Effect of Epoxy Latexes on the Mechanical Behavior and Porosity Property of Cement Mortar with Different Degrees of Hydration and Polymerization.

Pengfei Li,Sanlin Du,Wei Lu,Xuehui An,Li Zhou

doi:10.3390/ma14030517

Pengfei Li, Sanlin Du + Show 3 more

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https://doi.org/10.3390/ma14030517

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Abstract

In this study, an analysis of the influence of polymer modification on the mechanical behavior, porosity, and microstructure of mortar is carried out. Epoxy latexes contents of 5%, 10%, 15%, and 20% of cement were employed in the preparation of cement mortars based on the same workability. The specimens were subjected to dry, wet, and wet–dry curing regimes. Compressive strength, flexural strength, Mercury intrusion porosimetry (MIP), and scanning electronic microscope (SEM) tests were conducted to analyze the effect of epoxy latexes on the mechanical property and porosity of modified mortars. Based on the compressive strength test results, a quantitative method was established to calculated the degree of hydration and polymerization. The results show that the mechanical behavior and porosity property of epoxy latexes modified mortar are influenced by the degree of hydration, the degree of polymerization, and the volume changing effect of mortar. The polymerization of epoxy latexes could improve the flexural strength of the mortar. The macropores of specimens tended to decrease with the increase of the degree of epoxy latexes polymerization and cement hydration. In practical engineering, it is necessary to ensure the degree of hydration and increase the polymerization rate. Thus, the wet–dry curing regime is recommended.

Highlights

Concrete is the most widely used material in China’s hydropower construction thanks to its low cost and relatively good strength in compression
In the case of dry curing, the compressive strengths of mortars with different P/C ratios had a reduction of 30–45% compared with control mortars without epoxy latexes at the age of 90 d
The reduction in compressive strength may be caused by both the retardation effect of epoxy latexes on cement hydration and the change of the volume of mortar in unit volume, which will be discussed

Summary

Introduction

Concrete is the most widely used material in China’s hydropower construction thanks to its low cost and relatively good strength in compression. In the construction of hydropower, the extreme environmental conditions put forward higher requirements for the properties of concrete materials. Polymer latexes modified mortar (PMM) and concrete (PMC) have been widely used as construction materials in the past decades to overcome some disadvantages of conventional cement-based materials, such as brittleness and deformation property [2,3]. As the composite material combines the advantages of polymer and concrete, PMM and PMC can effectively improve the properties of concrete structures. Organic–inorganic nanocomposite materials possess unique properties as new materials and compounds for academic research as well as for the development of innovative industrial applications [7,8]. The resulting composite might exhibit improved thermal, mechanical, rheological, electrical, catalytic, fire retardancy, and optical properties [9,10,11,12,13,14,15]

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