Stone Structures Research Articles

Improving concrete quality for transport construction

The creation of a transport network with high performance characteristics of the roadbed is an urgent task in the field of road construction. Foreign practice in the construction and operation of such facilities indicates the need for research studies aimed at obtaining an optimal concrete stone structure by optimizing the concrete composition (controlling the concrete mixture properties at the microlevel) and using state-of-the-art complex additives. The technological properties of concrete mixture and concrete were studied in accordance with the requirements of the current regulatory documentation using verified equipment. The compressive strength of concrete was determined using an MS2000 testing machine (with a measuring range of up to 2000 kN and a loading error of no more than 1%). The abrasion level was estimated by the loss of the sample mass during operation of an LKI-3 device (abrasion disc). The mass water absorption was determined by variations in the sample mass during water saturation. The article presents the physical and mechanical characteristics of heavy concrete (strength, abrasion, water absorption) obtained using TechniFlow-61, TechniFlow-178 PRO, and PowerFlow-3100 additives. The results indicate the positive effect of the above additives, which can be used to decrease the water-cement ratio for obtaining concrete mixtures of a given mobility, produce concretes of a denser structure, and reduce the number of open pores. The conclusion is made about the effectiveness of new-generation additives with plasticizing and water-reducing agents for improving the technological properties of concrete mixtures, as well as the physical and mechanical characteristics of the resultant concretes.

IDENTIFICATION OF RISK FACTORS FOR URINARY TRACT INFECTION IN PATIENTS WITH UROLITHIASIS

Urinary tract infections (UTIs) are common among patients with urolithiasis, making treatment complicated and even dangerous. This study aimed to identify risk factors associated with UTIs in urolithiasis patients. A retrospective study was conducted at Mayo Hospital Lahore, which included 300 patients with kidney stones. The patients were separated into two groups: those with UTIs and those without. Various factors were examined, including age, gender, smoking history, stone structure, alcohol use, stone location, and presence of blockages in the urinary tract. Out of the 300 patients, 73 (24.33%) had UTIs. The most common pathogens found in the urine cultures were gram-negative bacteria, followed by gram-positive bacteria and fungi. The study concluded that gender, age, blockages in the urinary tract, stone structure, and multiple stone locations could be considered independent risk factors for UTIs in urolithiasis patients. However, no statistically significant relationship was found between drinking and smoking and the incidence of UTIs. The most common organism found in UTIs among urolithiasis patients was a gram-negative bacillus.

Influence Substitution of Tabas Stone Waste which Coated Polyester Resin to Concrete Compressive Strength

The need for the use of concrete raw materials is increasing in line with the increase in the use of concrete in construction. The availability of concrete raw materials is dominated by the exploitation of natural resources, namely components of cement, sand and crushed stone or gravel. If the availability of this material is exploited in excess, it will have an impact on environmental damage. On the other hand, many stone crafts for decoration and building ornaments in Bali also utilize tabas stone which is also exploited from nature, where the processed rock leaves a lot of waste that is disposed of without any wise processing actions. Tabas stone waste management is expected to maximize the utilization of natural resources and also reduce environmental pollution caused by the disposal of tabas stone waste that is not managed properly. This research is expected to provide an alternative to maximize the use of tabas waste as a partial substitution of crushed stone or gravel as coarse aggregate in concrete mixtures. The porous structure of tabas stone and the high level of water absorption in the concrete mix can reduce the compressive strength of the concrete. Steps to reduce water absorption in tabas stone are carried out by maximally closing the pores using a polyester resin coating. The study was carried out by making normal concrete mixture objects according to SNI 03-2834-2000. The percentage of substitution of crushed stone with waste stone that is coated with polyester resin is 0%, 25%, 50%, 75%, 100% of the required weight of coarse aggregate. The compressive strength of the concrete will be tested at the age of 7 and 28 days using a cylindrical specimen measuring 150x300mm. Test results in the laboratory showed that the coating of tabas stone using polyester resin was able to reduce the level of water absorption from 9.96% to 3.24% or 67.5% compared to tabas stone that was not coated with polyester resin. The optimum compressive strength of coarse aggregate substitution using tabas was obtained at variations of 50% crushed stone 50% tabas stone at the age of 7 days and 28 days, respectively, reaching 15.06 MPa and 21.55 MPa.

