Fractal Characteristics Of Floating Beads Low Density Cement Stone Admixture And Pore Structure

Cement stone is a complex material system consisted of multiphase (gas phase, liquid phase and solid phase), multicomponent, porous structure, multi-level (microscopic, mesoscopic and macroscopic). As to irregularity, uncertainty, fuzziness, and nonlinear macroscopic behavior of cement stone, a study carried on the mechanical behavior and durability which was related to its microscopic structure complexity, accumulation of macro and micro porous structure.Firstly, this article embarked from the material particle characteristics, and the fluctuation of particle size was evaluated by using the fractal theory and laser particle size instrument's test. The relationship between particle volume fractal dimension and particle size was discussed, and how it worked on mechanical properties was analyzed. Secondly, the porosity structure parameters of microsphere low density cement paste were detected by mercury porosimetry and the pore volume fractal dimension was counted up by Menger sponge model. Pore fractal characteristics of microsphere low density cement paste was analysed and appraised. Moreover, relation between pore fractal dimension and porosity, general pore area, mediated pore diameter and mechanical properties was explored.Results showed that:(1) Microsphere's particle volume fractal dimension ranged from 1.10 to 1.21. Meanwhile, micro-silicon's particle volume fractal dimension fluctuated from 1.79 to 2.30. Mixture materials' particle volume fractal dimension was 1.54 to 2.19. The particle size distribution of the mixture composited of microsphere and micro-silicon tended to be more continuous and the distribution range seemed wider which made up to the shortage of intensive distributed micro-silicon. (2) Particle volume fractal dimension resulted from the particle size and the homogeneous distribution of particles, the numerical size of particle volume fractal dimension was attributed to the range of particle size, the proportion of particles in each fraction and particle spherical degree. (3) Particle volume fractal dimension attributed to the specific surface area and median diameter of particles, which worked against the mechanical strength. Those indicated that particle fractal dimension integrated embodiment of particle characteristics.(4) The pore structure inside the microsphere low density cement paste revealed specific pore fractal characteristic and the pore volume fractal dimension arranged from 3.25 to 3.69; The porosity, general pore area and median pore diameter were all enhanced with the increase of pore volume fractal dimension, however, compressive strength and tensile strength decreased.(5) Pore volume fractal dimension not only characterized the pore structure, but also revealed the relative merits of the macroscopic properties of material.