جستجوی مقالات مرتبط با کلیدواژه "بازیافت" در نشریات گروه "عمران"

A large amount of waste from sugar factories is accumulated as waste. The purpose of this research is to recycle the waste of these factories, called carbonate cake (calcium carbonate mud, lime carbonate and lime sludge), which production is a serious problem for these factories and the environment, as a substitute for part of cement used in concrete. Due to the heterogeneous size of particles and for the greater similarity of the size of its grains with cement particles, carbonated cake with three methods dissolved in water of mixing plan, sieved and ground, was used in different designs. Laboratory concrete samples were made with a water-cement ratio of 0.35 and with different percentages of replacing carbonate cake instead of cement equal to 5, 10, 20, 30 and 40, and finally, the compressive strength of 28- and 56-day samples and the tensile strength of 28-day samples was measured. It is possible to replace it up to at least 20% by weight of cement, without significantly reducing the compressive and tensile strengths in concrete; Quantitatively, the results indicate that the compressive strength of 28- and 56-day samples and tensile strength of 28-day samples with 20% waste powder instead of cement have decreased by 6.5, 10, and 5.4%, respectively, compared to the control samples without powder. It is worth noting that carbonate cake recycling causes reduction in industrial waste, waste transportation cost, waste disposal cost and removing inappropriate smell and organic materials. The use of this green concrete in construction industry is recommended.

Principal recycling and reuse of industrial waste is one of the most important human challenges to protect the environment. In recent years, due to the unique properties of pervious concrete, the use of pervious concrete pavement as a good alternative to asphalt procedures has been considered. In this study, in order to assess a new method for the manufacture of high -environmentally friendly concrete pavements with aluminum slag replacement with 0, 5, 10, 15 and 30 % cement weight, the concrete samples were made and the tests including compressive strength, bending strength, water absorption percentage, permeability and porosity done. The results showed that aluminum slag replacement with 5 % of cement weight, compressive strength, bending resistance and water absorption percentage compared to the control sample did not change significantly. But using the replacement of aluminum slag with 10, 15 and 30 percent of the cement weight, compressive strength and bending strength comparing to the control sample were decreased by 16, 24 and 50% and by 6, 15 and 24 %, respectively. By replacing aluminum slag with 10 and 15% by weight of cement, the permeability comparing to the control sample was increased by 61 and 97%, respectively. It was also observed that due to the high porosity of the samples containing aluminum slag replacement with 30 % of the weight of the cement, water passed immediately and quickly.

The purpose of this paper is to study some properties of building materials made with plaster (commercial - CGP and recycled - RGP)and waste (red - RC, and chinese - PW ceramics)using Press pressure. The brick is made with a solid mass composition containing 50 wt% of cohesive material and 50 wt% of waste material and is proportional to the amount of dry water / dry powder (0.22). According to these findings, there are various industrial waste materials such as plaster recycling, as well as materials from red (RC)and chinese waste (PW)waste. In this study, specimens were cast before using a single - core inquiry (10 kN)before obtaining a uniaxial compressive strength (10 kN). After treatment and characterization of specimens, the stress and flexural strength, porosity and microstructure of samples were investigated. The results of the compressive strength were in the range of 12MPa to 35MPa. The ratio of solid water / mass and the applied force applied to the uniaxial compressive stress before getting caught in reducing the porosity of specimens had a significant effect on their mechanical properties. The results show that this increase of waste material will cause a better quality of brick building materials.

In the last two decades, the increase in quality and strength in new concrete technology has grown significantly. One of the new generation concretes that is considered as a powerful and efficient concrete in the construction industry today is fiber concrete, which has improved mechanical properties such as higher tensile strength and even improved compressive strength. This concrete, which has a compressive strength in a range of 15 to 200 MPa, is mainly used in the construction of structures resistant to dynamic loads and thin walls, and its use in new construction projects has a high potential. In the present study, the role of human hair as fibers in reinforcing concrete and the characteristics of hardened concrete have been investigated and its details have been studied from the point of view of mechanical characteristics. For this purpose, 6 types of mixing schemes with different percentages of crushed hair (0-1-2-3-4 and 5% by volume) were considered and the desired mixtures were reached and molded with the help of lubricant. Tests of compressive strength, tensile strength, modulus of elasticity, and water absorption were performed to evaluate the mechanical and physical properties of concrete. The results of compressive strength of the samples showed that 2% of the consumed hair caused a 9.8% increase in compressive strength compared to the control design. Tensile strength also increased by 34.3% in the same percentage of consumption compared to the control design. The modulus of elasticity increased by 8.65% in 1% of hair consumed and then decreased. Water absorption had an increasing trend and in 2% consumption, showed a 24.2% increase compared to the control.

