A NEW TEMPERATURE INDEPENDENT CEMENT FOR LOW AND ULTRA LOW CEMENT CASTABLES

摘要

The new temperature independent cement CA-470 TI shows a clear advantage in the setting behaviour of all test castables at low temperature whether with or without silica fume. When using CA-470 TI, the castables can be adjusted to a normal setting start time in the range of 1.5 to 2.5 hours at 20℃, and they will still provide a reasonable setting start time of 7 to 10 hours at 5℃. Normal 70 % alumina cements show an increase of setting start to 20 hours and even more at 5℃ if the additive system is not tailored to such low ambient temperatures. Castables with CA-470 TI will exhibit a much more robust setting behaviour and will avoid the setting time variability and uncertainty which are especially apparent during winter time. Risky countermeasures of adding tiny amounts of accelerating additives during on site installations can be avoided. No tests have been made yet using CA-470 TI with other aggregates such as Andalusite, which could also contribute to a retarded setting of low cement castables. The stable results with CA-470 TI and different silica fume grades in the LCC FUME indicate a more robust behaviour of CA-470 TI against impurities from other castable compounds. This will be investigated by a further series of tests in the future.