Sclerometric Tests Research Articles

Correction Factors for Sclerometric Test Results in the Technical Assessment of Timber Structural Elements under Diverse Conditions.

Research on existing wooden structures relies on non-destructive and semi-destructive techniques. One of the methods enabling the estimation of the physico-mechanical characteristics of wood in building structures based on established correlational relationships is the sclerometric method. The challenge in utilizing these known correlational relationships is the lack of data regarding the impact of frequently occurring factors in objects on sclerometric test results. This paper presents the influence of selected factors on the results of sclerometric tests, such as temperature, the direction of testing in relation to annual growth rings, and the physical orientation of the measuring device. The research was conducted on pine, spruce, and fir elements, each subjected exclusively to the influence of one of these factors. The study indicates that these factors should not be overlooked in assessing technical conditions using sclerometric testing methods. The impact of temperature on sclerometric test results is relatively small; a change in temperature of 10 °C results in an average test outcome change of approximately 3%. Conversely, changing the orientation of the measuring device from horizontal to vertical can alter the test result by up to 10%. The direction of testing relative to the annual increments of wood also has a significant impact on the test results, but incorporating this factor into practice seems to be quite difficult, and in the case of elements with substantial cross-sections, it is also not required. The obtained results enable the application of established correlational relationships in the structural analysis of wooden elements for which access is challenging, especially under temperature conditions different from the reference, 20 °C.

Assessment of the Technical Condition of Timber Structural Elements Using Sclerometric Tests.

The technical assessment of wooden elements is the primary step in their repair and reinforcement design. Normative requirements currently mandate additional tests, including semi-destructive ones, beyond traditional visual assessment. Despite the growing feasibility of semi-destructive tests for qualitative assessments, there remains a paucity of data enabling quantitative assessments. This study investigated the hardness of structural timber, specifically pine, spruce, and fir, from Central Europe using sclerometric methods. The outcomes of these tests were compared with those of conventional destructive tests and correlational relationships were established. A strong correlation was found between the sclerometric tests and density (r = 0.62 ÷ 0.82), while a range of strong to moderate correlations was found (r = 0.40 ÷ 0.70) for mechanical characteristics (bending and compressive strength). The correlation strength varied among different wood species, with the strongest for pine and the weakest for spruce. All established relationships were compiled into 40 functions to facilitate their future utilization in quantitative assessments during the technical evaluation of wooden objects. The study also examined the influence of wood defects on the derived correlations by considering the knot index. Sclerometric methods accurately reflect the physico-mechanical properties of elements with a small or medium defect content. However, for wood with a high proportion of defects (knots), the correlations are very weak (r = 0.23 ÷ 0.52, including statistically insignificant results). This research offers new insights into the potential of semi-destructive methods in the structural evaluation of wooden elements, highlighting the need to account for wood species and defect content.

Enhancing mechanical and thermal properties of sustainable cement mortar through incorporation of olive solid waste aggregates

This research paper presents a comprehensive investigation into the characterization of cement mortar incorporating olive solid waste aggregates (OSW) as a partial replacement for natural sand. Different levels of OSW content (0%, 5%, 10%, and 15%) were used to create samples, enabling a comparison of their mechanical and thermal properties against the reference mortar. The primary objective of this study is to analyze the mechanical and thermal performance of lightweight cement mortar, with a secondary focus on establishing correlations between distinct testing methods, including compressive strength, sclerometer, and thermal tests. Mechanical properties were assessed through compressive strength testing. After a 28-day curing period, the mortar containing 5% OSW exhibited a compressive strength of 33 MPa. Notably, it demonstrated a 15.6% reduction in density compared to the reference mortar. An examination of the relationship between destructive compressive strength tests and non-destructive sclerometer tests (NDST) revealed a linear correlation, suggesting the effectiveness of the sclerometer test in estimating cement mortar compressive strength. Furthermore, we investigated the thermal characteristics of OSW-incorporated cement mortar. The mixture containing 5% OSW exhibited a thermal conductivity of 0.87 W/m·K, representing a 21% reduction compared to the reference mortar. These findings underscore the potential of OSW to enhance the thermal properties of the resulting cement mortar. Additionally, the observed correlation between compressive strength and thermal conductivity highlights a significant connection between these properties. This study primarily addresses the mechanical and thermal attributes of cement mortar incorporating OSW while also exploring correlations between testing methods. The resulting cement mortar meets the minimum strength requirements for structural applications as a construction material.

