Mechanical Performance of Polymer-Modified Mortar With the Newly Designed Gradient Structure: Effect of Polymer Types and Content

The varied damage faced by concrete in the pavement can be effectively alleviated by adding polymer latex. However, their required high dosage and prices limit their application. Hence, a new structure with the gradient distribution of polymer particles in concrete was designed. Furthermore, the performance and the corresponding mechanism of varied polymer types and contents on the mechanical performance of polymer-modified mortar (PMM) were systematically evaluated. Compared to the sample with a homogenous polymer distribution at the same dosage, a great enhancement in compressive and bond strength was found for PMM with the gradient structure. Besides, the flexural strength can also be slightly increased. Compared to styrene-acrylic (SA) and ethylene-vinyl acetate (EVA) latexes, styrene-butadiene (SB) latex with the highest charge density shows the lowest capability in modifying the mechanical performance of PMM, which could be caused by its high adsorption amount and low ductility of formed polymer film. It further indicates that, compared to the tensile stress of polymer film, its ductility is more important in determining the flexural strength of PMM. To confirm the obtained experimental results, a finite element model of mortars with different gradient structures was established, and the modeling results match well with the mechanical measurements.