Saverio Spadea

Recycled nylon fibers as cement mortar reinforcement

We investigate engineering applications of recycled nylon fibers obtained from waste fishing nets, focusing our attention on the use of recycled nylon fibers as tensile reinforcement of cementitious mortars. We begin by characterizing the tensile behavior of both unconditioned and alkali-cured recycled nylon fibers obtained through manual cutting of waste fishing net filaments, with the aim of assessing the resistance of such materials to chemical attacks. Special attention is also given to evaluating the workability of fresh mortar and the possible impacts of contaminants released by waste fishing nets into the environment. Next, we deal with compression and bending tests on cementitious mortars reinforced with recycled nylon fibers, and establish comparisons with the experimental behavior of the unreinforced material and with results given in existing literature. In our analysis of different weight fractions and aspect ratios of the reinforcing fibers, we observe marked increases in the tensile strength (up to +35%) and toughness (up to 13 times greater) of the nylon reinforced mortar, as compared with the unreinforced material. The presented results emphasize the high environmental and mechanical potential of recycled nylon fibers for the reinforcement of sustainable cement mortars.

Shear Strength of FRP Reinforced Concrete Members with Stirrups

AbstractThe mechanisms of shear transfer in fiber-reinforced polymer (FRP) reinforced concrete members with shear reinforcement are discussed, and it is explained how these were used to derive the shear design provisions of the Canadian standard for design and construction of building structures with FRPs. Subsequently, the accuracy of these provisions and the validity of their underlying assumptions are assessed by comparing the predicted shear strengths of over three hundred FRP-reinforced beams with their corresponding experimental values. Although the focus of the paper is mainly on beams with FRP shear reinforcement, for completeness beams with and without shear reinforcement are analyzed. It is determined that the mean and standard deviation of the ratio of the test to predicted shear strength of the beams without shear reinforcement are 1.16 and 0.24, respectively, whereas those of beams with shear reinforcement are 1.15 and 0.23. The strengths of these beams are also computed using the recommendat...

Wound FRP Shear Reinforcement for Concrete Structures

AbstractThis paper describes the outcomes of recent research that is, for the first time, aiming to completely replace internal steel reinforcement in concrete structures with knitted prefabricated...

Development of new FRP reinforcement for optimized concrete structures

With the goal of achieving sustainable design, being able to combine optimized geometries with durable construction materials is a major challenge for Civil Engineering. Recent research at the University of Bath has demonstrated that fibre-reinforced polymers (FRP) can be woven into geometrically appropriate cages for the reinforcement of optimised concrete beams. This innovative construction method enables the replacement of conventional steel with non-corrosive reinforcement that can provide the required strength exactly where needed. The manufacturing of the reinforcement is achieved by means of an automated process based on a filament winding technique. Being extremely lightweight, the wound-FRP (WFRP) cages are well suited to speeding up construction processes, as they can be delivered on site ready to be cast.

Bespoke Reinforcement for Optimised Concrete Structures

Flexible formwork for concrete structures has been shown to be an appropriate method for the construction of optimised concrete structures (Veenendaal et al. [1], Orr et al. [2]). With the goal of achieving low carbon design, two major challenges exist: 1) to reinforce structures with complex geometries and 2) to provide durable and resilient infrastructures. Meeting both challenges would allow one to capitalise on the fluidity of concrete to meet long-term emissions reductions targets. This will require an entirely new approach to design and construction of concrete structures. Research underway at the University of Bath is attempting to completely replace internal steel reinforcement with a knitted composite cage made from fibre reinforced polymer (FRP) reinforcement. By fabricating the cage in exactly the right geometry, it will be possible to provide the required strength exactly where it is needed. This paper will outline ongoing work which aims demonstrate that CFRP can be woven into geometrically appropriate ‘cages’ for the reinforcement of concrete beams, including consideration of the manufacturing process, construction technique, and technical design requirements.

Wound FRP for concrete beams with optimised geometries

Fabric formwork is a casting system that uses woven fabrics as the mould for concrete, utilising the fluidity of concrete to create optimised structural geometries. Fabric formed beams normally have variable depth along their longitudinal axis which makes it extremely time and labour consuming to install steel shear links because of this changing geometry. We propose the use of Wound Fibre Reinforced Polymer (WFRP) in which carbon fibres tows coated in wet epoxy matrix are wound around the longitudinal reinforcement to create uniquely shaped reinforcement cages as a practical alternative to steel shear links.

Dataset for Journal Paper WOUND FRP SHEAR REINFORCEMENT FOR CONCRETE STRUCTURES

The Dataset contains the following files: - ‘Tensile tests wet layup’ - ‘Tensile tests prepreg’ - ‘Stirrups tests’ - ‘Flexural tests’

Innovative construction using flexible moulds

By replacing orthogonal concrete moulds with a system formed of flexible sheets of fabric it is possible to construct optimised, variable cross section concrete elements that can provide material savings of up to 40% when compared to an equivalent strength prismatic member, and thereby offer the potential for significant embodied energy savings in new concrete structures. This paper provides pointers on some research undertaken at the BRE Centre for Innovative Construction Materials (BRE CICM). The work demonstrate that a fabric formwork construction system may be used to facilitate a sustainable future for concrete construction, providing a design method by which structurally optimised elements may be cast in an economical manner while also providing significant durability and visual benefits.