modulus of elasticity

In pavement engineering, determining the structural properties of the pavement, including the elastic coefficients and layer thicknesses, is highly significant. These properties determine the performance of the pavement and have a direct impact on the pavement life. Using commercial software for numerical simulation engines to calculate pavement surface changes increases calculations cost due to the complexity of integrating it into the optimization engine. In these methods, there is a need for a pre-generated artificial database using the software, as well as the use of a neural network and an optimization algorithm. Therefore, to generate the analysis population, the software must be run with a set of different estimation modules to provide the necessary population for inverse analysis, which increases the need for computational costs. The main goal of the current research is to combine the quadrature differential numerical method as an accurate, efficient, and high-speed numerical method with the Gray Wolf Optimization (GWO) metaheuristic optimization algorithm in order to inversely calculate the redundant values ​​of the elastic modulus of pavement layers without using an artificial neural network and reducing the computational time. Results of the analysis with five independent runs showed that this method is able to achieve the desired response with a small number of populations and iterations.

Across the world, in an effort to reduce the use of plastic in packaging and its detrimental environmental impacts, innovative actions such as the production of composites are being undertaken. In this research, polyethylene was used as the polymer matrix, corn stalk fibers were used as the reinforcing agent, and maleic anhydride was used as a compatibilizer. The main objective of this study was to investigate the mechanical and physical properties of the produced composite material by varying the percentage and length of the corn stalk fibers. In this research, 20%, 30%, and 40% contents of corn stalk fibers were used in the composite product. Additionally, two different fiber length levels were tested, using mesh sizes of 40 and 80. Additionally, 5% of the compatibilizer maleic anhydride was also added to the product. The results have shown that the composite material with longer fiber lengths and higher fiber content (percentage) exhibited the highest moisture absorption. As the length of the fibers increased, the elongation or tensile strain of the samples decreased in the tensile strength tests. The findings show that longer fibers in the product increase the resistance to elongation or tensile deformation. In the flexural strength testing, increasing both the length and the percentage of the fibers led to an increase in the flexural modulus of the composite. The use of longer fibers and higher fiber content in the product leads to an increase in the flexural modulus of the composite. The results of this research show that varying the percentage and length of the corn stalk fibers in the polyethylene composite has a significant impact on the mechanical and physical properties of the material. Increasing the fiber length and percentage can improve moisture absorption and enhance resistance to dimensional and flexural changes in the composite.

In the present study, due to sustainable development and eco-friendly aims, alkali activated slag and fly ash were used as the geopolymer binder instead of cement in self-compacting concretes. The alkaline solution consisted of sodium hydroxide and sodium silicate solutions. Binder content was between 500-700 kg/m³ and water to binder (W/B) ratio varied from 0.45 to 0.48. Na₂O percentages were in the range of 5 - 7% and three ratios of coarse to fine aggregate (25/75, 30/70, 35/65) were used. Design of experiments was based on orthogonal L9 array of Taguchi methodology. A total of nine main mixes and three validation mixes were prepared. Fresh concrete characteristics and mechanical properties including compressive strength, splitting tensile strength, modulus of elasticity and water absorption were evaluated. The results demonstrated that the binder content and coarse to fine aggregate ratio were the most influential parameters on the mechanical properties. The highest compressive strength, splitting tensile strength and modulus of elasticity were belonging to the mixture with low W/B ratio and higher binder content by 58 MPa, 4.5 MPa and 32 GPa, respectively. Moreover, Taguchi method has a good capability (R²≥0.967) to analyze and predict the mechanical properties of self-compacting geopolymer concrete.

In this research, by reviewing the researches and articles, waste glass powder is investigated on the performance of asphalt mixture. In the last decade, these researchers have been using crushed glass in construction programs to prevent waste glass from being used as protective supplements and reducing the environment in construction. Crushed glass has been studied for use as materials in base and sub-base pavement layers, as well as concrete. Glass is the only material that can be completely recycled. This material is prepared by melting quartz sand, soda and lime, and also glass pieces. The glass game is collected as one of the recycled components. It is non-metallic and neither can nor does it burn, so its recovery is possible. Therefore, it is used in road construction as a substitute for stone materials in asphalt pavement with warm asphalt mixture. It showed that the addition of glass powder increases the stability of the mixture, because the glass powder filler improves the Marshall Stability results for all mixtures compared to Portland cement or limestone powder fillers. The results showed that the powder from the mixture decreases against the glass. Also, the obtained results investigated the suitability of glass as filler.

The use of conventional concrete has always faced challenges due to environmental pollution and low durability against corrosive chemical environments. In this regard, alkaline concrete with high properties and minimal environmental damage has attracted the attention of researchers. In the present laboratory research, a mixing design of control concrete and three mixing designs of reinforced slag concrete containing 0, 4 and 8% nanosilica were constructed. Three designs were selected from reinforced concrete and by adding 1 and 2% of polyolefin fibers to it, two more designs were made (designs 5 and 6). Concrete specimens were tested at 90 days of curing at room temperature and high temperature. The application of heat caused a decrease in the results so that, in high-strength concrete designs, the highest drop under the test of compressive strength, tensile strength and modulus of elasticity was 16, 21 and 42%, respectively, in Figure 2. Scanning electron images (SEM) of concrete microstructure were interpreted in overlap and coordination in interpreting the results of all tests.

