thermal decay of carbonate dimension stones fabric physical and mechanical changes this paper deals with the effects of thermal stresses on selected carbonate rocks used as dimension stones they are mesozoic calcareous and dolomitic rocks cropping out in apulia southern italy that for their physico mechanical and aesthetic properties have always been finding a large application both as ornamental stones and as simple construction materials their use is attested not only in italy in works of archaeological historical and artistic interest too the cause effect relationships of thermal degradation were studied by means of an artificial accelerated ageing test in order to provide a perspective about the decay of carbonate stones due to diurnal and seasonal temperature fluctuations as well as thermal shocks during events of fire development the stone samples were subjected to thermal cycles in a muffle furnace ranging from 100 to 700 c after each cycle several non destructive and semi destructive tests were carried out mass and volume measurements mercury intrusion porosimetry sclerometer tests ultrasonic tests thin section observations and determination of chromatic alterations through image analysis and munsell charts method in this way the qualitative and quantitative modifications induced in fabric physical and mechanical properties were discussed the results highlight the fundamental role of depositional and diagenetic fabric that together with mineralogical composition represents the most significant discriminating factor in the response of the stone to thermal stresses

correlation of triassic advanced rifting related neotethyan submarine basaltic volcanism of the darno unit ne hungary with some dinaridic and hellenidic occurrences on the basis of volcanological fluid rock interaction and geochemical characteristics comparative volcanological mineralogical petrological and geochemical studies of blocks of triassic submarine basalt occurrences hosted by the jurassic melange have been carried out the studied localities are located in displaced parts of the dinarides in ne hungary darno unit in the dinarides kalnik mts croatia and vares smreka bosnia and herzegovina and in the hellenides stragopetra greece the common characteristic of the studied occurrences is the well observable result of the lava water saturated sediment mingling i e the presence of the so called carbonate peperitic facies mixing of the basaltic lava with pelagic lime mud representing the unconsolidated stage of the red micritic limestone as well as fluid inclusion and chlorite thermometry data support that the carbonate peperite was formed above ccd and at the bosnian locality a shallower water about 1 4 km depth is proven the igneous rocks show mainly within plate basalt geochemical characteristics morb signatures are not common low temperature 200 c hydrothermal alteration is characteristic to the pillow basalt blocks with peperitic facies the similarities in the volcanological geochemical and textural characteristics observed at the different localities support a strong genetic connection among them the results of this study suggest to the advanced rifting stage origin of the triassic basaltic suits and their distinction from the true oceanic basalt pillow units of the dinarides can be based on the occurrences of the peperite facies

experimental investigation on the performance of schmidt hammer test in durability assessment of carbonate building stones against freeze thaw weathering although schmidt hammer test has been widely used for assessment of weathering state of rocks its application for evaluation of rock durability remains rare this study aims at investigating the performance of the schmidt hammer test in the durability assessment of carbonate building stones against frost weathering for this purpose nine types of carbonate rocks were collected from various quarries of iran and subjected to a series of tests including determination of petrographical physical mechanical ultrasonic and rebound hardness properties moreover long term weathering test of freeze thaw up to 100 cycles were carried out and ultrasonic detection was used to detect the weathering induced damages of rocks in ultrasonic detections ultrasonic parameters of maximum amplitude amax spatial attenuation s and compressional wave velocity vp were determined before and after freeze thaw tests and then their change rates were determined the change rates of amax s and vp including ka k and kp respectively were considered as the functions of the degree of the frost induced damages of rocks and consequently as indications of the rock durability results showed that there are close correlations between the schmidt hammer rebound value rn and ka k and kp however the correlation between rn and kp was weaker than those between rn and ka and k because of the disproportionate response of vp to the rock deterioration it was concluded that the schmidt hammer test is capable to evaluate the durability of carbonate building stones and can be used for a rapid and onsite evaluation of rock durability at different quarry faces hence it allows selecting more durable rocks for different applications in new constructions and also in replacement works in historical sites

isrm suggested method for determination of the schmidt hammer rebound hardness revised version with its portable simple and affordable attributes the schmidt hammer sh is an ideal index apparatus which underlies its increasing popularity and expanding range of applications the sh rebound hardness value r is perhaps the most frequently used index in rock mechanics practice for estimating the uniaxial compressive strength ucs and the modulus of elasticity e of intact rock both in laboratory conditions and in situ the sh is also widely used for estimating the ucs of discontinuity walls and assessing the workability excavatability and boreability of rocks by mechanical means cutting polishing milling crushing and fragmentation processes in quarrying drilling and tunneling

