorasvPeris Mora, E., Payá, J., & Monzó, J. (1993). Influence of different sized fractions of a fly ash on workability of mortars. Cement and Concrete Research, 23(4), 917-924. doi:10.1016/0008-8846(93)90045-bEvolución de las resistencias mecánicas de sistemas ternarios cemento/ceniza volante/ceniza de lodo de depuradora: Efectos puzolánicos complementarios https://www.upv.es/pms2002/Comunicaciones/038 PAYA.PDFCorinaldesi, V., Moriconi, G., & Naik, T. R. (2010). Characterization of marble powder for its use in mortar and concrete. Construction and Building Materials, 24(1), 113-117. doi:10.1016/j.conbuildmat.2009.08.013Influence of Marble and Limestone Dusts as Additives on Some Mechanical Properties of Concrete, SCI RES ESSAYS 2 (2007) 372-379 http://www.academicjournals.org/SREAliabdo, A. A., Abd Elmoaty, A. E. M., & Auda, E. M. (2014). Re-use of waste marble dust in the production of cement and concrete. Construction and Building Materials, 50, 28-41. doi:10.1016/j.conbuildmat.2013.09.005Rodríguez de Sensale, G. (2006). Strength development of concrete with rice-husk ash. Cement and Concrete Composites, 28(2), 158-160. doi:10.1016/j.cemconcomp.2005.09.005Khan, R., Jabbar, A., Ahmad, I., Khan, W., Khan, A. N., & Mirza, J. (2012). Reduction in environmental problems using rice-husk ash in concrete. Construction and Building Materials, 30, 360-365. doi:10.1016/j.conbuildmat.2011.11.028Madandoust, R., Ranjbar, M. M., Moghadam, H. A., & Mousavi, S. Y. (2011). Mechanical properties and durability assessment of rice husk ash concrete. Biosystems Engineering, 110(2), 144-152. doi:10.1016/j.biosystemseng.2011.07.009Nicoara, A. I., Stoica, A. E., Vrabec, M., Šmuc Rogan, N., Sturm, S., Ow-Yang, C., … Vasile, B. S. (2020). End-of-Life Materials Used as Supplementary Cementitious Materials in the Concrete Industry. Materials, 13(8), 1954. doi:10.3390/ma13081954García Arenas, C., Marrero, M., Leiva, C., Solís-Guzmán, J., & Vilches Arenas, L. F. (2011). High fire resistance in blocks containing coal combustion fly ashes and bottom ash. Waste Management, 31(8), 1783-1789. doi:10.1016/j.wasman.2011.03.017Poon, C.-S., Kou, S., Wan, H., & Etxeberria, M. (2009). Properties of concrete blocks prepared with low grade recycled aggregates. Waste Management, 29(8), 2369-2377. doi:10.1016/j.wasman.2009.02.018Sabai, M. M., Cox, M. G. D. M., Mato, R. R., Egmond, E. L. C., & Lichtenberg, J. J. N. (2013). Concrete block production from construction and demolition waste in Tanzania. Resources, Conservation and Recycling, 72, 9-19. doi:10.1016/j.resconrec.2012.12.003Xiao, R., Ma, Y., Jiang, X., Zhang, M., Zhang, Y., Wang, Y., … He, Q. (2020). Strength, microstructure, efflorescence behavior and environmental impacts of waste glass geopolymers cured at ambient temperature. Journal of Cleaner Production, 252, 119610. doi:10.1016/j.jclepro.2019.119610Xiao, R., Polaczyk, P., Zhang, M., Jiang, X., Zhang, Y., Huang, B., & Hu, W. (2020). Evaluation of Glass Powder-Based Geopolymer Stabilized Road Bases Containing Recycled Waste Glass Aggregate. Transportation Research Record: Journal of the Transportation Research Board, 2674(1), 22-32. doi:10.1177/0361198119898695Antoni, M., Rossen, J., Martirena, F., & Scrivener, K. (2012). Cement substitution by a combination of metakaolin and limestone. Cement and Concrete Research, 42(12), 1579-1589. doi:10.1016/j.cemconres.2012.09.006Scrivener, K., Martirena, F., Bishnoi, S., & Maity, S. (2018). Calcined clay limestone cements (LC3). Cement and Concrete Research, 114, 49-56. doi:10.1016/j.cemconres.2017.08.01

Microconcrete with partial replacement of Portland cement by fly ash and hydrated lime addition

[EN] The reduction in Portland cement consumption means lower CO2 emissions. Partial replacement of Portland cement by pozzolans sucha 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 the 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 acide-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.Lorca, P.; Calabuig Pastor, R.; Benlloch Marco, J.; Soriano Martinez, L.; Paya Bernabeu, JJ. (2014). Microconcrete with partial replacement of Portland cement by fly ash and hydrated lime addition. Materials and Design. 64:535-541. doi:10.1016/jmatdes.2014.08.022S5355416