Morphology and detachment mechanism of weathering crusts of porous limestone in the urban environment of Budapest

Abstract A fine-grained and a medium-grained oolitic limestone of Miocene age were studied on ashlars of monuments in Budapest. The studied buildings are located in a polluted urban environment. The surface alteration is characterized by the presence of white (thin and thick) and black (laminar and framboidal) weathering crusts. Flaking, scaling and blistering are common crust detachment forms. Crust detachment is followed by rapid surface loss in the form of granular disintegration or of secondary crusts stabilizing the stone surface. Non-destructive in situ mechanical tests such as Schmidt hammer rebound and Duroscope clearly document the presence of thin and thick weathering crusts, and the degradation of underlying fine-and medium-grained limestone. Crust formation is associated with a textural change, since precipitation of pore-occluding calcite and gypsum and reduction of porosity in the crust zone has been recorded. Crust detachment is attributed to the crystallization pressure of air pollution-related gypsum, to freeze/thaw cycles, and to differences in mechanical properties of crust and host rock

Petrophysical and Sedimentological Analyses of Siklós Ornamental Limestones, S-Hungary

The two studied ornamental stones, `Siklós-green´ and `Siklós-rose´ are quarried in the Villány Mountains in South Hungary. The former one belongs to the Middle \hboxTriassic Zuhánya Limestone Formation while the latter one is a part of the Upper Jurassic Szársomlyó Limestone Formation. Besides pinkish, yellow and white varieties of `Siklós-rose´ also exist. Zuhánya Limestone was formed in an outer ramp setting representing the deepest facies. Szársomlyó Limestone contains pelagic fauna, microoncoids and peloids. The microoncoids were accumulated in a relatively shallow part of a drowned platform and were redeposited. The petrophysical tests showed that uniaxial compressive strength of both limestones was in the order of 80 MPa. It is easy to polish them and their polished surfaces are decorative. Both stones are used as inner wall or floor cover but due to its frost resistance `Siklós-rose´ is also applicable for outer surfaces. The byproduct of ornamental stone quarries are appropriate for aggregates. Better petrophysical properties of `Siklós-rose´ are attributed to the more homogeneous texture of the Jurassic limestone

A dél-dunántúli középső triász karbonátos kőzetek ciklus-sztratigráfiai vizsgálata = Cyclostratigraphic analysis of Southern Hungarian middle triassic carbonates

A ciklus-sztatigráfiai elemzések alapján a délkelet-dunántúl középső triász karbonátok három harmadrendű, aszimmetrikus üledékciklust képviselnek. Ezek közül két teljes ciklus az anizuszi emelethez köthető. Ezek az üledékképződési ciklusok jól korrelálhatók a Germán-medence alsó Muschalkalkját alkotó két anizuszi ciklussal (lengyel és német szelvények). A nagy frekvenciájú, méteres vastagságú üledékes ciklusok legjobban a belső rámpa és a sekély középső-rámpa üledékeiben különíthetők el. Az ideális ciklusok a maximális elöntési zónával (mfz) kezdődő, majd korai HS (uralkodóan finomszemű márgásabb), késői HS (váltakozó meszes és márgásabb rétegek) jellemezhetőek. A szekvencia határt egy rendszerint markáns agyagos felület és a rá települő intraklasztos réteg jelzi, amely már a transzgresszív ciklustag (TS) bázisának tekinthető. A TS-et alkotó meszes padok felső részénél van a maximális tenger elöntést jelző zóna (mfz) és az újabb ciklus határa. A lassú tengerszint emelkedéshez köthetően, a maximális tengerelöntési fázisokban kondenzált márgás és bioklaszt dúsabb ('amalgamated') rétegek keletkeznek, amelyekben tengeri palynoflóra és makrofauna, valamint pozitív delta13C izotóp értékek mutathatók ki. Az üledékföldtani, palynofaciológiai és stabil izotópos mérések segítségével az uralkodóan mésziszapos rámpa üledékekben is sikerült kimutatni az üledékes ciklusokat: elkészült a délkelet-dunántúli középső triász üledékek ciklus-sztratigráfiai beosztása. | The cyclo-stratigraphy analyses of Middle Triassic carbonates of SE Hungary revealed three third-order asymmetric sedimentary cycles. There is a good correlation between the two Anisian Lower Muschelkalk cycles of Hungary, Poland and Germany. High-frequency cycles are best preserved within the outer ramp and mid-ramp carbonates. The ideal cycle begins with maximum flooding zone (mfz) which is followed by dominantly fine marly sediments of early highstand deposits (eHSd). Late HSd consist of alternating limestones and marls. Sequence boundary (sb) is marked by a thin clayey zone and capped by intraclastic sediments of transgressive system (TSd). The maximum flooding zone and the new cycle is located at the top of the TSd. During periods of long-term sea-level rise the maximum flooding is characterized by the deposition of condensed marls and amalgamated shell beds. In these sediments marine palynomorfs and macrofossils are common. A shift toward positive delta13C isotope values also marks these beds. Based on sedimentological, palynofacies and stable isotope analyses it was possible to identify sedimentary cycles within the mud dominated carbonate ramp sequence; the SE Hungarian middle Triassic was divided into sedimentary cycles

Közlekedés célú biodízel gyártás várható tendenciái

A kőolaj alapú tüzelőanyagok használatának további növekedése fenntarthatatlan, mert forrásuk szűkös és előállításuk, szállításuk, felhasználásuk során kimutathatóan, mind lokálisan, mind globális mértékben szennyezik környezetünket. A belátható jövőben várhatóan a fosszilis tüzelőanyagok maradnak a domináns energiaforrások. A gázolajnak – mint a dízel-motorok tüzelőanyagának - alapvető szerepe van az iparban, közlekedésben, mezőgazdaságban. Cikkünk célja a közlekedési célú biodízel gyártás lehetőségeinek áttekintése

