A very good document which includes information on thixotropic grout is Development of High-Performance Grouts for Bonded Post-tensioned Structures (1999). The document can be downloaded here: https://fsel.engr.utexas.edu/pdfs/1405_2.pdf.
In addition, the following article includes some information on promising developments in the use of an in-line density meter that can be used on jobsites to monitor and record the quality parameters of the grout in real time. The article can be downloaded here:
http://aspirebridge.com/magazine/2019Fall/CBT- AToolForContinousOnSiteMonitoring.