The Shrinkage Cone allows to measure the shrinkage or expansion of fluid building materials in the first minutes and hours after the start of mixing. With a touch-less laser beam is registered the length change of the building material.

It is possible to measure the plastic shrinkage of building materials with the Shrinkage Cone. 

The Shrinkage Cone apparatus has a basic setup that is made up of a laser unit which is mounted on a stand and a cylindrical bowl with a conical mold on the inside. The nominal height of the cone is 100 mm and the diameter of the opening is about 115 mm. The volume cone is 349 cm³, as reported on the technical data sheet of the product.

Furthermore, producer provides cone-shaped protection sheets, which allows to minimize friction (these cone shaped sheets may be used several times) and some reflectors made of PP coated with a dull aluminium sheet (20 x 20 x 3 mm). The data is recorded in a data-logger which can be connected and controlled by a common personal computer.

To test the plastic shrinkage of a building material, it is first poured into the cone. Then the reflector is placed on top of the material and the cone is positioned under the laser unit so that the focused laser beam is reflected by the reflector. The diffusive part of the reflected light is received by an optical sensor.

The length change is registered with a resolution of 1/10 micron.

A data-logger supplied with the system records the data as standard ASCII files. With a standard web-browser software it is possible readout the data and visualize it online graphical and numerical.

It’s important to specify that the geometric shape of the cone ensures that the change of the recorded distance to the surface corresponds to the relative length change, in fact the ratio of radius and height (r/h) is constant for any volume. Consequently, the ratio of two volumes V1 and V2 (where V2 is the volume after shrinkage or expansion) is equal to the third power of the ratio of the respective heights h1 and h2. In the case of a cylinder or a prism this is not possible, because the relation of radius and height is variable as long as the material is fluid. It’s evident that a cylinder isn't appropriate for the one-dimensional measurement of volume changes before setting.

 

 

Instrument capable of measuring the shrinkage or expansion of fluid building materials in the first minutes and in the first hours after mixing.Instrument capable of measuring the shrinkage or expansion of fluid building materials in the first minutes and in the first hours after mixing.Instrument capable of measuring the shrinkage or expansion of fluid building materials in the first minutes and in the first hours after mixing.