Comparison of Constraint Elastic Modulus (Ec) Behaviors of Sand Samples and Derivatives Relative to Stress (σ)

Abstract

Four different sand samples, designated Type 1, Type 5, Type 9, and Type 13, were selected for this study. The sands were subjected to milling operations of 30 (Types 6, 10, 14), 45 (Types 7, 11, 15), and 60 (Types 8, 12, 16) minutes to produce new samples. For Type 1 sand, new samples were obtained by grinding for 75 (Type 2), 90 (Type 3), and 120 (Type 4) minutes as determined by their mineralogical content. Resulting samples prepared from the Type 1 sand were named Types 2, 3, and 4; from Type 2 were named Types 6, 7, and 8; from Type 9 were named Types 10,11, and12; and finally samples prepared from Type 13 were named Types 14, 15, and 16. Physical properties were determined for Type 1sand at 55, 58, 61, and 73% relative compaction; for Type 5 at 48, 58, 83, and 85%; for Type 9 at 40, 58, 60, 65, and 68%; and for Type 13 at 45, 61, 65, and 68%.The samples prepared from the milled derivatives of the sands were subjected to 40% compaction. Grain distributions were determined to aid in understanding the effects of grain size on E c . Washed clean sand was used in the study and grain distribution shows poor distribution for all samples. According to this result, while the original sand samples consist of fine and medium grains, the grain sizes of the milled samples vary from fine sand to clay. Mineralogical properties of the sands used in the study were determined. The minerals contained in the sand were determined by Sem (electron microscopy sciences), optical microscope, electron microscope and X-ray diffraction. Results of the examination of the sand samples show that Type 1 sand is made up of augite, hedenbergite, and Anorthite; Type 5 consist of Quartz, Anorthite, Muscovite; Type 9 consist of Quartz, Anorthite; and Type 13 is composed of quartz, anorthite, muscovite, and Anortheclast. In this study, constraint elastic modulus (E c ) values were calculated for sand samples, and various graphics were constructed. The results obtained were analyzed, and an attempt was made to establish the effect of grain size and mineralogy on E c values by comparison.