Durability Of Stones Research Articles

Effect of multi-cycle freeze-thaw tests on the physico-mechanical and thermal properties of some highly porous natural stones

The durability of natural stone on a given project is generally quantified by evaluating its degradation ability caused by a multitude of factors. Frost action has significant effects on the fracturing and granular disintegration of the stone due to the occurrence of minor and major breakages, especially in the presence of water. It refers to more porous structure and so decrease in the strength and thermal conductivity of the mineral fabric. The aim of this study is to quantify the weathering damage of some porous natural stones caused by laboratory-based freezing-thawing cycles by means of the changes in some physico-mechanical (apparent porosity, P-wave velocity, colourimetric values, water vapour transmission rate and point load strength) and thermal (thermal conductivity) properties. For this purpose, an experimental physical weathering simulation was carried out on two carbonate and two magmatic, commercially available porous natural stone types as travertine, limestone (biocalcarenite), trachyandesite and tuff stone (ignimbrite), respectively. Laboratory studies reveal considerable variations for the trachyandesite and tuff stone with respect to changes in some intrinsic properties. The results clearly demonstrate a quite different resistance of these stones to freezing and thawing damage, and this was found to be strongly correlated with their thermal conductivity values.

Role of petrography in durability of limestone used in construction of Persepolis complex subjected to artificial accelerated ageing tests

Persepolis historical complex hosts palaces and tombs which are constructed by stone blocks. These stones suffer from various weathering. Hence, in this study, physico-mechanical properties of Persepolis stone are investigated in relation to some important weathering factors including freezing–thawing, thermal shock and salt crystallization. This study focused on role of the stone petrography on its durability against the weathering factors. Petrography studies showed that the stone is a nonporous-impermeable bioclastic-packstone which suffered significant diagenesis pressures and contain fractures filled by clay. Based on the obtained results, most of the observed deterioration for the stone is related to freezing–thawing cycles. The freezing–thawing cycles induced significant losses in the stone mechanical properties. Similar variations were recorded after the salt crystallization and thermal shock cycles, although the changes in the stone properties were not to the extent of freezing–thawing. Assessing values of decay constant (λ) and half-time (N1/2) obtained for the stone in relation to the ageing test cycles showed that freeze–thaw and thermal shock have more deteriorative effects on the stone durability than salt crystallization. It is suggested that porosity is the main factor that controls the Persepolis stone durability. Low permeability of the stone inhibits water percolation throughout the specimens, so their deterioration against salt crystallization is negligible. But in case of the freeze–thaw cycles, water uptake by clay minerals, which filled diagenesis fractures in the limestone, could be considered as the main factor for the observed deterioration during freezing–thawing. Also, effect of micro-cracks, caused by the thermal shock cycles, is the best explanation for reducing the mechanical properties of the stone.

Petrophysical-mechanical behavior of Grisolia stone found in the architectural heritage of southern Italy

Grisolia is one of the building stones most commonly found in the architectural heritage of southern Italy. Also known commercially as “gold stone” for its yellow intrusions, Grisolia was employed by the leading Calabrian schools of stonemasons, principally in the southern Italian regions of Calabria and Basilicata. It is an Upper Triassic crystalline carbonate quarried in the Verbicaro Unit on Calabria’s northern Tyrrhenian coast.
 
 Possessing petrographic, physical and mechanical properties that ensure stone strength and durability, it is a high-quality building material suitable for structural and ornamental uses. These properties can be attributed to its low open porosity and excellent hydric behavior (low capillary water absorption), as well as to its high mechanical strength and low anisotropy. These characteristics make it recommendable as a building material for both restoration and new construction.

