PORE VOLUME FRACTAL DIMENSION OF FLY ASH - CEMENT PASTE AND ITS RELATIONSHIP BETWEEN THE PORE STRUCTURE AND STRENGTH

Pore volume fractal dimensions of fly ash - cement paste at different ages and its pore volume fractal dimensions were determined by MIP(mercury intrusion porosimetry) on experiments. The relationship of pore volume fractal dimension with porosity, pore area, average pore diameter, pore size distribution, compressive and flexural strength of fly ash - cement paste were investigated. Results show that pore structures of fly ash - cement pastes have typical fractal nature and the values of fractal dimension are between 3. 3 and 3. 5. The higher fractal dimension is, the smaller average diameter of pore becomes, the lower porosity becomes, the larger pore area would be. Besides increment of the value of fractal dimension also means the increase of small size pores less than 20 nm and decrease of large size pores beyond 100 nm and the improvement of compressive and flexural strength of fly ash - cement paste as well.