Study of the influence of water saturation on main mechanical properties of laterite dimension stones from Burkina Faso

Materials and components employed in the presence of intense neutron and gamma fields are expected to absorb high dose levels that may induce deep modifications of their physical and mechanical properties, possibly causing loss of their function. A protocol for irradiating elastomeric materials in reactor mixed neutron and gamma fields and for testing the evolution of their main mechanical and physical properties with absorbed dose has been developed. Four elastomeric compounds used for vacuum O-rings, one fluoroelastomer polymer (FPM) based and three ethylene propylene diene monomer rubber (EPDM) based, presently available on the market have been selected for the test. One EPDM is rated as radiation resistant in gamma fields, while the other elastomers are general purpose products. Particular care has been devoted to dosimetry calculations, since absorbed dose in neutron fields, unlike pure gamma fields, is strongly dependent on the material composition and, in particular, on the hydrogen content. The products have been tested up to about 2 MGy absorbed dose. The FPM based elastomer, in spite of its lower dose absorption in fast neutron fields, features the largest variations of properties, with a dramatic increase in stiffness and brittleness. Out of the three EPDM based compounds, one shows large and rapid changes in the main mechanical properties, whereas the other two feature more stable behaviors. The performance of the EPDM rated as radiation resistant in pure gamma fields does not appear significantly better than that of the standard product. The predictive capability of the accelerated irradiation tests performed as well as the applicable concepts of threshold of radiation damage is discussed in view of the use of the examined products in the selective production of exotic species facility, now under construction at the Legnaro National Laboratories of the Italian Istituto Nazionale di Fisica Nucleare. It results that a careful account of dose rate effects and oxygen penetration in the material, both during test irradiations and in operating conditions, is needed to obtain reliable predictions.

Carbonate Rocks | Dimension Stones| Western Desert of Iraq | Physical and Mechanical Properties | ASTM | الصخور الكاربوناتية | الصخور البعدية | الصحراء الغربية العراقية | الخواص الفيزيائية و الميكانيكية | المواصفات الأمريكية لاختبار المواد

In Kurdistan NE of Iraq extensive beddings of well bedded carbonate rocks deposited within Tertiary- Cretaceous age. For this purpose various studies of petrographic, physical, mechanical, and chemical properties for building construction were carried out. Appearance of rocks was measured in the field by thickness of the beddings, joints, fractures, and brightness. The petrographic study achived under transmitted light microscope for diagenesis, weathering, allochems, and matrix. Measuring specific gravity, density, water absorption, moisture content, porosity, and saturation coefficient to qualify the rock according to its physical properties, whereas measuring compressive strength of the rocks were determined for qualifying the mechanical properties, the XRF test for determining the oxides and durability tests for qualifying their chemical properties. Eleven samples selected from Qamchuqa Formation in Binabawi anticline, Aqra-Bekhme Formation in Shakrok anticline, Shiranish Formation in Pirat anticline, Shiranish Formation in Harir anticline, Shiranish Formation in Safin anticline, Shiranish Formation in Shakrok anticline, Pila Spi Formation in Pirmam anticline, Khurmala Formation in Bina Bawi anticline, Fatha Formation in Kori syncline, Anah Formation in South Qara Chugh anticline, and Euphrates Formation in North Qara Chugh anticline. The results in terms of economic demand for building and dimension stones showed that samples of Shiranish Formation from Pirat, Safin, Harir, and Shakrok anticline are highly recommended as dimension stone and building stone, while samples of Qamchuqa, Aqra-Bekhme, Pilaspi, Khurmala, and Euphrates Formations are accepted but not recommended as dimension stone and dimension stone, samples of Fatha and Anah Formations are not accepted as dimension stone, but accepted as building stones as an insulator.

The escalating construction industry has led to a drastic increase in the dimension stone demand in the construction, mining and industry sectors. Assessment and investigation of mining projects and stone processing plants such as sawing machines is necessary to manage and respond to the sawing performance; hence, the soft computing techniques were considered as a challenging task due to stochastic optimization of this issue and to handle complex optimization problems. In this study, Particle Swarm Optimization (PSO) and Artificial Bee Colony (ABC) algorithms as soft computing techniques were used to classify the dimension stones based on physical and mechanical properties and ampere consumption. For this purpose, varieties of dimension stones from 12 quarries located in Iran were investigated. Studied dimension stones were classified into two and three separate clusters using the optimization clustering techniques. The results showed that the applied soft computing technique makes it possible to evaluate the performance of sawing machines in different complex conditions and uncertain systems.

