amin jamshidi

The present paper aims to investigate the performance of P–wave velocity (Vp) and Schmidt hardness (SH) to predict the uniaxial compressive strength (UCS) of the limestone using simple and multiple regression analyses. For this purpose, twenty limestone samples were collected from Asmari Formation, Lorestan Province (Iran) and their UCS, Vp, and SH were determined. The simple and multiple regression equations have been developed for predicting the UCS from Vp and SH. To check the accuracy and validity of the regression equations, the determination coefficient (R2), standard error of estimate (SEE), the diagonal line (1:1), and analysis of variance (ANOVA) were used. In addition, the validity and performance of the regression equations in predicting the UCS were investigated using the raw data obtained from the experimental works of several researchers and statistical indices. There are moderate correlations between UCS with Vp and SH with the R2 values of 0.86 and 0.71, respectively, whereas there is a strong multiple correlation with an R2 of 0.92 for predicting the UCS when both Vp and SH are considered. According to the results of R2, SEE, diagonal line, and variance analysis, the multiple regression equation was more reliable than the simple regression equations for predicting the UCS. Overall, it was concluded that the multiple regression equation has acceptable performance for predicting the UCS of the limestone in other regions of the world. As a result, the multiple regression equation avoids the UCS test, which is cumbersome and time-consuming for determining the UCS of the rocks.

Evaluating the cutting rate (CR) of stones is important in the cost estimation and the planning of the stone processing plants. This research used regression models to estimate the stones’ CR based on their physico-mechanical characteristics. Stone processing factories in Mahallat City (Markazi province, Iran) were visited, and the CR of diamond circular saws was recorded on six different travertine stones. Next, the stone block samples were collected from the quarries for laboratory tests. Stones’ porosity (n), uniaxial compressive strength (UCS), and Schmidt hammer hardness (SH) were determined in the laboratory as their physico-mechanical characteristics. Correlation relationships of CR with physico-mechanical characteristics were evaluated using simple and multiple regression analyses, and estimator models were developed. Results showed that multiple regression models are more reliable than simple regression for estimating the stones’ CR. The validity of the developed multiple regression models was verified with the published data of one researcher. The findings indicated that these models are accurate enough for estimating the CR of stones. Consequently, the multiple regression models provide practical advantages for estimating the CR and save time and cost during the planning and design of the stone processing factories.

Brittleness index is one of the important parameters in rock engineering, which affects the drillability of the rocks in various geotechnical projects such as tunnels, caves, dams, oil and gas wells, road trenches, and building stone quarries. Investigating the drillability of the rocks before drilling operations can significantly help planning and managing the implementation of geotechnical projects, which will save time and cost of exploration operations. In this paper, the drillability of two laminated sandstone samples (with various lamination spacing) has been investigated based on the brittleness index, considering the orientation and spacing of lamination. For this purpose, after preparing cylindrical cores, uniaxial compressive strength and Brazilian tensile strength of sandstone samples at lamination angles (β) of 0°, 30°, 45°, 60°, and 90° were determined. Next, based on the results of these strengths, the brittleness index values were calculated in the various βs. Based on the data analysis, lamination orientation plays a significant role in the drillability, so that the easiest and hardest drilling conditions are obtained at β of 30° and 90°, respectively. Also, the results indicate that the sandstone sample with lesser lamination spacing had more suitable conditions in terms of drillability compared to other sandstone samples. In the end, the findings of the present research can be useful and efficient in practice for geotechnical projects that require drilling in laminated rocks.

In this research, the process of growth and the optimum length of ZnO nanorods has been studied as a subject of semiconductors, that are used in the photoelectrochemical solar cell made by Sol-Gel and Hydrothermal method.These Nano structures, having suitable gap, cause the decomposition of water into its constructing elements, hydrogen and oxygen.The most length of nanorods achieved by the FTO sublayer and deionized water solvent, at 95°C growth temperature, while 3 hours growing time, and on these conditions caused the length of nanorods to be 1500 nanometers, with the biggest length to width ratio 15.Also, at the final stage, photoelectrochemical experiments and the effects of nanorods length to the decompositionof water was studied. The results of photoelectrochemical experiments showed the optimum quantity for nanorods.The best result of photoelectrochemical has been reached to the maximum ratio of length to width 10, and the maximum length of nanorods 1000 nanometers that has been grown at the temperature of 95°C and during 2 hours.