Spatial Structures of the Initial/Early Upper Paleolithic at Tolbor-21, Northern Mongolia

This article describes the spatial structures of archaeological horizon 4 at Tolbor-21 in northern Mongolia, on the basis of data from 2015–2017. The presence of non-utilitarian items, faunal remains with traces of human impact, and the use of fi re render this site near outcrops of raw materials promising for the reconstruction of the spatial organization of Early Upper Paleolithic sites in northern Mongolia. Spatial analysis included visual observations and statistical procedures (clustering with two algorithms) aimed at identifying patterns in the distribution of fi nds in various areas. The infl uence of natural processes on the distribution of artifacts was evaluated with fabric analysis based on the positions of the long axes of fi nds. As a result, it was found that solifl uction variously affected the archaeological horizon in different parts of the slope. The effect was strongest in excavation 2, where two possibly overlapping episodes of fi rerelated activity have been reconstructed. Nevertheless, it is possible to separate two complexes differing in terms of fi nds, including signifi cantly modifi ed tools and bones with traces of human impact (“fi replace 1”) and a concentration of small artifacts (“fi replace 2”). In the upper part of the slope (excavation 4), near the stone structure, an accumulation of cores at the advanced reduction stages is reconstructed, as well as an area where ungulate carcasses were butchered. An area associated with primary reduction has been separated in excavation 1. The differential use of the camp area by its inhabitants seems to be an important feature of the subsistence strategy of the population of northern Mongolia during the initial stages of the Upper Paleolithic.

P.D. BARANOVSKY AS AN ARCHAEOLOGIST: KOLOMENSKOYE IN THE 1920s–1940s

The article addresses the question of the need to publish a part of the archive of the renowned 20th century architect-conservator Pyotr Dmitrievich Baranovsky. It is associated with his studying of the regal residence of the 16th–19th centuries in the settlement of Kolomenskoye (now the territory of Moscow). This paper publishes part of the review of archaeological works in Kolomenskoye compiled by the researcher in the 1940s and newly found in his archive. The document contains a brief account of the 1930 excavations at the site of the “Wooden Palace of Tsar Alexei Mikhailovich”, a Moscow’s masterpiece of architecture. So far, no materials recording these works have been known. The found document also includes a description of the restoration of the palace’s stone structures conducted by P.D. Baranovsky in 1923–1928 and presents the context of the archaeological work of 1933 and 1935. Particular attention is paid to the reconstruction of the layout of the palace on the ground and the localization of its stoves, as well as the characteristics of their tiled decor. The article also publishes the analytical graphics by the architect of the 1940s associated with the reconstruction of the remains of the palace and the development of its new model.

Before the Holocene humid period: Life-sized camel engravings and early occupations on the southern edge of the Nefud desert

The Neolithic of northern Arabia is characterised by monumental stone structures, ephemeral ‘hearth sites’ indicative of a highly mobile lifestyle, and a rich rock art heritage with iconic representations of domesticated livestock. However, the character and timing of occupation prior to the spread of pastoralism (ca. 6000 BCE) remains elusive, with only one stratified Epipalaeolithic site and two surface early Neolithic sites so-far known in the Jubbah Oasis. Here we present Sahout, a newly documented rock art site with Neolithic and earlier occupations, on the southern edge of the Nefud desert. The rock art is dominated by life-sized, naturalistic, engravings of camels, which are in some cases superimposed with Neolithic imagery of domesticated sheep. Surveys and test excavations carried out in the vicinity of the rock art revealed a lithic assemblage with similarities to the late Epipalaeolithic and Pre-Pottery Neolithic of the Levant. Radiocarbon ages from two test trenches and two hearths indicate repeated occupation at Sahout between the Terminal Pleistocene and the Middle Holocene, which partly mirror the rock art sequence. Investigations at Sahout indicate that rock art production in northern Arabia may have begun earlier than previously thought. Research also suggests a broader geographical extent to human occupations prior to the Holocene humid period.

ПОВЫШЕНИЕ ЭКСПЛУАТАЦИОННЫХ ХАРАКТЕРИСТИК ГИПСОВОГО КОМПОЗИТА ДЛЯ ДЕКОРАТИВНЫХ ИЗДЕЛИЙ

The article discusses the results of research on the use of modifying additives in gypsum binder. Regulation of the structure and, therefore, the properties of gypsum stone can be carried out using small quantities of highly active additives that can effectively influence the formation of the structure of gypsum stone, and, consequently, its characteristics. Using functional modifying additives in small quantities, which practically do not affect the cost of the material, and using them to control the composition of gypsum binders, it is possible to obtain effective decorative and finishing gypsum products with improved characteristics.
 The work studied the effect of polyvinyl acetate additives together with synthetic polypropylene fiber on the properties of gypsum stone products. A comparison of the physical and mechanical characteristics of modified gypsum composites is presented, and the advantages of introducing fiber are revealed. By covering the pores and capillaries of gypsum stone with fiber fibers, the formation of shrinkage microcracks is significantly reduced, crack resistance increases, and strength characteristics increase.
 It has been established that modification of gypsum stone with polyvinyl acetate together with synthetic fibers helps to improve the physical and mechanical characteristics of gypsum stone. The developed compositions of decorative and finishing gypsum tiles using the additions of polyvinyl acetate and polypropylene fiber make it possible to obtain gypsum finishing materials products with improved characteristics, which demonstrates their increased efficiency as a modern finishing material and opens up broad prospects for use in housing and civil construction.

