HYDRATING CEMENT PASTES AS A COMPLEX DISORDERED SYSTEM

In small-angle neutron scattering (SANS) experiments, realized on the MURN facility of the pulsed reactor IBR-2 of the Frank Laboratory of N eutron Physics at the Joint Institute for Nuclear Research, Dubna, the hydration processes in samples of ordinary Portland cement (OPC) and single clinker minerals are studied. The measured scattering curve con tains information about the fractal behaviour of the interfaces and th e size distribution of the scattering particles. Furthermore, a variat ion of the heavy and light water composition for the hydration water s upports the selection of the observable microstructural objects. In de pendence on the size distribution of the clinker grains a various time -dependent behaviour of the potential law of the scattering curve is s hown. Considering the SANS results of hydrating OPC the exponents of t he scattering curve in a given Q-range are varying in dependence on th e hydration time and sample thickness. They lie in an interval from ab out -2 to -4. This is believed to be associated with fractal behaviour . A set of four hydrating C3S-samples is divided into 2 parts after an under water storage of 53 days. Then 2 samples were stored in an H2O/ D2O-mixture for reducing the variety of the several hydration products by changing the neutron optical contrast. Considering the time-depend ent change of the potential law of the scattering curves of hydrating C3S-samples some differences in contrast to hydrating OPC powder are v isible. Within about 100 days after mixing the dry C3S powder with wat er the exponents of the SANS curves in the measured Q-range are higher than -3. If the hydration products of C3S are forming fractal structu res then volume or mass fractals of some nanometers are shown.