This research was conducted in order to evaluate the level of heavy metal contamination of the soils in the vicinity of the Yellow Flower lead and zinc mine. For this purpose, heavy metals of 33 surface soil samples of the mining area were analyzed with AAS flame atomic absorption spectrometer. The indices of origin and determination of the degree of pollution including enrichment index (Ef), accumulation index (Igeo) and pollution index (Cf) were calculated to evaluate soil contamination with heavy metals. According to the results, the average concentration of heavy metals including scandium, arsenic, yttrium, cadmium, copper, nickel, vanadium, chromium, lead, barium, manganese and zinc are 20.93, 28.19, 35.84, 56.2, and 90 respectively. 63/69, 71/69, 141/39, 176/39, 197/22, 404/87, 475/55, 492/27 mg/kg, where zinc is the highest and scandium is the lowest. Also, the results showed that the studied area has no general pollution with heavy metals. The concentration of some heavy metals such as lead, zinc and cadmium is very high in some places, which has caused the soil pollution to increase. This issue is due to the type of minerals in the mining area, including sphalerite and galena

The salty running water from Gachsaran Formation in Robat Namaki region, north of Khorramabad city, has caused salt weathering of some rocks in the region. Salt weathering due to the salty running waters of the region is one of the reasons for changing the geomechanical properties of rocks, and as a result reducing their durability. In current research, the effect of salty running waters on the geomechanical properties of outcropping rocks in Robat Namki region has been studied by conducting salt weathering tests. For this purpose, two samples of limestone and sandstone have been prepared and salt weathering tests have been performed on them for 30 cycles in salty running water, spring water and saturated salt solution. After every 5 cycles, the point load index and porosity of the samples were determined. Fitting curves between salt weathering test cycles with point load index and porosity were developed for all three test solutions, and parameters of decay constant and half-life were obtained from them. The effect of the three test solutions on the samples has been evaluated using these parameters, as well as the percentage of changes of the point load index and porosity. The results show that saturated salt solution, spring water and salty running water had the greatest to least effect on the changes of point load index and porosity of the samples, respectively. Also, data analyses shows that sandstone is more affected by salt weathering due to its higher porosity and layered than limestone.

Soil is one of the essential building materials, and the primary support of structures has long been a human interest. However, due to weakness in shear strength and lack of resistance to tensile forces, researchers have consistently sought to increase its bearing capacity, strength, and improve its properties and various methods including mechanical modification such as compaction, chemical modification such as treatment with lime, cement or salt. The purpose of this study is investigation of the effect of sodium chloride salt on the geotechnical properties of loess soil. Loess soil was sampled from a Golestan province region and transferred to the Soil Mechanics Laboratory of the Shams University of Gonbad-e-Kavos. Sodium chloride salt was added to soil sample with content of 3, 6 and 9% by weight of soil. Soil samples were prepared in normal condition (without additives) and with different content of sodium chloride for geotechnical properties tests. The results show that the addition of sodium chloride salt reduces the plastic and liquid limits in the Atterberg limits test, increases the dry weight unit weight and decreases the optimum moisture in the compaction test, increases the strength in the unconfined compressive strength test and increases the cohesive and friction angle in the direct shear test.

Strength measurement of rock requires testing that must be carried out on test specimens with particular sizes in order to fulfill testing standards or suggested methods. Often, the coring process breaks up the weaker core pieces, and they are too small to be used in either index tests or conventional strength tests such as point load index (Is) and Brazilian tensile strength (BTS). One of the index tests to indirectly determine the rock strength is the block punch index (BPI) test, which requires flat disc specimens without special treatment. This study aimed to evaluate the applicability of the BPI test for predicting the uniaxial compressive strength (UCS), BTS and IS of the sandstones by empirical equations. Also, we have compared the performance of the BPI and IS for predicting the UCS and BTS. It was experimentally shown that BPI is a reliable method for predicting the UCS, BTS and Is of the sandstones under study. Moreover, the results indicate that BPI could be utilized with same importance as Is for predicting the UCS, while predicting the BTS by Is appears to be more reliable than BPI.