Investigation of Fluid Flow Through the Ureteral Canal with A Porous Media Approach in the Ureteral Stone Reduction Process

This study includes the examination of the stone removal process by computational fluid dynamics analysis in the kidney and ureteral canal, which is modeled as the fluid evacuation channel for the urine flow. SolidWorks 2020 R2 commercial software was used for three-dimensional modeling and Flow Simulation plugin for flow simulation analysis. The kidney with the size of 12x6x6cm and in addition to this, the ureteral canal with the largest internal diameter of 20 mm (at the kidney outlet) and the smallest diameter of 5 mm (at the canal outlet) were modeled. Pressure distribution in the presence of flow was determined in case of stone stuck in the middle part of the ureteral canal. To identify the partially occluded region allowing flow, the kidney stone region was defined as a porous medium for analysis. Four different conditions (between 0.90 and 0.99) for permeability in this region were included in the analysis to represent stone size and structure. The change in pressure-velocity distribution and its effect in the kidney area were seen at 5 different entry speeds. The effect of different permeability conditions on the pressure difference was shown graphically. The findings showed the presence of high pressure (peak 1850 mmH2O) throughout the flow volume at narrow passages and low permeability conditions, as expected. At 90% permeability, the maximum local velocity in the blockage zone was found to be 4.5 m/s and this value tends to decrease with increasing permeability. It was predicted that the pressure-velocity relationship along the flow can provide information on treatment and intervention, depending on the stone and canal structure whose properties are predetermined. It was concluded that a preliminary idea could be formed about the extent of pain due to high pressure, especially for the stone dropping process, which does not cause complete obstruction in the canal and is defined as a porous medium in this analysis.

Dynamic adsorption of 4-nitrophenol over shaped activated carbon produced from agriculture stones through microwave-assisted technique.

The aim of current work is to develop the uptake of 4-nitrophenol from the liquid phase in a dynamic system by the shaped activated carbon produced through the microwave-assisted technique. The emphasis of research is to understand the effects of production factors on the performance of adsorbents in the dynamic adsorption. Hence, the phosphoric acid ratio, microwave irradiation power, carbonization temperature, and time were changed to identify the suitable conditions for the fabrication of granular and rod-like beds from the cherry, and date stones. It was found that the stone structure and H3PO4/waste ratio significantly affect the adsorption efficiency. The proper acid/waste ratio was determined to be 1.43, and 1.80 for the activation of cherry and date stones to achieve the maximal efficiency in which the power should be fixed at the levels of 600 and 400 W respectively. The equilibrium efficiency increases with the rise in carbonization temperature and time which should be controlled exactly to reach the maximal adsorption capacity, ~ 45 mg g-1 according to the Langmuir isotherm. Owing to the high specific surface area of shaped adsorbents, 350-450 mg g-1, the fabricated beds indicated the appropriate performance for the uptake of nitrophenol due to development of micropores, < 2 nm, in the framework of activated carbon.

RELIABILITY ASSESSMENT OF STONE STRUCTURES

The article provides valuable information on methods for assessing the reliability of stone structures. The authors draw attention to the issues of diagnostics and calculation of the reliability of existing masonry structures, and also offer methods for determining the compressive strength of masonry using the theory of reliability. The destructive and non-destructive tests underlying the determination of strength masonry are also described. The authors emphasize the importance of structural safety and reliability, which depend on many factors, including the type and magnitude of loads and the bearing capacity of structural elements. A sufficient state of safety is ensured by compliance with the relevant standards and regulations. The article draws attention to the importance of carrying out tests and calculations in the reconstruction and repair of buildings in order to guarantee their safe operation. The authors note that the safety and reliability of the design also depends on compliance with the rules and regulations that take into account the social, economic and environmental consequences of failure. The emphasis on the probabilistic approach to assessing the reliability of a design is an important aspect of the article. Taking into account the probability of failure allows us to develop a rational approach to the repair and reconstruction of buildings, ensuring their normal operation. The authors also draw attention to the importance of determining the probability of failure (Pf) as a fundamental parameter for its assessment. Keywords: reliability assessment, masonry structures, masonry strength, structural safety, safety factors, deformations, fire resistance, reliability theory, failure probability.

