| Thin sheet concrete products are receiving increased attention because of the large number of potential applications. By using crushed glass as aggregate, a multitude of different esthetic effects can be produced, which again open up numerous architectural and decorative uses. Such thin sheets are most effectively reinforced with fiber mesh, whether made of polypropylene, AR-glass, or other types of materials.; The experimental project presented in this work explored the possibilities of prestressing thin sheet glass concrete products with fabrics. Aramid fibers, known under their trade names Kevlar, Twaron, and Technora, have been found to be well suited for prestressing applications in the form of fiber-reinforced polymers (FRP). For prestressing thin sheets, however, the material was utilized to date in a more unprotected form, covered just with a thin coating agent.; The constitutive materials, aramid and glass concrete are introduced. Especially the deformation mechanisms of aramid fibers and their relaxation properties are explored in great detail. Glass concrete, which by now is produced commercially, was utilized as the matrix for the prestressed composite, because it offers several advantages beside its esthetic potential, such as excellent workability, superior durability and high-early strength. Glass concrete beams with cross-sections of 1/4 in x 1 in have been produced with prestress levels varying from 0 to 2 ksi.; It has been observed that a large amount of the prestress force in the fiber rovings is lost during the first few hours of hydration, while they are still anchored against the formwork. Once the concrete has hardened, however, the prestress level stabilized. Understanding the interaction mechanisms between aramid fibers and hydrating concrete is critical to successfully produce thin sheets prestressed with high-performance polymeric fibers. The mechanical properties of prestressed thin beams correspond well with traditional prestressed concrete theory during three-point bending tests. The prestress delays the formation of distributed cracking and greatly enhances the stiffness of the section in the cracked state. |