Esfidan village is one of the historical and tourist areas in 45 km southeast of Bojnourd in North Khorasan, which is located in a mountainous area. The rock falls in this area can lead to the closure of the village communication road and also damage to part of the village houses. In this paper, the possible occurrence of rock fall is analyzed by software and also the risk of rock fall in it is evaluated. Field investigations have shown that rock falls in this area are mostly due to the tectonics of rock units, the presence of discontinuities, seasonal precipitation or a combination of these factors. Jointing studies have shown that the main discontinuities in the rock slope consist of three sets of joints with two major layers. Also, sampling of rock layers and performing various physico-mechanical tests indicated that the rock layers are mainly made of high-strength limestone. Software analysis of rock fall in this slope was performed on two selected sections by Rock fall software. Then, by combining the data obtained from the software analysis of rock fall and also the field data collected from the status of the slope activity, using evolutionary method, the potential of rock fall in two selected sections was evaluated. The results showed that the slope is in the middle to high risk category in terms of the risk of rock fall and needs to implement protective measures to prevent damage to roads and residential houses.

Accurate estimation of the rotary drilling rate of the rock can save time and cost on exploration operations of the geotechnical projects such as dams, tunnels, oil and gas wells and building stone mines. In this study, the rotary drilling rate in limestone is estimated based on brittleness indices. To achieve this goal, the values of rotary drilling rate, Uniaxial compressive strength (UCS) and Brazilian tensile strength (BTS) were determined in three exploratory wells drilled in limestone. Based on the data, the regression relationships of one, two and three variables between rotary drilling rate as a dependent parameter and brittleness indices as an independent parameter were developed. The results suggest that based on one- and two-variable regression relationships, rotary drilling rate can be estimated based on brittleness indices with relatively good accuracy. In addition, the results showed that the three-variable regression relationship was more accurate than the one- and two-variable in estimating the rotary drilling rate. Finally, the three-variable relationship presented in this study could be appropriate in the early stages of exploration operations for geotechnical projects in limestone, which saves time and money.

The ultrasonic pulse velocity including P-wave (Vp) and S-wave (Vs) velocity and elastic constants including the elastic modulus (E) and Poisson’s ratio (ν) are among most important parameters for estimating the strength and deformability properties of rocks. The specimen diameter size is one of the main factors that influence Vp, Vs, E and ν. This study presents the influence of specimen diameter size on the Vp, Vs, E and ν of sandstones. Moreover, we have investigated the accuracy of porosity (n) for estimating the Vp, Vs, E and ν at different diameters size. For this purpose, 10 sandstone samples were collected and core specimens with a diameters size of 24, 40, 54, 68, and 80 mm were prepared. Then, density (ρ), n, Vp, Vs, E and ν of sandstones were determined. It is concluded that the specimen diameter size has a significant influence Vp, Vs, E and ν. Moreover, the results showed that n is in good accuracy for estimating the Vp, Vs and E, while there are no meaningful correlations between ν with n.

Soils are discontinuous cover at the surface that may be composed of rocks and sediments in situ or by material transport. Heavy metals are one of the most important soil pollutants that can have a major impact on the health of living things and, above all, humans. Heavy metals, which enter the human body, can accumulate in the tissues and affect the nervous system and circulation. These metals also impair the normal functioning of the internal organs or may be auxiliary to other diseases. Elements such as mercury, lead, cadmium, chromium, nickel, zinc, selenium and the like are elements that are highly resident in the soil and have low mobility, so they may remain in the soil for many years. Such contaminants in the soil are caused by the addition of sludge, phosphate fertilizers, atmospheric sinks, color wastes and smoke from natural fuels, coal and other sources. Numerous studies have been carried out on the distribution of heavy metals in various soils such as urban, industrial, etc. Considering the importance of heavy metal contamination in soil and its effect on the health of living organisms, especially humans, this study was conducted to evaluate the concentration and contamination of heavy metals in soils north of Fereydoon Shahr (Isfahan province) using environmental indices; Geoaccumulation index, pollution load index, enrichment factor and pollution index were performed. The spatial distribution of heavy metal concentrations in the study area is also investigated.

