SYNTHESIS AND STRENGTH STUDY OF CEMENT MORTARS CONTAINING SiC NANO PARTICLES
A. BAHARIa,b*, A. SADEGHI NIKc, M. ROODBARIb, K. TAGHAVIb, S.E. MIRSHAFIEIc
aDept. of Physics, Islamic Azad University, Science and Research Branch, Mazandaran, Iran.
bDepartment of Physics, University of Mazandaran, Babolsar, Iran.
cYoung Researchers Club, Jouybar Branch, Islamic Azad University, Jouybar, Iran.
dDept. of Civil Engineering, Islamic Azad University, Jouybar Branch, Jouybar, Iran.
In this work we have demonstrated a series of experiments for the synthesis of nano scale silicon carbide (SiC) crystallite in cement mortar in powder form and studied the stress- strain (and strength) of cement mortar containing SiCnano particles using AFM (Atomic Force Microscopy)and XRD (X-ray Diffraction) techniques and X- powder, Williamson- Hall andNanosurf methods.The obtained results show a more stable structure of the sample with 10% SiCnano particles.
(Received June 18, 2012; Accepted September 26, 2012) Keywords: Cement, SiC, Nanoparticles and AFM technique.
1. Introduction
Many current strategies and investigations for material synthesis integrate both synthesis and assembly into a single process, such as characterizes mechanical, physical and chemical synthesis of nanostructuralmaterials [1-3].Major efforts in cement mortar powder nanocrystallite and nanoparticle synthesis can be done using sol- gel methods.
Furthermore, nanocompositematerials have shown many potential applications due to their functionality, their chemical reactivity and/or physical compactionto integrate nanostructure building blocks within the fine final material structure [4-9].
In the last decade, many workers have studied the high performance multifunctional cementitiousnanocomposite materials with different types of nanoparticles[11], mostly Si, Co, C, Fe and nanoclayparticles [11 and references therein]. However, their concrete samples containing above nanoparticles are less resistant to bending than samples with SiCnanopparticlesinthe present work.
We firstly synthesized the SiC nanoparticles using the sol-gel method at different temperatures and nanoparticles molarity. After that we dispersed these nanoparticles in a cement solvent and sonicatedthe mixture. The different samples have been prepared and tested during two weeks to detect variation incompression, bending and contraction properties as studied using AFM and XRD techniques and evaluated with X- powder, Nanosurf and Williamson- Hall, methods.
The obtained results showed an increase in the resistance to bending for 3% SiCnano particles concretein comparison with undoped concrete.
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*Corresponding author: [email protected]
The surface morphology and crystal structure of nanometerSiC powders have been investigated using XRD, AFM, Nanosurf and X- Powder techniques. The crystal phases of the nanocrystallites were identified by XRD analysis (figures 1 and 2) and the nanocrystallitessizes were also appraised by X-powder method. The crystal phases of the SiCnanocrystallites were identified by XRD analysis. The Miller index in figure 1 is not clear as in figure 2 due tocement structure.
The SiCnanocrystallitesize (corresponding to figure 1) was appraised by X-powder method. The typical diameter foundfor 3% SiCnanoparticles andundoped cement were 48 nm and 29 nm, respectivly. X- Powder technique (figures 3 and 4 for SiC crystallite phase) shows that typical diameters reach nanometer magnitude. The smaller size of cement with 3%
SiCnanoparticleswith respect to that of undopedcement, indicates that temperature and SiC affect the crystallites structure.Experimental results show that the samples have better crystalline state with 3% SiCnano particles. As shown in figure 2 (down), a relatively amorphous structure could be formed at room temperature, as well.
Microscopy and surface morphology analyses were performed by using AFM (figures 5 and 6) and Nanosurf techniques(figures 7 through 10). AFM topography images of the SiCnanocrystallites at pH = 8 and the image of height distributions of SiCnanocrystallites at pH = 8 are shown in figures 11 and 12, respectively.
