Influence of Cement and Emulsion Content on the Mechanical Response of Cold Recycled Mixtures

Abstract

The current study investigates the influence of cement and emulsion dosage on the evolution of the volumetric and mechanical properties of cold recycled mixtures. Four mixtures with varying emulsion and cement dosages were prepared, having different emulsion-to-cement (E/C) ratios. The volumetric and mechanical properties were monitored at 3, 7, and 14 days of curing. The mechanical properties were measured through a repeated haversine compression test at different temperatures (10°C, 20°C, 30°C, and 40°C) and frequencies (25, 20, 10, 5, 2, 1, 0.5, 0.2, 0.1, and 0.01 Hz). It was seen that mixtures with a 1% increase in cement dosage influences the mechanical properties substantially more than a 1% increase in emulsion content. The viscoelastic response of the mixtures was evaluated using master curve and relaxation spectrum. Mixtures with lower E/C ratios showed higher dynamic modulus over the considered frequency range, particularly at initial curing days. The storage modulus is primarily influenced by cement dosage, whereas the loss modulus is affected by both the cement and emulsion contents. The influence of emulsion on the mixture was observed through the loss modulus master curve and relaxation characteristics. Based on the observation of moisture loss and air void variation over different curing periods, it is concluded that curing not only leads to the depletion of moisture but also facilitates volume changes as a result of cement hydration. Overall, as curing progresses, there is an increase in air voids; however, emulsion breaking and cement hydration enhance the mechanical response.