Atiye Tugrul

Correlation of mineralogical and textural characteristics with engineering properties of selected granitic rocks from Turkey

Abstract Granitic rocks show a variety of engineering properties that may affect quarrying operations, tunneling, mining, slope stability and the use of rock as a construction material. The physical and mechanical properties are a function of the mineralogical and textural characteristics of the rock. The purpose of this study is to apply correlation analysis to investigate the relationships between petrographical and engineering properties of granitic rocks. A variety of granitic rock samples from different parts of Turkey were subjected to petrographic studies. The same samples were then tested to determine specific gravity, dry and saturated unit weight, water absorption, effective and total porosity, sonic velocity, Schmidt hardness, point load strength index, uniaxial compressive strength, tensile strength and modulus of elasticity. The relationships between these properties and the petrographical characteristics are described by simple regression analyses. The study revealed that the influence of the textural characteristics on the engineering properties appears to be more important than the mineralogy. It also determined that the types of contacts, grain (mineral) shape and size significantly influence the engineering properties of the granitic rocks.

The Influence of Weathering on the Engineering Properties of Dunites

Weathering processes cause important changes in the engineering properties of rocks. In this study, dunites in the Bursa region in western Turkey were investigated and the changes in engineering properties due to weathering were evaluated. The studies were initiated with field observations including measurement of the characteristics of discontinuities such as spacing, aperture, fill material, roughness, and Schmidt hammer rebound value. Subsequently, laboratory studies were conducted in two stages. The first stage comprised mineralogical, petrographic, and chemical analyses. The second stage included physicomechanical tests to determine specific gravity, unit weights, water absorption, effective porosity, uniaxial compressive strength, P-wave velocity, and slake-durability index. According to these evaluations, the changes in engineering properties were determined to be mostly related to serpentinization at every stage of weathering. The most suitable parameters for characterizing the degree of weathering of the studied dunites are loss-on-ignition values, specific gravity, unit weight, water absorption, and effective porosity.

Estimation of Cerchar abrasivity index of granitic rocks in Turkey by geological properties using regression analysis

The estimation of abrasivity on granitic rocks is very important in mechanical excavators. The mineralogical composition and physico-mechanical properties of the rock affects of abrasivity properties such as the type and size of the mineral grains and strength. Tool wear is an important parameter in hard rock tunnelling and mining applications that are highly affected by rock abrasivity. The estimation of the Cerchar abrasivity index (CAI) from geological properties is useful for excavation costs. For this purpose, CAI, chemical, petrographical, physical and mechanical tests were carried out on 12 granitic rocks taken from different regions of Turkey. The test results were analysed using the method of least squares regression. Multiple regression models having good correlation coefficients were obtained for the granitic rocks. The CAI tests were correlated with chemical compound and a weak relation was determined. The regression analysis was also repeated for petrographical, physical, and mechanical properties. Statistically meaningful correlations were determined between all geological properties and CAI. Then multiple regression analysis was applied to all geological properties to find the more significant relations. Results show that shore scleroscope hardness, water absorption, and the waveness average prove to be the best for estimating CAI of granitic rocks.

Prediction of the durability of limestone aggregates using computational techniques

The durability of aggregates is an important factor that is used as an input parameter in desirable engineering properties along with resistance to exposure conditions. However, it is sometimes difficult to determine the durability of aggregates in the laboratory (with a magnesium sulfate test) because this test is time-consuming and expensive. In this paper, the physical and mechanical properties including water absorption and the Los Angeles coefficient are tailored to the specific evaluation of the durability of limestone aggregates. However, the predictive capabilities of artificial neural networks (ANN) and hybrid particle swarm optimization-based (PSO) ANN techniques have been evaluated and compared using the same input variables. To assess the reliability of the model, some performance indices such as the correlation coefficient (R2), the variance account for, and the root-mean-square error were calculated and compared for the two developed models. The results revealed that even though the two developed models reliably predict the durability value (magnesium sulfate value), the proposed PSO–ANN method displays an obvious potential for the reliable assessment of the value of magnesium sulfate according to the model performance criterion.

Numerical Modelling of Steep Slopes in Open Rock Quarries

The key question regarding steep rock slopes along rock quarries is their stability because a rock slope failure can have critical results. In this study, the aim is to investigate the areas with potential risk for jointed karstic limestones in a rock quarry. First, to determine rock mass properties, scan-line surveys were performed, and the major orientations of discontinuities were analyzed using stereographic projection. Then, the physicomechanical properties of the slope-forming rock were determined in the laboratory, and geomechanical properties of the rock mass were determined using an empirical failure criterion. Finally, the quarry slope stability was assessed in accordance with numerical modelling. According to the results obtained, the numerical modelling of steep rock slopes can be efficiently evaluated by using finite element method. Beside this, the presence of joints intersecting the main discontinuity sets, the filling materials of discontinuities resulting from weathering of limestone and surface deposits, surcharge load due to mine waste dumped on the slopes and excavation blasting during construction of quarry area play a key role when modelling the steep rock slopes by using finite element method.