physical weathering of marbles caused by anisotropic thermal expansion marbles as building stones as well as in their natural environments show complex weathering phenomena the most important damage scenario is based on the highly anisotropic thermal expansion coefficient of calcite i e extreme expansion parallel and contraction normal to the crystallographic c axis therefore the rock fabric and especially the lattice preferred orientation texture of calcite and or dolomite as the predominant mineral phases in marbles have a significant influence on the mechanical weathering the textures of marbles from five different locations vary from a more or less perfect prolate to moderate oblate shape of the 006 pole figure tensor accordingly the texture derived bulk thermal dilatation anisotropy covers a broad range from 0 048 to 0 680 the modelled thermal dilatations correlate with those obtained from experimental measurements the difference in magnitude is basically explained by the microcrack fabrics which was not considered in the computations all samples show a deterioration due to thermal treatment regardless of the strength of texture the directional dependence of a the total magnitude of the thermal dilatation coefficient and b of the residual strain is highest in marbles with a strong texture whereas the carrara marble with a weak texture exhibits a uniform crack formation the progressive loss of cohesion along grain boundaries due to dilatancy may serve as an example for the initial stage of physical weathering

physical and mechanical properties of the repaired sandstone ashlars in the facing masonry of the charles bridge in prague czech republic and an analytical study for the causes of its rapid decay the facing masonry of the gothic charles bridge in prague czech republic has been largely altered during nineteenth and twentieth century repairs due to extensive replacements of weathered sandstone ashlar blocks natural stone varieties used during these replacements show different responses to a variety of weathering processes which lead to their rapid decay the decay of the newer stone has been accelerated by use of portland cement paste as the binding and fill material instead of the original hydraulic lime based and cocciopesto type mortars the hardened portland cement paste makes an almost impermeable barrier with permeability three to four orders of magnitude lower compared to the original mortars and natural stone the low permeability of this new alien material results in the accumulation of water soluble salts specifically nitrates but also sulphates and chlorides in the facing masonry ashlars with their crystallisation coming in the form of both sub and efflorescence as well as the development of various decay forms blistering granular disintegration and or scaling and flaking the source of the water soluble salts can be traced back to previous restoration attempts these included chemical cleaning black crust removal by nitric acid ammonium hydroxide ammonium water or ammonium hydrogen carbonate all which can be linked to high nitrate content in the efflorescence

direct observation of microcrack development in marble caused by thermal weathering one of the properties that makes marble such an excellent construction and ornamental material is its low porosity it is very difficult for water or decay agents to penetrate the internal structure of materials with no or few pores so enhancing the durability of these materials however environmental temperature fluctuations bring about significant physical changes in marbles that result in an increase in porosity due to the appearance of new microcracks and the expansion of existing ones these cracks offer new paths into the marble which make it easier for solutions containing pollutants to penetrate the material thermal expansion tests were performed on three different types of marble known as white tranco and yellow macael almeria spain after which an increase in porosity from 17 to 73 depending on marble type was observed mainly due to crack formation the structural changes occurring during thermal expansion tests were more significant in the case of white macael samples a fact that is not only related to its mineralogical composition but also to the morphology of the grains grain boundaries and crystal size our research suggests that thermally weathered white macael marble could be more susceptible to decay by other contaminant agents than tranco or yellow macael the use of hot stage environmental scanning electron microscopy is proposed as a valid tool for observing both in situ and at high magnification changes in the fracture system of building stones induced by thermal stress

weathering behaviour and construction suitability of dimension stones from the drei gleichen area thuringia germany the construction suitability of a dimension stone depends on its weathering properties along with the petrology and the petrophysical properties the aim of this study was to evaluate the suitability of the dimension stones from the drei gleichen area for construction and replacement purposes in total six sandstones ingersleben wachsenburg hindfelden seeberg rohnberg gleichenberg upper triassic as well as two carbonates wachsenburg sinter quaternary wandersleben dolomite middle triassic were analysed the results from our laboratory and on site studies of the dimension stones show that rocks from the same stratigraphic layer like the sandstones from the upper triassic can show major differences in their petrophysical and weathering properties these differences are attributed to their different diagenesis resulting e g in varying pore space water balance and strength properties the pore size distribution can be divided into four different groups based on their occurring maxima and micropore content the determined water balance properties as well as moisture expansion and salt attack depend on these groups next to this the mineralogical composition significantly influences the weathering resistance sandstones with a high content of altered lithoclasts show a high amount of moisture expansion low strength and in consequence a low weathering resistance against salt attack based on the results of the present study an evaluation of construction suitability could be accomplished from the analysed sandstones only the seebergen sandstone is suitable for construction purposes due to its good availability good strength properties high compressive and tensile strength low softening degree as well as a low porosity furthermore the wachsenburg sandstone also shows good petrophysical and petrological properties but exploitable deposits are too sparse to be of commercial interest from the carbonates the wachsenburg sinter shows very suitable rock parameters but only sparse outcrops occur which are not appropriate for mining