In situ investigation of stone heritage sites for conservation purposes: a case study of the Sz\xe9kesfeh\xe9rv\xe1r Ruin Garden in Hungary

This paper demonstrates the application of in situ diagnostic tools to document stone heritage sites prior to conservation interventions using a Medieval ruin of Central Europe (Székesfehérvár, Hungary). The applied methods included lithological mapping and characterisation and mapping of decay forms as well as in situ measurements of physical parameters such as Schmidt hammer rebound, moisture content and micro-drilling resistance. The combination of these methods allowed the condition assessment of different lithotypes and demonstrated the role of micro-fabric, mineralogical composition and climatic conditions in stone durability. Differences were found in the properties and in the weathering forms of fine-grained and medium-grained porous oolitic limestone and travertine. The black crust observed in porous limestone is less prone to detachment on medium-grained oolitic limestone ashlars, while scaling was observed on fine-grained oolitic limestone blocks. The micro-drilling resistance of exposed porous limestone showed higher drilling resistance at the crust zone (upper 1–2 mm) than below, marking the upper cemented zone, while the drilling resistance of porous limestone under shelter showed an opposite trend. The shelly limestone, the sandy calcarenite and red compact limestone also showed an increase in drilling resistance at the topmost app. 2 mm zone. The applied in situ, non-invasive and micro-destructive techniques helped in the identification of endangered zones at Székesfehérvár, thus, they can provide key information on condition assessment of stones at heritage sites, where sampling is limited and preventive conservation is important.

Micro-porosity and minero-petrographic features influences on decay: Experimental data from four dimension stones

Sedimentary stones have been used since long as dimension stones, constituting the primary building material of several monumental structures all over the world. The understanding of their behaviour when exposed to weathering factors is crucial for preservation, replacement and restoration intervention. Although not directly involved with decay mechanisms, micro-pores (i.e. open pores with radius <0.1 µm) and their interconnection to the wider ones are important for air and water flow inside rocks. In fact, micro-pores are not directly the site of ice or salt crystallization, nor of oil and gas entrapment, but are the main pathway for fluids during both adsorption and evaporation processes. The study of narrow pores is therefore crucial to predict e.g. stone durability and physical properties. This study presents the study on four different sedimentary lithotypes vastly employed as dimension or ornamental stones in Italy, both sound and artificially weathered. In particular, coupled MIP and hygroscopic sorption based micro-porosimetry were used to uncover liability to relative humidity variation, in association with a thorough mineralogical characterization. The MIP intrusion pattern attained pore shapes and typology description for the different rock types; but only the hygroscopic sorption helped deciphering the on-going processes. Moreover, the coupling of petrography and petro-physical analyses (i.e. MIP and hygroscopic sorption based micro-porosimetry) pointed out that phyllosilicates have a role in decay processes of rocks due to swelling and/or suturing of the adjacent voids.

Statistical approach of the influence of petrography in mechanical properties and durability of granitic stones

The influence of petrographic features on the strength of granitic stones is a wide studied topic which finds different correlations depending on the research and the granite type. The aim of this article was to provide an accurate statistical analysis in which the amount of analysed data did not imply any doubt about the representativity of the samples and the accuracy of the results. The focused principal component analysis was used because it allows to explain a determinate property in relation to several variables. In addition, the expression of the results was done as a simple and graphical representation that allowed to interpret the results in a global way. Data of texture, mineralogy and strength of 12 granites were obtained in this study and were completed by those of more than 100 granites obtained from the literature. The durability of the twelve granite characterized was also assessed. A thermal fatigue test was carried out in 5 × 5 × 5 cm cubes revealing that the thermal expansion experimented by the different minerals was enough to produce variations in the crack network even if temperature was lower than the microfissuration threshold.

Durability assessment of Gerdoi and red travertines from Azarshahr, East Azerbaijan province, Iran

Durability is the most important characteristic of stones in sustainable architecture. Salt crystallization has been known to damage porous building stones. Gerdoi and red travertines are extensively used in new buildings in East Azerbaijan province. To this end, petrographic and physical properties, dry and saturated P-wave velocity, uniaxial compressive strength and Brazilian tensile strength were obtained for each freshly quarried stone in the laboratory. The samples were subjected to an aging test in order to examine their resistance against sodium chloride crystallization. Water saturated-to-dry strength ratio (a crude immediate estimator) and a decay function model were applied to assess durability of stones. Gerdoi travertine consists of alternation of densely packed layers (laminated fabric) while red travertine exhibits massive fabric. Albeit Gerdoi travertine has laminated fabric, it shows higher initial strength, P-wave velocity and lower effective porosity and water absorption than Gerdoi travertine. The results showed that a crude immediate estimator is not a sensitive indicator for estimating durability of travertine stones. P-wave velocity, uniaxial compressive strength and Brazilian tensile strength decreased with increasing number of salt cycles. A decay function model confirmed that the integrity loss was higher in red travertine in comparison with Gerdoi travertine. It was found that the integrity loss of both stones based on Brazilian tensile strength is highest than those based on uniaxial compressive strength and P-wave velocity.