Groundwater salinization in semiarid regions is a limiting factor of use with strategic importance. In this study, the sources of salinity, chemistry, and quality of groundwater in Robat (Khorramabad plain, Iran) were identified through the geochemical methods. Using data analysis, the concentration of cations and anions were recognized with the order of Ca2+>Na+ >Mg2+>K+ and HCO3-> Cl-> SO42+> NO3-> F-, respectively. The high concentration of Na+, Cl-, and EC in some places is attributed to the gypsum and salty formations. In the study area, the salinization processes are identified by natural and artificial activities. The salinization mechanisms are identified by the natural dissolution of gypsum and salt from Gachsaran formation and man-made sources including boreholes drilled through Gachsaran Formation, salt mining, and agricultural activity. Also, the high concentration of nitrate is related to agricultural fertilizers and karstification effects. It is seen that the atmospheric NO3-. HCO3-, Ca2+, and Mg2+ concentration exceeded the standard limit in a few samples probably due to the calcareous formation. Besides, hydrochemical facies of the groundwater are Ca- HCO3 and Na-K-HCO3. Due to the presence of calcareous and salt bearing formations, 46%, 26%, and 20% of all samples show a higher concentration of Ca2+, Na+, and Mg2+, respectively, which exceed the permissible limits. Sulfate and fluoride concentrations are less than the permissible limits. However, due to the presence of calcareous formation, salt bearing formation, and use of agricultural fertilizers, 100%, 26%, and 20% of all samples show a higher concentration of HCO3-, Cl-, and NO3- than the permissible limits.

Loess soil is one of the problematic soils that should be improved its geotechnical properties before the project is implemented. Lack of attention to this issue has caused in many problems for civil projects in Golestan province. This has been more evident in some of the rural areas built on this type of soil. Moreover there are many reports regarding different geological hazard such as subsidence, divergence, erosion and landslide in Golestan loess soil. Among the different types of loess soils found in Golestan province, silty loess should be given more attention due to their large extent and being the bed soil of many villages, and many reports of its hazards.One of the methods for improving soil mechanical behavior andits geotechnical properties is to use additives to reduce geological hazards. Due to the fine-grained structure of loess soils, the application of nanoparticles is more efficient and could result in solving many of the related problems. Nanotechnology is new scientific field which affects many aspects of engineering and in recent years, many efforts have been made to use this new technology in various geotechnical branches.So far, research has been carried out on the improvement of various soil types with additives such as cement, bitumen, ash, lime and various types of nanoparticles. Nowadays, the use of nanoparticle additives due to reduction of environmental pollution than other additives has a wider application in improving the physical and chemical properties of problematic soils.In the present study, the effect of nano-kaolinite on strength properties including uniaxial compressive strength, elasticity modulus, cohesion, and internal friction angle of silty Loess in Kalaleh city of Golestan province have been investigated.

In order to carry out the present research, sample of the silty loess soil from Kaleh city of Golestan province was collected and prepared. Then, 0.5, 1, 1.5, 2, 3 and 4 weight percent of nano-kaolinite were added to soil samples. The soil samples were prepared in a natural state (without additives) and with the additive for uniaxial compressive strength and direct shear tests. Strength properties of soil specimens including uniaxial compressive strength, elastic modulus (based on uniaxial compressive strength test), cohesion and internal friction angle (based on direct shear testing) were determined for native soil and its mixture with different percentage of nano-kaolinite. The data were analyzed and the effect of nano-kaolinite on the strength properties of the silty loess soil sample was investigated.

Uniaxial compressive strength and modulus of elasticity have been increased with increasing amount of nano-kaolinite, and after 2% nano-kaolinite, increase in nano-kaolinite did not have any significant effect on uniaxial compressive strength and modulus of elasticity. The uniaxial compressive strength and the modulus of soil elasticity in the natural state (without nano-kaolinite) are 1.12 and 15.89 kg/cm2 respectively, and when 2% of the nano-kaolinite is added to the soil, the values ​​of these properties are maximal and reached to 1.19 and 18.10 kg/cm2, respectively.For native soil (without nano-kaolinite), the cohesion value is equal to 0.09 kg/cm2, and with increasing nano-kaolinite from 0.5 to 2%, the cohesion shows an incremental trend and reached to 0.16 kg/cm2. With increasing the additive percent from 2 to 4% the amount of cohesion were constant and equal to 0.16 kg/cm2. The increasing of cohesion can be attributed to the fact that nanoparticles enhanced water absorption of soil particles which caused in better cohesion and also they affected chemical actions and surface electrical charge of soil particles.

