GP1.a – Fresh properties and setting
Leader: Ivan Gabrijel (HR)

The main objective of this GP1 is to provide a platform for mutual validation of advance, non-standardised experimental techniques developed in European laboratories. Some of the techniques that will be included are:

- Heat of hydration;
- Ultrasonic testing;
- Rheology tests.

The main anticipated outcome is to evaluate efficiency and accuracy of considered advanced techniques to obtain certain parameters of concrete at early ages, as well as their repeatability and reproducibility.

GP1.b – Chemical and microstructural characterization
Leader: Özlem Cizer (BE)

The main objective of this GP1 is to provide a platform for comparison of different protocols used in different participating laboratories for evaluating microstructural properties of CBM. Following techniques are planned to be included:

- Thermogravimetric analysis/differential scanning calorimetry (TGA/DSC);
- SEM-BSE image analysis;
- Selective dissolution (to identify unreacted SCMs by XRD analysis);
- Mercury intrusion porosity (MIP);
- X-ray computed microtomography (X-CT).

The main anticipated outcome is better understanding of the hydration and microstructure development of CBM in particular when SCMs such as conventional materials (blast furnace slag, fly ash, limestone) and new materials (locally available by-products and residues according to a specific interest of each country) are incorporated in the binder system to create eco-concrete mixtures.

GP1.c – Transport properties and boundary effects
Leader: Sreejith Nanukuttan (UK)

The aim of this work package is twofold:

- (1) to determine the transport properties that can be linked to a deterioration mechanism with emphasis to standard error and scope, and
- (2) to outline the boundary conditions, so that transport properties can be linked to models for predicting future behavior as identified in WP2.

GP1.d - Mechanical properties and creep
Leaders: Violeta B. Bosiljkov (SL) & Bernhard Pichler (AT)

In the present GP the following properties are mainly targeted:

-Compressive strength;
- Bending strength;
- Tensile strength;
- Young's modulus and Poisson’s ratio.

Most of these methods are standardized and performed routinely in most of the participating laboratories. Nevertheless, there is still potential for improving repeatability and reproducibility of these methods and initiatives for their customization, which is the main objective of GP1d.

GP1.e – Volume stability
Leader: Emmanuel Rozière (FR)

The following techniques are planned to be included in the scope of this Group Priority:

- Autogenous shrinkage;
- Restrained shrinkage (dog-bone/TSTM, ring test);
- Creep or relaxation;
- Thermal dilation.

The main benefit of this GP in the scope of the RRT+ programme is to give a platform where all of the developed methods can be compared and validated under controlled conditions.

GP1.f – Fracture properties and cracking
Leader: Aljosa Sajna (SLO)

The following relevant properties are involved in the context of this GP:

- Fracture toughness, KI;
- Fracture energy;
- Bending strength;
- Fracture toughness index Τ100,2.0.
- Fracture behavior of ordinary concrete and fiber reinforced concrete will be monitored, to highlight the applicability and benefits of standardized and non-standardised non-destructive methods.