Nano-level management of calcium silicate-hydrate nanoparticles structure formation during portland cement hydration process

Cement-containing building materials durability depends both on the original clinker composition and on the structure of hydrated portland cement compositions on micro and nanoscales. To calculate structural parameters of silicate-hydrate calcium nanoparticles during portland cement hydration process, the researchers applied the method of small-angle neutron scattering which included distribution of nanoparticles in size, medium nanoparticles radius, fractal dimension. Modifying nanoparticles blending with portland cement composition affects structural parameters of silicate-hydrate calcium nanoparticles. The authors used complex modifying nanoparticles in this study. Nanoparticle composition included a component that served as a filler and a chemically active component that was used as a modifier. The first component was a mixture of alpha oxide aluminum, gamma oxide aluminum and carbonate sludge. The second component presented a mixture of alumoalkaline sludge with alumocalcite sludge. These sludges were of technogenic origin. The research showed that application of complex nanoagents made it possible to control process of silicate-hydrate calcium nanoparticles structure formation, and, as the result, to influence durability of cement stone.

Effect of additives on hydration and hardening of magnesia compositions

The article is devoted to the investigation of the influence of technological factors on the hydration and hardening of magnesia compositions. The objective – is investigation magnesia compositions with different additives. Factors which impact activity of magnesium oxide in compositions of different structure are investigated. Influence of liquid density on hardening of magnesium bindings is defined. Processes of hydration and hardening of magnesium bindings with participation of minerals – silicates are investigated. It is revealed that the addition of semi-aquatic calcium sulfate contributes to the hardening of magnesia binders. Defined effect of concentration calcium sulfate hemihydrate to the hardening of caustic magnesite. Here are proposed structures of sulphomagnesium compositions containing technogenic components. It revealed a beneficial effect on the hardening of ferrous component of the mixed magnesia binder. Composition of hydration products of magnesium binding with participation of ferriferous minerals is presented. Transformations of phases at hydration of magnesium binding are revealed. Influence of structure of bindings on transformations of hydrates is established. Results of research of magnesia bindings of long hardening are given. It is shown that the durability of stone of bindings is provided with dense structure of hydrates. In researches are used X – Ray and thermal methods, electronic microscopy.

Influence of physical and mechanical properties on the durability of limestone subjected to freeze-thaw cycles

The frost sensitivity of five French limestones (Massangis (MA), Lens (LS), Savonnières (SA), Saint-Maximin (MX) and Migné (MI)), with different physical and mechanical properties, was studied. The total porosity ranges from 10% to 35% and the uniaxial compressive strength ranges between 10 MPa and 60 MPa. The freeze-thaw tests were applied on the samples saturated in natural condition. During freeze-thaw cycles we recorded the evolution of temperature and volumetric strain of a specimen for each stone and after the freeze-thaw cycles, the weathering evolution in stone samples was monitored by measurement of different physical and mechanical parameters (porosity, P-wave velocity, fracture toughness, compressive strength and elastic static modulus). Two behaviors were observed: a volumetric expansion during freezing phase accompanied by a very important damage from the first cycle until the failure of specimen for MI and MX stones, and a volumetric contraction accompanied with a light damage for the high number of freeze-thaw cycle in the cases of MA, LS and SA. Following the freeze–thaw tests, the durability of stones was evaluated using a decay function model. The decay constant values determined from the evolution of P-wave velocity were correlated with different fresh stone properties. Contrary to generally accepted ideas, the correlation coefficients between the decay constant and total porosity or degree of saturation are very low. Porosity in natural condition seems to have the strongest influence on the decay constant. However, its negative impact can be offset by a bigger part of trapped porosity. The results indicate that it is possible to predict the frost damage of the stones, with a better level of confidence, from the ratio of the volume fraction of water to that of air rather than from only the total porosity or degree of saturation.