According to the national vision of the country twenty years, the overall economic policies of resistance to jihadist approach, flexibility, opportunity, and leading was notified. The overall economic structure of the resistance from the Leader of the heads of the three branches and the head of the Expediency Council was notified on 24 paragraphs. Therefore, Paragraphs 3, 5, 10, 11 overall economic policy of strength in the location, survey, installation and support of recycling and papers of ships and authorities is considered the supreme leader. So, the first segment of this paper, the author endeavors to describe about the required Conventions related to the safe and sound ship recycling activities. The IMO has in 2009 adopted the Hong Kong International Convention in this regards, the Hong Kong Convention needs to be ratified by at least 15 major flag and recycling countries in order to enter into force. In March 2010, the Parties of the Basel Convention adopted the assessment which was submitted by the EU as "An assessment of the link between the IMO Hong Kong Convention for the safe and environmentally sound recycling of ships, the Basel Convention and the EU waste shipment regulation". After reviewing the related Conventions, the next part of this article is designated to evaluate the creation of a ship recycling yard at the Iran Southern Ports with a focus on the Arvand Free Zone in order to increase the Iran’s economic growth. It should be noted that in this research, the Kolmogorov –Smirnov test was used to test for normality of the distribution, samples are standardized and compared with a standard normal distribution. As result of that for the statistical hypothesis test which the test statistic follows a Student's t-distribution under the null hypothesis, therefore the research variables verified by the Binomial test.

In this research, 0, 5, 10, 15 and 20 percent of crumb rubber mix was used as a fine grained substitute for concrete pavement. Also, in another state, half percent of the steel fibers recovered from worn tires were added to these samples. The results of this study indicate that the compressive strength of samples with 5, 10, 15 and 20% crumb rubber in comparison with the control sample was reduced by 1.6, 36.9, 49.9% and 63.1%, and samples with 0, 5, 10, 15 and 20% crumb rubber and 0.5% steel fibers, respectively, decreased by 0.3, 11.2, 33.7, 5 / 41% and 44.3% respectively. Therefore, it is observed that the compressive strength of concrete containing crumb rubber and steel fibers is better than specimens with crumb rubber. Also, by replacing 5%, 10%, 15% and 20% of crumb rubber in concrete, its indirect tensile strength would be reduced by 7.5%, 15.3%, 41.4% and 31.2% , and by adding 0.5% of the steel fibers to the concrete by replacing 0, 5, 10, 15 and 20% of crumb rubber in concrete, Indirect tensile strength increased by 67.8%, 46.7%, 32.4%, 17.8% and 3.5%, respectively, and it is concluded that the tensile strength of concrete increases due to the addition of steel fibers.

Disposal of Waste materials is a major challenge in each country and the use of plastics materials is increasing every day. A large part of the plastic wastes are bottles of drinks which are made of Polyethylene terephthalate (PET). The reuse of plastic wastes plays an important role in sustainable solid waste management. Plastic waste management helps to save natural resources that cannot be replenished, decreases pollution of the environment and also helps to save and recycle energy production processes. Now a days , PET has been widely used to produce fibers, particles, or lakes to obtain cement-based products with improved properties One transcendental alternative to recycling PET materials consists of using them as substitute of concrete aggregates. Due to demands of technological development in the construction area, the possibility for generating alternative materials that can be applied with increasing functionality, low costs, and better physical, chemical, and mechanical properties than conventional materials is being explored Fiber-reinforced concrete is a composite material resulting from the addition of reinforcing fibers to the brittle matrix of ordinary concrete. The idea of using fiber reinforcement comes from the need to find a remedy to the phenomena of cracking, such as produced by shrinkage, which inevitably affects the service life of concrete buildings. Concrete is a material that is well resistant to compression, but has low tensile strength. The low level of tensile strength is caused by phenomena such as plastic and/or hydraulic shrinkage with the formation of unwanted micro and macro cracks Fiber-reinforced concrete represents the current tendency to apply more eficient crack-resistant concrete. The ability to enhance flexural and tensile performance of the concrete matrix, together with the opportunity for improving its durability, pushed boundaries in developing new materials to be used as fibres. Several studies using reinforced concrete with polymer fibers like polypropylene, polystyrene, polyethylene terephthalate, and polyethylene have evidenced variation of concrete properties according to the nature and size of the aggregate . The level of fibre performance depends strongly on the quality and amount of the employed fibres applied, on their shape and dimensions as well as on their bond to the concrete matrix . One way for recycling and efficient use of PET is adding to the concrete as fibers. Use of PET fibers in concrete will solve environmental problem of this waste material in addition to improvement of mechanical properties of concrete. Research on the use of PET fibres as dispersed reinforcement in concrete and mortars has been ongoing for about a decade with sporadic studies. In this research physical and mechanical behavior of concrete containing recycled PET fiber has been studies. For this purpose 10 concrete mixture, including 1control mixture and 9 pet fiber concrete mixtures were made. Fibers in volume percentage of 0.15%, 0.30% and 0.45% with the length of 1, 2 and 3 cm were used separately. Compressive strength, tensile strength and flexural strength tests were done on the samples. Fibers deformed with deforming machine to improve the adhesion of fiber with concrete. Compressive strength were performed ater 7 and 28 days. The results show that PET fibers increase. Compressive strength and flexural strength of concrete between 5-18% and 6%- 30% respectively. No significant efects on tensile strength were observed with the addition of fibers.

