Influence of polymer modification on the microstructure of shielding concrete.

Kamil Zalegowski,Andrzej Garbacz,Tomasz Piotrowski

doi:10.3390/ma13030498

Abstract

In this paper an analysis of the influence of polymer modification on the microstructure, shielding properties against neutrons, and compressive strength of heavy-weight magnetite concrete is carried out. The modifications involve the addition of acrylic or epoxy dispersions as well as micro- or/and macrofibers. A computer image analysis method is used to evaluate the microstructure of concretes and parameters of pore structure are calculated; these parameters include relative volume fraction, relative specific surface area, and pore arrangement ratios, including a proprietary ratio based on Voronoi tessellation. An assessment of significance of differences between stereological parameters of reference concrete and polymer modified concretes, as well as the impact of polymer form (dispersion or fibers) on shielding properties and compressive strength is carried out using Student’s t-test. The results show that except for the effect of the addition of both polypropylene micro- and macrofibers on the relative volume of pores, all other modifications result in statistically significant changes in the values of stereological parameters. Nevertheless, it is shown that neither polymer dispersions nor fibers have a statistically significant impact on shielding properties, but that they do influence compressive strength.

Highlights

The behavior of every material is related to its microstructure somehow
The modification of reference concrete M had a different influence on the halfaccording value layer (HVL)
The addition of acrylic dispersion (MPCC1) or macrofibers (MF1) to M had a minor effect on the HVL, namely, changes were dispersion (MPCC1) or macrofibers (MF1) to M had a minor effect on the HVL, namely, changes only up to about 3.0%

Summary

Introduction

The behavior of every material is related to its microstructure somehow. This is why understanding the relation between microstructure and properties is a basic approach of materials science and engineering. Concrete microstructure encompasses a wide range of structural levels, from the atomic scale to that of the engineering macroscale. It may be composed of phases like aggregate grains, cement hydration products, unhydrated cement particles, fibers, and additions (e.g., microsilica, polymer dispersion, or waste materials [1,2,3]) as well as all discontinuities inside and between phases such as phase interfaces (e.g., the internal transition zone between aggregate grains and hardened cement matrix), pores, and cracks. The type, volume fraction, and arrangement of phases in the microstructure, the quality of their connection, and the characteristics of the pore structure vary depending on the quantitative and qualitative selection of the ingredients in the concrete

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Conclusion