Dependence of the Surface Morphology and Micromechanical and Sclerometric Properties of Al2O3 Layers on the Parameters of Anodizing Aluminum Alloy

The article presents the dependence of the morphology as well as micromechanical and sclerometric properties of Al2O3 layers on the parameters of anodizing of aluminum alloys. The oxide layers were produced on the EN AW-5251 aluminum alloy by means of a direct current anodizing in a three-component electrolyte. The input variables (current density and electrolyte temperature) were selected based on the overall design of the experiment. The current density was 1, 2, 3 A/dm2, and the electrolyte temperature was 283, 293, 303 K. The surface morphology was examined using a scanning electron microscope (SEM), and then the microscopic images were analyzed using a graphics program. The micromechanical and sclerometric properties were examined by determining the HIT hardness and three critical loads: Lc1 (critical load at which the first damage of the tested layers occurred-Hertz tensile cracks inside the crack), Lc2 (critical load at which the first cohesive damage of the layers occurred) and Lc3 (load at which the layers were completely damaged). Sclerometric tests with the use of scratch tests were supplemented with pictures from a scanning microscope, showing the scratches. The produced layers are characterized by a hardness above 3 GPa and a porosity of 4.9-10.3%. Such a range of porosity of the produced layers allows their wide application, both for sliding associations with polymers and for their modification.

Diagnostic Campaign Aimed at Assessing the Seismic Vulnerability of Existing Buildings Applied to Strategic Buildings in Trentino Alto Adige (Northern Italy)

In order to assess the seismic vulnerability of existing buildings, the Italian structural codes require that the geometric characteristics of the structural elements and the mechanical characteristics of the materials shall be determined through diagnostic investigations. The level of deepening of the investigations carried out depends on the Level of Knowledge (LC) achieved; on this basis it is determined a Confiance Factor (FC) which must be applied in the subsequent verification activity to reduce the mechanical characteristics determined for the materials in the diagnostic way. Furthermore the legislation identifies the buildings that are “strategical” because of the effects consequent the seismic events: on these buildings the vulnerability assessment is mandatory. The paper describes the diagnostic activities carried out on some buildings located in Trentino Alto Adige (Northern Italy) built between the mid-19th c. and the first decades of the 20th c., which were originally intended for the headquarters of the Judicial Prisons and the Court (in Rovereto) and for the Casa del Fascio (in Bolzano). Currently they are aimed for public offices (state offices, barracks of the financial guard and police). These are very common situations in Italy: historic buildings, built with different construction techniques (both masonry and Reinforced Concrete and mixed techniques) and subject to multiple functional transformations over time, even linked to the repair of war damage. The analysis carried out involved the geometric and material survey, the historical analysis of the events and interventions undergone, the mechanical characterization of the materials, foundations and foundation soil. In particular, given the architectural interest of the building and the need to minimize disturbance to users, the tests that have a limited impact on the construction (e.g. sampling on the concrete and tests with flat jacks on the masonry) were accompanied by non-destructive tests (endoscopies, sonic and ultrasonic tests, penetrometric tests on mortars, sclerometric tests and magnetometric investigations) in order to extend the results and guarantee their representativeness. It was thus possible to reach the Level of Knowledge LC3 (the maximum expected level) and apply the Confiance Factor FC = 1 (the minimum value), operating with the best compliance with the real state of the building. It was of particular interest also the building up of a BIM (Building Information Modeling) model, implemented from the laser scanner survey and carried up to the appropriate Level of Development (LOD = 300) which allowed to embed in the model all the acquired structural diagnostic information and to develop the consequent static and seismic assessment.

