Brazilian and axial tension tests were carried out with 7 rock types and 2 groups of concrete samples

with a test apparatus of direct tension developed by the authors. The result shown that the strengths of Brazilian tests

SB

were greater than the strengths of direct tension

ST

for all rock (concrete) types tested

with the ratio of SB/ST varies among 1.06 and 1.97. The Coefficients of variation of the tested data from direct tension were generally greater than those from Brazilian tests. Corrections on strength values of Brazilian tests were performed following the research results of Sundaram et al. (1980) for the rock types having Young’s modulus in tension

ET

much smaller than the modulus in compression

EC. This makes the SB/ST ratio smaller and shown that the difference between ET and EC was one of the reasons of making SB greater than SC. However

it can also be concluded that

the difference between ET and EC was not the only reason of making SB/ST difference

since the SB/ST ratios for some of the tested rock types were the largest ones while their differences between ET and EC were smaller.