Physical and Chemical Effects in Blended Cement Pastes Elaborated with Calcined Clay and Nanosilica

Supplementary cementitious materials (SCMs) are commonly used in the manufacture of commercial cements with lower clinker content and carbon footprints, enabling environmental and performance improvements. The present article evaluated a ternary cement combining 23% calcined clay (CC) and 2% nanosil...

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Bibliographic Details
Published in:Materials 2023-02, Vol.16 (5), p.1837
Main Authors: Pinheiro, Divino Gabriel Lima, Sousa, Matheus Ian Castro, Pelisser, Fernando, da Silva Rêgo, João Henrique, Moragues Terrades, Amparo, Frías Rojas, Moisés
Format: Article
Language:English
Subjects:
Calorimetry
Cement
Cement hydration
Cement industry
Cement paste
Chemical effects
Clay
Clinker
Compressive strength
Diffraction
Laboratories
Particle size
Porosity
Portland cements
Roasting
Silicates
Thermogravimetric analysis
Thermogravimetry
X-rays
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Summary:Supplementary cementitious materials (SCMs) are commonly used in the manufacture of commercial cements with lower clinker content and carbon footprints, enabling environmental and performance improvements. The present article evaluated a ternary cement combining 23% calcined clay (CC) and 2% nanosilica (NS) to replace 25% of the Ordinary Portland Cement (OPC) content. For this purpose, a series of tests were performed, such as compressive strength, isothermal calorimetry, thermogravimetry (TG/DTG), X-ray diffraction (XDR), and mercury intrusion porosimetry (MIP). The ternary cement studied, 23CC2NS, presents a very high surface area, which influences hydration kinetics by accelerating silicate formation and causes an undersulfated condition. The pozzolanic reaction is potentialized by the synergy between the CC and NS, resulting in a lower portlandite content at 28 days in the 23CC2NS paste (6%) compared with the 25CC paste (12%) and 2NS paste (13%). A significant reduction in total porosity and conversion of macropores in mesopores was observed. For example, 70% of pores in OPC paste were macropores that were converted in the 23CC2NS paste into mesopores and gel pores.
ISSN:1996-1944
1996-1944
DOI:10.3390/ma16051837