State-of-the-art sessions on Textile Reinforced Concrete/Fabric Reinforced Cementitious Matrix (TRC/FRCM) will be supported by ACI Committee 549 in collaboration with RILEM TRC and fib C-Cubed committees. This forum will provide an opportunity to collect information and present the state-of-the-art knowledge in the field of TRC and FRCM as sustainable construction materials. The term TRC is typically used for new construction while the term FRCM refers to repair of existing concrete and masonry elements. The aim is to promote the technology, document, and develop recommendations for testing, design, analysis, and to showcase the key features of this ductile and strong cement composite system. New methods for characterization of key parameters will be developed and the results will be collected towards the development of state-of-the-art papers. Textile types include polymer based (low and high performance), glass, natural, basalt, carbon, hybrid, matrix may consist of cementitious, geopolymers, light weight matrix (aggregates). Additives such as short fibers, fillers, nanomaterials are also considered. This session will communicate methods to characterize, analyze, and design with TRM/FRCM.
(1) Focus on topics of serviceability and durability of TRC/FRCM a sustainable Construction Material for new and repair and retrofit applications;
(2) Development of materials, applications and the technology offered by the use of textiles in reinforcing thin section cement composites into strain hardening and ductile materials;
(3) Knowledge of testing methods and mechanical and durability properties of TRC and FRCM and procedures for design and application in the new construction and repair field;
(4) Procedures for modeling and analysis and structural design.
On the Mechanical Behavior of Carbon Textile Reinforced Concrete – Material and Structural Assessment
Presented By: Flavio Silva
Affiliation: Pontifícia Universidade Católica Do Rio De Janeiro
Description: Textile reinforced concrete (TRC) is a relatively new cementitious composite material made of fine-grained concrete and non-corrosive fabrics, such as glass, aramid and carbon textiles. This material presents an excellent mechanical behavior aligned with an elevated load-bearing capacity. Due to these reasons, TRC is a highly recommended material for structural applications. The fact that the textile reinforcements are not prone to suffer corrosion makes the TRC an interesting material to replace R/C structures. This work presents a study on the mechanical response of a carbon TRC submitted to direct tensile and bending loadings. Direct tensile tests were carried on composites reinforced with carbon TRC coated with styrene butadiene and epoxy resin. The effect of number of layers and an additional epoxy resin and sand coating was addressed. In order to evaluate the carbon fabric-matrix interface pull-out tests were carried on. In addition, the potential of the use of carbon TRC as a structural element is also presented. For this purpose, structural beams reinforced with two layers of carbon fabrics in the tensile zone were submitted to four-point bending tests. The influence of dispersed steel fibers, and the use of textile reinforcement as a shear reinforcement was evaluated. The results obtained showed that the type of polymeric coating used on the reinforcement fabrication, the additional epoxy resin and sand coating have more influence than the number of layers on the mechanical behavior of the composite. Furthermore, the behavior of hybrid carbon TRC with dispersed steel fibers beam under flexural loading was similar to the behavior of a R/C beam with the same dimensions.
On the Mechanical Behavior of Carbon Textile Reinforced Concrete – Material and Structural Assessment
Presented By: Barzin Mobasher
Affiliation: Arizona State University
Description: The influence of engineered hydrophilic polypropylene fibers in the formation of distributed cracking and the associated strengthening and toughening of cement-based composites under mechanical loading was studied. An automated filament winding system was developed to manufacture continuous fiber composites, which comprises of state-of-the-art integrated motion control and data acquisition systems. Test results indicate significant strain capacity of the order of 10%, tensile strength at cracking of up to 4-6 Mpa and ultimate tensile strength of up to 20 MPa. The automated system provides agility, precision, and quality control to develop economic and versatile composite materials. Digital image correlation technique was used for damage characterization using quantitative analysis of crack width and spacing and correlated with the tensile response and stiffness degradation. It was observed that the mechanical properties as well as crack spacing, and composite stiffness were significantly affected by the micro-structure and dosage of continuous polymeric fibers.
