Application of Nanoparticles in Regular and Foamed Cement-Based Systems
Date
2024-01-19
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Abstract
Nano-modification of cement-based materials (CBMs) has the potential to enhance the mechanical properties of conventional CBMs and provide sustainable and energy-efficient solutions to mitigate the environmental footprint of cement manufacturing. Over the past years, the addition of nanoparticles (NPs) into cement paste, mortar, and concrete has shown outstanding enhancements in their mechanical properties and durability. Large-scale application of NPs in CBMs still, however, faces challenges such as improper dispersion, poor economics due to the cost of NPs, and potential health concerns associated with NPs handling. This work attempts to tackle these barriers by proposing inexpensive methods of NPs incorporation into oil well cement slurry and foamed concrete (FC). For oil well cement slurry, an easily scalable approach of NPs synthesis during cement slurry mixing is developed. Three methods for preparing in situ Fe(OH)3 NPs are presented. At 0.7 wt% of dry oil well cement, in situ prepared Fe(OH)3 NPs increases the 1-day compressive strength of the cement slurry by up to 90% and 38% at 25 oC and 80 oC, respectively, outperforming commercial NPs. Significant reductions in porosity (up to 48%) and permeability (up to 93%) are also achieved. Moreover, cement slurries with Fe(OH)3 NPs exhibit high resistance to fatigue from repeated compression cycles. In addition to oil well cement slurry, incorporation of NPs into FC through NP-stabilized preformed foams has been shown to overcome major FC drawbacks such as slurry instability and poor durability. In this study, the formulation of a stable in-house CaCO3 NPs/ hexadecyltrimethylammonium bromide (CTAB) dispersion is achieved. In the presence of pure N2 and a 2:1 CO2/N2 gas mixture, foams produced from this dispersion have half-lives of 5 – 6 h compared to 5 – 7 mins for CTAB alone. The presence of CaCO3 NPs also reduces the average bubble size by 67% and enhances foam thermal stability. The utilization of CaCO3 NPs/CTAB aqueous foam in FC improves slurry stability and leads to a narrower and more uniform pore size distribution than FC made with CTAB alone. CaCO3 NPs also accelerate the formation of hydration products and promote the formation of a denser solid matrix. These combined effects contribute to a less connected pore structure, reduction in atmospheric carbonation, and improved heat transfer and fire resistance properties.
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Keywords
cement, compressive strength, dispersion, fatigue, nanoparticles, porosity, permeability, foam, foam stability, foamability, CaCO3, CO2 capture, foamed concrete, CO2, thermal insulation
Citation
Mehairi, A. (2024). Application of nanoparticles in regular and foamed cement-based systems (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.