جستجوی مقالات مرتبط با کلیدواژه « Steel Slag » در نشریات گروه « عمران »

Steel slag aggregate is by product material witch was produced by the steelmaking industry, in large quantities in Iran and usually withdraw from iron making factories. This material contain calcium silicate, manganese, magnesium, iron oxide and calcium. This paper evaluate effect of steel slag aggregate on the frictional properties of asphalt mixtures using British Pendulum apparatus. On the other hand, few special aggregate samples such as lime stone and steel slag was produced by resin glue with special mold and then subjected to the polishing effect using accelerated polishing machine (APM) for exploring micro texture those aggregates. Evaluating mechanical properties of asphalt samples done by Marshall Stability and rutting susceptibility using dynamic creep test through the UTM machine. Test results show positive effect (about 20%) in BPN when adding steel slag as replace of lime stone aggregate. Also potential rutting resistance of steel slag asphalt mixtures rise doubled and finally, better resistance on polishing the surface of steel slag aggregate respect to lime stone was shown.

The existence of waste materials from various physical and chemical processes is one of the important problems of industrialized and developing countries. For this reason, extensive research is being done on the methods of recycling or disposing of them in order to minimize the damage to the environment. In the present study, the effect of using recycled asphalt crumb (RAP) as a substitute for natural aggregate and steel slag as a substitute for cement in self-compacting concrete (SCC) mixtures for the construction of road pavements has been investigated. For this purpose, fresh concrete tests including slump flow, V funnel, L box, J ring and hardened concrete tests of compressive, tensile and bending strength were performed on the samples. The results showed the effect of using slag instead of cement and asphalt chips. Instead of coarse grain, it reduces the compressive, tensile and bending resistance of self-dense concrete. Also, by replacing up to 25% of stone materials with small asphalt materials and 30% of slag with cement, minimum acceptable standards were achieved according to the relevant standards. Also, for the design of double mixes, the design containing 30% asphalt crumb instead of stone materials with 25% slag instead of cement has shown more suitable results. The most optimal mode of using these materials is respectively using 30% slag instead of cement and 25% asphalt crumb instead of stone materials.

Cold recycling is one of the methods of pavement rehabilitation, which has become popular in recent years. One of the advantages of cold recycling is that its operations are performed at ambient temperature. However, there are still some concerns regarding the use of emulsified cold recycled mixtures. These pavements are susceptible to problems such as raveling, stripping, low initial strength, and long curing time, which are often countered by the use of additives. In this study, the mechanical behavior of the mixture recycled with emulsion bitumen containing cement kiln dust as a waste from the cement production process and steel slag as a pozzolanic waste were compared with the non-additive mixture and the mixtures with 1% and 2% cement content (as a conventional emulsified cold recycled mixture additive). To evaluate the mechanical properties, Marshal stability, indirect tensile strength, resilient modulus and fatigue test were performed on the samples of different ages at different temperatures. The results showed that the combined use of cement kiln dust and steel slag improves the mechanical properties, especially after prolonged curing periods. In some cases, this improvement was even greater than the improvement resulting from the addition of cement. The fatigue test results showed that the mixture containing the new additive had a better fatigue behavior than the non-additive mixture and a comparable behavior with the cement-containing mixture specially at lower strain levels.

It is necessary to stabilize the road bed in the areas that have fine-grained sand soil or the so-called dune sand. On the other hand, there is no justification for using traditional methods to do this, considering the advancement of technology and the emergence of new materials that are environmentally friendly. In the past years, the concern of researchers in the field of geotechnics has been to choose the best stabilizing material by testing different materials to determined the possible suitability for this purpose.Today, geopolymer materials are considered as one of the best environmentally friendly materials due to their availability, reduced consumption of energy resources, and reduced production of greenhouse gases, and on the other hand, with the development of nanotechnology and researchers' understanding of their properties, nanomaterials can also be used in the preparation of geopolymers. be placed In the past, researchers have conducted studies on the stabilization of some types of soils using geopolymeric materials, but the use of geopolymeric materials based on iron slag and in combination with nano silica to stabilize fine sand soil is a subject that has not been studied in the past. This research has been addressed.This research studies the effect of adding 0-3% of nano-silica to the mixture of sandy soil with 5-20% of geopolymer based on industrial pozzolan obtained from iron smelting furnace slag. In order to achieve the best percentage of preparation of geopolymer mixture, 5-20% alkaline solution with a concentration range of 4-12 M has been used, and the samples have been examined in the processing time of 1-28 days. In this regard, according to the increase of the investigated factors, Taguchi test design optimization method has been used to reduce the number of tests.

