Capillary Pressure Sensor System(710)

Capillary Pressure Sensing System (710)

毛细管压力传感系统

Plastic Shrinkage Cracking in Concrete

中峤博联（北京）仪器设备有限公司

Chiao Broadlink(Beijing)E Co.,Ltd

Capillary Pressure Sensor System (710) for the on-site measurement of the capillary pressure in plastic concrete, i.e., during the first few hours after casting. On the basis of the measurement results, it is possible to evaluate the cracking risk, to estimate the demand for curing measures, and to prove the efficiency of the same.

The sensors are applied directly to fresh concrete surfaces. This appears to be not very time-consuming since the sensor system may be set up prior to the construction process. The latter is not hindered due to the wired data transmission to a base station which is connected to a computer. By using the measurement software, the data may be displayed in real time and recorded.

Capillary Pressure Sensor System (710), manufactured by Chiao Broadlink(Beijing)E Co.,Ltd The cone of the sensor is to be filled with degased water and should penetrate the concrete surface down to about 1-5 cm distance from the concrete surface. 710 can measure the capillary pressure down to -100 kPa. Each sensor is connected to the temperature and humidity sensor through the host to measure the ambient temperature, humidity and atmospheric pressure. At the same time, the host can connect the sensor to monitor the temperature change inside the concrete.The measured data can be seen in real time through an interactive interface on a software installed on the computer.

Plastic or capillary shrinkage is a physical process which may be observed in cementitious as well as in inert materials like soils. It is caused by the loss of pore water mainly due to evaporation. This water loss results in the build-up of a negative capillary pressure in the pore system and leads to the contraction of the material. In concrete, plastic shrinkage occurs when the material is still in its plastic stage, i.e., in the time period between placing and final setting . Figure contains a schematic presentation of this process.