Towards standardization: Testing and design of carbon concrete composites

Abstract

The standardization of testing methods and design approaches is one key to overcome barriers which interfere radical innovation in the AEC (Architectural, Engineering and Construction) industry. Currently, the radical innovative Carbon Concrete Composite, including textile reinforced concrete (TRC), embraces a widespread set of testing methods. Depending on the fiber material, the textile binding type and its impregnation material properties, different methods are suitable to determine tensile strength, flexural strength and bond stress characteristics of the composite material. However, different test setups lead to scattering results and thus to a varying statistical distribution of the key input values for design. Furthermore, the testing methods must be consistent with the current design concepts for tension, bending and shear. The formulation of design models and design equations must account for the structural effects influencing the effective cross-sectional properties. For example the tensile strength of textile reinforcement can be identified by testing the filament material, a single roving, multiple rovings (testing of the fabrics) or a TRC specimen (textile fabrics embedded in concrete). The strength of the assembled element does not equal the sum of the component strength due to material heterogeneity, internal scatter and imperfect geometry of the fabrics. Tests at the component level generally lead to higher values of the maximum tensile strength than at the level of the composite. Hence, as part of the formulation of a standardized final design concept, the underlying testing methods must be examined and agreed upon within the engineering community. Standardization of testing methods is one major step towards the formulation of a guideline for design of this innovative material. The existence of guidelines which function as a boundary object between different actors within the AEC industry is essential in order to facilitate the common use of TRC.