Serpentinites are widely distributed in Egypt, particularly in central and southern parts of the Eastern Desert. There are several inter-related factors that affect the use of serpentinites as dimension stone. These factors involve mineralogical characteristics (including mineral compositions and microstructural parameters), physical properties, and mechanical properties. The main factor identified in this study is orientation of foliation planes in serpentinites. Samples that are selected parallel to foliation planes have higher mechanical properties than those perpendicular to it. Antigorite is the essential serpentinite mineral with minor amounts of chrysotile. Talc, carbonates (magnesite and dolomite), and tremolite are the main associated minerals. Quality and quantity of associated minerals such as talc and carbonates greatly influence the proper use of serpentinites as dimension stone. Studied serpentinites are characterized by relatively small grain size and foliated texture, low water absorption, low porosity, and high abrasion resistance. Physico-mechanical properties of studied serpentinites as well as mineralogical characteristics lead us to conclude that these serpentinites are suitable for specific applications as dimension stone.

In this research work a direct extrusion unit has been designed and manufactured for circular section using the theoretical die design concepts for designing of the die profile, as constancy of the ratio of successive generalized homogeneous strain increment (CRHS). This was carried out by studying the final mechanical properties of the direct extruded products through dies with theoretical concept (ACRHS) and (UCRHS). Commercial alloy AA1100 round section billets was subjected to uniform extruded compressive load using two types of extrusion dies i.e. (ACRHS) and (UCRHS) at room temperature. The product of these dies with as received were conducted to testing under tensile and fatigue tests without corrosion and with corrosion of 90 days fully submersed in 0.35 % NaСl solution. The experimental results show that the reduction percentage (RP) in the main mechanical properties, UTS, YS and BHN due to corrosion were 14.28 %, 5.88 % and 12.12 % for as received samples, 2.74 %, 5.08 % and 6.12 % for the ACRHS samples and 7.79 %, 6.86 % and 8.88 % for UCRHS samples respectively. It was concluded that the less reduction percentage was occurred in the ACRHS samples compared to other samples. Corrosion fatigue testing of the above three samples were made and compared to the same samples without corrosion. The testing results revealed that the corrosion is significantly reduce the fatigue strength at 107 cycles from 40 to 33.65 MPa for as received samples, from 49.47 to 46.73 for ACRHS samples and from 49.5 to 45.89 MPa for UCRHS samples. The results may be lead to the best mechanical and fatigue properties under corrosion action are the ACRHS samples. The obtained results show that the extrusion die (ACRHS) is the most efficient die design

Multifractal analytical method and experimental study on crack evolution of dismantled RC hollow-slab beam

Mechanical properties of flexible graphite: review

This study presents two objective evaluation tools for assessing the feasibility of granitic rocks in dimension stone applications. The developed methods integrate fundamental physical and mechanical properties, including dry density (ρd), effective porosity (ne), P-wave velocity (Vp), uniaxial compressive strength (UCS), and Böhme abrasion value (BAV). Feasibility analyses based on the conditional formatting (CF) and ranking method RM reveal that the adopted input parameters are essential for determining the suitability of granitic rocks as dimension stones. The strong relationship between the CF and RM results highlights their consistency and broad applicability. Both methods exhibit good agreement with the recommendations of the American standard for granitic rocks. Consequently, the suggested methods provide practical guidance for selecting suitable rock exposures in field studies, also offering a time- and energy-efficient decision-making framework for the dimension stone industry. To comprehensively evaluate the strengths and limitations of the proposed approaches, it is recommended that these tools be applied to a wider range of dimension stone types and geological settings.