assessment of the european standard for the determination of resistance of marble to thermal and moisture cycles recommendations for improvements the bowing phenomenon is so relevant that two projects eu funded from 1999 studied it and a european standard to assess the resistance to thermal and moisture cycles influencing bowing has been recently adopted in particular according en 16306 2013 measurements of bowing and flexural strength should be performed before and at the end of the ageing cycles additional non destructive tests are recommended but are not compulsory for the standard moreover annex a of en 16306 contains guidance on the limit values for the selection of marble types suitable for outdoor uses especially facade applications eleven varieties of marble have been tested by means of this laboratory ageing test non destructive tests such as the measurements of ultrasonic pulse velocity upv adjacent grains analysis open porosity and water absorption have been executed together with the conventional flexural strength test the results obtained from image analysis on thin sections indicate that the aga index may not always be correlated with the other tests amount of bowing loss of flexural strength or loss of upv some consideration of the decrease in mechanical resistance and the bowing in relation to the variety of marble tested and the limit values indicated in annex a of en 16306 can be noted it is known that bowing and rapid strength loss occur in some varieties of marble when used as exterior cladding and other exterior applications additional conclusions have been drawn bowing and flexural strength correlate well and can be used to assess the suitability of the marble to be employed in outdoors

quality assessment of replacement stones for the cologne cathedral mineralogical and petrophysical requirements owing to its long building history different types of building stones comprised the construction of the cologne cathedral severe damage is observed on the different stones e g sandstones carbonate and volcanic rocks especially when the different stone materials neighbor the medieval drachenfels trachyte from the siebengebirge the question arises is the insufficient compatibility of the implemented building materials causatively related to the strong decay of the drachenfels trachyte the present investigations focus on the petrography and mineralogical composition of eight different stones from the cologne cathedral petrophysical data i e phase content moisture and thermal characteristics as well as strength properties are determined and discussed in correlation to each other showing that not only in terms of lithology great differences exist but also the petrophysical properties strongly diverge the ascertained parameters are discussed in view of the deterioration behavior and decay mechanisms of the different stones to evaluate the compatibility of original replacement and modern building materials the properties of the investigated stones are compared to those of drachenfels trachyte by means of constraints given in the literature besides optical properties petrophysical criteria are also defined as well as strength values it could be shown that primarily moisture properties i e capillary and sorptive water uptake water saturation drying processes and moisture dilatation can be addressed to the deterioration processes

near surface temperature cycling of stone and its implications for scales of surface deterioration abstract many previous studies into internal temperature gradients within stone have assumed smooth exponential increases and decreases in sub surface temperatures in response for example to diurnal patterns of heating and cooling and these have been used to explain phenomena such as large scale contour scaling this high resolution experimental study in which a porous limestone block was subjected to alternate surface heating and cooling using an infrared lamp demonstrates that internal temperature gradients in response to short term environmental cycles measured in minutes can in fact be complex and inconsistent results confirm the significance of very steep temperature stress gradients within the outer 10 mm or less of exposed stone below this the data indicate complex patterns of temperature reversals the amplitudes of which are attenuated with depth and which are influenced in their intensity and location by variations in the relative duration of heating and cooling phases it is suggested that the reversals might represent interference patterns between incoming and outgoing thermal waves but whatever their origin they are potentially important because they occur within the zone in which many stone decay processes especially salt weathering operate these processes invariably respond to temperature and moisture fluctuations and short term interruptions to insolation could for example trigger these fluctuations on numerous occasions over a day in particular the reversals occur at a scale that is commensurate with decay by multiple flaking and could indicate an underlying control on this previously little researched pattern of weathering in the context of this publication however the main lesson to be learned from this study is that differing scales of behaviour require different scales of enquiry

in situ annealing experiments of octachloropropane as a rock analogue kinetics and energetics of grain growth abstract two dimensional in situ observation of the change of size of individual grains of octachloropropane ocp during post deformation annealing revealed that grain boundary migration occurred to reduce the grain boundary energy within the polycrystalline aggregate studied some grains show a cyclic change in grain size others have a stable grain size while most grains were consumed and disappeared in order that the mean grain size could increase during grain coarsening some grains were dissected then coalesced amalgamated with others and their centers migrated across the aggregate the average grain size d can be expressed by d k 0 exp q rt t n where k0 is a constant q is the activation energy r is the gas constant t is the temperature t is the annealing time and n is a constant we obtained n 0 1 0 2 and q 6 2 kcal mol the driving force p is the surface energy stored at grain boundaries the driving force can be expressed as p tm where m is the constant and hence the grain growth rate d can be expressed as d p n 1 m the value of n 1 m ranges from 4 to 10