Quality control and safety assessment of prestressed concrete bridge decks through combined field tests and numerical simulation

This paper presents a systematic approach for the quality control and safety assessment of existing bridge decks through combined field tests and numerical simulation. The methodology is described in the context of a case study represented by the Zappulla multi-span viaduct (southern Italy), whose deck is realized with simply supported prestressed concrete girders and overlying reinforced concrete slab. Quality control is carried out through an extensive in-situ testing campaign comprising concrete coring, carbonation tests, sclerometric tests combined with ultrasonic pulse velocity for concrete strength evaluation, as well as pachometer and georadar tests for identification of steel reinforcement and prestressing tendons, respectively. Additionally, field tests including static and dynamic loading tests are performed to investigate the bridge response under serviceability conditions. Field-test results along with experimental findings on the material characterization are used to calibrate a finite element (FE) model of the bridge deck, which is subsequently adopted for structural safety assessment of the bridge deck at ultimate limit state (ULS). Two methods for evaluating the safety conditions at ULS are comparatively investigated, namely the Eurocode-compliant semi-probabilistic partial factor method and a deterministic method that computes the global safety factor of the bridge deck in its actual working conditions based on nominal values of loads and resistances. In addition to linear analysis, incremental non-linear static analysis is performed to determine the push-down response of the bridge deck via a concentrated plasticity approach. The proposed procedure, inherently encompassing both serviceability and ultimate loading conditions and synergistically combining material characterization and field-test results with a critical statistical interpretation, accompanied by numerical FE simulation with an eye to design code requirements, provides a reliable tool for the quality control and safety assessment of other similar existing bridges.

The Sclerometrical, Mechanical, and Wear Behavior of Mg-Y-Nd Magnesium Alloy after Deep Cryogenic Treatment Combined with Heat Treatment.

The paper investigates changes in the structure, microhardness, and sclerometrical and tribological properties of a Mg-Y-Nd alloy under the influence of deep cryogenic treatment (DCT) in combination with heat treatment. The solution treatment was carried out at 545 °C for 8 h, aging was carried out at 250 °C for 24 h, and the deep cryogenic treatment applied at different treatment stages was performed at −196 °C. Tests showed a significant increase in the number of β-phase precipitates identified as Mg46.1Y6.25RE3.45 in the alloy subjected to DCT after solution treatment followed by aging. In addition, an approximately 20% reduction of the grain size was observed. Changes in the structure in the precipitation process strengthened the alloy and resulted in an increase of its hardness. At the same time, sclerometric tests allowed the micromechanism of wear and the coefficient of resistance to abrasive wear to be determined. Tribological tests showed a three-fold reduction in the volumetric wear and a considerable reduction of the friction coefficient, with the main mechanism observed during friction being abrasive wear. The most favorable properties of the alloy were obtained after precipitation hardening combined with DCT, resulting in a large increase in resistance to abrasive wear. Additionally, the formation of deep scratches in the examined material was reduced. The introduction of sub-zero treatment reduces the precipitation hardening time, and the results obtained indicate that the service life of the Mg-Y-Nd alloy can be extended.

A multidisciplinary approach to the mortars characterization from the Town Walls of Gubbio (Perugia, Italy)

In the frame of the HERACLES (HEritage Resilience Against CLimate Events on Site) project, a set of cultural heritage sites was studied to improve their resilience against climate events. The mediaeval Town Walls of Gubbio, in the centre of Italy, are among these. Over the centuries, several factors including environmental actions and structural and material repairs have produced different criticalities, involving both structure and materials. A severe problem consists in the progressive degradation of the mortars binding the masonry. Since the wall body structure behaves/reacts properly only if the cohesion between mortar and stones is sufficiently large, it follows that mortars degradation represents a quite significant issue that deserves a special attention. The present work focuses on the characterization of the mortars sampled in various parts of the Walls, corresponding to different historical periods, restoration measures and interventions. They were characterized to determine the corresponding mineralogical and chemical compositions along with morphological features and to investigate their mechanical properties. For that purpose, penetrometric and sclerometric tests on site and ex situ laboratory techniques, such as X-ray diffraction, polarized light microscopy, scanning electron microscopy, thermogravimetry and differential thermal analysis, were used to examine the weathering effects on mortars and more generally their degradation state, in order to plan appropriate restoration and repair actions.

Lateral Inhomogeneities of Sapphire Plates Determined with the Aid of X-Ray and Probe Methods

X-ray diffractometry, X-ray profilometry, atomic-force microscopy, and sclerometer tests are employed in the study of R-cut plates of sapphire single crystals grown with the aid of the Kyropoulos technique and used as substrates for the silicon-on-sapphire structures. Regions with different degrees of perfection can be found even on a single plate. Mutually consistent results of the four experimental methods based on different physical principles can be used to reveal regions of structural imperfection on the surface of a plate. It is expedient to employ a complex procedure for multipoint monitoring of the parameters of plates to reduce the number of defect samples that serve as substrates in the production of electronic devices.