Deformational and breakage behaviors of concrete and cement mortar greatly influence various engineering structures, such as dams, river bridges, ports, tunnels, and offshore rig platforms. The mechanical and petrophysical properties are very sensitive to water content and are controlled by the liquid part in pore spaces to a large extent. The objective of this paper is to investigate the water saturation effect on the strength characteristics and deformability of cement mortar under two loading conditions, static and dynamic compression. A set of cement mortar samples was prepared and tested to study the mechanical behavior in dry and saturated states. The first part of the research incorporates the study of static mechanical properties for dry and brine-saturated cement mortar through uniaxial compressive strength tests (UCS). Second, drop-weight impact experiments were carried out to study the dynamic mechanical properties (impact resistance, deformation pattern, and fracture geometry) for dry and saturated cases. The comparative analysis revealed that water saturation caused substantial changes in compressive strength and other mechanical characteristics. Under static loading, water saturation caused a reduction in strength of 36%, and cement mortar tended to behave in a more ductile manner as compared to dry samples. On the contrary, under dynamic loading conditions, water saturation resulted in higher impact resistance and fracture toughness as compared to dry conditions. In addition, fractures could propagate to smaller depths as compared to dry case. The study will help resolve many civil, mining, and petroleum engineering problems where cement structures undergo static as well as dynamic compression, especially in a hydraulic environment where these structures interact with the water frequently. To the best of our knowledge, the effect of water saturation on the dynamic mechanical properties of cement mortar has not been well understood and reported in the literature.

The investigation of the effects of water saturation and fatigue stress on rock's mechanical properties is crucial for designing and maintaining water-rich roadways. Fatigue loading and uniaxial compression tests were performed on shale samples subjected to varying water saturation durations. Mechanisms governing the deterioration of the samples' mechanical properties due to water saturation and fatigue loading were analyzed. Both factors reduced the peak strength and peak strain of the samples. Longer saturation durations increased global damage. As saturation duration increased, the stress–strain curve under fatigue loading showed greater irregularities, and fatigue damage between hysteresis loops progressively diminished. The effects of water saturation and fatigue damage on mechanical properties were interdependent. Their combined impact was less than additive, following a “1 + 1 < 2” pattern. Fatigue loading's influence on deformation, strength, and damage decreased with increasing saturation duration. Prolonged saturation also reduced the cumulative Acoustic Emission (AE) parameters and plastic strain under fatigue loading. In terms of failure characteristics, under the same proportion of fatigue loading, fatigue failure degree was negatively correlated with damage extent from saturation. By integrating water saturation duration, AE parameters, and plastic strain, a water saturation and fatigue damage model based on the complex plane was developed. This model, with cumulative AE parameter analysis, identified a threshold for the interaction between water saturation and fatigue-induced damage. Beyond this threshold, the sample's sensitivity to fatigue damage decreased.

A study was conducted to determine the influences of initial planting densities, thinning intensities, exposures and slope sites on physical property (wood density) and mechanical properties such as modulus of elasticity (MOE), bending strength, impact strength, compression strength along grain and hardness) of Pinus sylvestris var. mongolica plantation in Mao’ershan Forest Farm, Northeast China. Results show that the different initial planting densities (1.5 m×1.0 m, 1.5 m×2.0 m and 1.5 m×2.5 m) had significant effects on wood density and MOE, and the highest mean wood density and indexes of mechanical properties occurred in the stand with an initial planting density of 1.5 m×1.0 m. The indexes of mechanical properties such as hardness of end, bending strength, MOE and compression strength along grain of wood increased after mild thinning, but decreased after violent thinning. The exposures (sunny slope and shady slope) had a significant effect on MOE, and the highest mean MOE occurred on sunny slope. The slope sites (upper site and lower site) had a significant effect on wood density and main mechanical properties, except hardness. The highest mean wood density and mechanical properties occurred at lower site.

