Deciphering the contribution of polymer latexes on the viscoelastic behavior of hardened cement pastes by means of dynamic-mechanical analysis

The enhanced workability and durability of mortars and concretes incorporating polymer latexes have led to their increased prominence in restoration projects and engineering constructions. However, the unique viscoelastic behavior of these composite systems has restricted their widespread applications compared to unmodified equivalents. In this study, the dynamic-mechanical analysis (DMA) technique was employed to decipher the viscoelastic characteristics of polymer-modified hardened cement pastes. The impact of three different latexes and varying polymer dosages was investigated at two different sample ages. The experimental outcomes demonstrate a significant contribution of the pores formed to the elastic part of the overall viscoelastic behavior, while the glass transition temperature of the latexes is the dominating factor for the viscous part. The results also reveal that the magnitude of the contribution to the viscous properties is independent of the curing duration (7 and 28 days). Moreover, qualitative correlations were established between DMA measurements and the microstructural features of the hardened cement pastes, suggesting promising avenues for the development of tailored mix designs in practical applications of these materials. • The study discusses the influence of different polymer types and different polymer contents on the viscoelastic behavior of hardened cement pastes. • The elastic properties of polymer-modified cement pastes are more dominantly governed by the polymer content and the structural characteristics, like the porosity, rather than the specific polymer composition • The viscous part of the viscoelastic properties of polymer-modified cement pastes are significantly governed by the polymer type, especially the glass transformation temperature, while the specific pore structure of the hardened cement pastes only plays a minor role. • The results obtained by means of DMA are qualitatively comparable to other mechanical tests. There is also a quantitative relation of the storage modulus measured by means of DMA and the dynamic modulus measured by means of ultrasonic testing. • Dynamic-mechanical analysis is a convenient method to determine the temperaturedependent mechanical properties of polymer modified cement pastes and thus represents a tool for quality assurance of polymer modified cement.