ZEOLITE WONDERS: DECODING UNIAXIAL STRESS-STRAIN DYNAMICS IN ENHANCED PAVEMENT STRUCTURES

Abstract

Semi-flexible pavements (SFP) play a crucial role in modern transportation infrastructure, and their performance is heavily influenced by the proportion of cement mortar content filling the voids in the mixture. While higher grouted mortar content enhances the performance of SFP, there exists an optimal level beyond which further improvements are not significant. Repeated traffic loads exert stress and strain on the pavement structure around the wheel axis, leading to accelerated degradation with the emergence of cracks and permanent defects. Consequently, developing stress-strain models for SFP becomes imperative.

This study focuses on the stress-strain relationship of SFP containing waste tire rubber (WTR) and natural zeolite as cement replacements in the filling mortar. A stress-strain model under uniaxial compressive load is developed to understand the behavior of such mixtures. At lower compressive loads, the stress-strain response follows Hooke's Law, exhibiting a proportional relationship between stress and strain. Moreover, stress relaxation tends to decrease with an increasing number of passes, enabling the mixture to return to its original shape without deformation upon load removal. However, under maximum load (Pmax), the stress-strain curve depicts a mixed condition with full strength and stress, gradually decreasing until the test object is crushed. Additionally, the stress-strain relationship of the SFP mixture can be represented as an elastic, perfectly plastic (bilinear) behavior. The initial phase of this bilinear curve corresponds to linear elasticity, followed by a stage where small cracks develop, leading to a linear relationship again, albeit no longer elastic. The behavior of this mixed bilinear stress-strain relationship is illustrated in Figure 1.

Understanding the stress-strain behavior of SFP mixtures, especially those incorporating WTR and natural zeolite, is essential for designing durable and sustainable pavements. Such knowledge will aid in optimizing cement mortar content, ensuring maximum performance without excessive material usage. The findings from this study contribute to the advancement of semi-flexible pavement design and promote eco-friendly practices by utilizing waste materials as cement replacements