Stone Grains Research Articles

КАМЕННЫЕ ПЕСТЫ И ЗЕРНОТЕРКИ НА КОМПЛЕКСЕ АРХЕОЛОГИЧЕСКИХ ПАМЯТНИКОВ ТОРОПОВО-7 В КУЗНЕЦКОМ ПРИСАЛАИРЬЕ

The article publishes and examines the archaeological collection of stone objects found during excavations at the Toropovo-7 archaeological site complex in the Kasma River valley in the Kuznetsk Prizalairye. The archaeological objects under investigation have been found in different excavations, which are dated to two chronological periods of the Late Bronze and Developed Middle Ages and correlate with the circle of antiquities of the Irmen and Shandin archaeological culture. The stone pestles and grain grinders found are indirect evidence of agriculture among the population who built this site. The grain grinders found are of the “saddleshaped” type, which were used before the advent of millstones. The studied collection of finds of primitive stone grain grinders and pestles allows us to raise the question of the emergence of agriculture during the Late Bronze Age and conclude that the population of the developed Middle Ages has agriculture in the valley of the middle reaches of the river Kasma.

An efficient microbial sealing of rock weathering cracks using bio-carbonation of reactive magnesia cement

Bio-carbonation of reactive magnesia cement (RMC) was proposed as a promising strategy to stabilize the weathered stone grains for the efficient sealing of rock weathering cracks near surface. The physical and mechanical properties of the sandstone grains stabilized by bio-carbonation of RMC was first investigated to verify the feasibility of applying the method to the rock weathering cracks when subjected to the condition of compression failure. Except for initial water content, RMC content and urea concentration, two new effects including bacteria concentration and bacteria solution composition on the underlying stabilization mechanism were systematically studied. The experimental results showed that bio-carbonation of RMC can effectively stabilize the sandstone grains. The highest unconfined compressive strength (UCS) of bio-carbonated sample was up to 5.5 MPa, which was 7.8 times higher than that of the sample stabilized by RMC hydration only. UCS increased as the RMC content and bacteria concentration increase, while the effects of initial water content and urea concentration were opposite. The dry density, resistance of water absorption, electrical resistivity and P-wave velocity were in proportion to the UCS. The effect of bacteria solution composition indicated that the well stabilization performance can be attributed to the coupling effect of the biomolecules and bacteria. Biomolecules-induced amorphous brucite can form a dense structure to fill the pore spaces. Bacteria-induced hydrated magnesium carbonates (HMCs) can form a stable spatial network structure with high cementation strength. The bacteria and biomolecules inhibited the air-based carbonation but facilitated the bacteria-based bio-carbonation and made the microstructure denser. A better bio-carbonation effect and stabilization performance can be obtained by increasing bacteria activity, such as increasing bacteria concentration or using low concentration of urea.

Pottery vessels from a collective burial in the mound of the Pazyryk Culture (Northern Altai)

In one of the barrows examined in 2007 at the site of Choburak-II (the territory of the Northern Altai), an in-trusive, and not quite ordinary, a collective burial of people was found. Accompanying burials of two horses were also recorded there and a variety of artefacts was found (a fragment of a stone grain grinder, elements of horse harness, miniature knives made of non-ferrous metal, a dagger, a chisel, a quiver hook, fragments of gold foil from clothing decoration and other items). The recovered materials made it possible to attribute the excavated burial site to the Pazyryk Culture and to carry out its dating, including the radiocarbon method. In this publication, a special attention is given to the pottery finds. Two vessels appeared to be severely damaged, and to determine their parameters it was necessary to use the bespoke technique of computer-aided restoration based on photo-grammetry and aimed at obtaining the most probable shape of these ancient containers. In this respect, an algo-rithm, being tested by the authors, of modern demonstration in publications of the category of products in question was implemented. Based on the reconstructions performed in the paper, the restored dimensions of the pottery vessels are given, as well as their closest analogies. The third pot (of a closed jar shape with well-marked han-dles) was found intact. It reflects a different cultural tradition. Such products are very rare in the Altai Mountains. However, they are found in the neighboring and somewhat remote territories. This circumstance influenced the in-terpretation of the recorded situation. Pottery ware is an important archaeological source. Unfortunately, it has not yet become a separate research area in the study of the Pazyryk Culture. It is hoped that the developments of the authors of the paper will contribute to the research. The specific nature of this additional burial of the deceased person is noted. The investigated archaeological site to a certain extent may reflect the processes of interaction of the Pazyryk popula-tion with their northern neighbors. The body of the considered data complements the content and features of the culture of the Altai population of the Scythian-Saka period.

