## 1 Introduction  
The signification of Cement and Concrete Composites (CCC) can vary and often have a broad meaning in the scientific field. European standard EN 197-1 [1] lists 27 common types of cement, divided into five groups (ordinary Portland cement and cement mixes) with a notation that those are hydraulic binders [2]. Furthermore, the ASTM C 125 [3] standard acknowledges concrete that primarily employs hydraulic cement as a binding medium but does not entirely exclude the existence of non-hydraulic binders [4]. From a scientific point of view, materials such as aluminosilicates and calcium silicates are also recognised as cementitious materials, even though they do not imply hydration as the main hardening process. The former is a powdered substance, also called alkali-activated cement or geopolymer [5, 6], whereas the latter hardens through a carbonation process [7]. Because of the above, concrete, mortar and grout are composite materials that can contain either hydraulic or non-hydraulic binder. In this research paper, the term concrete composite is associated with any concrete mix (containing fibres or other types of reinforcement, special aggregates and polymers) that can be viewed as ageing viscoelastic materials [8, 9, 10]. Viscoelastic behaviour (creep and relaxation) of CCC is considered when evaluating material suitability for practical use, as are the restrained and unrestrained shrinkage properties. Estimation of such effects must be integrated into the design process [11; 12; 13]. Thus, long-term properties of CCC have been widely studied over the years, especially to acquire applicable knowledge about world-known and novel structural materials [14; 15; 16; 17; 18]. In terms of CCC mechanical properties, mainly qualities such as compressive strength and behaviour under sustained compressive loading have been researched and appreciated. Conventionally, in the design process of reinforced concrete, the CCC capacity of withstanding tensile stresses is neglected [19; 20]. However, crack propagation under tensile loading is one of the main types of CCC failure mechanisms at the service limit state (along with crushing under compression at ultimate limit state), and even uniaxial compression failure can be considered as being due to tensile stresses [8; 21]. Fibre reinforcement is proven to increase ductility, tensile and flexural resistance, as well as to diminish shrinkage at an early age and crack propagation [19; 22; 23; 24]. To date, scientific progress has led to interests in various subfields of fracture mechanics and tensile bearing capacity with respect to diverse loading rates [21; 25; 26; 27]. CCC tensile properties are investigated mainly by performing indirect tensile tests, where specific characteristic values can be derived. Direct uniaxial tensile tests are less common since it is problematic to maintain a test specimen within a loading rig under sustained uniform tensile stress [14; 20; 25; 28; 29]. Assessing the tensile strength of CCCs depends on the testing method used. The indirect tensile strength test provides higher strength than the direct uniaxial tensile tests, but the latter is considered more accurate [30; 31]. Nevertheless, there is no standardised method for performing such a test [31]. RILEM TC232-TDT [32] recommends using parallelepiped shape specimens (with minimum dimensions of 500 \(\times\) 60 \(\times\) 6 mm) for testing textile-reinforced concrete in uniaxial tension. The document recommends the use of LVDTs but also refers to ISO 9513 [33] regarding the required accuracy of extensometers. According to ISO 9513:2012 [33], extensometers can be either contacting or non-contacting (e.g., laser, DIC). Digital image correlation (DIC) is a non-contact, optically based research technique that allows the monitoring of various derived quantities-of-interest (QOIs) at the surface of a test specimen. Through this method, point displacements, strains, surface curvature and velocities can be tracked.