Increasing the Speed of Formation of the Structure of Fine-Grained Concrete and its Strength

It was determined that the active component of modern concrete is water. Water has a variable structure, the type of which depends on the temperature at which the water was processed. The use of water in the production of concrete, which has a certain changed structure, allows influencing the rheological properties of concrete mixtures and modifying the structure of cement stone in such a way as to give concrete properties that ensure high operational reliability of structures. However, this method of increasing the strength of concrete has certain disadvantages that prevent its wide application. The purpose of the research is to determine the effect of a mixture of water of different structure on the strength of fine-grained concrete and the speed of its formation.

Optimization of Water Activation Technology for the Production of Fine-Grained Concrete

One of the main active components of modern concrete is water. Water has a variable structure, the type of which depends on the water treatment technology. The use of water in the production of concrete, which has a changed structure as a result of the action of certain substances, allows influencing the rheological properties of concrete mixtures and modifying the structure of cement stone in such a way as to give concrete properties that ensure high operational reliability of structures. However, this method of increasing the strength of concrete has certain disadvantages that prevent its wide application. The purpose of the study is to determine the influence of the type of plasticizers used for water activation on the speed of structure formation and the strength of fine-grained concrete.

Using aerial survey to record new sites in the Keimoes kite landscape of South Africa

The recent identification of kite sites on the Keimoes landscape, in the Northern Cape Province of South Africa, has shed light on how past populations built and utilised low stone structures to funnel and capture game. By strategically identifying and using certain aspects of the surrounding landscape, in conjunction with key design aspects, local groups maximised hunting proficiency. With this contribution, we revisit the Keimoes landscape to continue our search for more funnel sites and to establish whether there is consistency in some of their key design aspects, as identified in earlier publications. We introduce three more kite sites and provide their morphological and landscape details. For the first time, we also demonstrate that some of the kites were purposefully located near rocky outcrops from which construction material could be collected.

Investigating the operational modal response and updating the finite element model of a prototype stone structure

In this work, the analysis of the dynamic behavior of a prototype stone structure has been presented in two ways: (1) the first way is to instrument the structure with two three-component velocity sensors to measure the structure's response to ambient solicitations. An acquisition and processing chain has been developed in our laboratory to record the acquired vibratory signals. The data processing is obtained using different methods of operational modal analysis (OMA) such as Frequency Domain Decomposition (FDD), Random Decrement Technique (RDT), and Stochastic Subspace Identification (SSI). The results obtained by these methods allowed us to extract the modal parameters (damping and natural frequency) of the structure. (2) The second way consists of characterizing the structure's dynamic behavior in a numerical way using Finite Element Modeling (FEM). However, it has often been noted that the experimental dynamic characteristics obtained do not agree with those of the numerical model. The present study aims to extract the dynamic parameters experimentally and numerically and to update the finite element model for stone construction. A good agreement was found between the two approaches.

Comparison of contact treatment methods for rigid polyhedral discrete element models

Blocky rock and stone structures (such as jointed rocks mass, masonry structures and railway ballast) are often submitted to dynamic effects. Their mechanical behaviour can be simulated with the discrete element method (DEM) using polyhedral elements. DEM models differ in how they compute the contact forces. Several studies have compared different contact constitutive laws, but little information is available in the literature on which contact treatment method (i.e. number of contacts between two elements, contact detection, contact orientation, area and overlap computation) to choose. The inclined slope, the perpendicular impact and the rocking block problems were simulated and applied as benchmark tests in the present study to compare three most popular polyhedral DEM contact treatment models for rigid elements, namely the Eliáš (available in Yade), the Gilbert-Johnson-Keerthi (GJK, widely implemented, here tested with PFC3D) and the Sub-Contact model (available in 3DEC), to see which ones could be precisely calibrated to analytic and experimental solutions. Sensitivity studies were also carried out on the effect of subdivision density of element surfaces and on the admissible timestep length. Experiences showed that while there are serious doubts about the applicability of the Eliáš volumetric model as it is sensitive to both variations in geometry and the results vary randomly with the timestep length, the GJK model is suitable to simulate granular materials because of its computational efficiency and robustness, and the Sub-Contact method is the proper choice to model structures where the contact surfaces are relatively large, as it operates multiple contacts between two elements and gives information about the force distribution on the surface of the elements.

