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

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.

The Influence of Cement Substitution by Biomass Fly Ash on the Polymer–Cement Composites Properties

“…Additionally, the lower activity index of mineral additives (compared to Cement AI) used further reduced the compressive strength of tested components. This is in agreement with reported research which concluded that the reduction in compressive strength could be due to both the decelerating effect of polymer modifiers on cement hydration and the volume change of the mortar [ 51 ].…”

“…and M0) resulted in improved flexural strength. The increase in flexural strength may be due to the formation of a polymer film, which increases the strength of the binder interface between the cement hydration products and the aggregate [ 51 ]. However, by introducing mineral additives, this interface may be impaired due to either weakening of the formed polymer film or lower content of active silica in mineral additives [ 29 ].…”

“…The improvement in tensile strength was found to mainly depend on the polymer content. This is related to the superior tensile performance of the polymer film that creates the polymer–cement matrix [ 51 ].…”

“…This may indicate that pores were formed in the binder microstructure during curing, which increased the total porosity of the PCC mortars in comparison to the reference, cement mortar. The increase in porosity may be due to the decelerating effect of the polymer on cement hydration or the change in mortar volume [ 51 ]. In addition, the introduction of mineral additives with irregular shapes may also contribute to the increase in the porosity of mortars and therefore to the reduction in resistance to carbonation [ 11 ].…”

Improved Powder Equivalence Model for the Mix Design of Self‐Compacting Concrete with Fly Ash and Limestone Powder

“…Nie and An [12] visualized the threshold theory by the selfcompacting paste (SCP) zone, which is the set of all points satisfying the theory. Higher costs, higher hydration heat, and greater shrinkage during drying may occur as a result of SCC with a large amount of cement [13][14][15]. erefore, mineral admixtures such as FA and LP are usually used to replace partial cement [16][17][18][19][20][21][22], which may reduce hydration heat, optimize the particle packing, and maintain the SCC workability [23][24][25][26].…”