CORRELATION BETWEEN TRIAXIAL AND HUBBARD -.FIELD TESTS FOR UNGRADED SAND BITUMEN STABILIZED MIXES.

Abstract

The purpose of this investigation is to find a suitable mix for ungraded sand bitumen stabilized mixes. Single sized sands of various gradings which are found in desert regions, are,therefore , investigated Lime filler is used so as to work out an economical mix as otherwise , the optimum bitumen content to produce maximum stability is liable to increase due to large percentage of voids in thes types of sands. Hubbard-Field Stability Test is adopted to test the sand bitumen mixes. An attempt is made in this investi- gation to correlate this with Triaxial Test as the latter is capable of giving more fundamental. information of the proper ties of the mix. The immense utility of the Triwd.al. test in its application in the design of bitumenous mixes and the work done in this field by Dr. Mcleod, Smith and others is emphasised in this investigation. • The study also includes discussions of the effect ofbitumen and filler on air voids, 7.M. A., stability, shear strength angle of internal friction and cohesion an the various factors that are likely to effect the strength properties of the mixes. The results obtained in this investigation indicat that single sized sands are suitable to carry heavy traffic but they suffer from one disadvantage, that is,tbe percentag of voids is more and hence this type of sand can be used for base course with surface painting over it. The results also indicate that there exists no linear relationship between Hubbard-Fieldtability and shea strength and the mixes which are found to be suitable from the stability diagrams are found to be unsuitable with respect to Hubbard -Field Stability values as specified by Hubbard and Field for heavy traffic. The investigation.‘ shows that Hubbard-Field Stabil ty test is incompetent in giving a correct judgement as to the suitability of the bituminous mix for paving purposes as compared to triaxial test. •