modulus of elasticity

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.

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.

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.

The application of additives is the factor affecting the properties of asphalt mixture. These additives can also change the performance and response of the pavement versus loading. Sassobite is used as an additive to produce warm asphalt. So far, there has not been done a complete study on the impact of these materials on the performance of the pavement, on the software scale. In this research, it has been tried to develop a three-dimensional model of pavement based on experimental results and by using finite element software, with its surface layer being from semi-warm asphalt and to identify critical reactions of the pavement under the surface layer and on the subgrade soil. The research process is such that changes were made in different modeled pavement variables, and a comparison was made between the variation of the reactions in the control pavement and the pavement having the additive. In addition, the effect of changes in the thickness of the pavement and the modulus of the subgrade has been the subject of this study. The aim of this study was to compare the performance of the two types of asphalt mixtures on conventional and stabilized subgrade. The results of the analysis show that the use of additives, in addition to increasing the modulus of elasticity of the asphalt pavement, significantly reduces the tensile strain of the asphalt substrate in the control pavement. In addition, the compressive strain on the subgrade also decreases. The results showed that increasing the thickness of the asphalt pavement layer in comparison with the use of the additive has a greater effect on the reduction of critical strains.

Plastic concrete have been used for some four decades in watertight structures. In these four decades, plastic concrete has been successfully used in engineering control projects for seepage. Plastic concrete is produced by mixing of cement, bentonite, aggregates and water. Presence of bentonite and high water-cement ratio is difference between plastic concrete and conventional concrete. These two factor cause plastic concrete, besides possession of water tighting property, have a very lesser comperssive strength and modulus of elasticity in comparsion with conventional concrete and therefore be more deformable. Researches that fulfilled on this type of concrete in the word and especially in Iran, were not extensive and most of done works have been typical studies on relative projects. In order to make more economical plastic concrete, it is necessary to evaluate the effects of changes in the properties of bentonite, and in particular the effect of its plastic index change, and given that there is no extensive research in this field in our country, we try to move toward this goal in this these. Therefore after primary stduies and test, 51 mix designs were teseted and compressive strength, modulus of elasticity and workability of them were determined. Based on the results, with increasing amount of plastic index of bentonite, compressive strength, elasticity modulus and workability decrease.

Around 25 billion tons of concrete is used each year globally that means over 3.8 tons per person in the world each year. Occupying about 60% to 70% of the volume, aggregate is a main ingredient of concrete. Nowadays, there is an increasing trend toward using sustainable concrete and reusing of aggregates from demolished concrete is one way to achieve this aim. Although using recycled concrete aggregate (RCA) does not lead to significant reduction of CO2 emission, but it reduces using natural resources (natural aggregate) as well as helping to reduce dumping construction and demolition wastes in landfills. More than 900 million tons of construction and demolition waste is produced each year only in Europe, the U.S., and Japan. A comprehensive literature review on mechanical properties of recycled aggregate concrete (RAC) including compressive strength, splitting tensile strength, modulus of elasticity and modulus of rupture is presented. In addition, databases are created for mechanical properties of RAC in order to lead to changes or acceptance in design codes and standards’ provisions. These data were compared with the American, European, Australian, Japanese, Canadian standards provisions. Results of this study show that existing code provisions are not always conservative for mechanical properties of RAC.

Concrete, as one of the main components of the manufacturing industry since the beginning of the process of production, operation and destruction, plays a major role in the creation of environmental pollution. Since more than 70% of the main body of concrete is aggregate, the promotion of culture and considerations based on the principles of sustainable development in design, construction and demolition process of concrete is of great importance. One of the basic principles of sustainable development is the importance of recycling. Recycling of damaged concrete in the last century has become one of the most important interests of researchers. So, after studying and recognizing their durability and mechanical properties (MP’s), today in developed countries, the necessary relationships for the recognition of structural performance of these concretes is under construction. The purpose of this research is to investigate the results of research carried out in different countries in the field of recognition of the MP’s of recycled concretes (RC’s). More than 80 articles published in prestigious technical journals were examined and classified together in the six groups that the researchers considered in analyzing the MP’s of RC’s. The effect of each of these groups on compressive and tensile strengths and elasticity of concrete were studied. The results showed that the type, size and quality of recycled aggregates (RA’s) are very effective in determining the level of replacement of recycled materials (RM’s) in concrete. Curing conditions, water reducing and pozzolanic materials, although effective in improving the MP’s of RC’s, cannot reduce the adverse effects of increasing the replacement of RM’s on the mechanical properties of concrete. Concerning the effect of age on the mechanical properties of RC’s, it is common ground that some of these properties are similar to conventional ones.

In recent years, the need for consistency between thepractical implementation steps of construction processand the design stage of high-rise concrete structurethrough the use of nonlinear sequential construction anal-ysis has been strongly recommended by researchers. Be-sides, it is known by research and experiment that con-crete structures are subjected to larger displacementsand stresses because of the long-term behavior andthe time-dependent parameters of concrete such as creepand shrinkage. This brings about the increase in beamde ections, expansion of tensile cracks in members, ex-cessive column shortenings, di erential displacements ofhorizontal structural members, such as beams, causedby unequal and increasing axial displacements in ad-jacent frame members and considerable redistributionof stress in structure. All these outcomes, which a ectstructure's response directly or indirectly, must be con-sidered in the nonlinear and time-dependent sequentialanalysis of multi-story buildings. In this paper, the mostimportant methods of predicting the long-term behaviorof concrete, stating the advantages and disadvantages ofeach, has been introduced, and the proposed equationsto describe the manner of applying certain features ofthe aforementioned methods in the updated version ofthe common analysis and design software for structuresare presented. In addition, for getting familiar withthe manual method of calculation of creep and shrink-age e ects, the exact implementation of the Fintel andKhan's model is expressed by establishing the tables ofbefore and after the casting of concrete and consideringthe changes that illuminate the obscure aspects of thecorresponding method. Proper compliance of the ob-tained results with the corresponding values of the sim-ilar method, named PCA, which has the nite-elementmodeling functionality, indicates the possibility of pro-viding a reliable sample for error calibration and valida-tion process. For vivid understanding of the e ects oftime-dependent parameters of the concrete on the axialdeformation of the vertical elements of the structures,the invoked example of Fintel and khan has been ap-plied similarly to all the studied methods under conven-tional one-step and nonlinear staged analyses. More-over, the column shortening results have been comparedafter 1,000 days of construction time.