Засорение и загрязнение щебеночного балласта при эксплуатации железнодорожного пути

Purpose: Determination of legitimacies of clogging, pollution for broken stone ballast, perceiving vibrodynamic load from a rolling stock, as well as of the ballast life. Methods: Theoretical and empirical research methods are used in the study. Theoretical methods are based on the analysis of known models describing broken stone degradation processes during railway track exploitation, and empirical methods — on the pursued experiments and trials. The identification of the legitimacies for pollutants and clogs accumulation in broken stone ballast was based on the results of dynamic bench tests and laboratory determination of broken stone grain composition removed from ballast layer of exploited railway track with various tonnage workout. The methods of statistical processing of test results and regression analysis were used in the study. Results: According to the statistical processing of test results and laboratory determinations of broken stone grain composition, functional dependencies were established for the accumulation in broken stone ballast of the products of own crushing, abrasive wear as well as of external pollution, depending on broken stone initial physical and mechanical properties, railway track exploitation conditions and the system of its maintenance. Mathematical model for the prediction of broken stone ballast life depending on railway track section exploitation conditions was developed in the study. Practical significance: The results of the study make it possible to prognose broken stone ballast life from the condition of its maximally acceptable pollution and clogging and also to plan reasonably railway track maintenance work.

An investigation of the effect of thermoplastic additives in asphalt concrete mixtures on the properties of different types of asphalt concrete

The effect of modification of asphalt concrete mixtures of different grain sizes with “Ric-Polycell” (Ukraine) and “Duroflex®-SMA” thermoplastic polymers (Germany), which were added directly to the asphalt mixer during their preparation, on the properties of asphalt concrete was studied. It is confirmed that it is more expedient to use stone mastic asphalt concretes with a larger size of mineral crushed stone grains on high-traffic roads, as they are more rutting-resistant compared to asphalt concretes with smaller size and content of crushed stone grains. The effect of the temperature of preparation and thermostating of asphalt concrete mixtures modified with the investigated thermoplastics on the compressive strength of asphalt concrete at a temperature of 50 °С, which were made of the studied mixtures, was investigated. It was found that the maximum possible temperatures of preparation and thermostating of asphalt concrete mixes provide a more complete modification. The effect of the content of thermoplastic polymers in the composition of asphalt concrete mixtures on the properties and rutting resistance of fine-grained asphalt concrete, as well as stone mastic asphalt concrete, was studied. It was found that adding the “Ric-Polycell” polymer in the amount of 1.5 % and 3 % by weight of bitumen in the composition of the studied asphalt mixtures in the asphalt mixer during their preparation increases the rutting resistance of asphalt concrete under the studied conditions by 2.52–3.86 times. Modification of asphalt concrete mixtures with the “Duroflex®-SMA” additive in the amount of 0.3 % and 0.6 % by weight of the aggregate by a similar technology also allows increasing the rutting resistance of the obtained asphalt concrete by 1.86–3.16 times. Using these modifiers in the future will have a positive effect on the service life of the entire pavement structure

Метод оценки коэффициента формы зерен щебня, применяемого в балластном слое железнодорожного пути

