The mechanical behaviour of construction materials determines how well they perform in service. Alongside the classical standardised test procedures, the institute carries out detailed fracture-mechanics analyses to build a more precise picture of the fracture process itself. Our focus falls on newly produced cements and, above all, on recycled materials. Sea ice has strikingly similar mechanical properties to concrete. We therefore bring the methods of civil engineering and fracture mechanics to sea-ice research, in order to understand local sea-ice behaviour in relation to environmental influences such as wind, temperature and ocean currents, and so supply sea-ice models with the experimental parameters they need.