시멘트 나 모르타르의 초기 경화 거동 측정을 위해 새롭게 탄생한 세계 최초 초음파 경화도 측정 장치 출시 - 2006년 8월
Measuring the Early Setting and Hardening with the Schleibinger Ultrasonic Datalogger
The early setting is usual measured with the penetrometer or the Vicat apparatus. This kind of measurement has some disadvantages. In the early sixties some researchers sugested to use the ultrasonic transition time as method for measuring the setting of mortars or fresh concrete. In cooperation with the German dry mix company Hasit, Schleibinger developed a special datalogger which controls up to 2 common ultrasonic puls indicators, like the well known Pundit 7 .
Fresh mortar is setting between two ultrasonic transducers, which are supplied with 1..10 pulses per second at a frequency of 54 kHz. The mortar changes, according to the setting, the ultrasonic transition time. From the beginning of first contact of the growing binder-stone, the ultrasonic sound speed increases. If there is a complete cristaline structure the change of the sound speed will be slower. Until a further aggregation of the cement stone it increases again.
Each measurement cell is supplied with a pair of ultrasonic transducers. A common Pundit 7 ultrasonic test instrument continously measures the ultrasonic transition time. The data sets are sent digitally to the Schleibiunger data-logger. This data-loger controls the Pundit7 and records the data on a non valotile memory. Two Pundit 7, and therefore to measurement cells may be connected to one Schleibinger data-logger. As an option you may also record temperature and humidity of the specimen or the enviroment.
The Schleibinger data.logger is an aoutonomous instrument, during the tests no PC is required. The data logger has a network interface (Ethernet), and may be integrated directly in your laboratory network. For setup and data upload, a browser software like the Internet Explorer or the Firefox is necessary, but no special software must be installed on your PC. Also a direct link from the logger to your PC is possible. The data plots may be displayed in your browser or may be directly imported into your Excel worksheet. The software was developed at Schleibinger and my be adapted to your special requirements.
Dr. B. Gerstner and F. Richartz from the Hasit central lab ( http://www.hasit.de ) made some tests to compare the Vicat and the ultrasonic method.
Penetration depth in mm over time in minutes - 5 times measured with same material and the same water/binder ratio
Tests with the Vicat Apperatus
With the Vicat apperatus the deviation in percent depends on the penetration depth. With this tests the deviation range was from 27% to 40%.
Ultrasonic sound speed in m/s over time in minutes - 5 times measured with same material and the same water/binder ratio
Test with the Ultrasonic Method
With the ultrasonic test the deviation was 18%. So the ultrasonic method is more accuray the the Vicat method.
Pentetration depth (blue) in mm and and ultrasonic sound speed (magenta) in m/s over time in minutes - 5 times measured with same material and the same water/binder ratio
Pentetration depth in mm over the ultrasonic sound speed for 2 materials (KIS) with different water/binder ratio and another material (RGB)
Comparision of Both Methods
The correlation between teh Vicat test and the ultrasonic method is different for various materials and mix designs. For each mix design a calibration betwen both methods must be done. Once you have got his curve the Vicat test may be replaced by the ultrasonic test.
The costs for the equipment are moderate higher for the ulrasonic setup, but you can do this test with less man power and you will get more objective results.
Specification Pundit 7:
Transit Time Measurement Range
0.1µs to 6553µs
Auto-ranging of two scales
0.1µs .. 999.9µs and 1.000ms .. 6.553ms
54kHz, others available (24kHz..1MHz)
Over Range Indication
shown on the display
Calibrated Refernce Range
- 99.9µs + 199.9µs
10kHz .. 1.25MHz
Transmitter Excitation Voltage
250V, 500V, 750V & 1000V
Puls Repetition Frequency
1 .. 100Hz in 1 Hz Steps
Mains or Internal Battery
85V .. 265V 50/60Hz
Nickel Metal Hydride
Liquid Crystal 56mm x 38mm
BNC Rx Output
10 x Received Signal
BNC Tx Output
Rectangular pulse width a length equal to the non zeroed transit time
BNC Sync Puls
9p Sub-D -plug Baud Rate variable, Parity None, 8 Data Bits, 1Stop Bit
Specification Schleibinger Data-Logger
256 MByte ca. 90 days
2 * RS232 for. Pundit7
Ethernet, 10BaseT, RJ45
FTP, HTTP, Telnet, DHCP, DNS
90..240V 50..60 Hz
Setup over Browser
Sampling Rate, Puls Repetition Frequency, Excitation Voltage, Specimen Width for each Pundit 7
ASCII, Date, Time, Ultrasonic Speed
Temperature Sensor (optional)
RTD PT1000 / -20..90 °C / ±0,3 K
Humidity Sensor (optional)
2..90% ±2% rel. Hum.
Schleibinger Data Logger
Pundit 7 with 54 kHz transducers
Option Temperature Measurement
Option Temperature and Humidity Measurement