Proceedings of SerbiaTrib '13

sulphides, chlorides and hydroxides. To get amore complete picture about number of differentminerals that rocks are made of, it is necessary toemphasize that only the silicate group containsabout 800 minerals, categorized into varioussubgroups. Mineral masses in the Earth’s crustcan be found in forms of compounds – as solidrocks or in the unbound – dispersed form. Thusthe rocks are being divided, according to strength,into weak, solid and exceptionally solid rocks,since minerals can be in the crystal, crystallite oramorphous form. Rock properties can besignificantly changed due to action of water, frostor heat; thus it is highly important to know thelaws of those changes. The most importantproperties of rocks are petrographic, physical,mechanical and technological [1-8]. All the rocksthat are contained in the Earth's crust can beclassified in three major groups: magmatic,sediment and metamorphic rocks.In this paper are investigated properties ofstones from the four near-by sites: limestone,dolomite marble, calcite-dolomite marble andandesite. The most exploited (over 70 %) is thelimestone from the "Vučjak" site, thus this particularstone was taken as representative for rocks'properties experimental investigations.3. DETERMINATION OF PETROGRAPHICPROPERTIESThe most important petrographic properties ofrocks are: mineral composition, structure andtexture. The structure of rocks consists of mineralcrystallite grains, whose shape and strengthdepend on way of coalescence during the rockformation. The texture of rocks consists ofminerals spatial distribution and occupancy.Petrographic properties of rocks were testedaccording to standard SRPS.B.B8.002:1989.The limestone site "Vučjak" mainly consists oforganogenic-detritic 1 limestone. The rock's textureis massive. i.e., the mineral grains are notregularly distributed within the substrate. InFigure 1 are presented macroscopic andmicroscopic appearances of this rock [6].The dolomite marble site "Samar" mainly consistsof the dolomite marble. The structure of thistype of rock is granoblastic. Texture is massiveand noncompact. In Figure 2 are presentedmacroscopic and microscopic appearances of thisrock [6].The calcite-dolomite marble site "Gradac"mainly consists of this type of rocks. The rock's1 Detritus (latin): aggregate of small particles ofcrushed rockstexture is homogeneous and compact. In Figure 3are presented macroscopic and microscopicappearances of this rock [6].The andesite site "Šumnik" mainly consists ofthis type of rock. The rock's texture is massive. InFigure 4 are presented macroscopic and microscopicappearances of this rock [6].4. EXPERIMENTAL DETERMINATION OFSOME ROCKS PHYSICAL PROPERTIESFor construction of roads the most frequentlyexperimentally tested are the following rocks'physical properties: specific mass, bulk mass,porosity, water absorption and compactness, sincethose properties directly influence changes ofmechanical and technological properties of rocksand their aggregates.4.1. Determination of specific mass (density) ofrocksIn Table 1 are presented average values ofspecific mass of various rocks' samples [6].4.2. Determination of rocks' porosityWater absorption is defined by ratio of watermass and mass of solid mineral substance; for varioustypes of rocks it ranges from 1.5 to 4.4% [6].4.3. Determination of rock compactionpossibilitiesDetermination of the rock bulk mass can serveas criterion for estimates of possibility of theircompacting in the infilling state, what is of a greatimportance in construction of building objects.Complete investigation of compaction possibilityof rocks requires: determination of granulometriccomposition, compacting possibility by theProctor test and the Californian capacity index (cf.[1], [3-4], [7], [9 - SRPS B.B8.030: 1986]).4.4. Influence of water, low and elevatedtemperatures on rock content changesWater, low and high temperatures significantlyinfluence some of the rocks' properties. In contactwith water at low temperatures (< 0° C) and hightemperatures (>100° C), the minor changes inrocks are observed, while at temperatures lowerthan - 25° C and higher than 500° C, thesignificant changes occur.Low temperatures (frost) significantly affectrock properties, especially if the temperatures arevariable. Alternating heating and cooling of rocks276 13 th International Conference on Tribology – Serbiatrib’13