Strength Characteristics of Clay-Rubber Waste Mixtures in UU Triaxial Tests

Abstract

This paper presents results of undrained and unconsolidated (UU) triaxial tests related to the influence of tire waste addition on strength characteristics of red clay from Patoka in Southern Poland. Angle of internal friction and cohesion values were estimated for 30 specimens prepared from pure red clay (RC), its mixtures with two different fractions of shredded rubber in 5%, 10%, and 25% mass proportions as well as for pure powder (P) and granulate (G). It has been observed that the addition of granulate contributes more to the increase in the angle of friction than the addition of powder (uu = +1% (G-5) / +16% (G-10) / +31% (G-25), uu = +1% (P-5) / +10% (P-10) / +19% (P-25)). On the other hand, rubber additions reduce cohesion in mixtures, and the effect is enhanced with increases in their grain size and percentage composition (cuu = −31% (G-5) / −63% (G-10) / −87% (G-25), cuu = −67% (P-5) / −58% (P-10) / −58% (P-25)). It has been noticed that a change of parameters uu and cuu causes a decline of shear stresses at increasing granulate content. There is an inverse relationship for powder. At the same time, it has been shown that the failure strain, hence a change in red clay-rubber (RCR) mixtures plasticity, is related to the level of confining stress 3 and the type of rubber waste. Results of tests and their comparison with results of other researchers show that each time it is necessary to experimentally verify a given soil with specific rubber waste.