A decrease in the strength properties of crushed stone in combination with an increase in its contamination during tonnage operation reduces the load-bearing capacity of the ballast layer and intensification of the accumulation of residual deformations of the track. The strength properties of crushed stone ballast depend on the shape (rolling edges) of crushed stone grains. The paper discusses the theoretical and practical foundations for determining the shape of crushed stone ballast grains. As an indicator characterizing the shape of crushed stone grains, it is proposed to use the grain shape coefficient indicator. The grain shape coefficient refers to the ratio of the actual specific surface of the grain to the specific surface of a perfectly round particle of the same volume. The paper proposes a method for determining the specific surface based on the Kozeni-Karman theory of the flow of a liquid or gas through a granular layer and the equation relating the water permeability of a porous medium to its specific surface. The basic design of the device for the specific surface area of crushed stone ballast grains is presented. The article describes and presents the results of the experiment on calibration of the device, establishes recommended and boundary conditions for its use, as well as the results of the experiment to determine the specific surface in experiments with crushed stone of category II according to GOST 7392-2014 in comparison with an alternative method of measuring the specific surface of crushed stone grains.

НОВИЙ ПІДХІД ДО РЕМОНТУ НЕЖОРСТКИХ ДОРОЖНІХ ОДЯГІВ ПЕРЕХІДНОГО ТИПУ

Earlier, due to insufficient financing of the road industry, funds were allocated on a leftover basis for the repair of local roads, over time the condition of these roads has deteriorated significantly. So, given the ramified network of local roads, the issue of restoring the condition of local roads is a very urgent problem. Conducted exploratory studies of the application of stabilization technology to restore the condition of local roads show that this technology is progressive, since it allows reusing existing materials while ensuring the required strength of the pavement. However, design engineers rarely use this technology, probably due to insufficient research on this approach. The task is to investigate the possibility of using stabilization technology with the use of crushed stone layers of different composition and their maximum reuse, when repairing transitional pavements. Analysis shows that there are many cases where transitional structures have significant heterogeneity and low strength. This is formed due to a weak crushed stone base and waterlogging of the subgrade soils. Over time, soil particles penetrate into the crushed stone layer and weaken the contacts between the crushed stones, as a result of which rut, pits and subsidence form on the road, which significantly complicates the movement of vehicles. Studies of the composition of existing bases show that if in a dispersed system the amount of crushed stone grains is more than 50% by volume, then a contact frame is formed in the material. Intergranular voids are filled with soil or fine aggregate, processing with such a small amount of a mineral binder (cement or lime) allows it to be significantly strengthened, as well as to create bonds between the soil and crushed stone. Modern self-propelled soil mixing machines (recycler-stabilizer) allow in one pass to perform milling (loosening) and mixing of materials of existing transitional pavement to a depth of 40 cm. Taking into account the dependence of the distribution of normal stress in a two-layer half-space, it can be seen that stabilization of the foundation to a depth of 40 cm will allow the subgrade soil to work without exceeding the permissible shear deformations. The construction of the experimental site in Berezivka, Odessa region, confirmed the assumptions about the effectiveness of the proposed solution to restore the strength of transitional pavement. Keywords: non-rigid pavement of transition type, modulus of elasticity, stabilization, rubble, soil, cold recycling.

An Inorganic Magnesium-based Consolidant for the Consolidation of Silica Sand (A Substitute for Weathered Sandstone): A Preliminary Exploration

ABSTRACT Sandstone is a common sedimentary rock that is easily carved due to its weakly cemented fine grains and relatively low strength. Therefore, numerous large-scale grottoes in China are made of sandstone. However, these sandstone cultural heritage structures are often seriously damaged due to temperature and humidity changes, air pollution, biodeterioration, and repeated dissolution and crystallization of soluble salts. In general, it is imperative that a consolidant capable of providing cohesion by infilling pores between the stone grains is synthesized. In recent years, it has been reported that using organic consolidation materials for sandstone protection comes with various negative effects, such as a short lifetime, poor compatibility, and preservation damage. Using inorganic consolidation materials to protect sandstone seems to be one of the research trends for the future. Herein, this paper introduces a permeable, inorganic magnesium-based material (MMH solution) for silica sand consolidation. To assess this consolidant, the paper investigates the influence of varying molar ratios of MgO:MgCl2·6H2O:H2O on properties such as penetration depth, consolidation weight, colour variation, and compressive strength. The results demonstrate that the molar ratios of MgO:MgCl2·6H2O:H2O can significantly affect the consolidation performance. Additionally, it is believed that the MMH solution of MgO:MgCl2·6H2O:H2O = 5:1:16 can be successfully used for the consolidation of silica sand, as the cubic specimens’ surface micrographs show good compatibility between the consolidation product and sand grains. Experiments (i.e. weight loss rate and mineralogical compositions analysis) are performed to evaluate the cubic specimens’ water resistance properties after being immersed in water. Furthermore, the consolidation material’s failure mechanism as a self-sacrificing material is preliminarily analyzed. Results indicate that MMH solution is a promising conservation material that shows great potential for consolidating severely weathered sandstone.

