A Determination of Properties of Alternative Material Used for Immobilization of Samples in Standard Direct Shear Apparatus : Master's Thesis

Postupak određivanja posmične čvrstoće stijena metodom izravnog posmika jedan je od najčešće korištenih postupaka određivanja posmične čvrstoće pukotina ili intaktne stijene. Prema naputku ISRM-a, postupak se provodi na neporemećenim uzorcima stijene uzetim iz bušene jezgre ili blokova, pomoću prijenosnog uređaja za izravni posmik. Prilikom ugradnje u uređaj, testni uzorak je potrebno imobilizirati koristeći materijale koji postižu veliku čvrstoću (dovoljnu da se slom odvije preko uzorka) u kratkom vremenskom roku (zbog zahtjeva racionalnosti provedbe pripreme testa). U ovom radu prikazane su recepture s aluminatnim cementom nastale variranjem litijevog karbonata kao ubrzivača vezanja te su njihove karakteristike uspoređene s karakteristikama referentnog morta, kao i rezultati izravnog posmika provedenog na pet različitih uzoraka stijena s područja Dalmacije.The procedure of determination of the shear strenght of rocks by using direct shear test is one of the most commonly used procedures in which the shear strength of cracks or of intact rocks is determined. According to ISRM, the test is conducted on undisturbed samples of a rock taken from drilled core or blocks, while using a portable apparatus for shear test. During the installation into the device, the test sample must be immobilized using materials it with high strength (high enough for the shear to occur through the sample) in short period of time (because of requirement of rationality of test preparation implementation). Calcium aluminate cement mortar formulations are designed by variating lithium carbonate content as an accelerator and its characteristics are compared with characteristics of a standardly used mortar. To select the optimum mortar, direct shear test that were conducted on five different samples of rocks from the area of Dalmatia