Jaime Gonzalez-Libreros

Experimental behavior of glass-FRCM Composites Applied onto Masonry and Concrete Substrates

The use of Fiber Reinforced Polymer (FRP) composites has become a popular solution for retrofitting and strengthening of existing concrete and masonry structures. However, some drawbacks of this technique, mainly associated with the use of organic resins, have been reported. To overcome such drawbacks, the development of composite materials in which the organic resins are replaced with inorganic matrices has recently caught the attention of the civil engineering industry. Among these newly developed systems, Fiber Reinforced Cementitious Matrix (FRCM) composites, which are comprised of high strength fibers embedded within an inorganic matrix, have shown promising results. However, research on this topic is still limited and important aspects, such as the bond behavior between the composite and the substrate, are not fully understood and require further study. This paper presents the results of an experimental campaign aimed at investigating the influence of the type of matrix and substrate on the bond behavior of FRCM composites. Glass-FRCM composite strips were applied onto concrete and masonry substrates and then tested by means of a classical push-pull single-lap direct-shear test set-up. A cementitious and a lime-based matrix were employed to apply the same type of fiber on concrete and masonry substrates, respectively. FRCM-concrete and FRCM-masonry joints reported the same failure mode. However, higher values of the peak load were obtained for the lime-based glass-FRCM composite applied onto masonry substrates than with the cementitious glass-FRCM composite applied onto concrete substrates.

Performance of Different Types of FRCM Composites Applied to a Concrete Substrate

This research aimed to investigate the performance of fiber reinforced cementitious matrix (FRCM) composites employed as externally applied strengthening system for reinforced concrete members. The results of an experimental campaign conducted on FRCM composites applied to a concrete substrate are shown and discussed. The composites were comprised of different types of fibers, namely carbon, glass, steel, and basalt fibers, and different types of cementitious matrix. Single-lap direct-shear tests were performed to study the behavior of the different composites. Specimens with different bonded lengths were tested to investigate the stress-transfer mechanism and to investigate the existence of an effective bond length. Comparisons between the peak loads obtained with the direct-shear tests and the tensile strength of the fibers, which provide an indication of the exploitation of the fibers, were carried out.

Effect of Confinement with FRCM Composites on Damaged Concrete Cylinders

Confinement of axially loaded concrete members in existing structures is required when a change in use is expected or when there is a need to upgrade the structure to meet current design standards. In addition, after unusual overloading events (e.g., earthquakes), axially loaded members can suffer damage that increases the need of their retrofitting by means of confinement. The study of fiber reinforced cementitious matrix (FRCM) composites for confinement of compression members has gained attention in recent years due to the capability to overcome some of the disadvantages associated with more traditional strengthening techniques. However, the available experimental evidence is still scarce, and research on the topic is necessary. In this paper, the results of an experimental campaign performed on concrete cylinders confined with FRCM jackets are presented. Before strengthening, some specimens were preloaded in order to achieve specified damage levels. The specimens were then subjected to uniaxial concentric compressive loading. The axial load and axial strain response was recorded for each specimen. In addition, the elastic modulus of confined and unconfined specimens was determined. Results show that confinement with FRCM composites is able to provide an increase in the axial capacity of undamaged and damaged concrete cylinders.