| Functionally Graded Materials (FGM) is that the components and the structure of the material are gradient distribution from one side of the material (product) to the omer. So far, FGM has been widely used in modern Industries.In this paper, the concept of FGM is firstly applied in cement-based materials to study the effect of dispersion phase gradient distribution in cement-based materials on physicomechanical property and functions after the effect of dispersion phase and its mechanism in cement-based materials were analyzed. Without special forming equipment, the gradient distribution of components and the designed properties of the material can be achieved by the component graded change, layering formation and mechanical vibration. And the study shows that more layers of the structure, smoother transition from one layer to another.Three aspects are studied: (1) The methods of carbon fibers (CF) dispersion; (2) The effect of CF gradient distribution on thermal and electric properties; (3) the effect of aggregates and glass fibers (GF) with linear and parabolic component gradient variation on mechanical property.The test results indicate that the properties and functions of the cement-based FGM can be obviously improved by the gradient distribution of different disperse phases. Namely:(1) The CF can be dispersed by methyl cellulose and superfine silica fume used together and the electrical resistivity is low. So it provides a good way for CF dispersion;(2) The results on CF cement-based FGM include four aspects. Firstly, the electrical resistivity is influenced little by CF content increase after the conductive circuit formation. The results in this paper show that the conductivity increases quickly when CF weight percentage is 0.3-0.8% and turns to low after 0.8%; Secondly, it indicates that thermal expansion is restrained by CF obviously. Furthermore, electric-thermal property can be realized and thermal stress can be reduced in CF cement-based FGM in which the discontinuous carbon fibers are gradient distribution. Lastly, the test results show that the increase of the temperature of the carbon fiber reinforced cement-based FGM is quick when the electric circuit passes through it, and the heat quantity of the matrix decreases (the electricresistance of the matrix increases) as the temperature of the matrix increase and the temperature of the matrix may tend to a constant value at last when the heat generating quantity of thg matrix equal to the heat radiating quantity of the matrix.(3) Compared with that of the homogeneous distribution of the high strength aggregates and the activation aggregates, the higher strength of the gradient distribution of the disperse phase of the cement-based FGM are achieved, especially the bending strength. It is because the clinker is distributed much more in tensile area which bears more stress. For example, with linear and parabolic component gradient variation of aggregates, linear component gradient variation of aggregates reinforces higher than parabolic variation. Linear component gradient variation of aggregates improves 16% of aggregates homogeneous distribution on bending strength; parabolic component gradient variation does 8%. GF is widely used as composite reinforcement due to low cast and excellent properties such as high tensile strength and high elastic modulus. When the reinforced glass fibers (GF) gradient distribution, the same reinforced role can be achieved in the lower volume of the reinforced fibers, because the distribution of the reinforced fibers is coincident with the stress distribution of the specimen. For example, with linear and parabolic component gradient variation of GF, parabolic component gradient variation of GF reinforces higher than linear variation. Parabolic component gradient variation of GF improves 18% of GF homogeneous distribution on bending strength; linear component gradient variation only does 6%.In conclusion, different properties (or functions) of the dispersion phase improve cement-based FGM and t... |
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