Profiled yarns with adjustable bond properties

Project data 

Titel | Title Erforschung und Modellierung des Verbundverhaltens profilierter Carbongarne und Methodenentwicklung zur gezielten Steuerung des Verbundes zwischen Garn und Beton | Research and modeling of the bond behavior of profiled carbon yarns and development of methods for the defined control of the bond between yarn and concrete Förderer | Funding Deutsche Forschungsgemeinschaft (DFG) Zeitraum | Period 05/2025 – 04/2027 Leiter | Project manager Prof. Dr.-Ing. Dr.-Ing. E.h. em. Manfred Curbach Team | Team Iurie Vakaliuk, Silke Scheerer Partner | Project partner Institut für Textilmaschinen und Textile Hochleistungswerkstofftechnik (ITM), TU Dresden

Short description

The project addresses one of the key challenges in carbon-fiber-reinforced concrete construction: the bond between carbon rovings and the surrounding concrete matrix, which is crucial for force transmission, crack control, and efficient structural design. The bond of conventional textile reinforcements relies primarily on adhesion and friction. In this project, which is being carried out in collaboration with the Institute for Textile Machinery and High-Performance Textile Materials (ITM), we are now investigating how a defined geometric profiling of the roving can create a precisely controllable mechanical interlocking. In principle, this is comparable to the effect of ribbed steel reinforcement, but adapted to the anisotropic and filament-based nature of carbon yarns.

The overarching goal is to establish a numerically and experimentally validated basis for the targeted modification and control of the composite properties of fiber-based reinforcement structures in concrete construction. In the first project phase, a methodological investigation of the reference materials will be conducted: conventional smooth carbon yarns, the base variant of a profiled yarn, and a high-strength concrete, each on their own and as composites. The test program for the concrete includes standard prism tests and compression tests on cylinders. The carbon yarns will be tested under tension. A series of yarn pull-out (YPO) tests has been planned to assess the bond behavior and determine the bond stress-slip relationship. In addition, a series of uniaxial tensile tests (DK) has been designed to document the crack pattern for each yarn type. The core experimental program then comprises YPO tests and tensile specimen tests with parameter variations regarding yarn types, ambient temperatures of 20 and 80 °C, various concretes ranging from normal-strength to high-strength, and different concrete cover thicknesses. The resulting experimental database is subsequently used for the calibration of numerical models.

To achieve high precision in the production of test specimens, minimize manual errors, and optimize the workflow given the large number of samples and parameter variations, the manufacturing process for YPO and uniaxial tensile test specimens was redesigned. A special setup was developed based on the most extensive possible use of parametric components, which are manufactured via 3D printing using PLA and combined with standard components available on the market.