Correlation Analysis between Microscopic Pore Parameters and Macroscopic Mechanical Properties of Rock-like Materials from the Perspective of Water-Cement Ratio and Sand-Cement Ratio

Abstract

To explore the effects of water-cement ratio and sand-cement ratio on micro-pore structure characteristics and macroscopic mechanical properties and thus improve the understanding of rock-like materials, the mechanical test and detection of micro-pore structure combining NMR and SEM were carried out. The effects of WCR and SCR on different porosity parameters and mechanical properties were discussed. The correlation and internal relationship between mechanical properties and parameters of different porosities and fractal dimensions were analyzed. Experimental results showed that the different porosity parameters and fractal dimensions increased with the increase in WCR. 1.0 (SCR) was the turning point of different porosity parameters and fractal dimensions. When the SCR was less than 1.0, the porosity parameters and fractal dimension gradually decreased, while when the SCR was greater than 1.0, the porosity parameters and fractal dimension gradually increased. Microscopic porosity parameters and fractal dimension played an important role in the influence of experimental factors on mechanical properties. Different porosity parameters and fractal dimensions were negatively correlated with mechanical properties. Compressive strength and different porosity parameters conformed to a good exponential relationship, while the fitting relationship between tensile strength and mechanical properties was not obvious. This study can provide a reference for the follow-up study of rock-like materials.

Pore Structure Quantification and Fractal Characterization of MSA Mortar Based on 1H Low-Field NMR

“…Pores with each size exhibit a distinct inner surface morphology. Therefore, in this study, three methods, namely, the spectral valley-based pore fractal calculation (F−sv method), the T 2c −based pore fractal calculation (F−T 2c method) [30], and the pore size-based pore fractal calculation (F−ps method) [23,29], are employed to analyze the fractal characteristics across varying pore gradations (Figure 9). According to the PSD spectral valley, T2c value, and pore size characteristics, the pore fractal dimensions of five types of single-graded mortars are obtained (see Figures 10 and 11, Table 2).…”

“…Fractal theory is applied to the PSD spectrum obtained by NMR to obtain the fractal dimension pores with different gradations [26], and to quantitatively analyze the pore size characteristics [27]. As a new non-destructive analysis method, NMR has been used to determine the fractal dimension of porous materials such as cement, tailings mortar [28], natural sand aggregate mortar [7], and rock [24,29]. Additionally, the pore fractal dimension characteristics of MSA mortar deserve attention.…”

The Freeze-Thaw Strength Evolution of Fiber-Reinforced Cement Mortar Based on NMR and Fractal Theory: Considering Porosity and Pore Distribution

“…However, these methods cannot realize the tracking detection of the same sample during freeze-thaw because the detection process will cause damage to the sample. In recent years, NMR non-destructive technology has been used to detect pore structure, which can obtain pore information by detecting the signal released by water molecules in saturated media [ 15 , 16 , 17 ]. This technology is becoming a helpful method to study the evolution law of fiber-reinforced concrete under freeze-thaw cycles from a microscopic perspective.…”

Relationship between Fractal Dimension and Properties of Engineered Cementitious Composites with Different Aggregates

“…However, it is not accurate to express the pore structure by using only single parameters. Notably, fractal dimension shows advantages in characterizing the discontinuity and irregularity of the pore structure [ 17 , 18 , 19 ], which can effectively quantify and compare the complexity of the material pore structure. Zeng et al [ 17 ] investigated the fractal dimension of cement paste and mortar with/without ground granulated blast-furnace slag (GGBS) and obtained by different maintenance methods.…”