The results of the uniaxial compressive strength tests show that adding up to 2 weight percent Nano-kaolinite to the dry soil increases the uniaxial compressive strength and modulus of elasticity of silty loess soil in the Golestan province, which can be due to proper locking between the nanoparticles and soil particles and increased cohesion.The results of direct shear tests showed that adding up to 2% nano-kaolinite to dry soil increased the cohesion of the soil and consequently increased the shear strength of the soil.On the other hand, adding the different amount of nano-kaolinite has not changed much in the internal friction angle of the silty loess soil in the Golestan province.

In this study, lime and glass fibers were used to improve the silty loess soil. To achieve this, the silty loess soil was sampled from a region of Golestan province and transferred to the Soil Mechanics Laboratory of the Shams University of Gonbad-e-Kavos. Then, in order to compare soil stabilization and reinforcement, the effect of lime and glass fiber each individually and simultaneously on geotechnical characteristics of silty loess soil has been investigated. The percentages of mixing for lime is (0%, 4% and 8% of dry weight of soil) and glass fiber (0%, 0.3%, 0.6%, 0.9%, 1.2%, 1.5% and 2% of dry weight of soil). The effect of mixing rate and different curing periods on the compaction behavior, compressive strength and shear strength of the samples have been investigated. The results of unconfined compressive strength tests showed that adding glass fiber to lime stabilized soil significantly increases the compressive strength of the samples and increases the strain of the rupture and also reduces the width of the cracks. In the direct shear test, it was observed that mixing the soil with lime and glass fibers increases the shear strength, increases displacement at failure, increases the friction angle of the soil and increases cohesion. Unconfined compression strength and direct shear tests showed that there is a fiber percentage that by increasing the fiber percentage from that, the strength decreases. This amount of fiber was obtained in most tests between 0.9 to 1.2% fibers.

Uniaxial compressive and Brazilian tensile strengths (UCS and BTS) of rocks are considered important properties in the design of most the geotechnical projects that interact with rock such as slope stability and underground excavation. Measuring UCS and BTS using standard laboratory tests are time consuming, tedious and expensive. Moreover, it requires a large number of well-prepared rock cores that is often not, particularly in soft or highly jointed rock masses. For these reasons, indirect tests such as Schmidt hammer hardness (SH) can be used for prediction of UCS and BTS of rocks. There is a wide variation in the recommended SH test procedures by institutions and various researchers. The objective of this study is to evaluate the performance of SH testing procedures for prediction of UCS and BTS of rocks. For this, 22 sandstone samples from Qum Province, central Iran, were selected and their UCS, BTS and SH were determined. Using data analysis, correlation equations have been developed between UCS and BTS with SH. To check the validity of the correlation equations, a t–test was performed. Results showed that SH test procedures based on continuous impacts at a point reveals the lower values than that based on single impacts. Further, it was found that SH test procedures have different performance for prediction of UCS and BTS of rocks

In the present study, the effect of density (ρ) and porosity (n) on the accuracy of correlation between uniaxial compressive strength (UCS) and modulus of elasticity (E) with Schmidt rebound hardness (HR) was investigated. For this purpose, 15 different limestones were selected and their petrographical characteristics, physical (ρ, n) and mechanical (UCS, E, HR) properties were determined. In the following, simple and multivariable regression analyses based on the HR, ρ and n for estimating the UCS and E were proposed. The relationships proposed based on the statistical tests have been investigated, which indicates their appropriate accuracy. Comparison of simple and multivariate relationships shows that ρ, n play an important role in increasing the estimation accuracy of UCS and E from HR. Moreover, the results show When HR and ρ be used as the input parameter in the regression analysis, the value of the determination coefficient for estimating the UCS and E are 0.88 and 0.83, respectively. Whereas, if HR and n be used as input parameters, the value of the determination coefficients for estimating the UCS and E are 0.91 and 0.74, respectively.

