Direct tensile failure of cementitiously stabilized crushed rock materials

Abstract

Tensile behaviour plays a very significant role in the performance of cement-stabilized pavements under traffic, as well as under environmental loading. This paper reports the results of direct tensile strength tests undertaken using new equipment. The tests were performed on specimens of crushed basaltic rock stabilized with three binders, namely, general purpose Portland (GP) cement, general blended (GB) cement, and alkali activated slag (AAS), with application rates of 2%, 3%, and 4% by dry weight. Some tests were conducted by adding 6% and 15% highly plastic clay to crushed basaltic rock. The tests showed that while the tensile strength increased with curing time, the failure tensile strain decreased. The ratio of unconfined compressive strength to tensile strength decreased with curing time, but it stabilized within the range 8–12 after about 7 days of curing. For AAS and GB cement, the failure tensile strain decreased with curing time, stabilizing at about 50 microstrains after 7 days of curing, whereas for GP cement, the failure tensile strain did not change significantly during curing, displaying a value around 40 microstrains. The test results also indicated that the presence of reactive fine-grained soil may have had a significant adverse effect on the potential for cracking in the stabilized pavement materials.Key words: pavement materials, cement stabilization, tensile strength, cracking potential.