The Volume Changes of Cement Composites in the Early Stage of Setting and Hardening

The Volume Changes of Cement Composites in the Early Stage of Setting and Hardening

en

The article deals with the volume changes of the cement composites. It presents the results of an experimental assessment of the development of cement composite volume changes especially in the early stage of their setting and hardening. The measurement of shrinkage was performed using a modified test device made by Schleibinger Geräte Teubert u. Greim GmbH. Shrinkage drains of 1000 mm in length and with 60x100 mm in cross-section were used for recording the length changes measured along the central axis of the specimen. The drains were filled with concrete and placed onto a special weighing table which allowed continuous recording of mass losses caused by free drying of the specimen surfaces. In this way, the mass losses and changes in the length of the concrete in the shrinkage drains were measured simultaneously. Along with this measurement, the acoustic emission method was employed for the continuous non-destructive monitoring of changes in the internal structure, especially at an early age. The outputs of the measurement are presented as diagrams which display the relationship between the relative length changes, mass losses and the time of cement composites ageing. Events recorded by means of acoustic emission and temperature measured inside the specimens are also presented in the paper.

The article deals with the volume changes of the cement composites. It presents the results of an experimental assessment of the development of cement composite volume changes especially in the early stage of their setting and hardening. The measurement of shrinkage was performed using a modified test device made by Schleibinger Geräte Teubert u. Greim GmbH. Shrinkage drains of 1000 mm in length and with 60x100 mm in cross-section were used for recording the length changes measured along the central axis of the specimen. The drains were filled with concrete and placed onto a special weighing table which allowed continuous recording of mass losses caused by free drying of the specimen surfaces. In this way, the mass losses and changes in the length of the concrete in the shrinkage drains were measured simultaneously. Along with this measurement, the acoustic emission method was employed for the continuous non-destructive monitoring of changes in the internal structure, especially at an early age. The outputs of the measurement are presented as diagrams which display the relationship between the relative length changes, mass losses and the time of cement composites ageing. Events recorded by means of acoustic emission and temperature measured inside the specimens are also presented in the paper.