Alkoxysilane-based sols for consolidation of carbonate stones: Impact of the carbonate medium in the sol-gel processes

Abstract This investigation addresses the impact of the carbonate medium in the sol-gel processes of stone consolidants and the possible detrimental effects in practical applications. The results demonstrate that the carbonate medium influences the sol-gel paths and that silicate materials developed in the carbonate stone pores can be structurally different from those formed within “inert” conditions, as a consequence of the combined effect of pH and ionic interactions between Si-O− and Ca2+. The trend is that the formation of the silica films around stone grains (silica growth mechanism through typical condensation) evolves into less advantageous growth processes (Oswald ripening and/or coagulation), resulting in a material that is unlikely to consolidate carbonate stone. Furthermore, pH measurements and different ratios between NMR Q3:Q4 species along stone depth showed that this effect seems more important at greater depths. The results underline the importance of the carbonate medium in the failure of alkoxysilane-based treatments and, accordingly, that an efficient design and development of new alkoxysilane-based consolidants must consider this effect.

Modelling of motorway bridge spans under modernization with consideration of rheological properties of the materials

The paper presents a computer modelling technique for modernization of bridgework operations by building-up a mounted reinforced concrete slab. It implements the technique of the evolutionary transformation of a model in one calculation cycle with redistribution of forces between the elements of the built-up section, and consideration of the impact of elastoplastic and rheological properties of the materials. Consideration of the concrete creep implies the application of the generalized kinetic curve of prolonged deformation and phenomenological deformation development equations based on the colloid-chemical concept of the prolonged concrete deformation mechanism. The creep control was implemented through new structural coefficients which determined the structure of matrix interlayers between the sand grains, and mortar between the crushed stone grains. The technique proposed was realized in the program complex “LIRA-SAPR” based on the building information modelling (BIM) and the finite element method (FEM). The multistage modelling technique was shown by an example of calculation of a motorway bridge slab span within the transport structures under modernization along the Lev Landau Avenue in Kharkiv (Ukraine).

ВЛИЯНИЕ ФОРМЫ ЗЕРЕН ЩЕБЕНОЧНОГО БАЛЛАСТА НА ЕГО ПРОЧНОСТНЫЕ СВОЙСТВА

Objective: To assess the influence of grain shape in railroad ballast, taking dynamic impact of moving trains, on its strength properties – unit bite and the angle of internal friction. Methods: Laboratory compression tests of 25–60 mm fracture ballast stone were carried out with different shapes of grains in a triaxial compression tool by the method of consolidated R-tests. Results: The values of ballast stone unit bite and the angle of internal friction with a different degree of grain rounding were obtained. Test findings demonstrate major effect of ballast stone grain shape on its unit bite, which reduced up to 60–70 % in certain trials depending on the degree of grain rounding. Practical importance: New results were obtained which make it possible to specify the amount of reclaimed ballast, returned to track after fine cleaning, depending on the degree of grain rounding.