Fig. 1.The crystal phases of the mortar cement nanocrystallites were synthesized at 3000C and identified by XRD analysis. The Miller indicesare not clear due to the cement structure.There are no significant peaks after 40 o and we eliminated these peaks.
Fig. 2.The crystal phases of the cement mortar with 3% SiCnanocrystallites were synthesized at room
temperature (down) and 3000C (up) and identified by XRD analysis.
Fig. 3 -The size of SiCnanocrystallite (corresponding to figure 1) is appraised by X-powder method.
It is shown that the typical diameter is of 48 nm.
Fig.4- The size of SiCnanocrystallite (corresponding to figure 2 at 3000C) is appraised by X-powder method. It is shown that the typical diameter is of 29 nm.
Fig. 5 -Microscopy and surface morphology analyses of cement prepared at 3000C and performed by using AFM technique.
Fig. 6.Microscopy and surface morphology analyses ofcement mortar with 3% SiCnano particles prepared at 3000C and performed by using AFM technique.
Fig. 7.Dislocation study of thecement mortar with 3% SiCnano particles prepared at 3000Cby using the Nanosurf (see closed square) technique and the results of stress and strain are shown in the left hand side of the AFM image. The SiC crystallite length of the cement is 468.8 nm.
Fig. 8.Dislocation study of thecement mortar with 3% SiCnano particles prepared at 3000Cby using the Nanosurf (see closed square) technique and the results of stress and strain are shown in the left hand side of the AFM image. The SiC crystallite length of the cement is 1019 nm.
Fig. 9.Dislocation study of the cement mortar with 3% SiCnano particles prepared at 3000Cby using the Nanosurf (see closed square) technique and Williamson- Hall data for stress and strain are shown in the left hand side of the AFM image.
Fig. 10.Dislocation study of the cement mortar with 3% SiCnano particles prepared at 6000Cby using the Nanosurf (see closed square) technique and Williamson- Hall data for
stress and strain are shown in the left hand side of the AFM image.
Fig. 11.AFM topographical images of synthesized cement mortar with 3% SiCnano
particles at 3000C at pH = 8. The scan size was 25.12 pm2. Sa of the synthesized SiCnanocrystallites is about 7.121 nm at pH = 8.
Fig.12. This image shows the height distribution of synthesized cement mortar with 3%
SiCnano particles at pH = 8. It reveals that the SiCnanocrystallites at pH = 8 with tight surfaceare suitable in temperature sensor.
In addition, the present matrix is a standard silica fume and cement produced by Mazandaran, Iran agglomerated diamond Si/C. Cement mortar specimens of a polyhedron shape, 5×5×20 cm3 in size, are manufactured and cured in wet air media. AFM topographical image in figure 11 shows synthesized SiCnanocrystallites at 3000C at pH = 8. The scan size was 25.12 pm2. Sa of the synthesized SiCnanocrystallites are given in the Nanosurf images at pH = 8. Uniform surface was observed with many nanoparticles at pH = 8. There is rougher surface, as revealed in topography spectrum in figure 11. The Gaussian distribution of mortar cement with 3% SiC nanoparticles in figure 12, indicates a homogeneous distribution of siCnano particles in the mortar cement structure.
4 1
Where L is the size of the nanoparticle and θ is the full- width half- maximum.Fig. 13. The Williamson – Hall method based on X- Powder findings shows linear diagrams of βcosθ versus 4sinθ.
XRD spectra and AFM images in the above figures show that cement mortar with 3%
SiCnanoparticlesis a more rigid matrix than that without SiCnano particles. The penetration of SiCnanoparticles through the cement can make much more room for nanoparticles to improve the plain cement mortar properties. The scattering spectrum in figure 12 shows that particles are uniformly dispersed. The reasoncould be due to their great surface energy.
4. Conclusion
It is clear that the temporal change of the bending strength for concrete with 3% SiCnano particles and undoped cement has shown measurable differences. In figure 13, one can see that harder and less resistant to bending samples can be produced with SiC nanoparticles.
Acknowledgment
This work, a national project entitled "Concrete material stability with SiC Nanoparticles", was supported by Iran National Science Foundation (INSF).
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