Trass

Dense rock of volcanic origin - volcanic tuff. It is used as a finely ground hydraulic additive in the preparation of pozzolanic cements and to improve workability, prevent mixture separation, and achieve high concrete density. Construction dictionary.

Trass (German: Trass) is a dense light rock from the group of volcanic tuffs, rich in amorphous silicic acid. The track includes numerous small fragments of volcanic glass, partially transformed into zeolites. It is used in the cement industry in finely ground form as an active additive in Portland cement, after which the cement acquires the ability to harden in sea water. TSB.

Note : The use of trace in cement mixtures reduces the risk of efflorescence.