Specifics of Studying Crushability of Construction Rocks

Objectives: The existing techniques of studying crushability of rocks are based on the determination of power consumption and aggregate size of the resulting products. Given that during disintegration of the construction rocks it is required to retain rock strength in the crushed stone grains, to improve methodology for crushability assessing is an urgent task. Method: When choosing a method to study crushability of rocks it should be considered that the processes of disintegration in various crushing machines have different mechanisms of action, the most accurate forecast figures are provided by the technique using the destruction mechanism similar to an industrial crusher. A deformation field is created in the entire volume of the body under the load, which leads to a change in the structure and strength of the products formed. In this regard, the strength of crushed stone grains being a final product of disintegration is introduced as an additional indicator that characterizes crushability of rocks. Findings: The article presents the results of studying crushability of construction rocks by different methods. It was found that porosity, particle size, grain shape and loading effort application rate are the factors affecting the strength of crushed stone grains. Mechanical stresses undergone by the rocks during blasting and disintegration result in increased porosity and, consequently, reduce strength. Theoretical dependence of increased strength while reducing the fraction size appears for gabbro-diabases being homogeneous in texture. For granites that are non-uniform in composition and texture there is no unique relationship between the strength and the fraction size. Increased grain cubicity of crushed stone enhances its strength. The study of the crushing kinetics revealed that with decreased loading rate the strength of granite crushed stone having high porosity is reduced, while the strength of the low-porous crushed stone made of gabbro-diabase remains practically unchanged. When choosing a crushing method, either shock or static one, it is necessary to take into account, first, the size of the crushed objects and, second, mineral composition and texture-structural features of the rocks. Improvements: The results obtained are of practical value in selecting rational processing technology and relevant equipment, as well as in the crushing process management to reduce energy costs and improve product quality.

RATIONALE FOR CHOOSING THE CHANGE MODEL OF THE DIELECTRIC PROPERTIES OF DISCONTINUOUS SYSTEMS

Purpose. The article deals with the insulation resistance of the track circuit as one of the parameters that affect the operating performance of the railway transport. To reduce the influence of the insulation resistance on the operation modes of the track circuits and the performance indicators of railway transport it is assumed to study the influence of crushed stone treatment on the value of dielectric permeability of the ballast bed. Methodology. The influence of material type for the surface treatment of crushed stone on the value of the dielectric permeability was assessed on the basis of the physical nature determination of the relative dielectric permeability. Determination of the relative dielectric permeability of granular media can only be indirect, as a consequence of incomplete adjoining of crushed stone grains and uncertainty of the pore volume. Thus, the calculations were performed by comparing the measured capacity for a medium with the known with measured medium capacity, for which it is necessary to define. That is, the more the measured capacity is changed, the more changes the dielectric permeability of the medium. Findings. Sleepers and ballast significantly change their electrical conductivity depending on the presence of moisture, ambient temperature changes, the presence of pollutants and other factors. The article analyzes the existing models to describe the dielectric properties of such systems. It has been established that coating the crushed stone ballast with organic substances influences the value of its relative dielectric permeability. The greatest effect of reducing this value is observed for the coatings based on rosin mixture and silicone. Originality. Authors proposed original method of dielectric properties increase of the permanent way by grains’ coating with nonwettable substances, on the surface of which is not formed a water film. Practical value. The article shows the possibility of minimizing the negative influence of reducing the isolation with maximum its elimination. It is proposed the solution of actual problem by eliminating the influence of insulation resistance on the modes of track circuits operation, which will eliminate the part of causes of the failure of signaling devices and reduce the number of cases of «false business».

Exploration Results of Applying Limestone Powder in Crushed-Stone-Sand Mixtures for Road Pavement Layers

