Fundamental properties of industrial hybrid cement: utilization in ready-mixed concretes and shrinkage-reducing applications

Abstract

Utility properties of novel hybrid cement (H-Cement) are influenced by pozzolanic reaction of fly ash, latent hydraulic reaction of metallurgical slag together with the alkali activation of inorganic geopolymer based on precipitated waste water coming from bauxite residues. Content of Portland cement clinker is at maximum of 20 mass %, the remaining portion consists of inorganic geopolymer. Up to 80% of CO 2 emissions are saved by H-Cement manufacture compared to ordinary Portland cement (OPC). No heat treatment or autoclaving is needed at H-Cement production. The field application of H-Cement is performed by the same way than that of common cements listed in EN 197-1, and is also connected with highly efficient recovery and safe disposal of red mud waste. H-Cement is suitable for ready-mixed concretes up to C30/37 strength class and is specified by beneficial shrinkage-reducing property of the concrete kept in long dry-air cure opposite to common cements. RESUMEN:Características básicas de un cemento híbrido industrial: utilización en hormigón premezclado y aplicaciones como reductor de la retracción. Las propiedades de un nuevo cemento híbrido (cemento-H) vienen determinadas por la reaccion puzolánica de cenizas volantes, la hidráulica latente de las escorias metalúrgicas y la activación alcalina mediante las aguas residuales generadas por el tratamiento de la bauxita para dar un geopolímero inorgánico. La proporción máxima de clínker de cemento en este nuevo material es del 20%, y por ello, en su fabricación se emite hasta un 80% menos de CO 2 que en la producción del cemento portland (OPC). El cemento-H se prepara sin necesidad de tratamiento térmico ni de estancia en autoclave y su aplicación es la misma que los cementos convencionales definidos en la norma EN 197-1. Por otra parte, su fabricación supone la recuperación y la valorización segura de los lodos rojos de bauxita. El cemento-H es apto para la preparación de hormigones premezclados hasta la categoría C30/37, presentando el nuevo material, además, una menor retracción que los cementos convencionales, por lo que su empleo resulta especialmente ventajoso en los hormigones que se curan al aire.

Portland Versus Alkaline Cement: Continuity or Clean Break: “A Key Decision for Global Sustainability”

“…For example, and to mention just a few cases: ✓ Alkaline activation (with salts such as carbonates, sulphates, silicates, etc.) of mixtures of blast furnace slag (AAS), fly ash and small proportions of clinker, at room temperature, can achieve compressive strengths of more than 40 MPa (more than enough for most of the applications in architecture and civil engineering) ( Donatello et al, 2013 ; Garcia-Lodeiro et al, 2013a ; Martauz et al, 2016 ; du Toit et al, 2018 ). ✓ For synthetic glasses, depending on the CaO content and the activation conditions, it is possible to generate materials with compressive strengths of between 10 and 60 MPa ( Buchwald, 2012 ; Garcia-Lodeiro et al, 2016a ; Ruiz-Santaquiteria et al, 2016 ).…”

“…The first industrial-scale pilot tests to produce H-cement began in 2011 at a plant where Považská cementáreň normally manufactures EN 197-1 class CEM I 52.5 R cement. Industrially produced hybrid H-Cement, is characterized by ready grindability, to a specific surface of 6,100 cm 2 /g, an output of 22 t/h and an energy consumption of 63 kWh/t, compared to an output of 12 t/h and energy consumption of 115 kWh/t for conventional CEM I 52.5 R cement with a specific surface of 5,100 cm2/g produced in the same facility (Martauz et al, 2016). In recent years, much information has been published on the hydration mechanisms in hybrid cements (such a H-cement) and their physical and mechanical properties, along with their durability (Garcia-Lodeiro et al, 2018;Fernández-Jiménez et al, 2019b;Askarian, et al, 2018;Valencia-Saavedra and de Gutiérrez, 2020;Xue et al, 2021).…”

“…Descriptions of at least two examples of one-part AABs produced in industrial facilities can be found in the literature: Le Purdociment ( Buchwald et al, 2015 ), and H-cement ( Martauz et al, 2016 ).…”

“…The first industrial-scale pilot tests to produce H-cement began in 2011 at a plant where Považská cementáreň normally manufactures EN 197–1 class CEM I 52.5 R cement. Industrially produced hybrid H-Cement, is characterized by ready grindability, to a specific surface of 6,100 cm 2 /g, an output of 22 t/h and an energy consumption of 63 kWh/t, compared to an output of 12 t/h and energy consumption of 115 kWh/t for conventional CEM I 52.5 R cement with a specific surface of 5,100 cm2/g produced in the same facility ( Martauz et al, 2016 ).…”

THz Fingerprints of Cement-Based Materials

“…Considering the approximate nature of the force fields employed, the atomistic simulations have reproduced quite satisfactorily the experimental positions of these peaks. Future research on this topic should explore in greater detail the impact of the water content on the THz response of these materials and extend the scope to other binders like novel hybrid cements (H-CEM) [39], or well established calcium sulphoaluminates (C$A) or calcium aluminates (CA).…”