PECULIAR PROPERTIES OF STRUCTURAL FORMATION OF CEMENT COMPOSITES IN THE PRESENCE OF FUELEROID TYPE CARBON NANOPARTICLES

The paper deals with the application of fulleroid carbon nanoparticles (FCN) for the cement com-posites modification. In particular, the thermokinetic analysis was performed to assess the change in the rate and completeness of the cement hydration when the nanomodifier was introduced into it. The study of exothermic heterogeneous interactions and thermal effects in the binder - water - nanomodifier system allows one to estimate the hydration rate and depth and to assess the degree of nanomodifier’s influence. The conducted studies revealed the increase in the hydration temperature when carbon nanoparticles are introduced into the cement dough, while the induction period is prolonged, that indicates a more complete course of the reactions. It is confirmed by the results of qualitative X-ray structural analysis. The dynamics of decrease in calcium silicate peaks characterizes the completeness of hydration and binding of portlandite, that explains the increase in the modified cement stone strength. Microstructural analysis allows to detect the structure characteristic of control samples with a large number of large chaotically located crystals, the bulk of which is formed on the first day of solidification. Under the same conditions, the modification of the cement stone contributes to the creation of the more dense spatial structure consisting of small crystalline hydrate formations. All that process positively influences the formation of the rigid matrix with a smaller number of pores, which determines the in-crease in strength and durability of cement stone and concrete on its basis.

STRUCTURE FORMATION PROCESS OF HYDRATED PORTLAND CEMENT COMPOSITIONS: NANOSCALE LEVEL CONTROL

Durability of cement-like construction materials, as well as durability of cement stone, depends on their humidity resistance, frost resistance, corrosion resistance. All of these properties depend not only on the composition of the original clinker, but also on structural organization at micro-and nanoscale level of hydrated portland cement compositions. In this research the authors used the method of small-angle neutron scattering to define structural parameters of hydrated portland cement compositions on nanoscale level, distribution of calcium hydrate silicate nanoparticles in size, medium nanoparticles radius, fractal dimension. It is shown, that introduction of modifying nanoadditives into portland cement compositions affects structural parameters of a cement stone. The following nanoadditives were used: of artificial (alpha aluminium oxide, gamma aluminum oxide) and of anthropogenic (carbonate and alumo-alkaline sludges) origin, as well as integrated nanoadditives containing surfactants. The change in structural parameters of portland cement compositions with nanoadditives in the process of hydration is investigated. It is shown that use of nanoadditives allows to control the process of forming the structure of hydrated portland cement composition on the nanoscale level, directly affect the values of structural parameters and, as a result, modify properties of cement stone.

Modification of water transport properties of porous building stones caused by polymerization of silicon-based consolidation products

Abstract This work studies the polymerization process of four different commercially available silicon-based polymers and their consequent effect on surface tension and water transport properties of natural stones used in architectural monuments, essential for modeling and predicting the durability of natural stones against weathering action of aqueous solutions. The four products studied consisted of two ethyl-silicate based materials, an alkyl-alkoxy siloxane oligomer with hydrophobic agents and finally, a silane/siloxane emulsion. In all cases, the morphology of the amorphous material deposited into the pore network of stones was examined by electron microscopy (SEM). The polymerization process was studied by infrared spectroscopy (FTIR) on both inert surface and porous stone substrate. The treated stone specimens were further tested after polymerization in terms of determination and comparison of water absorption coefficient, open porosity, pore size distribution (mercury intrusion porosimetry) and surface tension (contact angle measurements) properties. According to the analysis, the modification of the wetting properties of the stone surface should be related rather with the chemistry than the microstructure of the xerogels alone.

