Synergistic effect of graphene oxide and coloidalnano-silica on the microstructure and strength properties of fly ash blended cement composites

Subramani, Kalaiselvi; Ganesan, Arun Kumar

doi:10.1590/1517-7076-RMAT-2023-0305

Kalaiselvi Subramani

Sona College of Technology, Department of Civil Engineering, Salem, India.

https://orcid.org/0009-0003-0604-1751

Arun Kumar Ganesan

Government College of Engineering, Department of Civil Engineering, Thanjavur, India.

e-mail: skalaiselvi1515@gmail.com, arun_8112005@yahoo.com

Corresponding Author: Kalaiselvi Subramani

Figures (21)
Tables (12)

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Figure 1.
XRD image of (a) nano silica and (b) fly ash.

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Figure 2.
Characterization of Fly Ash a) SEM analysis and b) Scatter plot.

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Figure 3.
Characterization of Nano Silica a) SEM analysis and b) Scatter plot.

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Figure 4.
Characterization of GO a) SEM analysis and b) Scatter plot.

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Figure 5.
GO Structure Proposed by Heyong _{et al}.

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Figure 6.
EDX Electromagnetic emission spectrum.

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Figure 7.
FTIR Spectrum of GO.

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Figure 8.
a) Preparation of Specimens, b) Casted Specimen c) Some Prepared Specimen and d) Sonication A homogenous mix of cement, fly ash, and sand, 70% water was mixed dry by hand, and the lasting 30% of the water was used in the diffusion of GO and NS. All mortar specimens are cast in 50 cm2mould and ured. Samples are tested for each category, and hence a total of 72 specimens have been cast. Fig. 8 shows the Schematic representation of Cement + FA + GO + NS formation.

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Figure 9.
Schematic Representation of Preparation of Mortar.

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Figure 10.
Fluidity of Cement Paste.

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Figure 11.
Compressive Strength of Cement Mortars.

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Figure 12.
Percentage increase in Compressive Strength.

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Figure 13.
Water Absorption by Mortars.

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Figure 14.
UPV on Mortars.

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Figure 15.
Carbonation Test.

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Figure 16.
Heating the Specimen.

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Figure 17.
Compressive Strength at Different Temperatures.

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Figure 18.
Compressive Strength of Mortar Specimen after Acid Attack.

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Figure 19.
SEM images of Mortars.

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Figure 20.
EDX Spectrum of Mortars.

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Figure 21.
XRD pattern of C and C+FA+NS+GO0.03 cured at 7 days.

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Table 1:
Authors and their contributions.

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Table 2:
Chemical composition of fly ash, NS and cement (%).

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Table 3:
Elemental composition of GO.

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Table 4:
Mortar mix proportion.

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Table 5:
Strength of mortars.

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Table 6:
% increase in strength.

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Table 7:
Water absorption by samples (%).

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Table 8:
UPV test.

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Table 9:
Mortar strength at various temperatures.

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Table 10:
Compressive strength of mortar specimen after acid attack.

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Table 11:
EDX analysis on control and C+FA+NS+GO0.03 based cement composite (%).

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Table 12:
Phase identification of the specimens.

AUTHORS	SPECIMEN	DESCRIPTION	COMPRESSIVE STRENGTH
WANG et al. [¹⁶[16] WANG, Q., CUI, X., WANG, J., et al., “Effect of fly ash on rheological properties of graphene oxide cement paste”, Construction & Building Materials, v. 138, pp. 35–44, 2017. doi: http://dx.doi.org/10.1016/j.conbuildmat.2017.01.126. https://doi.org/10.1016/j.conbuildmat.20... ]	GO+Fly ash	Enhancement of Strength due to drop of pores in the composite.	25% increase due to reinforcement of 0.01% (wt) GO and 5% (wt) FA
PRABAVATHY et al. [¹⁷[17] PRABAVATHY, S., JEYASUBRAMANIAN, K., PRASANTH, S., et al., “Enhancement in behavioral properties of cement mortar cubes admixed with reduced graphene oxide”, Journal of Building Engineering, v. 28, pp. 101082, 2020. doi: http://dx.doi.org/10.1016/j.jobe.2019.101082. https://doi.org/10.1016/j.jobe.2019.1010... ]	rGO–Cement	The presence of needle-shaped hydration crystals forms a dense and compact structure.	44% increase due to reinforcement of 0.1% (wt) rGO
LEE et al. [¹⁸[18] LEE, S.J., JEONG, S.H., KIM, D.U., et al., “Effects of graphene oxide on pore structure and mechanical properties of cementitious composites”, Composite Structures, v. 234, pp. 111709, 2020. doi: http://dx.doi.org/10.1016/j.compstruct.2019.111709. https://doi.org/10.1016/j.compstruct.201... ]	GO (2D - Nano Structure)	The formation of dense and compact microstructure improves the compressive strength.	22.7–45.5% enhancement in Strength was found by the combination of 0.03% (wt) GO
LI et al. [¹⁹[19] LI, X., LIU, Y.M., LI, W.G., et al., “Effects of graphene oxide agglomerates on workability, hydration, microstructure and compressive strength of cement paste”, Construction & Building Materials, v. 145, pp. 402–410, 2017. doi: http://dx.doi.org/10.1016/j.conbuildmat.2017.04.058. https://doi.org/10.1016/j.conbuildmat.20... ]	GO	Compressive Strength was improved due to the alteration of pore structure.	A 6% rise in Strength was found by the addition of 0.03% (wt) GO
WANG et al. [²⁰[20] WANG, Q., LI, S., PAN, S., et al., “Effect of graphene oxide on the hydration and microstructure of fly ash-cement system”, Construction & Building Materials, v. 198, pp. 106–119, 2019. doi: http://dx.doi.org/10.1016/j.conbuildmat.2018.11.199. https://doi.org/10.1016/j.conbuildmat.20... ]	GO+FA	Speeding up of secondary hydration, reduction in the volume of pores, and modification of CH crystal enhances the rise in durability and mechanical properties of the composite	8.9% increase in compressive Strength at 0.03% of GO with 10% of FA.