Sacred Stones and Stone Structures in the Ritual Practice of the Turkic Population in the Southern Urals: Archaeological Evidence and Modernity

The article summarises, analyses and structures the beliefs of the Turkic population of the Southern Urals that are associated with stones, mountains, menhirs, karaski, stone mounds, tombstones, etc.Based on the works of Russian and foreign authors, as well as on field materials gathered during the expedition trips in 2011–2023, two groups of beliefs are singled out: cults associated with stones of natural (divine) origin, and beliefs associated with stone constructions of man-made origin. Various forms of the use of stone and stone constructions by the Turkic people in modern ritual practice are described. The processes of sacralisation and desacralisation at the cult sites of the Southern Urals occurring at the present stage of development are considered. Beliefs related to gemstones, to which people gave special symbolic meaning, and attributed protective, magic and healing properties, are analysed separately.

The Precarious Survival of an Ancient Cultural Landscape: The Thousand-Year-Old Olive Trees of the Valencian Maestrat (Spain)

The object of study of this article is the Valencian Maestrat olive growing system (eastern Spain). Its landscape and heritage values are evaluated through a qualitative assessment method based on a Spanish research project studying MTASs (Multifunctional, Territorialized Agrifood Systems), which can be described as an alternative agricultural model to the worldwide agro-industrial model. The results of this analysis show that this olive growing system coincides with the MTAS criteria as regards the landscape, which offers ecosystem services (food, structured soil, and absorption of CO2 emissions) and possesses cultural and heritage values (ancient olive trees, traditional rain-fed lands, unaltered plot structures, and dry stone structures). However, as far as production is concerned, the Maestrat olive growing system does not respond fully to MTAS principles: its particular environmental conditions (soil and climate) restrict the production of quality oil, which is processed and marketed mainly through cooperatives and is economically viable only thanks to CAP (Common Agricultural Policy) aid. Nevertheless, the cooperative system allows for the survival, albeit precarious, of this agricultural system. Only a small number of Maestrat olive growing farmers produce quality oil in accordance with MTAS criteria (such as local single varieties, unique flavour, proximity sales, territory closeness, or good farming practices).

EXAMINATION OF NEW GROWTHS IN MODIFIED SULFATE-BASED COMPOSITES BY SCANNING ELECTRON MICROSCOPY

The structure of a gypsum matrix, which is characterized by the size, shape, and morphology of crystals, the state of the interfacial surface, and the number and strength of contacts between new growths, determines the basic physical and technical properties of materials. The effect of various modifiers, mainly of technogenic origin, on the gypsum stone structure has been examined by scanning electron microscopy and energy-dispersive X-ray analysis. In the study, building gypsum and metallurgical dust, granulated blast furnace slag, and siltstone mineral modifiers have been used. It has been established that the introduction of modifiers improves the physical and mechanical properties of a binder. This is probably due to the fact that the additives act as crystallization centers during the matrix structure formation and facilitate filling of the stone pore space.

CONSERVATION STRATEGIES OF BUILT HERITAGE OF ASSAM

Assam is a state in north-east India located on the crossroads of Southeast Asian and Indic culture. In the close contest of the two, the Indic culture prevailed however the conflict continues. The appearance of mainland Indic culture had a lasting impact on the socio-cultural landscape of Assam. To propagate and present the magnanimity of mainland Indic culture among the natives, edificial brick and stone structures were raised. However being located in highly active geological and extreme climatic region these structures were continuously under the threat of these forces. In addition there are also anthropogenic and biological threats. The present article deals with the threats and remedies suggested for the structures dating up to 1200 AD. It is to be noted that almost all the structures are in ruins and under the protection of certain agencies hitherto they are in pitiable condition. The present study notes the nature of deterioration faced by the structure and possible remedies in detail

M. K. Kadyrbaev’s Archive as a Source for Studying the Stone Monuments of Kazakhstan

The article describes the unpublished archives collected by M. K. Kadyrbaev from his field work in Central Kazakhstan in 1955–1979. It provides information on eight stone statues and structures. The authors attributed and dated them in line with the contemporary rules of archeology. One of the statues appeared to belong to the Saka period of the Tasmola culture. Another monument had no obvious analogies but, possibly, was part of a Qipcaq sanctuary. The authors also touched upon some challenging or debatable issues raised by M. K. Kadyrbaev and other expedition members, e.g., the validity of correlating statues without sings of sex with images of women; the secret Polovtsian sanctuary, which have to be studied in the context of similar Qipcaq sites, etc.