Evaluation of the efficiency of consolidants on Hungarian porous limestone by non-destructive test methods

Abstract Three types of porous limestone from Sóskút quarry and two limestone types obtained directly from Matthias Church of Budapest (both in Hungary) were used to test the performance of five stone consolidants. The quarry specimens were treated under laboratory conditions by saturation. Three types of silicic acid ester, an aliphatic uretan resin and a polymethyl methacrylate were applied to the stone. Physical parameters such as density, porosity, ultrasonic sound velocity and Duroscope rebound value were measured on untreated and treated samples. The absorption rate of different consolidants was also detected. The physical properties of untreated and treated specimens were compared in order to analyze the performance of the consolidants. Duroscope tests have shown that after consolidation there is an increase in surface strength

Long-term durability tests of andesite aggregates from Hungary

The Micro-Deval test method is used for testing of aggregate durability. The present paper focuses on two Hungarian andesites obtained from the quarries of Recsk (Mátra Mountains, Hungary) and of Nógrádkövesd (Cserhát Mountains, Hungary). The aim of this study is to find a simple test method based on the original Micro-Deval test method to assess the long-term durability of aggregates. An additional part of the research was to develop suitable mathematical models that can describe the behavior of the andesite aggregates under continuous abrasive impact. The relevant standard (EN 1097-1:2012) recommends 12,000 rotations to determine the Micro-Deval coefficient required for classification of the aggregates. Within the framework of this research, a modified Micro-Deval test was applied: the number of rotations was increased in several steps and the degree of abrasion was measured afterwards. Regression analyses were used to outline mathematical forms which characterize the dependence between the number of rotations and the degree of abrasion. According to the results, the long-term Micro-Deval tests significantly modify the assessed durability and thus provide information on the long-term abrasive impact. The degree of change depends on the studied material: the ratio of the long-term Micro-Deval coefficients of the two studied andesite types is larger than 3. The regression analyses of the measured Micro-Deval coefficients revealed that quadratic curves are suitable to describe these tendencies for both andesite aggregates

Heat-related Changes of Density, P-wave Velocity, and Surface Hardness of Granite

Low- and intermediate-level radioactive waste is stored in the National Radioactive Waste Repository in Bátaapáti in Hungary. The repository is located in the Carboniferous Mórágy Granite Formation. This paper focuses on heat-related changes of physical properties such as bulk density, P-wave velocity, P-wave modulus, and Duroskop surface hardness of the dominant lithology: monzogranite. Cylindrical specimens were tested at laboratory conditions (22 °C) and were heat-treated up to 250 °C, 500 °C, and 750 °C. The properties were measured before and after the thermal strain. After heat-treatment, the monzogranite samples became brownish, and at 750 °C, cracks appear at the surface of the specimens. Laboratory test results show that bulk density values slightly decrease from room temperature to 250 °C treatment and further dropped at 500 °C and especially at 750 °C. P-wave velocity values and the connected P-wave modulus tend to decrease from room temperature to 750 °C significantly. Duroskop rebound values show slight declines in the surface strength of the specimens until 500 °C, and then a drastic decline at 750 °C. Heat treatment tends to alter the physical properties of the monzogranite. From room temperature to 500 °C, a slight but apparent decrease between 500 °C and 750 °C significant reductions in the bulk density, P-wave velocity, and Duroskop values. Behind the physical alterations are the different thermal-induced expansion of minerals and mineral alteration at elevated temperatures

Engineering Geological Survey for Railway Extension in the Nile Valley

Egyptian National Railway (ENR) called for a tender for doubling the railway line Edfu/ Aswan in the mountainous terrain. The engineering geological works were carried out by the authors for MÁVTI Co. Ltd. The study includes two parts El Serag and El Gaafera sections having a length of 6.5 km. One side of the railway track is bordered by steep sandstone cliffs of 30 - 40 m in height that forms the edge of rugged low relief topography often dissected by wades. The other side is on the right bank of the Nile where a narrow flood plain is cultivated and covered by dense vegetation. Several alternatives were studied for the second rail track including tunnel open cut, rock excavation, land bridge and gabion versions. ENR chose the rock excavation version. As a consequence the cliff wall geometry, joint system and rock formations were studied in details. By using these data the necessary rate of rock excavations, the schedule of works, machinery, safety conditions and excavation methods - blasting, swelling cement - were prepared. Finally swelling cement was used by Egyptians. No Hungarian expertise was used during the construction phase

Effect of Thermal and Freeze-thaw Stress on the Mechanical Properties of Porous Limestone

This paper focuses on the effect of high temperature on the mechanical properties of a porous limestone that is widely used as dimension stone in Hungary. The changes in physical properties of 3 types of porous limestone were analyzed at 22 °C, 300 °C and 600 °C, respectively. The limestone specimens were also subjected to freeze-thaw cycles to assess the other extrinsic factor that influences the behavior. Parameters such as material density, bulk density, ultrasonic pulse velocity and tensile strength were measured and compared in different test conditions. The tests results indicate that fabric differences significantly influences the durability of tested limestones. Bioclastic grainstone is more frost resistant that ooidal grainstone or bioclastic packstone, but heating seems to reduce the pulse velocity and tensile strength of all tested limestone. It is suggested that cyclic freezing-thawing reduces the strength depending on the micro-fabric, while heating to 600 °C and the reduction of strength is less controlled by the fabric of the porous limestone