ABSTRACT
There are s e v e r a l q u e s t i o n s c o n c e r n i n g l o a d i n g r a t e e f f e c t s w i t h r e s p e c t to t e s t i n g . F i r s t , the t e s t i n g method must be c l e a r and p h y s i c a l l y sound so t h a t the q u a n t i t y which has to be de termined can be measured. Second, t e s t i n g methods s h o u l d be d e s c r i b e d or deve loped which are s u i t e d to i n v e s t i g a t e the reason f o r the r a t e e f f e c t f o u n d . An example may c l a r i f y the two a s p e c t s : i n a bending t e s t , i n e r t i a e f f e c t s must be c o n s i d e r e d i n o r d e r to c a l c u l a t e the t r u e f r a c t u r e energy , which i s the f i r s t a s p e c t . Whether the i n c r e a s e of f r a c t u r e energy at h i g h l o a d i n g r a t e s i s caused by an i n c r e a s e of the p r o c e s s zone s i z e or by the f o r c e d f r a c t u r e of aggregate or o t h e r causes s h o u l d be i n v e s t i g a t e d by o t h e r t e c h n i q u e s , which i s the second a s p e c t .