An efficient approach to road safety coupled with preventive maintenance of asphalt pavements is the application of colored slurry seal, as it improves the road visibility while enhancing the aesthetic aspects of the urban space. Around the globe, application of colored surface treatments on roads has witnessed a growth in recent years, especially in urban areas. This study aims at investigating the feasibility and effectiveness of using electric-arc furnace steel slag as an alternative to natural aggregates in the colored slurry seal mixture design followed by a performance assessment of the resultant mixture. For this purpose, first, characteristics of the aggregate and steel slag were investigated. Next, performance of the designed slurry seal mixture was assessed by testing five different mixtures containing the slag at 0, 10, 20, 30 and 40 wt.%. Evaluation and comparison of the asphalt specimens were performed by conducting 30- and 60-min wet cohesion tests, 60-min wet track abrasion test, loaded wheel-sand adhesion test, and loaded wheel-displacement test according to ASTM D3910. Based on the XRF results, the considered steel slag powder contained a significant amount of calcium oxide (~ 57% of natural aggregate). The high CaO/SiO2 ratio for the steel slag indicates its alkalinity, which suggests its improved adhesion to bitumen thanks to its rather acidic nature. According to FESEM results, the steel slag material was found to be composed of particles of angular geometry with a rougher surface and higher porosity than natural aggregates, further indicating better slag-bitumen adhesion. Performance assessments indicated superior performance of the steel slag-containing specimens of colored slurry seal. Among the studied mixtures, the one with 40 wt.% steel slag exhibited the best performance, as shown by 27.8 and 37.3% increase in the mixture cohesion upon 30- and 60-min wet cohesion tests, respectively, as compared to the control specimen. Furthermore, 47.7% lower moisture sensitivity and 50.8% and 40% smaller vertical and lateral displacements, respectively, were observed for the slag-containing mixture. The bleeding potential of the mixtures decreased with increasing the steel slag dosage from 0 to 40 wt.%, so that the mixture containing steel slag at 40 wt.% exhibited 23.7% lower bleeding potential. Trying to optimize the asphalt emulsion dosage, it was figured out that the optimal content of asphalt emulsion increases with the added content of steel slag to the mixture. Accordingly, the mixture containing steel slag at 40 wt.% required 1.9% more asphalt emulsion to achieve a given cohesion level within a certain time. Based on the results of this research, in order to improve performance characteristics of colored slurry seal mixtures while observing environmental obligations, it is recommended to use steel slag as an alternative to natural aggregates in this type of surface treatment. Therefore, according to the environmental issues and the limitations of natural resources, it is recommended that steel slag be replaced by natural aggregates up to 40% in the colored slurry mixture. By replacing steel slag, proper adhesion and cohesion between asphalt mixture materials is achieved and its resistance to moisture sensitivity, traffic loading and bleeding is improved.

In this research, in order to construct environmentally friendly green asphalt mixtures, steel slag with a size of 9.5-4.75 mm to a volume ratio of 60% of aggregates and red mud waste with 50 and 100% ratios of filler has been used as an alternative to limestone filler, and self-healing index and moisture sensitivity of these mixtures have been evaluated. To do that, the semi-circular bending test (SCB) was performed by seven damage-healing cycles using the microwave irradiation heating method. Results indicated that the steel slag and 50% red mud waste in the first healing cycle increased the optimum healing ratio compared to the control sample, respectively; 53.01% and 32.35%. Also, the moisture susceptibility test results showed that the amount of moisture resistance in mixtures containing steel slag and 50% red mud decreased by 16% and 21%, respectively, compared to the control sample. Using 50% and 100% carbonation cake as a replacement for limestone filler in mixtures containing steel slag has increased the moisture resistance by 9% and 13%, respectively. Also, this weakness of moisture resistance in the sample containing 50% of red mud was compensated by using 50% of carbonation cake, and moisture resistance was increased by 12%. According to the obtained results, the use of these waste materials instead of non-renewable natural resources such as aggregates, in addition to preserve the non-renewable natural resources, will improve the healing performance of asphalt mixtures.

