Study of Pore Volume Fractal Dimension for Different Air Content Cement Mortar

Abstract

The pore structure parameter of cement mortar with different air contents was tested through Automatic Mercury Porosimeter and Air Void Analysis of Hardened Concrete. A fractal model based on the thermodynamic method was used in the calculation of different scale pore structure fractal dimensions of cement mortar. The relationships between fractal dimensions and porosity, average pore diameter, pore specific surface area, pore spacing coefficient, and total pore volume were analyzed. Results show that the fractal dimension presents multiplicity, which is calculated by the fractal model based on thermodynamics; it can represent the complexity of cement mortar very well. The increase of air content increases the fractal dimension by more than 102 nm pore diameter, and the fractal dimension decreased while the pore diameter was under 102 nm. The increase in age decreases the fractal dimension in the range of 103 nm to 104 nm, and the others showed an increasing trend. The fractal dimension has good correlation with porosity, average pore diameter, and total pore volume among the pore structure parameters and has poor correlation with pore specific surface area in the range of 103 nm to 104 nm and pore diameter in the range of 102 mm to 103 nm. In considering that the pore diameters ranging from 102 nm to 103 nm have a high proportion in the total pores, they can be used as a unified fractal dimension to signify the change of pore structure parameters.