This paper presents results of exploration related to C2 and C6 crushed-stone-and-sand ready mixtures strengthened with limestone powder used in road pavement layers. Limestone powder is an industrial waste, which in Ararat region is in big volumes. The samples were taken composed of different fractions of crushed-stone and two types of sand produced from crushed basalt and crushed gravel, and were tested. The composition of ready mixtures meets the requirements of corresponding standard on grain size. To these mixtures limestone powder was added of the percentage range 0-30% of the mixture mass. The main purposes of experimental exploration were to determine the influence of different percentages of limestone powder on compression strength of crushed-stone-and-sand ready mixtures and optimal content of powder. The change of the influence grade was studied by applying different types of sands. Three cylindrical samples were made for each percentage of limestone powder according to a standard method. Compressive strengths of samples have been determined. It was concluded, that the applying limestone powder in C2 and C6 ready mixtures contributes to the cohesion of stone grains as well as to obtaining high indicators of compaction in road pavement layers. The received results allow to arrive to a conclusion that applying limestone powder according to the optimal range distinctly increases the strength characteristics of crushed-stone-sand ready mixtures which in tur contributes the effective implementation of the compacting process. Especially the influence grade is considerable in C6 ready mixtures containing a large amount of crushed stone, as well as in mixtures using sands with smaller fineness modulus.

Adsorption of natural surfactants present in sea waters at surfaces of minerals: contact angle measurements

The wetting properties of solid mineral samples (by contact angles) in original surfactant-containing sea water (Gulf of Gdansk, Baltic) were characterised under laboratory conditions on a large set (31 samples) of well-classified stones of diverse hydrophobicity using the sessile drop (ADSA-P approach), captive bubble and inclined plate methods. An experimental relation between the static contact * The study was supported by grants BW/5200-5-0214-06 and 828/BW/GU/2008 (provided to K.B-Sz.) from the Polish Council for Scientific Research (KBN), and carried out in part within the framework of the scientific activity of the University of Gdansk (supported from DS/5200-4-0024-09). The complete text of the paper is available at http://www.iopan.gda.pl/oceanologia/ 378 A. Mazurek, S. J. Pogorzelski, K. Boniewicz-Szmyt angle θeq and stone density ρ was obtained in the form θeq = Bρ + C, where B = 12.23± 0.92, C = −(19.17± 0.77), and r = 0.92. The histogram of θeq distribution for polished stone plates exhibited a multimodal feature indicating that the most abundant solid materials (hydrophilic in nature) have contact angles θeq = 7.2, 10.7, 15.7 and 19.2◦, which appear to be applicable to unspecified field stones as well. The contact angle, a pH-dependent quantity, appears to be a sensitive measure of stone grain size, e.g. granite. The captive bubble method gives reproducible results in studies of porous and highly hydrophilic surfaces such as stones and wood. The authors consider the adsorption of natural sea water surfactants on stone surfaces to be the process responsible for contact angle hysteresis. In the model, an equation was derived for determining the solid surface free energy from the liquid’s surface tension γLV; it also enabled the advancing θA and receding θR contact angles of this liquid to be calculated. Measurements of contact angle hysteresis ∆θ(= θA − θR) with surfactant-containing sea water and distilled water (reference) on the same stone surfaces allowed the film pressure ∆Π (1.22 to 8.80 mJ m−2), solid surface free energy ∆γS (−17.03 to −23.61 mJ m−2) and work done by spreading ∆WS (−1.23 to −11.52 mJ m−2) to be determined. The variability in these parameters is attributed to autophobing, an effect operative on a solid surface covered with an adsorptive layer of surfactants. The wetting behaviour of solid particles is of great importance in numerous technological processes including froth flotation, demulgation, anti-foaming procedures and the coal industries. It is believed that the approach presented here and the examples of its application to common sea water/solid mineral systems could be successfully adapted to optimise several surfactant-mediated adsorption processes (see below) of practical value in natural water ecology.

A neuro-fuzzy approach to generating mold/die polishing sequences

A neuro-fuzzy approach to generating polishing sequences is presented. The measured initial surface roughness of the EDMed mold or die and the desired final polished surface roughness are the major inputs fed to the system. After receiving this input, the system consults its database for the polishing efficiency curves of the abrasive stone grain sizes available to it. With the outputs of this system being optimized for minimum polishing time, there is a selected sequence of grain sizes from among an available set, with each grain size used for each polishing step. There was a series of initial polishing experiments which were conducted for the different available grain sizes and workpiece roughness at different pressures and RPM's, with a change in roughness measured for polishing duration. From this, the database is constructed for designing the fuzzy logic rules. For constructing the exact membership function of the fuzzy interface, the neuro-fuzzy technique is combined with learning ability of neural network and the inferring ability of fuzzy logic system. Finally, while considering the stone-changing time, the actual experimental results from suggested polishing sequences are compared with the predicted value in order to establish the proposed approach.

