The modern construction revolution throughout the past two decades has brought the need for ground vibration mitigation, and this has been one of the major study areas. These studies were mainly focused on the effect of forestation on vibration reduction as the available natural metamaterial. Physical methods such as the finite element method and the boundary conditions of 2D and 3D applications in ground vibration reduction have been developed. Many researchers, scientists, and organizations in this field have emphasized the importance of these methods theoretically and numerically. This paper presents the historical context of resonant metamaterials (MMs), the current progress of periodic 2D and 3D structures, and the possible future outcomes from the seismic metamaterials (SMs), and it relates them with their elastic counterparts to the natural metamaterial (NMs). The idea of bandgaps (FBGs) in the frequency range of interest is reviewed and discussed in some detail. Moreover, the attenuation associated with ground vibrations, noise, seismology, and the like is explained by managing the peculiar mechanisms of ground vibrations. However, a comprehensive computational review focuses on shielding MMs for ground vibration mitigation in urban areas. This phenomenon led to unique features for various techniques to control the bandgap width for various construction applications. Ecological solutions involve the creation of an economic, environmentally based seismic shield for both the Bragg scattering and the local resonance bandgaps. Reportedly, additive studies based on numerical simulation and experiments have improved the functionality of the 2D and 3D periodic structures. It was found that the mechanical properties differ (i.e., stiffness, Poisson’s ratio, and bulk density) and that the geometrical parameters (i.e., lattice, model dimensions, distance from vibration sources, and number of periodic structures) exhibited strong effects on the width and location of the derived FBGs. The geometrical properties of the used unit cell have a strong effect on the attenuation mechanism. Although deep analysis was created in much of the previous research, it was revealed, based on that research, that the attenuation mechanism is still unclear. However, this review article presents a detailed exposition of the recent research progress of the seismic metamaterials, including 2D, 3D, and the main mechanisms of the theoretical backgrounds of energy attenuation. It also summarizes the effects of the factors on the width and location of the bandgaps at a low frequency. In addition, the natural metamaterials and the study of the urban environment are surveyed. The major findings of this review involve the effectiveness of NMs for different functionalities in ground vibration attenuation, which leads to diverse purposes and applications and proposes a roadmap for developing natural materials for clean and quiet environments.

There are serious environmental issues as a result of the increasing amount of waste generated worldwide, especially from industrial and commercial growth. In order to improve the mechanical characteristics of concrete and address waste management, this study explores the possibility of adding three distinct waste materials—plastic fibers, walnut shells, and tire rubber fibers—as additives. In addition to a reference mixture devoid of waste materials, four concrete mixtures were made, each including 1.0% of the cement weight of waste materials. To assess the mechanical properties, such as compressive, splitting tensile, and flexural strengths, extensive testing was carried out on cubic, cylindrical, and prismatic specimens. The findings showed clear differences in performance between the various waste materials. Notably, in comparison with the reference mix, the compressive strength of tire rubber fibers and walnut shells increased by 4.9% and 8.7%, respectively. Likewise, improvements in flexural strength were observed, with tire rubber fibers improving strength by 8.9% and walnut shells by 11.1%. On the other hand, in every evaluated property, plastic fibers continuously showed decreased mechanical performance. Workability studies revealed that all waste-modified mixtures had decreased slump values; nevertheless, because of its porosity and rough surface, the walnut shell mix had the lowest workability. Across waste-modified mixes, splitting tensile strength dropped consistently, with decreases ranging from 11.5% to 12.4%. By showing the potential of waste materials in concrete production, this study sheds light on the mechanical behavior of concrete that incorporates various waste materials, thereby promoting sustainable construction practices.

This study presents a comparative durability assessment of Engineered Geopolymer Composites (EGCs) against a Engineered Cementitious Composite (ECC) under prolonged sulfuric acid (H₂SO₄) attack. This work addresses a critical gap by systematically comparing the strain-hardening performance and degradation mechanisms of lightweight fiber-reinforced composites under aggressive chemical exposure. Four lightweight mixtures—three EGCs with varying slag/fly ash contents (S-EGC: 100% slag; FAS-EGC: 50% slag; FA-EGC: 100% fly ash) and one lightweight ECC control—were fabricated using expanded glass granule (EGG) aggregates and immersed in a 5% H₂SO₄ solution for up to 120 days. Before exposure, the incorporation of slag significantly enhanced pre-exposure mechanical properties; S-EGC showed the highest ultimate strength, while the FAS-EGC mixture provided the best balance of strength and ductility, achieving a tensile strain capacity of 3.21%. The lightweight EGCs demonstrated superior acid resistance compared to the lightweight ECC. After 120 days of exposure, the S-EGC composite retained the highest residual compressive strength (81.59%), while the ECC retained significantly less. Significantly, all exposed EGC and ECC specimens maintained their multiple cracking and deflection-hardening behavior, retaining approximately 50% of their total deflection capacity after four months. Microstructural analysis confirmed that the superior resistance of S-EGC is attributed to its stable, cross-linked alumino-silicate polymer structure. These findings confirm that lightweight slag-based EGCs are a highly durable and ductile sustainable alternative for structural applications in aggressive environmental settings, such as wastewater treatment infrastructure and chemical plants.

3D printers have been the focus of many researchers in recent years. Many thin-walled structures can be produced using 3D printers. One of the thin wall structures that can be made with 3D printers is the core of sandwich panels. In this research, cores with rectangular cross section have been made using Acrylonitrile Butadiene Styrene (ABS) and Polylactic Acid (PLA) filaments. These cores were reinforced using aluminum and composite face sheets and subjected to a three-point bending test. Glass fibers with a density of 200 g/m2 were used to make composite shells. The results showed that the addition of aluminum and composite face sheets, although increasing the flexural strength, greatly reduces the flexibility of the core.