RECYCLING OF AURIFEROUS ORE FLOTATION TAILINGS IN SLAG-ALKALINE CEMENT

Research analysis aimed at stabilizing processes in industrial waste and other, similar hazardous ion containing materials, shows that these materials can be successfully stabilized, if they are bound as a mineral component in cement. Considering that auriferous ore flotation waste contains heavy metals that are useless for any production and accumulated in dumps, storages and sumps, this impairs the ecology of the country. This is why current study is conducted on recycling of auriferous ore flotation tailings by binding it as a cement component, which is also can be one of its effective applications. For heavy metal bonds stability evaluation in the composition of the cement matrix, the method of leaching elements by atomic spectroscopy was applied. According to the research it was found that application of slag-alkaline viscid systems for recycling of auriferous ore dump flotation tailings provides considerable advantages over traditional Portland cement systems based on PC I-500. It was shown that along with the physical blocking in the artificial stone matrix, based on slag-alkaline viscid systems, elements of heavy metals were also bound chemically as a part of structure-forming compounds. In this regard use of auriferous ore dump flotation tailings (10…30 %) in the compound of slag-alkaline cement results in the prolonged solidification and provides the same level of cement stone durability as the check sample compound.

Ten years of natural ageing of calcareous stones

In the recent years, as aesthetic criteria are predominant over structural criteria and the knowledge of stone materials is considered negligible, sometimes a stone is used on a building façade that, after a few years, shows structural problems. Decreasing decay resistance, in fact, can show itself by means of evident signals such as fractures and bowing that can compromise a building's structural stability. In this work, nine different kinds of calcareous stone slabs exposed for ten years to natural weathering in Turin (Northern Italy) have been studied. Petrographic characteristics and an enhanced petrographic Analysis of Adjacent Grains (AGA) were compared with the physical and mechanical properties of slabs exposed. Stone durability was detected by means of the following test methods: Ultrasonic Pulse Velocity (UPV), water absorption, superficial water absorption by means of a contact sponge, flexural strength, bowing measurements and image analysis. From the comparison of the results obtained to detect the decay with the different techniques, it is possible to assert that the UPV measurement best correlates with flexural strength. After ten years of natural weathering, the decrease of mechanical resistance of calcitic stones with similar grain size is inversely proportional to the value of AGA. The same tests are performed after various thermal and moisture cycles, according the recent EN 16306 European Standard. Comparison of natural weathering and artificial ageing, by means of image analysis, suggests that the natural external factors cause different types and degrees of porosity than artificial ageing.

Evaluation of the durability of Gerdoee travertine after freeze–thaw cycles in fresh water and sodium sulfate solution by decay function models

The reduced durability and service life of stones subjected to freeze–thaw action are significant and ongoing problems in stones used for commercial purposes such as building stones. Consequently, evaluating the durability of building stones subjected to freeze–thaw action is important for selecting of an appropriate stone for outdoor applications in cold climatic conditions, which involve excessive freeze–thaw cycles. In this research, the durability of Gerdoee travertine (northwest of Iran), after freeze–thaw cycles in fresh water and sodium sulfate solution (Na2SO4), was evaluated using its mechanical properties as well as decay constant (λ) and half-time (N1/2) parameters. For this, freeze–thaw tests in fresh water and sodium sulfate solution were carried out up to 60cycles, and the uniaxial compressive strength, Brazilian tensile strength, point load strength and ultrasonic wave velocity (quantifying by P-wave velocity) of the travertine were determined after every 10cycles. Finally, regression models were developed between the measured mechanical properties and various cycles of tests. The models postulate a first order process, and provide meaningful parameters of decay constant (λ) and half-time (N1/2) for the integrity loss of travertine's mechanical properties, and thus its durability, after freeze–thaw action. Using data analysis, the variation in the travertine's mechanical properties and their decay constant (λ) and half-time (N1/2) show that the travertine's durability after the freeze–thaw action in fresh water and sodium sulfate solution was different. Further, it was found that the effect of freeze–thaw action on the travertine's durability was more severe in sodium sulfate solution as compared with fresh water.

