Quantitative characterization of pore properties of concrete under on-site curing pressure

Concrete cured within curing pressure is a universal phenomenon for underground concrete structures. Most researches mainly focused on the effect of pressure total porosity and simple surface morphology of the pores in concrete. However, there is a lack of full understanding regarding the pore characteristics of concrete under ultra-deep formation condition (over 100 m). This study aims to investigate the impact of on-site curing pressure on the internal pore structure of concrete. This study analyzed the pore spatial distribution, the pore size-based characteristics, the pore shape-based characteristics and the pore tortuosity properties of concrete sample under varying curing pressure. The result shows that internal pore structure of concrete sample exhibited remarkable uniformity and well-dispersed network under high curing pressure. With curing pressure increased from 0 to 2 MPa, it could be observed that there was a more homogeneous pore spatial distribution, high small-sized pores fraction and uniform equivalent pore diameter in concrete. The curing pressure also could inhibit the development of flattened and elongated pores in the concrete system. The pressurized sample exhibited a more tortuous path on the horizontal direction and vertical direction. This suggests that the concrete samples cured in high curing pressure would present a better structural integrity and durability.