Investigation of the adhesion properties of calcium-phosphate coating to titanium substrate with regards to the parameters of high-frequency magnetron sputtering

The main goal of the work was to find the interconnection between the high-frequency magnetron sputtering parameters and the adhesion properties of CaP coatings formed on the surface of titanium substrate. Calcium-phosphate coatings, similar in composition to hydroxyapatite, were generated by high-frequency magnetron sputtering on titanium substrate at different values of high-frequency specific power over times of one and two hours. Afterwards, the generated coatings were studied using the method of X-ray phase analysis, and sclerometric tests (scratch test) were carried out. The adhesion strength of the deposited coatings was tested for different coating thicknesses from 0.45 to 1.1 × 10⁻³ mm. According to the results of sclerometry, it was found that with an increase in the high-frequency specific power of plasma to 3.15 W/cm², the adhesion strength of the calcium-phosphate coating also increases. For all the coatings, the critical loads at which the coating completely exfoliated from the substrate were determined. According to the research results, the most optimal conditions for obtaining high-adhesive calcium-phosphate coatings were determined.

SCLEROMETRIC AND TRIBOLOGICAL PROPERTIES OF POLYTETRAFLUOROETHYLENE WITH 40% BRONZE CONTENT FORMED BY ELECTRON BEAM IRRADIATION

The paper focuses on the improvement of sclerometric and tribological properties of polytetrafluoroethylene (PTFE) with 40% bronze content implied by irradiation with an electron beam of 10 MeV and a power of 10 kW, in a dose of 26–156 kGy. The results of the study confirm that radiation modification of the PTFE-bronze composite causes structural changes induced by breaking of bonds in long PTFE chains and the branching of the polymer structure. As a result, an increase in such properties as the wear resistance ratio, Wβ, is observed. In addition, sclerometric tests have shown that, with an increase of the absorbed radiation dose, the grooveto- elevation area ratio changes during scratching, which indicates a change in the micromechanism of wear, i.e. the material undergoes ploughing. From the operating point of view, the most important were tribological tests, which were carried out on a pin-on-disc test stand (T-01). The tests showed a nearly fourfold reduction in wear at a load of 20 N and more than a threefold reduction at 40 N. Controlled radiation modification leads to improved properties of the PTFE-bronze composite, which may result in a wider range of its applications.

Research on Metallurgic Active Precursors

The paper presents the current state of researches carried out in order to improve homogeneity of mixtures for metallic powders; our priority is those with different participation in the mixture, by mechanical alloying. Mixtures of this type are used in the production of welding and related materials.Recently, research has been done to improve deposited metal properties by welding with coated electrodes, by depositing nanostructures, with uncertain results due to the low degree of homogeneity of blends involved in the electrode coating.The performance enhancement method for coated rods, developed by introducing in their coat activating precursors, used for brazing, is well known. The solution to improve the degree of homogeneity of alloying systems by mechanical alloying has been successfully applied for the manufacture of coated electrodes and those tubular with a composite core which are deposited by manual welding or TIG welding, type Fe25% Cr-4% W-V-Ti-La. The grouping of powder components for mechanical alloying was done in such a way that, finally, we have groups with the granulation, respectively specific weight, close and a low potential of segregation.The method of mechanical alloying of the components was used in the manufacture of coated rods in order to improve the fluidity of silver-rich buffer layers deposited in order to favor the diffusion phenomena of brazing alloys in the base materials.Testing the homogeneity of the alloying systems was performed indirectly by metallographic analysis and sclerometric tests.

The investigation of high-temperature properties of metal by a method of sclerometric

The technique for high-temperature sclerometric tests of deposited wearproof metal are developed and various types of heat-resistant alloys are investigated on the basis of iron and nickel, build-up on steel by arc way in helium. The new criterion of an estimation of resistance of metals and alloys is offered to high-temperature deformation.

