Schleibinger Testing Systems

AKROMAT - Alkali-Silica-Reactor with Online Monitoring

State of the Art

The ASR test at 60°C and nearly 100% humidty is state of the art for predicting risks of alkali silica reactivity in concrete. 
Schleibinger, in ccoperation with BAM, the German Federal Institute for Material Research, has now clearly improved this test.  
Up to now the spcemen must be taken out of the test chamber periodically each 28 days for 140 days. Then the length change of each specimen must be measured in teh range and accuracy of several Mikrons. 

You got only 5 measurement days in 140 days. This procedure was difficulty to handle with a high risk of failures. 
 

Advantages of the new AKROMAT

• The expansion of each specimen is measured continously with an Eddy current sensor on the sub Mikron level.
• Each specimen is stored in an own closed container. 
• The temperature and humidity of six specimen is controlled in a small table top box. 
• The same specimen size of  280 x 75 x 75 mm is used then in the common test. 
• No extra power supply required. One mains plug is enough. 
• The data-logger is measuring and recording temperature and expansion each minute. 
• No influence by the lab staff after measurement start. 
• You get a continous function of expansion over time for 20 weeks, not only 5 measurment point. The early shape of the curve already enables a prediction of the expected max. expansion.
• If the max. expansion limit of  0.3 mm/m is reached, an alarm is triggered. The measuremen can be stopped, and a new measurment with a new specimen can be started. 
• The test of all 6 specimen can be startded and stopped independently.  

Patent granted. 

 

 

Literature

Wilma Wallau, Stephan Pirskawetz, Katja Voland, Birgit Meng, Continuous expansion measurement in accelerated concrete prism testing for verifying ASR-expansion models,  Materials and Structures, Open AccessOriginal Article, First Online: 14 June 2018, https://doi.org/10.1617/s11527-018-1205-0

Wallau, W., Pirskawetz, S., Greim, M. et al.: AKR-Schadensmonitoring im 60°C-Betonversuch, Abschlussbericht zum MNPQ-Projekt (19/14), 2017, https://doi.org/10.2314/GBV:106750463X

Krütt, E., Wallau, W., Meng, B., Greim, M. and Pirskawetz, S. (2019), Automatisierte AKR‐Prüfung im 60 °C‐Betonversuch. Beton‐ und Stahlbetonbau, 114: 911-918. doi:10.1002/best.201900040 (Abstract English, Text German)

Greim,  Pirskawetz, Teubert, Wallau: Vorrichtung zur Erfassung einer Längenänderung von Probekörpern bei hoher Temperatur und hoher Luftfeuchtigkeit; German Patent DE102018132624B4. 

 

AKROMAT Reactor for 6 specimen at 60°C and nearly 100% humidity. 

Temperature range	room temperature up to max. 65°C
temperature deviation	< 1 K
Accuracy of the temp. measurement	0.3 °C
Outer size (L x W x H)	85 x 63 x 64 cm
Weight	43 kg
Water volume	9 l
Voltage	200-240 V~ (110V on request)
Electrical power	340 W @ 230V

 

AKROMAT-Test Container with Eddy Current Sensor.

 

Measuring target	steel
Basic distance	0.3 mm
Measruement range	3 mm
Linearity over full scale	<= 0,25%  = 7.5 µm
Resolution	1.5 µm
Reproducability	<= 0,05% of full scale
Temperature stability	0,025% of full range / K
Range of temp. compensation	+10..+125 °C
Envirinmental cond. of the sensor	-30°C ..+125°C
Environmental cond. controller	-20..+70°C
Specimen size (L x W x H)	75 x 75 x 280 cm
Outer dimensions (L x W x H)	186 x 186 x 446 cm
Gewicht	4,2 kg
Water volume	0.25 l

 

AKROMAT Data Logger

The AKROMAT data logger is recording the data from the 6 Eddy current sensors and of 2 (max. 6) temperature channels.
The data aquisition can be started and stopped indepnently for each channel / specimen. 
If the limit of 0.3 mm/m expansion is exceeded, an alarm message s triggered. The AKROMAT data logger has a network connection and a built in WEB server. 
No extra software required. Simply connect the data-logger to your PC or lab network and start any browser like Chrome (R), Firefox, Opera, etc. 

The data can be shown in your browser as text or graphically. You export the date to Excel (R) or any other PC programm with one or two mouse clicks. 

 

  

Hardware requirements	PC or lab network. No Internet connection required.
Software	Windows 7..10, Linux, MacOS, Android with Edge, Firefox, Chrome, ...
TCP/IP	fix IP address or  DHCP
Dimensions	24 x 21 x 6 cm
Weight	1.8 kg
Power	90..240V AC / 50..60 Hz

Scope of delivery: Data-Logger for 6 AKROMAT container, user manual, network cable, power-supply.