Fractal characteristics of pore structure of hardened cement paste prepared by pressurized compact molding

Zhang, Lunchao; Zhou, Jikai

doi:10.1016/j.conbuildmat.2020.119856

Cited by 58 publications

(14 citation statements)

References 41 publications

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“…Qing [29] analyzed the relationship among pore fractal dimension, compressive strength and permeability of wollastonite concrete by mercury pressing test and electron microscope scanning test. Zhang [30] carried out the mercury pressing test and X-ray diffraction test on compacted concrete materials and discussed the microstructure and fractal characteristics. Zhang [31] studied the influence of electric breakdown energy on the microstructure, and the fractal dimensions of coal block was studied by means of NMR.…”

Section: Introductionmentioning

confidence: 99%

Research on Strength Prediction Model of Sand-like Material Based on Nuclear Magnetic Resonance and Fractal Theory

Deng

Tian

et al. 2020

Applied Sciences

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Micro-pore structure has a decisive effect on the physical and mechanical properties of porous materials. To further improve the composition of rock-like materials, the internal relationship between microscopic characteristics (porosity, pore size distribution) and macroscopic mechanical properties of materials needs to be studied. This study selects portland cement, quartz sand, silica fume, and water-reducing agent as raw materials to simulate sandstone. Based on the Nuclear magnetic resonance (NMR) theory and fractal theory, the study explores the internal relationship between pore structure and mechanical properties of sandstone-like materials, building a compressive strength prediction model by adopting the proportion of macropores and the dimension of macropore pore size as dependent variables. Test results show that internal pores of the material are mainly macropores, and micropores account for the least. The aperture fractal dimension, the correlation coefficient of mesopores and macropores are quite different from those of micropores. Fractal characteristics of mesopores and macropores are obvious. The macropore pore volume ratio has a good linear correlation with fractal dimension and strength, and it has a higher correlation coefficient with pore volume ratio, pore fractal dimension and other variable factors. The compressive strength increases with the growth of pore size fractal dimension, but decreases with the growth of macropore pore volume ratio. The strength prediction model has a high correlation coefficient, credibility and prediction accuracy, and the predicted strength is basically close to the measured strength.

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Section: Introductionmentioning

confidence: 99%

Research on Strength Prediction Model of Sand-like Material Based on Nuclear Magnetic Resonance and Fractal Theory

Deng

Tian

et al. 2020

Applied Sciences

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“…The ions content of Na + , Ca 2+ , Si 4+ and Al 3+ leached from the precast geopolymers at different periods of water immersion are presented in Figure 8 . Figure 8 a shows the evolution of Na + content, where it can be observed that the content of Na + gradually increases with an increasing period of water immersion [ 26 ]. At the same time, the content of Na + increases firstly and then decreases with increasing steel slag dosage.…”

Section: Resultsmentioning

confidence: 99%

“…Furthermore, mold pressing technology could significantly decrease the total porosity and total percentage of harmful pores (50–200 nm) and (>200 nm) of geopolymers. Zhang et al studied the pore structure of hardened cement paste and the microstructure regulation mechanism and defect reduction after pressure compaction [ 26 ]. Results indicated that the pore surface fractal dimension of cement paste become multisegmental fractal and scale dependent after being pressurized as compact molding, and the irregular drift behavior in the transition region was not obvious.…”

Section: Introductionmentioning

confidence: 99%

The Failure Mechanisms of Precast Geopolymer after Water Immersion

Wang

et al. 2021

Materials

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Precast geopolymers with lower water/binder (0.14), which mainly consists of alkali solution, fly ash (FA) and steel slag (SS), were manufactured through molding pressing technology. The failure mechanisms of precast geopolymers after water immersion were studied by testing the loss of compressive strength, the pH of the leaching solution, the concentration of ions (Na+, Ca2+, Si4+ and Al3+), the evolution of phases, pore structure and morphology, and further discussion of the regulation evolution was performed. The results show that the harmful pores (>50 nm) of geopolymers progressively decrease from 70% to 50% after 28 days of water immersion when the content of steel slag increases from 0 to 80 wt.%. Compressive strength of geopolymers sharply reduces in the first 3 days and then increases during the water immersion process, but the phase composition varies slightly. Furthermore, increasing the content of steel slag could decrease the total porosity and further prevent the water resistance.

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“…Due to the clear physical meanings, and elegant and simple expression, at present, various fractal theory-based models were developed to interpret the microstructure/pore structure data obtained by different test methods, including nitrogen adsorption/desorption [32][33][34], mercury intrusion porosimetry (MIP) [35][36][37], small-angle scattering of X-rays (SAXS) or neutrons (SANS) [38][39][40], nuclear magnetic resonance (NMR) [41], and scanning electronic microscopy (SEM) [42]. Meanwhile, great efforts were made to establish quantitative links between fractal dimensions and macro properties [43][44][45][46][47]. Niu et al [43] suggested that the microstructural complexity indexed by fractal dimensions can directly reflect the mechanical properties of concrete.…”

Section: Introductionmentioning

confidence: 99%

May the Piezoresistivity of GNP-Modified Cement Mortar Be Related to Its Fractal Structure?

et al. 2021

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High piezoresistivity of cement-based composites tuned by conductible fillers provides a feasible way to develop self-sensing smart structures and buildings. However, the microstructural mechanisms remain to be properly understood. In the present work, the piezoresistivity of cement mortar with different dosages of graphene nanoplatelets (GNPs) was investigated, and the microstructure was assessed by electron scanning microscopy (SEM) and mercury intrusion porosimetry (MIP). Two surface fractal models were introduced to interpret the MIP data to explore the multi-scale fractal structure of the GNP-modified cement mortars. Results show that the incorporation of GNPs into cement mortar can roughen the fracture surfaces due to the GNPs’ agglomeration. Gauge factor (GF) rises and falls as GNP content increases from 0% to 1% with the optimal piezoresistivity observed at GNP = 0.1% and 0.05%. The GF values of the optimum mortar are over 50 times higher than those of the reference mortar. Fractal dimensions in macro and micro fractal regions change with GNP content. Analysis shows that the fractal dimensions in micro region decrease first and then increase with the increase of GF values. GNPs not only impact the fractal structure of cement mortar, but also alter the tunneling and contact effects that govern the piezoresistivity of composite materials.

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Fractal characteristics of pore structure of hardened cement paste prepared by pressurized compact molding

Cited by 58 publications

References 41 publications

Research on Strength Prediction Model of Sand-like Material Based on Nuclear Magnetic Resonance and Fractal Theory

Research on Strength Prediction Model of Sand-like Material Based on Nuclear Magnetic Resonance and Fractal Theory

The Failure Mechanisms of Precast Geopolymer after Water Immersion

May the Piezoresistivity of GNP-Modified Cement Mortar Be Related to Its Fractal Structure?

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