The technique for rapid cooling and warming of a sample is based on the "directional solidification" concept. Directional solidification tests are commonly used by researchers in biology, thermal and fluid science in order to study liquid-solid interface morphologies during phase transformations. The experimental apparatus consists mainly of an optical microscope fitted with a directional solidification stage. It consists of two copper blocks machined to allow a distributive flow of cryogenic fluid throughout their volumes. Typically, one block (Tc) is set at a subfreezing temperature, while the other block is set at a temperature above the sample's freezing point (Th), thus imposing a linear temperature distribution between the copper blocks. To control the temperature, each block also includes a Minco heating element connected to a temperature controller. A thin section sample is placed at the top of a microslide and the temperature of the bases is taken through the microslide. A gap of d=2.4 mm separates the two temperature blocks, thus allowing the sample to be viewed through the objective of the microscope. To insure continuous visualization of this interface, the microslide is moved laterally at a constant velocity, V, which is almost the same as the speed of the interface growth. This movement is achieved by varying the voltage inputs into a motor mounted on the stage. The motor then connects to the guides that secure the microslide, thus effectively directing the movement of the specimen. Controlled cooling of the sample can be achieved by pushing the microslide and the sample at a constant velocity from the high temperature base to the low temperature base. Controlled warming can be achieved by pushing the sample in reverse from the low temperature base to the high temperature base.

Ice Propagation in Ionic Solutions

Ice Propagation in Concrete