Evaluating the Microhardness of Samples Based on Binder VST-1210 Cured under Various Conditions as a Method of Testing

Using a PMT-3M microhardness tester, the microhardness values depending on the distance of the spot of measurement from the frontal plane of the sample to its middle part are determined on the transverse sections of samples of binder VST-1210 hardened under various conditions. It is established that the microhardness value of a plastic depends on the conditions of its curing and also on the spot at which the measurement is carried out—the closer the sample core to the spot of measurement, the higher the microhardness value. The performed sclerometric tests have shown that the width of the groove trace also increases from the middle to the frontal plane of the sample.

Studies on the Tribological Properties and Structure of Antifrictional Iron-Containing Aluminum Alloys

Experimental aluminum alloys with the addition of iron (about 1%) have been considered in order to simulate alloys obtained from secondary raw materials (wastes of domestic manufacture, scrap, etc.). In particular, the alloys have been studied using sclerometric tests according to a criterion of relative shear strength (τ/σmc). The tribological testing of the alloys has been also carried out according to the block-pad and ball–plane schemes of loading. A mathematical model of the wear process has been used to process the results of wear testing for the ball-plane scheme of friction contact. As a result, the wear law parameter Kw has been determined for all of the experimental alloys. The results of testing have confirmed that, in general, it is possible to use aluminum alloys that contain iron for manufacturing monometallic plain bearings. The structure and chemical composition of the surface have been studied for both the initial samples and the samples after testing.

An environmental impact on the condition of an unfinished building in the OWT technology

The aim of the paper is to present the state of the building erected in the OWT technology. The construction of the building has not been completed due to the financial problems of the late 90's of the XX century. As a result of the long-term environmental impact, the object was degraded due to the lack of a flat roof and windows. The impact of precipitation, wind and biological corrosion led to significant degradation and deterioration of structural elements and joints. The paper will present examples of damage caused by environmental impacts. Examples of damage of wall and floor elements as well the deeply corroded steel plate joints will be presented. Highly grown lichens, mosses or mold will be also presented as the examples of biological interactions onto the surface of constructional elements. Structural elements have been tested in a nondestructive manner using sclerometer tests. The results will be described and the conclusions will be presented. The analyzed object presents in an interesting manner that environmental influences could destructively affect the construction of precast RC structural elements, which constitute a significant percentage of the Polish construction market.

The complex express evaluation of tribotechnical properties of antifriction aluminum alloys by sclerometric tests

The results of an investigation of experimental aluminum alloys proposed for replacing the highcost bronzes in friction units have been presented. The alloys were preliminarily selected using sclerometric tests based on the criterion of relative shear strength τ/σmc as being more informative compared with contact microcutting stress smc. Tribotechnical tests of selected alloys have been performed according to the three pins-on-disc scheme, which imitates the operation of the plane journal bearing. The results of tests confirmed the possibility of using these alloys as bronze substitutes. The structure and chemical composition of the surface of both initial samples and tested samples have been investigated. The influence of the chemical composition of the alloy on the tribotechnical properties of alloys under study has been shown.

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.

Thermal decay of carbonate dimension stones: fabric, physical and mechanical changes

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

Experimental study for non-destructive mechanical evaluation of ancient chestnut timber

The paper deals with an experimental study for in situ mechanical characterization of ancient timber members using combined Non Destructive Testing (NDT) techniques. An experimental campaign, including non-destructive and destructive tests, was developed on timber structural elements and defect-free specimens, made of old chestnut wood (Castanea sativa Mill.). The following NDT methods were employed in the research activity: hygrometric tests to estimate wood moisture content; ultrasonic investigations to determine stress wave properties; sclerometric tests to assess material hardness and superficial consistence; resistographic measurements to detect internal defects and density variations. Destructive tests in compression parallel to grain and in bending were performed to assess stiffness and strength properties, post-elastic behaviour and collapse mechanisms of the timber elements. Experimental results are discussed and statistically analyzed. Correlations between non-destructive and destructive parameters are provided, based on linear regression models, for the prediction of the wood density, strength and modulus of elasticity of the tested old chestnut timber. The analysis shows that the use of NDT techniques is a useful supplement to the traditional visual grading, allowing a reliable mechanical identification of timber members in practical applications, leading to the appraisal of the timber structures safety and integrity.