Monitoring of the development of hydration heat in concrete

During the setting of concrete, hydration heat is released, causing a pronounced increase of the temperature of the structure. This temperature increase only slowly diminishes because of the low thermal conductivity and high heat capacity of concrete. The knowledge of the temporal and spatial temperature development in the concrete is essential to assess its strength and the risk of crack propagation.

Fibre-optic temperature measurement is used to control the hydration heat development in mass concrete, which is responsible for build-up of thermal stresses and the associated crack propagation, e.g. in dam construction. With the cost-effective temperature monitoring along the cables in the boreholes, the temperature distribution in the setting concrete can be spatially recorded, simultaneously at many thousands of measuring points. In addition, the thermal material parameters of the concrete, thermal conductivity and heat capacity, can be determined along the cable by using hybrid fibre optic cables.