Uv Ink-Jet printability and durability of stone and foil

The use of ultraviolet (UV) printing technology has impacted printing industry in last years due to its applicability on many different »absorptive« as well as »non-absorptive« printing materials. The printability of building materials and recycled foils is relatively unknown. For primary building materials like stones, functionality can be explored with the use of UV printing technology; increased visual, informative effect or even “creative printing” of buildings. Also several aspects of recycled foils reusability as a printing material could be find (printed packaging material or also like secondary building materials). In the present study, printability of the stone and recycled foil and durability of UV prints was explored by means of macroscopically and microscopically characterization. Results indicate that higher print quality can be achieved on polished stone and on coated foil, which surfaces have higher smoothness. Durability of UV prints at freezing is higher at unpolished stone and coated foil that is at materials with the higher surface energy.

Porosity as key factor in the durability of two historical building stones: Neapolitan Yellow Tuff and Vicenza Stone

Porosity plays a decisive role in decay processes of stones, as the pore network allows the water penetration responsible for the several physical and chemical deterioration processes affecting stone materials. In this paper two stones (with porosity from high to medium) used in Naples and Vicenza architectures have been considered to investigate the effects produced by the application of an ethyl silicate consolidant and an anti-swelling protective agent on pore space and therefore on stone durability.A deep characterization of the pore system has been carried out as considered crucial to evaluate the effectiveness of conservation treatments and their performance through time. To this purpose, petrophysical and physico-mechanical measurements have been carried out before and after aging tests, on both untreated and treated stones.Conservation treatments, strongly affecting pore size distribution and the behavior towards water absorption, do not always improve the durability of stone, especially in Neapolitan Yellow Tuff (herafter NYT) where a set of meso-macropores was totally annealed as well as a relevant portion of ultramacropores. Such treatments favor the persistence of water in NYT rock structure still after a long time, further contributing to a fast decay of this stone after aging tests. By contrast, treatments in Vicenza Stone (hereafter VS) prevailingly occlude micro- and mesopores and only slightly affect larger pores thus again favoring the flow rate during water desorption test. Moreover, the increase of the average pore radii after treatments also improves the features of this stone that accounts for almost negligible effects after accelerated aging tests.

Fuzzy-Interaction Matrices Method as a New Approach for Evaluating the Durability of Building Stone

The Rock Engineering System (RES) has been widespread among the geologists as an analytical method of evaluation of complicated engineering processes. In this study, fuzzy mathematics is used in the coding of the matrix and in calculating of the weight of these parameters (rock engineering parameters). A new system suggested in this study, Fuzzy-RES, is used to estimate durability of the volcanic rocks stonewalls moderated landscape built in 1970 in Karadeniz Technical University (KTU), Trabzon NE Turkey. The meaningful statically relationships between fuzzy durability values obtained using this new method for the samples investigated and rock durability indicators.

Petrography, mineralogy, chemical and technical properties of the building stone of ostuni cathedral (Italy): Inferences on diagnostics and conservation

Ostuni Cathedral represents an outstanding example of the monumental sacred architecture spread in Apulia (southern Italy) during the Middle Ages. The church dates back to the 15 th century and combines the local Romanesque tradition with Gothic stylistic features and elements of Dalmatian, Venetian and Arabic architecture. Between 2006 and 2007, a conservative restoration was carried out on the Cathedral. The operations mainly concerned the masonry, which is built of a local stone material known as “Pietra gentile”, a soft and porous calcarenite with an excellent workability and carvability. This research aims at characterizing the stone used in the monument and its state of conservation. For this goal, on-site macroscopic observations were integrated with sample analyses by means of optical microscopy, X-ray powder diffraction and scanning electron microscopy equipped with microanalysis. In this way, the petrographic classification of the used lithotype and the chemico-mineralogical characterization of its alteration products were carried out. Finally, structural diagnostics of the masonry was performed, through on-site non-destructive ultrasonic and sclerometric tests. The results presented allow evaluating, only few years after the latest restorations, the weathering kinetics and durability of the monumental stone, with a particular highlight on its short-term modifications. The main alterations detected, i.e. black crusts, salt crusts, oxalate patinas and discolorations, are produced by cyclic weathering or previous conservative treatments; moreover, several patterns of physical decay are observable, alveolization and differential erosion principally, which highly affect the technical performance of the stone. These data supply further information about a material that has been studied only recently in archaeometry, although very significant in Apulia from a cultural point of view.