Capillary Water Absorption and Micro Pore Connectivity of Concrete with Fractal Analysis

Jinghai Zhou,Xiangqun Ding,Tianbei Kang,Yichao Zhang,Xinyu Liang,Yanfeng Fang

doi:10.3390/cryst10100892

Jinghai Zhou, Xiangqun Ding + Show 4 more

Open Access

https://doi.org/10.3390/cryst10100892

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Journal: Crystals	Publication Date: Oct 1, 2020
Citations: 12	License type: CC BY 4.0

Affiliation: Shenyang Jianzhu University

Abstract

This study focuses on the relationship between the complexity of pore structure and capillary water absorption of concrete, as well as the connection behavior of concrete in specific directions. In this paper, the water absorption of concrete with different binders was tested during the curing process, and the pore structure of concrete was investigated by mercury intrusion porosimetry (MIP). The results show that the water absorption of concrete with mineral admixtures is lower, mainly due to the existence of reasonable pore structure. The effect of slag on concrete modification is more remarkable comparing with fly ash. In addition, the analysis shows that the pore with different diameters has different fractal characteristics. The connectivity probability and water absorption of unidirectional chaotic pore are linearly correlated with the pore diameter of 50–550 nm, and the correlation coefficient reaches a very significant level, and detailed analysis was undertaken to interpret these results based on fractal theory.

Highlights

As one of the most commonly used building materials, concrete is inevitably subjected to various destructive factors, which stem from the production process or use environment of concrete
Total pore fractal dimension should have a good agreement with water absorption value
The key factor to establish the objective relationship between pore complexity and water absorption value is to select the appropriate section of pore size, accurately characterize its complexity by pore fractal dimension, and explain the most possible pore size of concrete

Summary

Introduction

As one of the most commonly used building materials, concrete is inevitably subjected to various destructive factors, which stem from the production process or use environment of concrete. Harmful ions dissolved in water (e.g., chloride ions, sulfate ions, or magnesium ions) are transported among the complex and disordered pores [3] Both theoretical and experimental results show that the capillary suction of unsaturated concrete absorbs chloride ions in water and accelerates the corrosion of reinforced concrete under the condition of wetting and drying alternation. Fractal theory has been applied to the study of concrete, and some valuable results have been obtained, especially in pore research, pore fractal dimension It has a close relationship with the transport performance (chloride diffusion coefficient, depth of carbonation, etc.) as a parameter of the complex transport channel [13,14], which can be used as an index of pore structure damage [15,16]. Fractal theory is used to analyze the relationship of the pore connectivity and water absorption

Materials and Mixture Proportions

Water Absorption Test of Concrete

MIP Test

Calculation of Pore Fractal Dimension

Results and Discussion

Conclusions