Pore size distributions and fractal characteristics of basalt fiber-reinforced coral sand concrete.

Coral sand is widely used as an aggregate in concrete to reduce costs and improve efficiency in marine engineering. However, it increases the porosity and brittleness of concrete, leading to steel corrosion. This study introduced basalt fibers to enhance the strength and corrosion resistance of concrete. The hydration process and pore structure of basalt fiber-reinforced coral sand concrete (BFRCSC) were analyzed through nuclear magnetic resonance techniques. During a 96 h hydration period, the intensity of total, gel, and small capillary water exhibited fluctuations, whereas large capillary and free water dropped sharply within the initial 10 h. The pore size distribution was analyzed using fractal theory. The analysis revealed that total fractal dimensions D, which corresponds to a combination of harmful and very harmful pores in the specimens after curing for 7 days, 14 days and 28 days, ranged from 2.84 to 2.923. Compressive strength decreased as porosity increased, but BF-0.1, which had a 0.1% basalt fiber content, achieved the highest strength due to its lower proportion of very harmful pores and higher total fractal dimension. This study emphasizes the importance of very harmful pores in determining the compression strength of BFRCSC, as analyzed using the fractal dimension.