Forschungsvereinigung Kalk-Sandstein e. V., Hannover, Germany
Bundesverband Kalksandsteinindustrie e. V., Hannover, Germany

Calcium silicate units are highly resistant masonry units, composed of mainly burnt lime and natural silicate raw materials. The most important material properties are the compressive strength and the gross dry density. The product standard for calcium silicate units (EN 771-2) [1] contains among other things requirements for these two quality properties. Compressive strength is determined according to EN 772-1 “determination of compressive strength” [2] and the density is measured according to the EN 772-13 “determination of net and gross dry density of masonry units” [3]. During the past five years the Research Institute of the German calcium silicate industry (Forschungsvereinigung Kalk-Sand eV) in Hanover has carried out various research and development projects in the field of non-destructive test methods for determination of the compressive strength and the density of calcium silicate units. The main aims of these activities are the application of rapid quality tests, the reduction of production costs and the further enhancement of the product quality. The test results show that it is possible to estimate the compressive strength with ultra sonic methods and the density with the help of microwaves and the water content.

Key words
calcium silicate, ultra sonic, microwaves, compressive strength, density, production