Current research has tried to study the effects of curing ages, curing temperature and Recycled Tire Polymer Fibers (RTPF) content on geotechnical properties of RLCC, such as unconfined compressive strength (UCS), secant modulus (Es), strain frailure ( and deformability index (. The UCS test is a criterion to estimate the geotechnical parameters of RLCC samples in the presented research.

In recent years, improving the mechanical properties of alkali- activated concrete with the aim of being superior compared to those of the conventional concrete and reducing environmental hazards caused by the lack of mineral resources and release of toxic carbon dioxide gas (in cement production process) has been noticed by civil engineering researchers. In this laboratory research, a mixing design of ordinary concrete containing Portland cement with a grade of 500 kg/m3 and a mixing design of alkali-activated concrete based on blast furnace slag were made. In order to check the mechanical properties, tests of compressive strength, tensile strength and modulus of elasticity of concrete were performed under the temperatures of 21 and 600 ℃ at the age of 90 days of curing.  Based on the results, applying high temperature (600 ℃) to concrete samples caused a 42% and 15% drop in compressive strength, a 56% and 21% drop in tensile strength, and a 63% and 49% drop in modulus of elasticity for ordinary and  alkali-activated concretes, respectively.  The compressive strength of alkali-activated concrete was 11% and 64% more than that of the normal concrete at 21 and 600 ℃, respectively. The tensile strength of alkali-activated concrete exhibited a 9% decrease and 63% superiority compared to normal concrete at 21 and 600 ℃, respectively. The elasticity modulus of alkali-activated concrete was 16% and 62% higher than that of the normal concrete at 21 and 600 ℃, respectively. The results of the scanning electron microscope images are in accordance with the other test results of this research.

Today, in the research of researchers, the use of waste materials with heat transfer capability in various asphalts, especially warm mix asphalt (due to environmental benefits) has been considered. Obtaining the modulus of elasticity is very important in determining the efficiency of asphalt, which can be achieved by various methods. Also, the sound absorption of this type of asphalt has been studied using ultrasonic waves. In this study, asphalt samples containing fillers of zinc slag, iron slag, converter sludge, copper slag and earth filler reducing electrical resistance each with 35%, 70% and 100% weight replacement of lime filler (normal) in asphalt. Through SCB three-point bending test, the amount of modulus of elasticity was obtained and then on Marshall samples using underwater method and using ultrasonic waves, the amount of longitudinal modulus and the amount of sound absorption of the samples were investigated. The results show the fact that on average, in the mixtures containing BOF, steel slag, GIM and copper slag, it can be said that mixtures containing BOF by 7% and mixtures containing steel slag, GIM and copper slag by 4, respectively. , 20 and 6% have more impedance than the control sample (WMA). Furthermore, the results showed that the longitudinal modulus obtained by ultrasonic wave method for the samples has the same trend of modulus of elasticity by three-point bending method. The results also showed that statistically, although the type of filler is effective on the performance of the longitudinal modulus, but the percentage of conductive filler (replacement of lime filler) is not effective on the performance of asphalt.

In this laboratory research, a mixing plan was made of ordinary concrete containing Portland cement type 2 with a grade of 500 kg / m3. Compressive strength, tensile strength and modulus of elasticity tests of concrete were performed on concrete samples at 90 days of processing age at 21 °C and 600 ° C. In order to further evaluate and validate the results, SEM and XRD tests were performed on concrete samples at 90 days of processing age. Application of heat in concrete samples caused a decrease in test results in this study. In this regard, in the concrete compressive strength test, the strength decreased from 64.92 to 37.45 MPa, which included a decrease of 42.31%. In the concrete tensile strength test, the strength decreased from 5.22 to 2.27 MPa, which included a decrease of 56.51%, and in the concrete modulus of elasticity test, the modulus of elasticity decreased from 33.73 to 12.24 gPa Which decreased by 63.71 percent. The results of SEM and XRD tests at 21 °C and high temperature, while coordinating with each other, overlapped with the results of other tests in this article.

The choice of concrete consumption and high strength in the structure of concrete dams is of particular importance. In this laboratory research, slag alkaline concrete containing 0, 4 and 8% nanosilica and 1 and 2% polyolefin fibers has been produced in 5 mixing designs. A design of control concrete containing Portland cement was prepared to compare with the test results of reinforced concrete. Modulus of elasticity, impact resistance of falling hammer and scanning electron microscope images were performed on concrete samples at 90 days of processing age. Addition of nanosilica to reinforced concrete improved (Module 4 compared to Scheme 2) in the modulus of elasticity test and the energy absorbed in the impact test by 13.42% and 36.36%, respectively. This superiority was increased by 7.5% and 8.26 times by adding fibers to concrete, respectively. The results of the SEM test overlap with other results.