Recycling is one of the most important issues in the construction industry in the world. Today, it is common to use different types of concrete in construction projects. One of these types of concrete is Roller Compacted Concrete (RCC), which has advantages such as fast and easy construction, lower construction costs and resistance in hot weather conditions and heavy loading. This concrete can be used in the construction of road pavements and all kinds of massive structures. In this study, the effect of replacing reclaimed asphalt pavements (RAP) as coarse aggregates and steel slag as fine aggregates with different percentages has been investigated on the mechanical properties of roller concrete. Samples were cured for 7 and 28 days after mixing design. The results of tests show that with increasing the replacement of RAP and steel slag in RCC samples, the compressive strength is significantly reduced; Compressive strength in the sample containing 100% RAP and steel slag, is approximately one third of the compressive strength of the sample; However, this declining trend has slowed down for the tensile and flexural strengths. Also, only the sample containing 25% of RAP and steel slag has the required minimum compressive strength in accordance with the relevant standards; While 28-day tensile and flexural strength in samples containing 25%, 50% and 75% of RAP and steel slag, is higher than the allowable values ​​in accordance with the relevant standards. The results of toughness test showed that with increasing RAP and steel slag, the maximum load was decreased; However, energy absorption capacity and consequently toughness increased, due to the increase in flexibility of RCC mixtures.

The present research seeks to investigate the modification of bitumen emulsion with polyphosphoric acid and study the feasibility of using steel slag powder as an alternative to conventional rock material filler in the design of microsurfacing mixture in an attempt to improve the ultimate performance of the mixture. For this purpose, firstly, polyphosphoric acid was used to modify the bitumen emulsion at 0.4, 0.8, 1.2, and 1.6 wt% (by weight of residual bitumen). Next, the optimally modified bitumen emulsion was used in different microsurfacing mixtures. Five different mixtures of micro surfacing containing steel slag filler at 0, 2.5, 5.0, 7.5, and 10.0 wt% (by total weight of aggregates), as an alternative to material passing through 0.075 mm sieve, were prepared. The asphalt mixtures were assessed by means of wet cohesion test, wet track abrasion test, loaded wheel-displacement, and loaded wheel-sand adhesion tests. Results of the bitumen tests showed that the use of the polyphosphoric acid tends to improve the bitumen properties in terms of decreased penetration, increased softening point, and reduced thermal sensitivity. With increasing the dosage of the polyphosphoric acid to up to 0.8 wt% by weight of the residual bitumen, significant changes were seen in the penetration and the softening point, which led to improved performance of the bitumen emulsion. Results of the asphalt tests on the samples showed that the mixtures containing steel slag filler at 7.5 and 10.0 wt% outperformed the other mixtures. Indeed, the mixture containing steel slag at 7.5 wt% could improve the cohesion, abrasion resistance, bleeding resistance, and vertical displace resistance by 29.2, 64.5, 18.6, and 44.0%, respectively. The corresponding figures for the mixture containing the slag at 10.0 wt% were 25.0, 64.3, 23.3, and 42.9 wt%, respectively.

Improving the physical properties of soil using industrial waste has always been of interest to researchers And it becomes more important when Accumulation of huge volume of borrowed Soil resulting from the development of Civil projects Due to improper engineering characteristics For reuse in Civil projects Cause a lot of problems. On the other hand Given that Iran is one of the hubs of steel production and Huge volumes of steel furnace slag are produced and accumulated annually in this country, It is necessary for the optimal recycling of this waste Conduct comprehensive research in various fields of science and technology. One of the goals for the optimal use of this waste, Their use is in soil improvement for use in road construction. The present study is based on the improvement of accumulated fine-grained soil in Mobarakeh Steel area Using processed steel slag in the size of 0 to 25 mm , Has been studied For use in road construction. Engineering properties of loan soil in Mobarakeh Steel Plant (Saba area), Includes Liquid Limit and Plasticity Index , classification and seive size, After sampling from different parts, Preparation and testing in the laboratory Was initially examined According to the specifications of road building materials, Soil unsuitable for use in road construction was identified. Eventually, by performing step by step experiments, Soil engineering properties were modified using different percentages of steel slag And achieve a suitable mixture for use in road construction. Also compare the geotechnical properties of soil samples to the samples of soil and slag mixture obtained Showed that these properties improved significantly by increasing the percentage of slag.

