What are the potential problems of using liquid nitrogen to cool concrete?

Based on the results of past research, there is minimal impact on the properties and performance of concrete by liquid nitrogen (LN). The addition of liquid nitrogen appears to decrease the slump value of fresh concrete. However, the slump loss is not caused by liquid nitrogen but by previous hot concrete mix, i.e. the slump of LN-cooled concrete is the same of original hot concrete. Liquid nitrogen can also be observed to extend the setting time of concrete.

The safety of workers is one of the major concerns when using liquid nitrogen. The extremely low temperature of liquid nitrogen is dangerous to workers as prolonged contact of liquid nitrogen with skin cause severe burns and frostbite. Most concrete mixing drums may not be capable to endure the thermal shock brought about by liquid nitrogen.

This question is taken from book named – A Closer Look at Prevailing Civil Engineering Practice – What, Why and How by Vincent T. H. CHU.