Over recent decades, numerous strong earthquakes have caused widespread devastation, including citywide destruction, significant loss of life, and severe structural damage. Seismic base isolation is a well-established method for mitigating earthquake-induced risks in buildings; however, its high cost often limits its implementation in developing countries. Simultaneously, the global rise in vehicle numbers has led to the accumulation of discarded tires, intensifying environmental challenges. In response to these issues, this study investigates the development of a seismic isolator matrix using recycled rubber from vehicle tires, proposed as a sustainable and cost-effective alternative. Ten recycled rubber matrices were experimentally evaluated for their physical and mechanical properties. The matrix with optimal granulometry and binder content, demonstrating superior performance, was identified. This optimized matrix underwent further validation through compression and cyclic shear tests on reduced-scale prototypes of fiber-reinforced isolators, which included five prototype designs, two of which featured flexible reinforcement. The best-performing prototype comprised a recycled rubber matrix with 15% binder and glass fiber, exhibiting vertical stiffness and damping characteristics superior to those of natural rubber. Specifically, this prototype achieved a damping ratio of up to 22%, surpassing the 10% minimum required for seismic isolation, along with a vertical stiffness of 45 kN/mm, critical for withstanding the vertical loads transferred by buildings. These findings suggest that the recycled tire rubber matrix, when combined with glass fiber, is a viable material for the production of seismic isolators. This combination utilizes discarded materials, contributing to environmental sustainability.

Base isolators, traditionally made from natural rubber reinforced with steel sheets (SERIs), mitigate energy during seismic events, but their use in developing countries has been limited due to high cost and weight. To make them more accessible, lighter, cost-effective reinforcement fibers have been utilized. Additionally, the increasing use of natural rubber has caused waste storage and disposal issues, contributing to environmental pollution and disease spread. Exploring recycled rubber matrices as alternatives, this study improves seismic isolators’ mechanical properties through modified reinforcements and layer adhesion. Eight reinforcement materials and eight adhesives, which may be activated with or without heat application, are systematically evaluated. Employing the chosen reinforcements and adhesives, prototypes are tested mechanically to examine their vertical and horizontal performance through cyclic compression and cyclic shear testing. Two innovative devices using recycled rubber matrices were developed, one using a layering technique and another through a monolithic approach shaped with heat and pressure. Both integrate a fiberglass mesh reinforced with epoxy resin; one employs a heat-activated hybrid adhesive, while the other uses a cold bonding adhesive. These prototypes exhibit potential in advancing seismic isolation technology for low-rise buildings in developing countries, highlighting the viability of recycled materials in critical structural applications.

In Colombia, low-cost unbonded fiber-reinforced elastomeric isolators made from natural rubber (UN-FREI) and recycled rubber (UR-FREI) have emerged as a solution to mitigate damage in low-rise structures during earthquakes. However, their performance under environmental degradation caused by factors such as carbon dioxide, saltwater, relative humidity, and UV radiation has not been sufficiently studied. These agents can compromise the mechanical properties of rubber, affecting its ability to dissipate energy. This study evaluates the performance of these isolators under different environmental conditions through the initial characterization of rubber, mechanical testing of small-scale prototypes exposed to controlled environments, and seismic analysis of an isolated structure. Modification factors (λ_(ae,max) and λ_(ae,min)) were determined to quantify the impact of degradation on structural behavior. The results indicate that UN-FREI specimens are more sensitive to environmental conditions than UR-FREI specimens, whereas the mechanical properties of UN-FREI small-scale prototypes remain more stable compared to those of UR-FREI. This leads to increased drift, base shear, and demand-to-capacity ratios (DCRs) in the structural analysis. The findings emphasize the need for experimental testing of isolators to establish modification factors that accurately reflect the effects of environmental conditions on structures throughout their service life.

One of the major challenges in developing a sustainable construction industry is the reincorporation of construction and demolition waste (C&DW) into the materials cycle. An interesting end-of-life cycle strategy is the recycling of C&DW as aggregates for new concrete. Although promising results have mostly been reported for applications with low mechanical and durability requirements, this research evaluates the use of a high-performance recycled concrete aggregate (HP-RCA), a low-porosity, high-abrasion-resistance aggregate obtained from the demolition of high-strength concrete, with almost no additional treatment, unlike what is traditionally required. First, the production and characterization of the HP-RCA was carried out, to continue with the manufacture of four high-strength concrete mixtures that included one reference (0%) and three with different natural coarse aggregate replacements (10%, 20% and 40%). Then, fresh and hardened properties were evaluated, with the main focus being mechanical properties (i.e., compressive strength, diametric compressive tensile strength and elasticity modulus). Results indicate that when the recycled aggregate content increased, the mechanical properties substantially improved, and the mixture with 40% replacement improved the compressive strength by 37.8% at 56 days. Although durability performance still needs to be further assessed, the mechanical results presented here are very promising for advancing a truly sustainable construction industry, especially considering that the extraction of natural coarse aggregates has significant environmental impacts and that the final disposal of C&DW remains a major environmental and economic challenge.

Seismic isolation systems are an effective passive protection strategy that decouples structures from ground motion. Their performance depends heavily on the elastomeric materials used, which must retain mechanical integrity under environmental stressors. In recent years, low-cost isolators made from natural and recycled rubber have gained attention as an affordable solution for protecting low-rise buildings in seismic-prone developing regions, particularly due to their environmental benefits and ease of installation. However, their long-term performance under real environmental conditions remains insufficiently explored. This study evaluates the durability of two types of low-cost seismic isolators: those made with natural rubber matrices (UN-FREIs) and those that use recycled rubber matrices (UR-FREIs). Mechanical tests were carried out before and after exposing the specimens to accelerated aging and low-temperature conditions, simulating environmental degradation. Changes in stiffness, damping, and energy dissipation were analyzed for both the rubber matrix and the scaled isolator prototypes. The findings indicate that both materials degrade over time, with recycled rubber exhibiting greater susceptibility to stiffness loss at low temperatures. Nevertheless, both isolator types maintained functional performance after aging, supporting their applicability in regions with moderate thermal variations. These results provide evidence for the feasibility of adopting low-cost isolators in low-rise buildings exposed to variable climates, while also emphasizing the need for standardized durability protocols during the design stage.