One of the new types of concrete that helps to solve problems such as cracking, grooving in concrete, and is known as one of the most popular concretes in the civil engineering community, is roller concrete (RCC) which is made in construction. Types of road pavements and structural uses can be used. In recent years Due to the high cost of pavement construction and environmental considerations, various waste and recycled materials have been used in concrete mixes and roller concrete. In this research, a relatively comprehensive review of the composition of waste and recycled materials on the mechanical properties of roller concrete is presented. The mechanical properties of roller concrete by replacing coarse and fine-grained materials in concrete with recycled materials including rubber chips and steel slag have been investigated in a leading study. In the researches, compressive strength, indirect tensile and three-point bending tests have been performed on 7 and 28 day samples.3-point bending test is used to obtain flexural strength and toughness and energy absorption.

Dredged soils are obtained from capital dredging (resulting from the construction of hydraulic structures) or maintenance dredging (from the maintenance of hydraulic structures). Due to the large volume, uselessness and low pollution of these soils; researchers are exploring using these materials as soil alternatives. Poor bearing capacity, fragmentation characteristic, and difficult behavior prediction; are some problems of carbonated soils. Also non-carbonated dredged soils often don’t have proper technical characteristics. The Persian Gulf has coasts covered with carbonated sediments, also forced to dredge. Due to the great importance of this waterway in the world economy and energy supply, as well as the problematic nature of its carbonated soil (for example, creating problems for oil extraction platforms); The Persian Gulf’s carbonated soil, like dredged soil, needs to be improved. One of the most widely used soil improvement methods is stabilization. Besides the use of new materials (such as polymer and fiber), stabilization by cement and lime are still the most common stabilization methods for variety of soils. In addition to economic value, it will also be environmental and technical importance to consider the possibility of using it in engineering structures such as road bodies as base and subbase. Soil improvement is done in various additives and methods. Depending on the type of soil and materials in each area, the appropriate stabilization method varies; therefore, the same prescription for soil stabilization cannot be proposed. This paper focuses on carbonated and dredged soils, their stabilization methods; and reviews some practical experiences of stabilizing them.

In recent years, due to the higher cost of pavement construction and environmental considerations, various waste and recycled materials have been used in concrete and Roller Compacted Concrete (RCC) mixtures. This study investigates the effect of partial and full replacement of natural aggregates with steel slag as a by-product of the steel industry and Reclaimed Asphalt Pavement (RAP) as a waste of the road pavement construction industry, on the mechanical and environmental properties of RCC pavements. For this purpose, compressive strength, indirect tensile strength and three-point bending tests were conducted on 7 and 28-day samples. Three-point bending test was used to obtain flexural strength, toughness, and energy absorbency. Also Cantabro abrasion test and Toxicity Characteristic Leaching Procedure (TCLP) were conducted on 28-day samples. The results showed that the compressive strength, tensile strength and flexural strength of RCC pavement reduced by replacing natural aggregates with steel slag and RAP. In the meantime, the effect of RAP on reducing mechanical properties of roller concrete is more pronounced. Increasing the content of steel slag and RAP increases the toughness, as well as the energy absorbency capacity of the specimens despite the decrease in the maximum load. On the other hand, the abrasion resistance of the roller concrete mixture increases, with increasing steel slag. Also, according to the results of this study, the mixtures containing up to 50% steel slag or combined steel slag and RAP, met the regulatory requirements. By incorporating 25% steel slag and 25% RAP as substitutes for natural aggregates, compressive, tensile and flexural strengths decreased and toughness increased up to 24%, 34%, 21% and 13%, respectively. Thus, the waste materials used in this study, are usable in RCC because of their satisfactory results and economic-environmental advantages.

Due to the growing technology of various types of vehicles and their increasing application in the transportation network, the development of road quantity and quality is of particular importance. One way to improve and increase the strength of pavements is to use high-quality materials such as steel slag, which will increase the bearing capacity of the pavements and their life span. Steel slags are by-products of the steel factory, which are often stored as deposits and massive masses around these factories. Over the years, extensive research has been conducted around the world for the use of this substance and several fields have been proposed for this purpose. One of these fields which use the steel slags in large amounts, is as the aggregate in the production of asphalt. This is because it has good physical and frictional properties as well as good durability in resisting the slippage of asphalt pavement and preventing the formation of some deterioration, such as rutting, stripping and polishing of asphalt aggregates. In the present study, in addition to studying the mechanical, physical and chemical properties of steel slag as an aggregate alternative in asphalt pavements, the most recent studies have been mentioned and the use of steel slag in road construction including base and sub-base, and asphalt mixes have been investigated.

