The application of FRPs in civil infrastructure has increased, particularly in the last 20 years. FRPs have gained importance because of their resistance to harsh environments, high strength-to-weight ratio, and good corrosion resistance, and they are faster and easier to apply than other traditional methods. The rehabilitation of structures is the main area in which FRPs have been developed, because they have allowed for compliance with architectural restraints in historic structures. This review is a compilation of the research conducted on the laboratory and field applications of FRPs, highlighting the different applied methods, installation difficulties, and failure modes of FRPs. Moreover, this review compares studies on the types of fibers such as CFRPs, GFRPs, and AFRPs, and their effects would affect the mechanical properties of civil infrastructure and the durability characteristics of civil infrastructure in challenging environmental conditions. In addition, this review focuses on the modification of the mechanical properties of structural elements using different methods of installing FRPs, including externally bonded reinforcement (EBR), and their main problem: debonding failure before the ultimate load.

The purpose of this qualification work is to study the physical and mechanical behavior of concrete with the addition of 0.5% and 1% coconut fiber, which has been subjected to two chemical treatments to reduce its degradation. The coconut fibers were extracted from the raw material and cut into pieces 4 cm long. Subsequently, the fibers were subjected to two chemical treatments. The first involved immersing the fibers in 4% sodium hydroxide (NaOH) solution, and the second treatment involved coating them with gum arabic and silica fume. A total of 50 samples of fibers were collected in their natural and post-treated state to be tested. The dosage was prepared for design strengths of 210 and 240 kg/cm² (20.59 and 23.54 MPa), so that the percentages of 0.5% and 1% volume of coconut fiber, for the two treatments selected, replaced the respective volume of coarse aggregates. The cylinders with 1% addition of fibers had the best performance for the design strength of 20.59 MPa, including the cylinders without fibers. Those with 0.5% addition of fibers presented better performance for the 23.54 MPa dosage, although this was lower than the cylinders without fibers. In all cases, the cylinders with NaOH-treated fibers outperformed their counterparts with fibers treated with gum arabic and silica fume. Finally, a CO₂ balance was determined, and an environmental gain up to 14 kg in CO₂ emissions was established for each cubic meter of composite concrete.

This study proposes a novel test method and corresponding procedure to evaluate how coconut fibres affect crack propagation rates resulting from plastic shrinkage during the accelerated drying of concrete slabs. The experiment employed concrete plate specimens, which were used to simulate slab structural elements with a surface dimension notably greater than their thickness. These slabs were reinforced with coconut fibre with 0.5%, 0.75%, and 1% fibre content. A wind tunnel was designed to simulate two significant climate parameters (wind speed and air temperature), which could impact the cracking behaviour of surface elements. The proposed wind tunnel allowed air temperature to be controlled alongside wind speed while monitoring moisture loss and the cracking propagation process. During testing, a photographic recording method was used to evaluate cracking behaviour, with the total crack length serving as a parameter to assess the impact of fibre content on the crack propagation of slab surfaces. Additionally, crack depth was measured using ultrasound equipment. The results indicate that the proposed test method was appropriate for future research, allowing for the evaluation of the effect of natural fibres on the plastic shrinkage behaviour of surface elements under controlled environmental conditions. Based on initial studies and the results obtained through the proposed test method, concrete containing 0.75% fibre content exhibited significantly reduced crack propagation on slab surfaces, as well as a reduction in the crack depth caused by plastic shrinkage during the early age of the concrete.

Organic soil is widely recognized for its low shear strength and high compressibility, which pose challenges for construction projects. One of the most commonly used methods for enhancing the mechanical properties of soil is chemical stabilization using various additives. In this study, the undrained shear strength of organic soil from Quito, Ecuador, with an average organic content of 43.84%, was reinforced using 0.5, 1, 3, and 6% nanosilica. A series of tests, including Atterberg limit, specific gravity, compaction, and unconfined compression tests, were conducted on specimens cured for 28 days. The results indicate that increasing the nanosilica content leads to higher plasticity, lower maximum dry density, and higher optimum moisture content. In addition, the modulus of elasticity and undrained shear strength improved. The optimal nanosilica content was found to be 1%, resulting in a 211.28% increase in the undrained shear strength. The mechanisms of soil improvement driven by the chemical interactions between nanosilica, mineralogical components (analyzed via XRD), and soil organic matter are discussed in detail.

Adobe construction is a longstanding practice in South America and is characterized by its affordability, accessibility, and ecological sustainability. However, the decision-making process regarding the choice of construction materials often relies on subjective factors, disregarding economic implications throughout the life cycle of a building. This study aimed to introduce life-cycle cost analysis (LCCA) as a valuable tool for optimizing decision making in the context of adobe construction materials in South America. This study emphasizes the significance of considering the life-cycle costs associated with adobe construction materials and their impact on decision-making processes. A comprehensive case study was conducted in South America to examine the various adobe construction scenarios. The life-cycle costs of different adobe materials and their associated maintenance strategies were assessed over a period of several decades, considering factors such as material acquisition, construction, maintenance, and repair. The values used in this study are specific to Ecuador, the country where the investigation was conducted.

Most soils in natural environments undergo wetting and drying cycles, without reaching full saturation. Therefore, it is essential to analyze their properties under unsaturated conditions. However, these analyses often require expensive equipment. This study proposes an empirical-experimental methodology to evaluate the elastic modulus and shear strength of unsaturated soils under total stress conditions using undisturbed and reconstituted samples of silty soil from Quito, Ecuador. Techniques for suction measurement, soil water characteristic curve (SWCC), and predictive models for shear strength and stiffness in partially saturated soils were reviewed. Unconfined compression tests were performed, and the SWCC was determined using the filter paper method. A three-dimensional (3D) plot was generated to correlate the matric suction, shear strength, and normal stress across varying suction levels. In the reconstituted samples, the shear strength and elastic modulus exhibited nonlinear increases in the low suction range (≤500 kPa). In the high-suction range, the strength declined beyond 2228 kPa (40.23% saturation), whereas the elastic modulus stabilized. Undisturbed samples displayed greater variability owing to their heterogeneity, macrostructure, and hysteresis. The results suggest that matric suction enhances the shear strength and stiffness of the surface layers, whereas a higher saturation at depth reduces these properties. This paper further discusses the limitations and practical applicability of the proposed methodology.