An apparatus for easy determination of the amount of bound water in cement pastes yielding highly reproducible results

An apparatus designed for the determination of the amount of bound water in cement pastes is described. The drying of the ground paste takes place at 105 °C in a container, the temperature of which is accurately controlled by means of a solid-state proportional temperature regulator. The vapour pressure of water in the container is kept constant independent of the laboratory conditions. This is achieved by letting a small pump force air to bubble through wash-bottles containing distilled water and submerged in a water bath kept at 1°C. The conditioned air stream is heated to 105°C and led into the drying container. The ignition is carried out at 1050°C. The precision of the method and the influence of various testing conditions are discussed. A couple of examples of experimental results are given.