stratigraphy petrophysical characterization and 3d geological modelling of the historical quarry of nueva tabarca island western mediterranean implications on heritage conservation abstract the historical quarry of the nueva tabarca fortress mediterranean sea se of spain was developed in a complex sedimentary miocene deposit five lithostratigraphic units have been defined including different lithologies such as breccias and microconglomerates unit 1 massive and laminated lithoarenites units 1 3 and 5 calcarenites and biocalcirudites units 2 and 4 a complete stratigraphic description of this sequence has been carried out as well as the petrophysical characterization of the most significant lithologies including the analysis of rock durability as well as hydraulic and mechanical properties regarding durability the softest rocks correspond to those from the unit 4 whilst samples from units 2 and 5 are the most durable three weathering patterns were observed during the artificial ageing test according to both the velocity and intensity of the sample decay each pattern is explained according to water circulation possibility through the rock its porous system and the mechanical strength rock weathering in monuments of nueva tabarca is quantified and discussed according to the results found in the laboratory several decay forms are observed in the building stones mainly differential erosion alveolization and rounding forms both 3d photogrammetric and 3d geological model of the historical quarry were elaborated in order to quantify the extracted volume of building stones differentiating the specific quarried percentage of each lithology correlation between the results obtained in the volumetric analysis of the historical quarry and the building stones used in the monuments has been carried out 3d models were also used for determining the remaining rock volume in the current outcrops finally a set of recommendations for future conservation works of the architectural heritage are proposed after the current availability of the different rock varieties and their petrophysical behaviour

the schmidt hammer in rock material characterization the schmidt hammer provides a quick and inexpensive measure of surface hardness that is widely used for estimating the mechanical properties of rock material however a number of issues such as hammer type normalization of rebound values specimen dimensions surface smoothness weathering and moisture content and testing data reduction and analysis procedures continue to influence the consistency and reliability of the schmidt hammer test results this paper presents a a critical review of these basic issues and b the results of tests conducted on granitic rocks of various weathering grades in the light of the conclusions of this review it was found that a very good correlation exists between l and n hammer rebound values and that both hammers are fairly sensitive to the physical properties particularly to dry density though less so to effective and total porosities the n hammer producing a lesser scatter in the data proved to be more efficient than the l hammer in predicting uniaxial compressive strength and young s modulus the exponential form of the correlation curves was found to reflect microstructural changes during the course of weathering and the differences in the probing scales or mechanisms in the means of measuring these mechanical properties and could be generalized to other crystalline igneous rocks the possibility of predicting weathering grades from rebound values was also explored the changes in the rebound values during multiple impacts at a given point produced a better indication of the weathering grade than a single impact value it was concluded that increasing the impact energy and plunger tip diameter should significantly reduce the scatter in coarse grained weathered rocks and hence improve the reliability of the schmidt hammer as a rock material characterization tool

rocky coast geomorphology and erosional processes a case study along the murgia coastline south of bari apulia se italy many sites along the apulian coast se italy are composed of weathered and fractured carbonate rocks affected by intense erosion and the development of slope instabilities here coastal morphology was mostly produced by quaternary tectonics the severe and selective action of modern erosion by sea waves and locally was strongly conditioned by human influences in addition due to the carbonate nature of rock masses the role exerted by karst processes has to be considered this paper provides a critical review of the common eroding processes and factors affecting coastal morphology in a typical mediterranean coastal carbonate environment a stretch of the murgia coastline south of bari between san vito and polignano a mare made up of cliffs and shore platforms interrupted by small pocket beaches was considered for qualitative and quantitative assessment of shoreline recession the coastal stretch was monitored by means of field surveys between 1997 and 2003 furthermore a comparison of vertical aerial photographs covering the period 1966 1997 scales 1 33 000 1 10 000 and 1 5000 topographic maps scales 1 5000 year 1987 1 2000 year 1982 and archival terrestrial photographs taken since the 1930s was also employed in some zones characterised by a gently sloping shore platform a significant shoreline retreat was calculated at about 20 m in the last 100 years 0 2 myr 1 which was caused above all by human activity here in fact the presence of small ancient coastal quarries