High electrical conductivity of metals such as gold, silver and platinum extensively increased the use of these metals in electronics. In addition to the platinum group metals, large amounts of copper, tin and lead are present in E-Waste. For an effective recovery of precious metals, and also from an economic perspective, it is essential to recover the mentioned metals. In this paper, separation of copper from tin and lead by solvent extraction was studied. Fluoroboric acid and LIX984N was used as leachant and organic solvent, respectively. Effective factors such as the concentration of organic solvent, pH, temperature and concentration of copper on the extraction of copper were investigated. The treatment of leach liquor for solvent extraction of copper with LIX984N showed that 20% LIX984N in kerosene, a 30 min period of equilibrium, and a pH of 3 were sufficient for the extraction of Cu(II) and 99.99% copper can be recovered from the leached solution.

Every year, a large volume of waste materials are produced in the world, however a very small part of it take place in recycling and reusing. Recycled Asphalt Pavement (RAP) is a waste material which may have undesirable influence on its environment. Considering these materials reported characteristics, there have been introduced different strategies to reuse RAP’s. One of these applications recently noticed by the researchers is using RAP’s in cement mixtures such as concrete.As RAP is mainly gathered from roadsides and highways, so it is desirable to use them in common mixtures for roads pavement construction. Hence, Roller Compacted Concrete -a concrete mixture with unique features such as ease of application and low costs - was selected as basic mixture. In this research, after introducing two mixing ratios with two designing strengths, replacing a part of aggregates with RAPs was carried out in three states: 1-with fine and coarse aggregates, 2-with just fine aggregates, and 3-with just coarse aggregates, with ratios of 0, 10, 20, 40, and 80 %. Then, in the next step regression models with acceptable correlation coefficients were presented for prediction of compressive strength as well as allowable percentages of RAP aggregate to use in theconcrete. Valid using other types of RAPs was another work conducted in this research.

Use of Reclaimed Asphalt Pavement in HMA is beneficial by reduction of initial costs. But the higher stiffness of aged binder may lead to workability issues in the field، therefore use of large percentages of RAP impacts the HMA properties. Utilizing Sasobit is a solution to use more RAP at a relatively lower temperature in HMA mixes. This study investigates the effects of 2 percent Sasobit on the reduction of compaction temperature by measuring low shear viscosity and workability of mixtures containing RAP binder. Low and intermediate temperature properties of RAP binder using mix designs were compared to properties of artificially aged binders. Virgin binder was aged in PAV to make artificial RAP binder. Comparison between physical parameters of RAP binder and binder aged in PAV was done and it was found that about 40 hours is sufficient for simulating the aging of RAP binder and making artificially aged binder. Results of this study on artificial RAP show that utilizing Sasobit is a feasible way to make HMA which contain 25% RAP. Utilizing RAP and Sasobit together in a HMA project would lead to select softer virgin asphalt binder with a lower performance grade.

Due to the critical situation of environmental issues, waste materials recycling and their reusing has been a research interest for many researchers. Recycled Asphalt Pavement (RAP) is a waste material which may have unfavorable influence on its surrounding environment. Considering the reported characteristics of these materials, different strategies to reuse RAP’s have been introduced. One of these applications recently noticed by the researchers is using RAP’s in cement mixtures such as concrete. As RAP is mainly collected from roadsides and highways, so it is desirable to use it in common mixtures for roads pavements. Hence, Roller Compacted Concrete - a concrete mixture with unique featues such as ease of application and low cost- was selected as the basic mixture. In this research, replacing a part of aggregates with RAPs in three states was carried out: 1- with fine and coarse aggregates, 2- with just fine aggregates, and 3- with just coarse aggregates, with ratios of 0, 10, 20, 40, and 80 percentages. Tests results indicated that use of RAPs as a part of aggregates in pavement Roller Compacted Concrete has no effect on the consistency of concrete compressibility, and cement and water batches; however, the compressive strength is reduced by increased quantity of RAP aggregates.

In recent years the recycling of concrete to produce aggregates suitable for non-structural applications, such as road construction materials, is emerging as an environmentally viable and technically feasible operation. While studies on the engineering properties of concrete made by recycled concrete aggregate abound only limited data are available on performance of crushed brick aggregate in road construction. This paper is an attempt to understand the physical properties of recycled masonry bricks and cement mortar or concrete made of natural aggregate. The study also provides the laboratory basic test results required to assess the mechanical performance of the unbound aggregates for use in road construction. In the present research study, the possibility of demolition debris recycling and its utilization in base and sub-base layers of roads, directly or after improvement, is investigated. A vast variety of physical and chemical tests has been carried on crushed bricks, mortar cement, concrete or different combinations of these materials. Freezing and thawing, durability, compaction and CBR tests are the most important tests to be executed for evaluation of the performance of these materials for use in construction of road layers. The initial test results indicate that these materials may be considered as sub-base materials for second degree (immediate traffic) roads. To enhance the quality of the recycled materials, two methods were employed. In the first method, different fractions of recycled construction debris were replaced with high performance materials. This led to an increase in CBR amount, i.e. increasing the new material performance. At the second method, cement with different percentages was added to the recycled materials including brick and cement mortar. Again, this resulted an increase in compressive strength of new materials. Also complementary experiments indicated increased quality of construction debris as base course material in highway construction.