Organophosphazenes are of interest due to the combination of increased mechanical and thermal properties of polymer materials obtained with their use, however, they are characterized by a complex multi-stage synthesis. Moreover, the high viscosity of phosphazene-containing epoxy resins (PhER) makes their processing difficult. To simplify the synthesis of PhER, a one-step method was developed, and bisphenol F was chosen, which also provided a decrease in viscosity. In the current study, PhER were formed by a one-stage interaction of hexachlorocyclotriphosphazene (HCP) with bisphenol F isomers and epichlorohydrin in the presence of alkali, which was a mixture of epoxycyclophosphazenes (ECPh) with a functionality from 1 to 4 according to the results of MALDI-TOF analysis. Conventional epoxy resins based on bisphenol F, also formed during the process, showed high mechanical properties and glass transition temperature, and the reactivity of the obtained resins is similar to the base epoxy resins based on bisphenols A and F. Cured PhER had higher or the same mechanical properties compared to base epoxy resins based on bisphenol A and F, and a glass transition temperature comparable to base epoxy resins based on bisphenol F: glass transition temperature (Tg) up to 174.5 °C, tensile strength up to 74.5 MPa, tensile modulus up to 2050 MPa, tensile elongation at break up to 6.22%, flexural strength up to 146.6 MPa, flexural modulus up to 3630 MPa, flexural elongation at break up to 9.15%, and Izod impact strength up to 4.01 kJ/m2. Analysis of the composition of the obtained PhER was carried out by 1H and 31P NMR spectroscopy, MALDI-TOF mass spectrometry, X-ray fluorescence elemental analysis, and contained up to 3.9% phosphorus and from 1.3% to 4.2% chlorine. The temperature profile of the viscosity of the resulting epoxy resins was determined, and the viscosity at 25 °C ranged from 20,000 to 450,000 Pa·s, depending on the ratio of reagents. The resins studied in this work can be cured with conventional curing agents and, with a low content of the phosphazene fraction, can act as modifiers for traditional epoxy resins, being compatible with them, to increase impact strength and elasticity while maintaining the rest of the main mechanical and processing properties, and can be used as a resin component for composite materials, adhesives, and paints.

The purpose of this study is the application of meta-heuristic algorithms and fuzzy logic in the optimization and clustering to predict the sawability of dimension stone. Survey and classification of dimension stones based on their physical and mechanical properties can be so impressive in the optimization of machine applications that are in this industry such as circular diamond saw block cutting machine. In this paper, physical and mechanical properties were obtained from laboratory testing on dimension stone block samples collected from 12 quarries located in Iran and their results were optimized and classified by one of the strongest meta-heuristic algorithms and fuzzy clustering technique. The clustering of dimension stone was determined by Lloyd’s algorithm (k-means clustering) based on imperialist competitive algorithm and fuzzy C-mean by MATLAB software. The hourly production rate of each studied dimension stones was considered as a criterion to evaluate the clustering efficacy. The results of this study showed that the Imperialist Competitive algorithm and fuzzy C-mean are very suitable for clustering with respect to the physical and mechanical properties of the dimension stone, and the results obtained showed the superiority of the ICA.

Zeolite-rich volcanic tuffs are widely distributed in almost every country of the world, where they are present in low-, medium-, or high-grade million-ton deposits. Even though the formation of the zeolite minerals may have followed different genetic paths, the zeolitic rocks have in common a matrix of finely crystalline zeolite that cements the other nonzeolitic particles and is responsible for the overall mechanical properties of the material. Zeolitic tuffs have been employed since pre-historic times in construction, mostly as dimension stone. This use is still the most common of natural zeolites in the building industry, although other applications have recently come to the forefront, such as lightweight aggregate or as additives for manufacturing blended cements. Given the fact that much of this material is excavated and used locally and that the market demand is strongly affected by the trends of the building industry, estimates of the worldwide zeolitic tuff production for construction purposes are difficult to make. In Italy, where the use of zeolitic tuff as dimension stone is commonplace, about 75 quarries were reported in operation in 1992 with total production of about 3 x 106 tons per year (Aiello 1995). More recently, this production has decreased, due to the crisis of the building industry, and in 1998 it amounted to about 1.5 × 106 tons per year. In Japan, the production of tuff as dimension stone is currently about 4 × 105 tons per year (N. Kuchitsu, National Research Institute of Cultural Properties, Tokyo, Japan, pers. comm., 1996). Considering that zeolitic tuff is used as dimension stone in many other countries as well, e.g. Bulgaria, Cuba, Germany, Greece, Hungary, Mexico, Romania, and Turkey, the current worldwide zeolitic tuff consumption as dimension stone is about 3 × 106 tons per year. Information is even more …