Pore structure and strength of waste fiber recycled concrete

Abstract

The pore structure is one of the major factors affecting the mechanical properties of waste fiber recycled concrete. In this article, the pore structure and strength performance of waste fiber recycled concrete are experimentally studied. The design variables are water–cement ratio, recycled aggregate replacement rate, waste fiber length, and volume fraction of waste fibers. The pore structure characteristic parameters of waste fiber recycled concrete are investigated using mercury intrusion porosimetry test and fractal theory. The complex distribution of pore structure in space is quantitatively described by fractal dimension, and the pore structure is comprehensively evaluated. The results show that the water–cement ratio has the largest influence on the pore structure, and the fiber length has the least influence. The optimum volume fraction of waste fibers is 0.12%. There is an obvious linear relationship between the pore volume fractal dimension and strength. With the increase in the fractal dimensions, the compressive and splitting tensile strengths increase. Macroscopic mechanical properties of waste fiber recycled concrete can be predicted by the pore structure.

Nanoindentation and Porosity Fractal Dimension of Calcium Carbonate Whisker Reinforced Cement Paste After Elevated Temperatures (Up to 900∘c)

“…12 presents the relationship between residual strengths and fractal dimension up to 900 °C. The residual compressive, flexural, and splitting tensile strength of fired CW reinforced cement pastes were nearly linearly related to the pore volume fractal dimension, which was similar to fiber reinforced concrete 64,65 . There was a positive correlation between the pore volume fractal dimension and the compressive strength in the case of fiber reinforced concrete.…”

“…While high temperature could coarsen and complicate the pore of cement paste, leading to the decreased strengths. Notice, however, the results about the relationship between strength and fractal dimension of cement-based materials are very different in literatures 64,65 . Some are coincide with this research 65 , but some are on the contrary with this research 64 .…”

“…Notice, however, the results about the relationship between strength and fractal dimension of cement-based materials are very different in literatures 64,65 . Some are coincide with this research 65 , but some are on the contrary with this research 64 . It can be seen that the research on fractal dimension of concrete pore structure is still in the exploratory stage at present, and a large number of researches are needed to verify the existing conclusions.…”

Investigation on the microstructural characteristics and quasi-static puncture resistance of both domesticated and wild silkworm cocoons

“…Previous studies have well established that a larger solid area fractal dimension means a more complex spatial distribution of solid phase in the materials, that is, the solids have a stronger ability to take up space. 15 The increase in fractal dimension of porous materials is associated with the increase of solid packing density and the more complex distribution of the solid phase, as well as the decrease of the porosity, the average pore size, the decrease of the large pore numbers and the increase of small pores and pore surface area. 12,32,33 In this study, using a linear regression method, fractal dimension was found to be negatively correlated with porosity (R 2 ¼ 0.90) and normal density (R 2 ¼ 0.67) of cocoon samples, and positively correlated with fiber intersectional density (R 2 ¼ 0.86).…”

“…12,13 In addition, it has a strong relationship with the compressive strength or tensile strength of fiber-reinforced composites. 12,14,15 These studies evidently proved that fractal dimension could well describe the microstructure and the mechanical properties of fiber composites. 15 Thus, fractal theory was adopted to study the microstructural characteristics of silkworm cocoons and predict their mechanical properties.…”