The durability of stone against environmental degradation factors is one of the most important issues related to stone selection for use in engineering structures, in particular stone stones. The crystallization of soluble salts is one of the most important weathering factors in nature, which can affect the mechanical properties of rock (such as uniaxial compressive strength and Brazilian tensile strength) and, over time, can decay and reduce its durability. In this research, a physico-mechanical parameter has been introduced that can assess the mechanical properties of rocks and thus their durability against salt weathering with accurate accuracy. To achieve the research objectives, 15 travertine samples were selected from different mines in Iran. Travertine samples were prepared to determine the physical properties (water absorption, mean pore diameter) and mechanical properties (uniaxial compressive strength and Brazilian tensile strength). Then, the physico-mechanical parameter was calculated, based on the combination of water absorption, mean diameter of the pores and mechanical properties. By performing bivariate regression analysis, the relationship between physico-mechanical parameter with uniaxial compressive strength and Brazilian tensile strength after the salt weather test was investigated and the most suitable relationships for estimating the durability of the samples using a physico-mechanical parameter against weathering is presented. The results show the correct accuracy of the physico-mechanical parameter for estimating the durability of the studied samples. As a result, the Physico-Mechanical Parameter avoids performing a salt crystallization test, which is time-consuming and expensive.
The durability of stone against environmental degradation factors is one of the most important issues related to stone selection for use in engineering structures, in particular stone stones. The crystallization of soluble salts is one of the most important weathering factors in nature, which can affect the mechanical properties of rock (such as uniaxial compressive strength and Brazilian tensile strength) and, over time, can decay and reduce its durability. In this research, a physico-mechanical parameter has been introduced that can assess the mechanical properties of rocks and thus their durability against salt weathering with accurate accuracy. To achieve the research objectives, 15 travertine samples were selected from different mines in Iran. Travertine samples were prepared to determine the physical properties (water absorption, mean pore diameter) and mechanical properties (uniaxial compressive strength and Brazilian tensile strength). Then, the physico-mechanical parameter was calculated, based on the combination of water absorption, mean diameter of the pores and mechanical properties. By performing bivariate regression analysis, the relationship between physico-mechanical parameter with uniaxial compressive strength and Brazilian tensile strength after the salt weather test was investigated and the most suitable relationships for estimating the durability of the samples using a physico-mechanical parameter against weathering is presented. The results show the correct accuracy of the physico-mechanical parameter for estimating the durability of the studied samples. As a result, the Physico-Mechanical Parameter avoids performing a salt crystallization test, which is time-consuming and expensive

The influence of magnesium content on the mechanosynthesis of ZrB2–SiC–ZrC composite in Mg/ZrSiO4/B2O3/C mixture was investigated. Thermodynamic evaluations revealed that the amount of Mg played a main role, thereby; the overall reaction enthalpy and adiabatic temperature (Tad) changed by variation of magnesium content. According to differential thermal analysis (DTA) results, after 45min milling, the temperature of combustion reaction decreased to 576 ◦C and all the reactions occurred, simultaneously. The experimental findings indicated the type of reactions in the mixture powder with stoichiometric ratio (7mol Mg) was mechanically induced self-sustaining reaction (MSR). When the Mg content was within a range of 6-7mol, the magnesiothermic reduction was occurred in MSR mode and the carbothermal reaction was activated, hence; the carbon acted not only as a carbide former agent but also as a reductant. MSR mode magnesiothermic reduction and gradual carbothermal reduction were occurred when the Mg value was 11/2-6 mol. At lower Mg contents in mixture (5mol), the reduction reaction proceeded through a gradual mode and no carbothermal reaction occurred.

Salt crystallization is one of the most important weathering agents and may limit the durability of building stones. Salt crystallization induces stresses inside the pores of stones. Consequently, stone durability is closely related to its physical properties and strength. The purpose of this study was to propose a statistical model for estimating stone durability against salt crystallization considering both the physical properties and strength of the stones -utilizing multiple regression. For this purpose, 14 samples of building stones were selected and their mineralogical characteristic, physical properties, and strength (density, porosity, water absorption, uniaxial compressive strength, and Brazilian tensile strength) were determined. Then, the salt crystallization test at a sodium sulfate solution of up to 20 cycles was carried out, and the Dry Weight Loss (DWL) of samples was measured. The durability of each sample was assessed by the percentage of weight loss after the salt crystallization test. The relationships between stone durability and the physical properties and strength of the stones- using simple and multiple regression analyses- were investigated. Moreover, statistical models for estimating stone durability were proposed. These models show that stone durability can be estimated accurately by considering both the physical properties and strength characteristics.

