scholarly journals PREDICTION OF FROST DAMAGE CONSIDERING PORE STRUCTURE CHANGE BY DRYING CONDITIONS

2021 ◽  
Vol 86 (781) ◽  
pp. 343-351
Author(s):  
Takumi NOGUCHI ◽  
Yukio HAMA
Keyword(s):  
Pore Structure ◽  
Frost Damage ◽  
Structure Change ◽  
Drying Conditions

scholarly journals Distribution Map of Frost Resistance for Cement-Based Materials Based on Pore Structure Change

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2509
Author(s):  
Nguyen Xuan Quy ◽  
Takumi Noguchi ◽  
Seunghyun Na ◽  
Jihoon Kim ◽  
Yukio Hama
Keyword(s):  
Prediction Model ◽  
Pore Structure ◽  
Frost Resistance ◽  
Frost Damage ◽  
Structure Change ◽  
Quantitative Prediction ◽  
Weather Data ◽  
Distribution Map ◽  
Cement Based Materials ◽  
Damage Risk

This paper presents a prediction method and mathematical model based on experimental results for the change in pore structure of cement-based materials due to environmental conditions. It focuses on frost damage risk to cement-based materials such as mortar. Mortar specimens are prepared using water, ordinary Portland cement, and sand and the pore structure is evaluated using mercury intrusion porosimetry. New formulas are proposed to describe the relationship between the pore structure change and the modified maturity and to predict the durability factor. A quantitative prediction model is established from a modified maturity function considering the influences of environmental factors like temperature and relative humidity. With this model, the frost resistance of cement-based materials can be predicted based on weather data. Using the prediction model and climate data, a new distribution map of frost damage risk is created. It is found that summer weather significantly affects frost resistance, owing to the change in pore structure of cement-based mortar. The model provides a valuable tool for predicting frost damage risk based on weather data and is significant for further research.

Calculation and Analysis of Multifractal Spectrum of Sinter Surface

2013 ◽  
Vol 750-752 ◽  
pp. 2267-2270
Author(s):  
Zhi Min Cui ◽  
Rong Li Sang ◽  
Yuan Liang Li ◽  
Qing Jun Zhang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Pore Structure ◽  
Multifractal Spectrum ◽  
Transmission Electron Microscopy Image ◽  
Structure Change ◽  
Electron Microscopy Image ◽  
Transmission Electron ◽  
Microscopy Image ◽  
Fractal Spectrum

Multifractal spectrums of sinter with different alkalinity were analyzed by multifractal software. The results show that sinter pore structure change from uniform to non-uniform with the improvement of alkalinity, Δα increases from 0.53 to 0.55. The structure of sinter pore is mainly microscopic by competition between macropores and micropores, Δf changes from 0.14 to-0.44. The distribution of sinter pores is quantitatively characterized by multi-fractal spectrum, which is consistent with transmission electron microscopy image.

scholarly journals Effect of Blast-Furnace Slag Replacement Ratio and Curing Method on Pore Structure Change after Carbonation on Cement Paste

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4787
Author(s):  
Junho Kim ◽  
Seunghyun Na ◽  
Yukio Hama
Keyword(s):  
Blast Furnace ◽  
Calcium Carbonate ◽  
Pore Structure ◽  
Calcium Silicate ◽  
Blast Furnace Slag ◽  
Calcium Silicate Hydrate ◽  
Structure Change ◽  
Replacement Rate ◽  
Replacement Ratio ◽  
Furnace Slag

The frost damage resistance of blast-furnace slag (BFS) cement is affected by carbonation. Hence, this study investigates the carbonation properties of pastes incorporating BFS with different replacement ratios, such as 15%, 45%, and 65% by weight, and different curing conditions, including air and carbonation. The BFS replacement ratio properties, determined by the Ca/Si ratio of calcium silicate hydrate in the cement paste sample, were experimentally investigated using mercury intrusion porosimetry, X-ray diffraction, and thermal analysis. The experimental investigation of the pore structure revealed that total porosity decreased after carbonation. In addition, the porosity decreased at a higher rate as the BFS replacement rate increased. Results obtained from this study show that the chemical change led to the higher replacement rate of BFS, which produced a higher amount of vaterite. In addition, the lower the Ca/Si ratio, the higher the amount of calcium carbonate originating from calcium silicate hydrate rather than from calcium hydroxide. As a result of the pore structure change, the number of ink-bottle pores was remarkably reduced by carbonation. Comparing the pore structure change in air-cured and carbonation test specimens, it was found that as the replacement rate of BFS increased, the number of pores with a diameter of 100 nm or more also increased. The higher the replacement rate of BFS, the higher the amount of calcium carbonate produced compared with the amount of calcium hydroxide produced during water curing. Due to the generation of calcium carbonate and the change in pores, the overall number of pores decreased as the amount of calcium carbonate increased.

scholarly journals Coal Matrix Deformation and Pore Structure Change in High-Pressure Nitrogen Replacement of Methane

Energies ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 175 ◽  
Author(s):  
Xiaofeng Ji ◽  
Dangyu Song ◽  
Xiaoming Ni ◽  
Yunbo Li ◽  
Haotian Zhao
Keyword(s):  
High Pressure ◽  
Pore Structure ◽  
Structure Change ◽  
Coal Matrix ◽  
Matrix Deformation

scholarly journals EFFECTS OF PORE STRUCTURE CHANGE AND MULTI-SCALE HETEROGENEITY ON CONTAMINANT TRANSPORT AND REACTION RATE UPSCALING

2013 ◽  
Author(s):  
W. Brent Lindquist ◽  
◽  
Keith W. Jones ◽  
Wooyong Um ◽  
mark Rockhold ◽  
...  
Keyword(s):  
Pore Structure ◽  
Contaminant Transport ◽  
Reaction Rate ◽  
Structure Change ◽  
Multi Scale ◽  
Scale Heterogeneity

Hydrothermal conversion of oil shale: Synthetic oil generation and micro-scale pore structure change

Fuel ◽  
2022 ◽  
Vol 312 ◽  
pp. 122786
Author(s):  
Shadi A. Saeed ◽  
Usman Taura ◽  
Yahya Al-Wahaibi ◽  
Ameen A. Al-Muntaser ◽  
Chengdong Yuan ◽  
...  
Keyword(s):  
Pore Structure ◽  
Oil Shale ◽  
Structure Change ◽  
Hydrothermal Conversion ◽  
Micro Scale ◽  
Synthetic Oil ◽  
Oil Generation
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