Solid Mass Fractal Model for Pore Structure in Cement Paste

2016 ◽  
Vol 711 ◽  
pp. 1084-1089 ◽  
Author(s):  
Yun Gao ◽  
Song Mu ◽  
Jin Yang Jiang
Keyword(s):  
Pore Structure ◽  
Cement Paste ◽  
Parametric Analysis ◽  
Fractal Model ◽  
Wide Scope ◽  
Solid Mass ◽  
Fractal Approach ◽  
Mass Fractal ◽  
Practical Challenge ◽  
Self Similar

Though discussed a lot, it remains a practical challenge to modeling pore structure in cement paste. The fractal approach shows a great advantage since it allows to generate complex pore structure via simple geometric iterations and to incorporate the wide scope of pores in a self-similar manner. In this paper, the solid mass fractal model is proposed for pore structure in cement paste. The parametric analysis is performed in conjunction with the porosimetric test. It is shown that the proposed solid mass fractal well describes pore structure in cement paste.

scholarly journals Fractal Modeling of Pore Structure and Ionic Diffusivity for Cement Paste

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Yun Gao ◽  
Jin-yang Jiang ◽  
Kai Wu
Keyword(s):  
Pore Structure ◽  
Cement Paste ◽  
Mercury Intrusion Porosimetry ◽  
Fractal Model ◽  
Homogenization Method ◽  
Solid Mass ◽  
Fractal Modeling ◽  
Mass Fractal ◽  
Chloride Migration ◽  
Ionic Diffusivity

Pore structure in cement based composites is of paramount importance to ionic diffusivity. In this paper, pore structure in cement paste is modeled by means of the recently proposed solid mass fractal model. Moreover, an enhanced Maxwell homogenization method that incorporates the solid mass fractal model is proposed to determine the associated ionic diffusivity. Experiments are performed to validate the modeling, that is, mercury intrusion porosimetry and rapid chloride migration. Results indicate that modeling agrees well with those obtained from experiments.

Influence of Lightweight Aggregate on Durability of High Performance Concrete

2009 ◽  
Vol 405-406 ◽  
pp. 197-203
Author(s):  
Bao Sheng Zhang ◽  
Li Juan Kong ◽  
Yong Ge
Keyword(s):  
Pore Structure ◽  
Cement Paste ◽  
Frost Resistance ◽  
High Performance ◽  
High Performance Concrete ◽  
Bound Water ◽  
Lightweight Aggregate ◽  
Normal Weight ◽  
Lightweight Aggregate Concrete ◽  
Aggregate Concrete

High performance concrete (HPC) with a water/cement ratio (w/c) of 0.32 and different lightweight aggregate (LWA) contents (0%, 25%, 50%, 75%, 100%) were prepared, and the influence of LWA on concrete frost-resistance and impermeability at different ages were studied, as well as the hydration degree, hydrated product, pattern and pore structure of the paste around aggregate. The results show that, by replacing normal weight aggregate (NWA) with 50% and 100% volume contents of pre-wetted LWA respectively, the chemical bound water of the cement paste surrounding aggregate are increased 12.1% and 22.7% as compared to concrete mixed without LWA. And at 28 days, lightweight aggregate concrete has the highest Ca(OH)2 content, whereas the 90-day Ca(OH)2 content of normal weight concrete is the highest. This proves that, with the increase of LWA content in concrete, both of the internal curing effect of pre-wetted LWA and secondary hydration effect of fly ash (FA) are strengthened, this can also be verified by the SEM study. Furthermore, the pore structure of the cement paste around aggregate can be improved consequently. The performance of frost-resistance of HPC can be improved by mixing LWA, the 90 day-frost-resistance of lightweight aggregate concrete is about 2.5 times of that of concrete mixed without LWA. The influence of LWA on the impermeability of HPC is different from normal concrete. When LWA content is more than 50%, the HPC impermeability decreased obviously, however at later age the difference between them becomes minor.

The Influence of Pore Structure on the Properties of Cement Paste: Initial Observations about Research-in-progress

1988 ◽  
Vol 137 ◽  
Author(s):  
D. A. Lange ◽  
H. M. Jennings ◽  
S. P. Shah
Keyword(s):  
Pore Structure ◽  
Fracture Energy ◽  
Optical Microscopy ◽  
Cement Paste ◽  
Material Properties ◽  
Direct Method ◽  
Total Porosity ◽  
Pore Geometry ◽  
Method Of Measurement ◽  
A Direct Method

AbstractInitial observations of the influence of pore structure on material properties of cement paste are described. The total porosity is held constant and pore structure is altered by use of a superplasticizer. Corresponding changes in strength and fracture energy are observed. Changes in the cement paste pore structure are evaluated by analysis of images obtained by optical microscopy. The technique is a direct method of measurement that avoids assumptions about pore geometry.

SEARCH FOR NEW METHODOLOGICAL APPROACHES AND METHODS IN RISK MANAGEMENT

2021 ◽  
Vol 54 (2) ◽  
pp. 35-47
Author(s):  
Svetlana N. Dvoryatkina ◽  
◽  
Arseny M. Lopukhin ◽  
Keyword(s):  
Risk Management ◽  
Large Scale ◽  
Quantitative Methods ◽  
Knowledge Bases ◽  
Fractal Model ◽  
Educational Process ◽  
Machine Learning Algorithms ◽  
Risk Modeling ◽  
Negative Consequences ◽  
Fractal Approach

The study actualized the complex and large-scale problem of adapting the theory of risk man-agement for the education system. A comprehensive analysis of domestic and international stud-ies revealed the lack of a theoretical framework, a general methodological vision of the problem of riskiness and risk-taking in the educational sphere. While effective management of education-al activities, ensuring the development of the competitiveness of the individual in the labor mar-ket and its potential for active participation in the life of society is possible on the basis of the modern paradigm of risk management, integrating achievements in pedagogical, economic, mathematical and computer sciences. A new methodology in the study is the fractal approach, which defines the idea of quantitative and qualitative analysis and assessment of the risk of non-formation of professional competencies, complex educational and cognitive constructs of subject activity. The fractal model of assessing the formation of knowledge and competencies, its risk landscape, taking into account the subject and cognitive divergence, will ensure the effective-ness of the structure of knowledge storage in the educational process, minimizing the time for building space and engineering knowledge bases, and the depth of solving the problem of pre-dicting educational risks. New methods of risk modeling based on machine learning algorithms and factor analysis, methods for constructing neural integrators, quantitative methods with and without taking into account the probability distribution will ensure the accuracy and speed of risk assessment and prediction, will allow one to identify new patterns of risk activity and further ways to develop the theory of risk. The presented effective strategies and innovative tools will solve the problem of minimizing unplanned chaos, the cascade of negative consequences of risky situations, including the COVID-19 epidemic.

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