MATERIAL	LOSS ON IGNITION (LOI)	SiO₂	CaO	MgO	Fe₂O₃	Al₂O₃
NS	0.73	99.06	–	–	–	–
Cement	2.39	26.47	62.08	1.65	2.74	1.13
Fly ash	2.54	67.42	1.75	0.40	3.80	19.68

ELEMENT	C	O	Mg	Al	Si	S
Atomic %	94.7	4.3	0.2	0.2	0.2	0.4

MIX ID	WATER	CEMENT	M-SAND	FA (% by wt)	NS(% by wt)	GO(% by wt)
	Ml	g	g	g	g	g
C	100	200	600	–	–	–
C+FA	100	180	600	20	–	–
C+FA+NS	100	175	600	20	5	–
C+FA+NS+GO0.02	100	175	600	20	5	0.04
C+FA+NS+GO0.03	100	175	600	20	5	0.06
C+FA+NS+GO0.04	100	175	600	20	5	0.08
C+FA+NS+GO0.05	100	175	600	20	5	0.10
C+FA+NS+GO0.06	100	175	600	20	5	0.12

MIX ID	COMPRESSIVE STRENGTH (MPa)
MIX ID	3 DAYS	7 DAYS	28 DAYS
C	23	37	54
C+FA	20	26	35
C+FA+NS+GO0.02	21.72	27.58	36.61
C+FA+NS+GO0.03	29.55	34.75	41.37
C+FA+NS+GO0.04	28.58	33.23	39.15
C+FA+NS+GO0.05	25.32	31.6	38.23
C+FA+NS+GO0.06	23.64	30.43	37.42

MIX ID	3 DAYS	7 DAYS	28 DAYS
C+FA	–	–	–
C+FA+NS+GO0.02	8.6	6.08	4.6
C+FA+NS+GO0.03	47.75	33.65	18.2
C+FA+NS+GO0.04	31.58	19.23	11.86
C+FA+NS+GO0.05	26.6	17.69	9.23
C+FA+NS+GO0.06	18.2	17.04	6.91

SPECIMEN	WATER ABSORPTION (%)
C	13.43
C+FA	11.5
C+FA+NS+GO0.02	9.32
C+FA+NS+GO0.03	5.92
C+FA+NS+GO0.04	7.74
C+FA+NS+GO0.05	8.03
C+FA+NS+GO0.06	8.65

MIX ID	VELOCITY OF ULTRASONIC WAVES (km/s)
MIX ID	3 DAYS	7 DAYS	28 DAYS
C	3.2	3.4	4.0
C+FA	3.6	3.8	4.2
C+FA+NS+GO0.02	4.0	4.5	5.0
C+FA+NS+GO0.03	4.2	5.1	4.5
C+FA+NS+GO0.04	5.0	5.2	4.0
C+FA+NS+GO0.05	4.9	5.2	4.6
C+FA+NS+GO0.06	4.2	4.8	5.0

ID	RESIDUAL COMPRESSIVE STRENGTH (MPa)
ID	AT ROOM TEMPERATURE	250°C	500°C
C	54	5.76	3.84
C+FA+NS+GO0.03	41.37	11.02	7.87

SPECIMEN ID	RESIDUAL STRENGTH (MPa)
SPECIMEN ID	ORIGINAL STRENGTH	AFTER 5% Hcl ATTACK	AFTER 5% H₂SO₄ ATTACK
C	54	6.35	6.92
C+FA+NS+GO0.03	41.37	15.87	13.68

SPECIMEN	C	Al	Ca	Fe	Na	Mg	O	Si	S
C	14.9	12.6	10.7	0.5	4.3	2.6	38.4	15.6	–
C+FA+NS+GO0.03	6.0	7.6	18.9	1.1	1.7	1.5	41.7	19.6	1.7

COMPOUND	ELEMENT NOTATION	2Ɵ ANGLE (C SPECIMEN)	2Ɵ ANGLE (C+FA+NS+G0.03)	CRYSTAL STRUCTURE
Portlandite	CH	18.08, 34.26, 47.18	18.26, 34.16, 47.20	Hexagonal
Jennite	CSH	28.88	28.80	Orthorhombic
Tobermorite	CSH	54.28	54.82	Triclinic
Elite	C3S	29.46,51.8,41.36	29.48,51,41	Triclinic
Belite	C2S	32.2	32.18	Monoclinic
Celite	C3A	32.32	32.32	Isometric
Ettringite	AFt	9.38,15.9,50.01	6.58,15.64,22.14,50.20	Hexagonal

[1] e-mail: skalaiselvi1515@gmail.com, arun_8112005@yahoo.com

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Synergistic effect of graphene oxide and coloidalnano-silica on the microstructure and strength properties of fly ash blended cement composites