Brazilian Tensile Strength Testing of Compacted Clay

Laboratory tests were conducted to examine the applicability of the Brazilian tensile strength (BTS) method (ASTM D3967-16) for measuring tensile strength of compacted clay. A correction function obtained from tests using disk-shaped kaolinite specimens compacted over wide range of void ratio was developed to account for variability in void ratio among replicate specimens. Tests using specimens prehydrated with water vapor in humidity-controlled chambers and then oven-dried revealed that tensile strength increased with increasing prehydration, an observation attributed to increasing cementation during the drying process. Specimens compacted with thickness-to-diameter (t/d) ratios ranging from 0.25 to 0.67 revealed a decreasing trend in tensile strength with t/d for ratios less than 0.42 and essentially constant tensile strength for larger ratios. Tests using loading rates ranging from 0.10 mm/min to 1.0 mm/min revealed no significant effect on measured tensile strength. Recommendations for BTS testing of compacted clay are provided.