Improvement of problematic soils, as an inevitable issue, has an important role in the construction projects. Adding some additive materials to the soil, has been considered as one of the effective procedure in improving characteristics behavior of soils. In this study, the effect of polypropylene fibers and nano-SiO2 in combination with clay was investigated, as a novel method, in order to refining mechanical properties of the soil. The purpose of this research is to investigate the effect of nano-SiO2 and polypropylene fibers on the properties of low plasticity clay by applying Unconfined Compression Test. Three different mixtures of the proportion of polypropylene fibers(0.25 %, 0.5%, and 1% of dry weight of clayey soil) and nano-SiO2 (0.5%, 0.75%, and 1% of dry weight of clayey soil) has been used. The results of this study show that adding the mixture of polypropylene fibers and nano-SiO2 into the clay soils, leads to 4.69% and 4.17% increment of unconfined compressive strength and modulus of elasticity, respectively, in comparison to the untreated clay. Also adding nano-SiO2 to the soil, causes more failure of samples occur respect to the case in in which the soil is getting mixed with fiber, though by increasing the amount of fibers, the failure mechanism of refined samples changes, thus the failure strain increases.

Fiber-metal composites are polymer composites reinfored with fibers and metal sheets.  In this study, the tensile properties of CARALL (CarbonReinforced Aluminum Laminate with CFRP (Carbon Fiber Reinforced Polymer) under the influence of moisture are compared and studied experimentally and numerically by finite element (FE) method. According to ASTM-D3039 standard, six samples of CARALL and CFRP composite are made using manual lay-up and carbon fibers, 3001 resin, and T6-7075 aluminum sheet and also, the samples were stored in dry and moisture conditions for 14 and 25 days. ANSYS software is used to simulate and compare the results with experimental tests. Comparison of the results shows that the moisture reduced the tensile properties of the samples. Also, the elasticity modulus for the CFRP and CARALL samples in humid environment during 25 days reduces respectively as 47.3% and 56.8% in comparison with the dry environment.

This study is aimed to examine the effect of Forta and polypropylene fibers on compressive behavior, modulus of elasticity, deformation, crack growth pattern, and absorbing energy of concrete materials. The laboratory specimens were made as cylindrical samples of 150 mm height and 100 mm diameter in two groups and 7 mix designs. Group A consists of two mix designs with 0.1 and 0.15 percentages of macrostetic fibers (Forta) with a water to cement ratio of 0.4. Group B specimens include three mixing designs with 0.2, 0.3 and 0.35 percentages of microsatellite fibers (Polypropylene) and with a water to cement ratio of 0.5. Digital Images Correlation (DIC) method has been used for measurement of displacements and strains in concrete specimens while finite element analysis (Abaqus software) has been used for the validation. The obtained results show that the absorbing energy is directly related to the amount of fiber used in the test. The fibers have a controlling effect on the cracks of the specimens so that they reduce the depth and the length of cracks. However, it should be noted that the number of cracks increased. The use of polypropylene fibers as reinforcing material reduced the compressive strength of the concrete specimens while it increased the ductility of specimens.

The use of concrete in special structures always faces challenges in implementation. By increasing the amount of cement to increase the compressive strength, the thermal gradient between the surface and the center of the concrete due to hydration heat will lead to an increase in thermal stress. On the other hand, due to the highly congested rebars in massive structural members of reinforced concrete such as columns of high-rise structures, the use of self-compacting concrete will facilitate the implementation and therefore understanding the thermal behavior of concrete and comparing it with ordinary concrete can be a good ground for studying crack risk. In this paper, the evaluation of thermal and mechanical properties affected by the application of high strength self-compacting mass concrete regime with three ratios of water to cement ratio and two cement content has been done in the form of twelve mixed designs. The results show that self-compacting concrete in addition to better mechanical properties on the surface and core of high strength mass concrete had different and more suitable thermal regime compared to ordinary concrete. Its lower strain and higher stress conversion time reduces thermal stress and ultimately reduces the risk of cracking up to thirty-six percent.

In this study, the effects of adding copper and plastic fibres and stone powder on flow parameters and hardening properties of self-compacting concrete have been investigated. The basic disadvantages of concrete include high specific gravity, low tensile strength compared to its compressive strength, low durability, and increasing tensile strength. By The use of fibres is expected to improve tensile strength, as well as reducing stiffness and, on the other hand, increasing the concrete plasticity. Today, self-compacting concrete solves one of the major problems in the implementation of concrete works in urban environments, which includes the noise pollution caused by the use of a vibrator to replacement concrete. Self-compacting concrete is a high-performance modern concrete that distinguishes its characteristics such as the lack need to internal or external density and the cross of dense reinforcement networks from conventional concrete. Another feature of self-compacting concrete is its high viscosity and stability as a result of the addition of fillers and the use of cement materials. But increasing the amount of cement materials and fillers in self-compacting concrete increases the brittleness of the concrete matrix, resulting in a decrease in deformability. Considering the successful experience of using fiber in concrete over the past years, in order to increase the deformability of ordinary, lightweight and high strength concrete, the use of fibres is an appropriate proposal to enhance of deformability of the self-compacting of concrete. Fiber concrete also has high energy absorption capacity and is not easily disassembled under impact loads.