Evaluation of the effect of nanosilica and recycled fine aggregate in Portland cement rendering mortars

Lima, Geannina Terezinha dos Santos; Zaleski, Alessandra; Júnior, Luís Urbano Durlo Tambara; Rocha, Janaíde Cavalcante; Pelisser, Fernando; Gleize, Philippe Jean Paul

doi:10.1590/s1983-41952022000500009

Cited by 4 publications

(4 citation statements)

References 48 publications

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“…The excellent adhesion of RCAT to the new mortar stems from intermolecular interactions formed at the interface between the two materials due to the hydration of silica fume, generating additional C-S-H, as highlighted by fig ( 8-9) [45]. These findings are supported by previous research, including articles [6,11] studies on splitting [46,47,48] as well as FS splitting, confirming the results obtained. indicating a weak (ITZ) (see Figure 8b).…”

Section: Splitting Tensile Strengthsupporting

confidence: 86%

Improvement of mechanical and interfacial properties (ITZ) of concrete based on treated recycled aggregates

Allal,

Zeghichi,

Larkat

2024

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The increasing utilization of solid waste from construction and demolition as a raw material for aggregate production for concrete is generating growing interest in the construction and public works industry. This practice contributes to preserving natural resources and reducing waste, which is essential for environmental protection. The use of recycled concrete aggregate (RCA) from demolition waste to produce new concrete, known as recycled aggregates concrete (RAC), is an eco-friendly approach. However, RCAs have poor physical and mechanical properties due to their low density and high absorption, compounded by a low interfacial transition zone (ITZ) compared to natural aggregates (NA). To address these issues, this study proposes encapsulating RCA in a cement slurry (with a water-to-cement ratio of 0.5) and examining the impact of adding 5% silica fume (SF) and 2% water-repellent agent (HF) to the cement grout on the properties of (RCA) made from treated recycled concrete aggregates (RCAT). Two types of treated aggregates, (RCAT-5%FS) and (RCAT-2%HF), were developed and hardened for 15 days in air. They were then used to manufacture RACT concrete. The experimental results demonstrate that the inclusion of (SF) and (HF) effectively enhances the properties of (RCAT). Moreover, the compressive and tensile strengths of RACT-SF are greater than those of the control concrete NAC, estimated at 43.5 MPa and 3.87 MPa, respectively. SEM-EDS analysis confirmed the uniformity of contacts within (ITZ) and assessed the compatibility of the Ca/Si ratio. The addition of silica fume contributed to the creation of solid, durable, and environmentally friendly concrete.

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Section: Splitting Tensile Strengthsupporting

confidence: 86%

Improvement of mechanical and interfacial properties (ITZ) of concrete based on treated recycled aggregates

Allal,

Zeghichi,

Larkat

2024

SEES

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“…Similar results were reported for the incorporation of other nanomaterials in CBMs, such as carbon nanotubes [44,50], titanium dioxide [49,51], and nano-silica [52][53][54].…”

Section: Isothermal Calorimetrysupporting

confidence: 82%

“…This effect became more pronounced at longer hydration times, possibly due to the additional surface area provided by niobium nanoparticles, facilitating the nucleation and growth of hydrated products [48,49]. Similar results were reported for the incorporation of other nanomaterials in CBMs, such as carbon nanotubes [44,50], titanium dioxide [49,51], and nano-silica [52][53][54].…”

Section: Rotational Rheometrysupporting

confidence: 76%

Assessing the Rheological, Mechanical, and Photocatalytic Properties of Niobium Oxide-Incorporated White Cement Pastes

et al. 2023

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Niobium oxide (Nb2O5) is a semiconductor that exhibits photocatalytic properties, making it potentially valuable in addressing air pollution, self-cleaning, and self-disinfection in cement-based materials (CBMs). Therefore, this study aimed to evaluate the impact of different Nb2O5 concentrations on various parameters, including rheological characteristics, hydration kinetics (measured using isothermal calorimetry), compressive strength, and photocatalytic activity, specifically in the degradation of Rhodamine B (RhB) in white Portland cement pastes. The incorporation of Nb2O5 increased the yield stress and viscosity of the pastes by up to 88.9% and 33.5%, respectively, primarily due to the larger specific surface area (SSA) provided by Nb2O5. However, this addition did not significantly affect the hydration kinetics or the compressive strength of the cement pastes after 3 and 28 days. Tests focusing on the degradation of RhB in the cement pastes revealed that the inclusion of 2.0 wt.% of Nb2O5 was insufficient to degrade the dye when exposed to 393 nm UV light. However, an interesting observation was made concerning RhB in the presence of CBMs, as it demonstrated a degradation mechanism that was not dependent on light. This phenomenon was attributed to the production of superoxide anion radicals resulting from the interaction between the alkaline medium and hydrogen peroxide.

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“…Sonication is widely used for nanomaterials dispersion for application in cementitious matrices, such as carbon nanotubes [1]- [5], nanosilica [6]- [10], silicon carbide nanowhiskers [11]- [13], nano-clay [14], [15], silica fume [16], among others. The high performance of nanoparticles used in cementitious materials is mainly due to their high specific surface area, which -in most cases -is reduced by its susceptibility to agglomeration.…”

Section: Introductionmentioning

confidence: 99%

Sonicating polycarboxylate-based superplasticizer for application in cementitious matrix

Silvestro

Ruviaro

Lima

et al. 2023

Rev. IBRACON Estrut. Mater.

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Sonication is widely used for nanomaterials dispersion in cementitious matrices. Polycarboxylate-based superplasticizer (SP) admixtures are usually incorporated in the aqueous nanomaterials suspension before sonication to improve the dispersion of these materials. Nevertheless, the effect of sonicating SP on its molecular structure or dispersing performance has not been fully investigated. This work assessed the effect of sonicating a commercial SP at 20 kHz, 750 W power, 50 or 80% amplitude, during 15 and 30 min. Initially, the sonication effect was evaluated in aqueous suspension by determining the SP size distribution (through dynamic light scattering – DLS) and zeta potential. Subsequently, the aqueous SP suspensions were used for Portland cement paste production. Rheological tests up to 120 minutes and compressive strength at 14 and 28 days were conducted. DLS and zeta potential results suggested that sonication reduce the size of SP chains. As a result, SP sonication increased the initial dynamic yield stress, viscosity, and hysteresis area of cement pastes. In contrast, SP sonication improved its time-dependent dispersing performance, resulting in pastes with reduced viscosity from 80 minutes onwards. Finally, SP sonication did not affect the compressive strength of cement pastes at 14 and 28 days of hydration. Overall, when SP is sonicated together with nanoparticles for application in cementitious matrices, the effect of sonicating the chemical admixture must be considered when the fresh-state properties of the composite are evaluated.

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Evaluation of the effect of nanosilica and recycled fine aggregate in Portland cement rendering mortars

Cited by 4 publications

References 48 publications

Improvement of mechanical and interfacial properties (ITZ) of concrete based on treated recycled aggregates

Improvement of mechanical and interfacial properties (ITZ) of concrete based on treated recycled aggregates

Assessing the Rheological, Mechanical, and Photocatalytic Properties of Niobium Oxide-Incorporated White Cement Pastes

Sonicating polycarboxylate-based superplasticizer for application in cementitious matrix

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