The concrete core samples from four typical locations of a hydropower station that has been in service for sixty years were selected to carry out the study. The compressive strength
impermeability and frost resistance of the concrete core samples were tested according to the specifications. The hydra - tion products
microstructure
porosity and pore size distribution of the concrete core samples were test - ed by the X-ray diffractometer (XRD)
scanning electron microscope (SEM) and low-field nuclear magnetic resonance. Moreover
based on the porosity and pore size distribution
the relationship between them and strength was explored. The results showed that the internal carbonization of the concrete core sam- ples was obvious
but the matrix was intact
and the bonding between the aggregates and the hardened paste was good. The results of low-field nuclear magnetic resonance indicated that the porosity of the concrete core sample was between 4.56%~8.40%
and the pore size was basically distributed between 1~ 200 nm. The lower the porosity of the core sample meant the higher the compressive strength and the higher the anti-permeability level. However
the correlation between porosity and frost resistance grade was poor. Compared with the porosity
the proportion of pores between 20~ 100 nm had a better correla- tion with the strength of the concrete core sample
and the correlation coefficient reached 0.954.
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references
Chen X,Wu S,Zhou J.Influence of porosity on compressive and tensile strength of cement mortar[J].Construction and Building Materials,2013,40:869-874.
Li D,Li Z,Lyu C,et al.A predictive model of the effective tensile and compressive strengths of concrete considering po- rosity and pore size[J].Construction and Building Materials, 2018,170:520-526.
Han X,Feng J,Wang B.Relationship between fractal feature and compressive strength of fly ash-cement composite ce - mentitious materials[J].Cement and Concrete Composites, 2023,139:105052.
Wang B,Guo J,Liu J,et al.Prediction method of permeability of textile- reinforced concrete based on fractal dimension theory[J].Construction and Building Materials,2022,327: 126868.
Lyu Q,Qiu Q,Zheng J,et al.Fractal dimension of concrete in- corporating silica fume and its correlations to pore struc - ture, strength and permeability[J].Construction and Build- ing Materials,2019,228:116986.
钱鹏 . 混凝土的微观裂纹结构与宏观渗透性能研究[D].北京:清华大学 .
Wang R,Zhang Q,Li Y.Deterioration of concrete under the coupling effects of freeze-thaw cycles and other actions: A review[J].Construction and Building Materials,2022,319: 126045.
Von Greve- Dierfeld S,Lothenbach B,Vollpracht A,et al. Understanding the carbonation of concrete with supple - mentary cementitious materials: a critical review by RILEM TC 281-CCC[J].Materials and Structures,2020,53(6):136.