The Effect of Feldspar, Mica and Clay Minerals on Compressive Strength of Mortar

The mineralogical composition of fine aggregates plays an important role when used in mortar production because they generally effect the strength and durability of mortar structures. In this work, some mechanical aspects are highlighted concerning the use of fine aggregates containing Na-feldspar, K-feldspar, mica and some clay minerals such as kaolinite, illite and montmorillonite. With in this scope, total of there series of mortar mixtures were made with different water/cement ratio. First mixture was referance mortar prepared by using standard sand. In second mixtures, standard sand was replaced with 20 % Na-feldspar, K-feldspar and mica. Third mixtures contained 4 % of kaolinite, illite and montmorillonite as partial replacement of standard sand. According to the results obtained, addition of mica and clay minerals such as illite and montmorillonite with different percentages in standard sand causes to increase water demand in mortar and therefore reduce the strength of mortar.

Abrasiveness Properties at Different Temperatures of Basalt, Marble and Limestone in Turkey

Turkey is a bridge between Europe and Asia. There are numerous historical monuments in Turkey that were built by using natural stones. Due to the geographical features of Turkey, natural stones were exposed to different climatic conditions over time. Temperature and humidity changes have affected physical and mechanical properties of natural stones. The aim of this study is to investigate the physical and mechanical properties of basalt, marble and limestone, which are frequently used in historical buildings in Turkey, in saturated and dry state at different temperatures. For this purpose, basalt, marble and limestone samples were collected from their today’s quarries. The obtained samples were dried and saturated with water, cooled to −15 °C and heated to 105 °C. In every 5 min temperature values of samples were measured to reach up to room temperature (about 23 °C), thus their CERCHAR abrasiveness index were determined. According to the results obtained CERCHAR abrasiveness index increased when the temperature value exceeded 40 °C. In water saturated samples CERCHAR abrasiveness index didn’t change when the temperature value exceeded 30 °C.

Aggregate Mining in Megacities and Existing Problems: An Example from İstanbul, Turkey

In addition to the increasing population and structuring in the growth/development process of a country or megacity, the obligation to maintain industrial and infrastructure investments makes aggregate (crushed stone, etc.) one of the most consumed building materials per capita. Crushed stone, cement and ready-mixed concrete are the basic building blocks of the construction sector and have a great contribution to the development of the industry as well as the increase in national income and employment. However, work safety, environmental problems and increased social opposition to aggregate (crushed stone) open pit mines is intensive and unplanned/irregular urbanization areas are hampering the future sustainable production of medium and large sized enterprises in technical, environmental and economic aspects. The city of Istanbul which has a high aggregate production (90 million tone/year) provides a good example of those issues. In order to maintain efficient and sustainable aggregate resources in Istanbul and its surrounding region, plan and program should be reviewed and new strategies evaluated to facilitate the sustainable management of resources. In this regard, the importance of existing resources and their possibilities, determining operable new resources and their management have been considered.

Assessment of Excavatability, Abrasivity and Slope Stability in a Sandstone Quarry in Istanbul, Turkey

The Cebeci region is characterized by outcrops of Carboniferous sandstone, including diabase dykes. This region is very important area for aggregate production in Istanbul, Turkey. The aim of this study is to determine the engineering geological properties of sandstones to assess the excavatability, abrasivity and stability of cut slopes in a quarry site. Firstly, the sandstone samples were used to determine their petrographical and mineralogical characteristics. Then, physico-mechanical tests were performed on these samples. In order to determine rock mass properties, scan-line surveys were performed, and the major orientations of discontinuities were analyzed through the stereographic projection technique. Kinematical analyses were also made to determine the potential failures at the quarry site. According to the results obtained, excavatability is changed from easy ripping to hard ripping on sandstones; the carbonated sandstone is less abrasive than other sandstones. Based on the field studies and stability analyses of the cut slopes, optimum slope geometry and necessary support measures, such as wire mesh and rock fall barriers, are suggested.

Deterioration Types of Stones Used in Suleymaniye Mosque (Istanbul, Turkey)

Suleymaniye Mosque located in the historic peninsula of Istanbul, is one of the most important monument of classical Ottoman Architecture. Different types of natural stones having varied lithological characteristics were used in the mosque. Chemical composition, mineralogical, petrographic characteristics and external conditions such as atmospheric effects, earthquake and human impacts have deteriorated these stones over time. The aim of this study is to investigate different natural stones and their deterioration types used in Suleymaniye Mosque. According to the results obtained, generally different types of granites, marbles, limestones, pudding stones, porphyry, serpentinite were used in Suleymaniye Mosque. Detachment, material loss, biological colonization, discoloration and deposits have been determined as a deterioration types on these stones.