Comprehensive Study of the Properties and Microstructural Characteristics of Rubberized Concrete Using Destructive and Nondestructive Techniques

Abstract

In recent times, rubberized concrete (RubCrete) has been considered a sustainable solution to address various issues associated with the environmental impacts of the waste rubber (WasRub) sourced from end-of-life tires. Though this strategy professes sustainable development goals (SDGs) associated with WasRub disposal, the question is what characteristics of the RubCrete surpass those of conventional concrete. To address this issue, the present study was conducted with the objective of providing insights into the viability and effectiveness of utilizing WasRub and how it impacts the overall properties of RubCrete. With this in view, extensive destructive and nondestructive tests (e.g., compressive strength, density, slump, rebound hammer, ultrasonic pulse velocity, nanoindentation) were conducted on the samples of the control and different WasRub compositions of the RubCrete. The results so obtained were analyzed to highlight the changes that the inclusion of WasRub makes to the complex concrete matrix, by investigating the microstructure of the RubCrete through scanning electron microscopy (SEM), nanoindentation, and four-dimensional (4D) X-ray microscopy. These investigations reveal the microscopic details related to the distribution and interaction of WasRub within the RubCrete matrix and the interfacial transition zone (ITZ). It was observed that the thickness of the ITZ lies between 5.18 and 60.45 μm. Furthermore, the role and influence of the ITZ on the macrocharacteristics of RubCrete were investigated elaborately in this paper by utilizing the mentioned characteristics. This study evaluated the interfacial transition zone of rubberized concrete by employing X-ray micro-computed tomography (CT) scanning, scanning electron microscopy, and nanoindentation. Efforts were made to analyze the microstructure in detail, providing insights into how the rubber aggregates interact with the cement binder, and thus the thickness of the interfacial transition zone was quantified by employing microstructure analysis. Furthermore, various destructive and nondestructive techniques were used to understand the engineering properties and microstructure of the rubberized concrete. It was realized that the inclusion of rubber in the cement matrix enhances the dampening and insulation properties of the concrete. Thus, rubberized concrete can be used for insulation and dampening applications and to manufacture lightweight structural components for infrastructure development. It is recommended that, depending on the specific projects, proper laboratory experiments should be conducted to determine the optimum rubber content.