Experimental study of the fine particles effect on the shear strength of tuff zeolites

Abstract

The effect of fine particles on the zeolite shear strength is assessed for possible construction applications. A brief geological description of the zeolite is presented. Three groups of zeolite samples were prepared, namely a coarse material with no fines, a finer material with 3% of silt and a silty material with 15% of clay. Results from standard classification, compaction and compressibility tests are shown and explained. It was found that due to the low specific gravity, low values of density were obtained in compaction tests. Additionally, shear strength tests were performed, resulting in different response in terms of shear stress and horizontal and vertical displacements. The coarse zeolite followed a similar friction-dilation response as in feldspathic and quartz sands. However, addition of 3% of fines reduced significantly the zeolite shear strength. Furthermore, the finest material was tested under two different displacement rates, reflecting also marked differences in shear strength and stiffness.