Numerical Modelling of FRCM Composites for the Seismic Retrofitting of Existing Concrete Structures
Presented By: Marco Rampini
Affiliation: Politecnico Di Milano
Description: Fabric-reinforced cementitious matrix (FRCM) composites are promising structural materials representing the extension of textile reinforced concrete (TRC) technology to repairing applications. Recent experiences have proven the ability of FRCMs to increase the mechanical performances of existing elements, ensuring economic and environmental sustainability. Since FRCM composites are generally employed in the form of thin externally bonded layers, one of the main advantages is the ability of improving the overall energy absorption capacity, weakly impacting the structural dead weights and, as a direct consequence, the inertial forces activated by seismic events. In the framework of new regulatory initiatives, the paper aims at proposing simplified numerical approaches for the structural design of retrofitting interventions on existing reinforced concrete structures. To this purpose, the research is addressed at three main levels: i) the material level is investigated on the uniaxial tensile response of FRCM composites, modelled by means of well-established numerical approaches; ii) the interface between FRCM and ordinary strength concrete is characterized via single-lap shear tests; iii) the macro-scale level is evaluated and modelled on a double edge wedge splitting (DEWS) specimen, consisting of an under-reinforced concrete substrate retrofitted with two outer FRCM composites. This novel experimental technique, originally introduced to investigate the fracture behavior of fiber-reinforced concrete, allows to transfer substrate tensile stresses to the retrofitting layers by means of the sole chemo-mechanical adhesion, allowing to investigate the FRCM delamination and cracking phenomena occurring about a notched ligament zone. It is believed that the analysis of the experimental results, assisted by simplified and advanced non-linear numerical approaches, may represent an effective starting point for the derivation of robust design-oriented models.
Behavior of Brick Masonry Columns Confined with Multi-layer SRG Jackets
Presented By: Lesley Sneed
Affiliation: Missouri University of Science and Technology
Description: This paper presents the results of an experimental study carried out to understand the behavior of solid clay brick masonry columns confined by multi-layer steel-reinforced grout (SRG) jackets. Forty-eight confined and seven unconfined columns with a square cross-section were tested to failure under a monotonic concentric compressive load. Test parameters considered were the number of jacket layers, number of jacket overlapping faces, column corner condition, and steel cord sheet density (i.e., steel cord spacing) in the SRG jacket. Results showed that SRG confinement improved the compressive strength, ultimate strain, and energy absorption of masonry columns relative to the unconfined condition. The increase in compressive strength, ultimate strain, and total energy absorbed was not linearly proportional to the increase in number of jacket layers. Increasing the number of jacket overlapping faces slightly increased the compressive strength and ultimate strain, while it did not change overall behavior and the failure mode. Increasing the fiber density increased the peak axial stress, however it decreased the ultimate strain. Models from the literature for FRP-confined masonry were examined for their applicability to predict the strength increase from the SRG jacket, and the Italian CNR-DT 200 (2013) was found to provide the most accurate predictions.
A Staircase and Wall Element Made of TRC
Presented By: Egbert Mueller
Affiliation: Technische Universitaet Dresden
Description: Textile reinforced concrete (TRC) is a great composite material which has a lot of fields of application. It can be used as a material for strengthening existing concrete structures, better known as Fabric Reinforced Cementitious Matrix (FRCM), or to build new structures. The goal of the project autartec® was to create a swimming house which is able to be self-sufficient for at least two weeks. The problem of an autarkic house is, many technical elements are needed to provide energy for living. Those elements can be batteries for example. In traditional autarkic houses, the technical elements are stored in household areas. Due to the amount of the necessary elements, this area takes up a lot of space in the house that can therefore not be used as a living area. To find a solution to this problem, typical cross sections of a house, such as walls or even a staircase, where designed completely new with the help of TRC. One big advantage of TRC is that the reinforcement does not corrode anymore. Therefore, the cross sections do not need a big layer of concrete cover to protect the reinforcement material. This new property opens up a wide field of new design possibilities. Within the project autartec® a wall element and a staircase were developed. The wall element looks similar to the well-known ribbed slab construction, which is a typical construction unit in steel reinforced concrete. Beside the vertical ribs, there are also horizontal webs existent. These webs divide the cross section in different parts and are also important to ensure a smooth production of the wall elements with its hollow bodies. The staircase looks like a spiral staircase. The designed step provides also a hollow body, which can be used to store technical elements as well. All steps are supported by a steel spindle that is anchored to the floor panel and in the ceiling element. All elements are designed to fit in a typical grid for construction units.