Mechanics of compression in talc considering sample quality

Abstract

Despite numerous applications and occurrences of talc, investigation into its mechanics particularly compression behaviour is limited. This paper presents the mechanics of compression behaviour in talc through a series of oedometer tests for the samples in the reconstituted and intact states. The stress and strain one-dimensional compression paths were studied considering the effects of sample quality and effects of geological structure. The engineering properties, fabric and composition as well as mineralogy were investigated using classification and index tests, scanning electron microscope equipped with EDS and XRD, respectively. The compression curves converge to unique normal compression line. The intrinsic compressibility of talc is low, the yield stress range from low to medium and the sample quality vary from excellent to poor. The sample quality index increases with the in situ specific volume and reduces exponentially with yield stress. Sample disturbance has effect on compression characteristics of intact samples. The commonly used normalising parameters in literature to analyse the effects of structure in compression for geomaterials were not able to capture the real behaviour in talc with low in situ specific volume. Two new stress sensitivity methods which do not require reconstituted samples were developed, and they were found to better represent the degree of enhanced stiffness in compression. The effects of geological structure in compression are positive and small in magnitude, and the destructuration process is rapid in sample with low quality.