Formation of Titania thin layer applied on steel substrate was prepared by dip coating method. Titanium Tetra Iso Propoxide (TTIP) was used as precursor. X-ray difraction (XRD) results showed that TiO2 crystallized in the anatase form. Formation of nano scale layer on the substrates was confirmed by scanning electron microscope (SEM)، transmission electron microscopy (TEM) and atomic force microscopy (AFM). The roughness of thin layer was affected by value of PEG، calcination temperature، number of dipping and pH of sol. In the samples without PEG، increase in number of dipping was led to decrease in roughness، however; different behavior was observed in the samples containing PEG. By increasing the pH value، the coating roughness was decreased.

In-situ testing techniques have proven to be successful in improving the speed and reliability of geotechnical investigations. One of the most common in-situ methods in engineering geology and site investigation is Cone Penetration Test (CPT)، which is mainly used for characterization of soils، as it is a robust، simple، fast، reliable and economic test that can provide continuous soundings of subsurface soil. Miniature Cone Penetration (Mini-CPT) Test is a new type of CPT but in diameter less than conventional CPT to determine the bearing capacity and strength parameters of loose to semi-dense soils at shallow depth. Mini-CPT needs lower force to penetrate into the soil، and its ability to identify very thin underneath layers is higher than CPT. In this research، a Mini-CPT apparatus was used in laboratory conditions to define the relationships between tip resistance (qc(MCPT))، friction resistance (f‌s(MCPT)) and some engineering properties of poorly graded sandy soils such as Relative Density (Dr)، Friction Angle (φ)، Elastic Modulus (E)، Shear Modulus (G)، and the Modulus of Subgrade Reaction (Ks) with different densities. Based on the results of the experiments، the relationships between both the qc (MCPT) and fs (MCPT) with engineering properties were obtained with a high determination coefficient (R2>0. 85).

Sialon ceramics are widely used in industrial applications because of high corrosion and oxidation resistance and high temperature properties. On the other hand, due to high costs of processing and raw materials, these materials used for special applications. The oxidation resistance of sialons is higher than that of Si3N4. Comparison between sialons showed that the highest amount of oxygen is available in x phase, therefore the oxidation resistance of x phase is higher than the others. X-sialon exhibits excellent chemical stability in contact with iron-based alloys at 1200°C. In this research, andalusite, kaolin, elemental Si powder and α-alumina were used as raw materials and the effects of aluminosilicate sources on the SRN process for x-sialon formation, with and without Y2O3, were studied. In order to study x-sialon formation, the samples were analyzed by XRD in different temperature and the reaction sequence of samples of andalusite precursor determined by DSC results. Results showed that in spite of more nitridation of Si in kaolin precursor samples, Y2O3 restricted nitridation process in all samples. In overall view, andalusite is more suitable precursor for x silaon formation via SRN process in comparison with kaolin, and Y2O3 leads to facilitate formation of x sialon from reaction between mullite and Si3N4. α-alumina is not appropriate source to supply lack of Al in component and it remains especially in kaolin precursor samples.

High refractoriness, chemical resistance to slag, production possibility of clean steel, environmental compatibility and low cost are some of the advantages of Dolomite refractories in steel industry. Because of availability of dolomite in Iran, production ofthese refractories is profitable. One kind of the Dolomite refractories is Doloma Graphite refractories that because of good resistance to corrosion and thermal shock have wide usage in cement and steel industries. In this research, the properties of Dolomite-Graphite refractories with different additives and tempering condition were evaluated. The samples were manufactured with different grain size distribution of Dolomite and various amounts of Graphite and resin. The raw materials and their thermalbehaviors were studied by XRF, XRD and STA. After preparing the samples, the physical and mechanical properties, slag corrosion and thermal shock resistances were evaluated. The properties of the samples were evaluated up to 11% total Carbon in thesystem. The reduction in MOR of the specimens, before and after heat treatment was determined as a measurement of thermal shock resistance. The slag corrosion test was conducted based on the crucible test, at 1600°C for 5 hrs. Then, the depth ofpenetration was measured. The obtained results showed that due to the gradual changes in thermal behavior of resin and its weight reduction, the low temperature properties of the system were affected. The results showed that CCS of the samples was increased at the beginning and then decreased, when Graphite was added to the system. The thermal shock and slag corrosion resistance were also improved by adding graphite to the system