Modeling surface roughness in the stone polishing process

In this paper, a new method for modeling and predicting the surface roughness of the workpiece in the stone polishing process is developed. This method is based on the random distribution of the stone grain protrusion heights and the force balance by contact grains. To do so, first, the topography of a polishing stone is generated based on a Gaussian distribution with the mean value and standard deviation determined from a given stone grit number. Second, the plasticity theory is applied to determine the micro depth of cut of a single grain for a given workpiece hardness (Brinell number). Third, a search method is developed to determine the number of the contact grains and the micro depth of cut, based on the force balance principle between the force applied on the stone and the forces transmitted to the grains that are in contact with the workpiece. Fourth, a method is presented for predicting the surface roughness based on the micro depth of cut and contact grains. A good agreement of the prediction results with the experimental data proves the effectiveness of the proposed method.

Conservation study of the stone material used in the Culture House of Almirante Oquendo, in San Sebastian

The historical heritage of our country is mainly made up of masonry, playing the sandstones an important role. However, because of the effect of environmental conditions and pollution, these materials can loose their cement, and eventually disintegrate. Chemical consolidants can be applied in order to prevent and stop these decay process, which, when there is a lack of cement, fix the stone grains, enhancing the strength and durability of the In order to ensure the success of the application of these products in restoration works, preliminary studies should he carried out, so as to define the suitability of their use, and select the most appropriate consolidant for each specific case, as the reliability of these products is mainly determined by the microstructure of the stone material under study. This paper describes a study which was carried out on Igueldo sandstone from the main facade of the Casa de Cultura del Almirante Oquendo, in San Sebastian, which aimed at establishing the most suitable consolidation technique for the stone degradation processes observed. Firstly, the study dealt with the diagnosis of the pathologies which affected the stone from this building. Furthermore, 6 commercial consolidants were tested on quarry stone. Finally, the results were validated applying these products in real work conditions, what enabled us to select the most appropriate treatment for the restoration of the main facade of the building.

Solidification of Powders in SiO<sub>2</sub>-Fe<sub>2</sub>O<sub>3</sub> and SiO<sub>2</sub>-ZrO<sub>2</sub> System by Hydrothermal Hot-Pressing

A silicastone powder (low-quartz) containing Fe2O3 and ZrO2 up to 30wt% was kneaded with 10N NaOH solution, and then hot-pressed at 300°C and 28MPa for 3h to produce solidified bodies. During hydrothermal hot-pressing, shrinkage of starting materials was measured. Solidified bodies containing Fe2O3 consisted of low-quartz, hematite and acmite (NaFeSi2O6). The formation of acmite suppressed linkage of silica stone grains and reduced compressive strength of the solidified bodies. It also reduced the shrinkage of starting materials. Solidified bodies containing ZrO2 contained low-quartz and monoclinic ZrO2. No reaction products were detected by X-ray powder diffraction. Addition of ZrO2 up to 20wt% increased the shrinkage of starting materials and compressive strength of the solidified bodies. Mobility of silicastone grains at the early stage of hydrothermal hot-pressing was increased by addition of ZrO2. Similar phenomenon was observed by addition of graphite, a solid lubricant.

Adaptation of the wearing test of crushed stones by the dorry test to the wearing machine by bohme

The wearing test by Dorry is described in BS 812, Chapter 3, issued in 1975. This method is intended for the determination of the surface wear of crushed stone grains tightly fixed. The wear is caused by the friction between the grains, the metal disc and quartz sand. The test pieces produced from crushed stone grains are of sizes 92×54 mm, i.e. the surface exposed to wear amounts to 50 cm2.