Instrument for nondestructive testing of gas concrete blocks

The developed stationary instrument measures two parameters of blocks in sizes of 600 by 300 by 250 mm: density in anhydrous state and strength. Density in anhydrous state is determined from the density in moist state and humidity. Density is measured by weakening the collimated gamma beam from a 0.32 GBq 137Cs source using two GM counters. Humidity is measured by the moderation of fast neutrons from a 10.1 GBq 239Pu-Be source. Used as sensors are two proportional counters filled with 3He. Strength is measured using an automated Schmidt hammer. The whole measuring cycle takes 15 mins and is automated, while conventional methods take 48 hours. (Ha)