The major national investment in the transportation sector is the creation and construction of pavements. Currently in Iran, most of the pavements are asphalt mixture. It has been damaged by the passage of time, traffic loads, and atmospheric changes. One of the most important types of flexible pavements is the change of permanent forms known as rutting. In recent years, the use of metal melting slag, one of the waste of the metal melting plants, has been considered as an alternative to parts or all rock materials in different layers of metal. in this study, we investigated the use of different percentages of steel slag as a percentage of coarse rock material in gradation of mixture (0 - 25 - 75 - 75 % of slag in alternative rock material)… using the method of mixing marshall, optimum bitumen and other Marshall parameters. In order to investigate the properties of the pure bitumen, penetration point, ductility, viscosity, and degree of fire were performed. Also, the tests of marshall and flow, indirect tensile, moisture susceptibility, resilient modulus, dynamic creep and wheel placement were performed to investigate the effect of the use of فولاد slag on the functional properties of asphalt mixture. The results of this study showed that the compressive strength, indirect tensile strength and tensile strength ratio (saturation to dry of mixtures containing electric arc furnace (EAF) steel slag were higher than control mixture.

Today, steel is one of the most used materials in industry and its annual consumption is increasing. One of the most important by-products of steel making is steel slag. The use of steel slag as a waste of this industry, can be applied in geotechnical  applications  such a road embankment in order to reduce of the slag disposal, as well as preventing the destruction of natural resources, is of particular importance. It is necessary to determine the geotechnical engineering properties of steel slag produced from different steelmaking operations and assess the potential usage in road and railways embankment construction.  In this paper, physical, compaction properties, California Bearing Ratio’s (CBR) and characteristics of steel slag as a base and sub base of road material and sub ballast of railway were studied. Two types of steel slag, Blast Oxygen Furnace (BOF) and Electric Arc Furnace (EAF) slags which produced in Esfahan Steel Company and Esfahan's Mobarakeh Steel Company respectively are used in this research. The range of the particle size distribution of the specimens has been selected in accordance with the characteristics of the road pavement as well as the existing laboratory facilities. In this research, California Bearing Ratio (CBR) tests were carried out on two types of slags (BOF, EAF) with two types of particle size distributions and with two different compaction methods (standard and modified) in soaked and un soaked conditions. Based on obtained results mentioned slag have no plasticity index. Moreover, dry unit weight varies between 1.94 to 2.74 gr/cm3 and optimum moisture content varied between 8% and 12.5%. The CBR values varied between 88 to 199 for BOF slags and 185 to 490 for EAF slags in socked and unsocked conditions. According to CBR test results; these materials can be used in road base and sub-base layers by applying less compaction effort than in normal condition.

Fatigue cracking is one of the most common damages in asphalt pavements. Hence, fatigue performance of asphalt mixtures is one of the most important parameters of the mixing design and structural design of pavements which ignoring it, leads to the existence of crack, rutting, and failure of the asphalt procedure. in this study, fatigue shot test was carried out to predict the fatigue behavior of mixtures containing steel slag or fatigue beam test using four - point loading in the constant strain mode at two levels of strain 600 and 800 micro strain, with a sinusoidal wave and frequency of 10 Hz. in this project, the addition of coarse and fine aggregates of coarse aggregate, fine - grained and all of aggregates was observed in the comparison that steel slag mixtures generally have more fatigue life than the observed mixtures, and the mixture containing fine steel slag aggregates have the highest fatigue life.

The adhesion between composite pavement layers plays a significant role in the long-term performance of these pavements. The purpose of this study is to investigate the effects of tack coats and their rate of usage on shear strength of interface between reinforced concrete and asphaltic pavements. In order to measure the adhesion properties, the direct shear test was used and also to measure the roughness of the surface of the concrete pavements containing the steel slag, the British pendulum and abrasion tests were applied in accordance with EN 1338. The results of the experiments indicated that the replacement of 50% of steel slag with aggregate caused an increase in mechanical properties and also in accordance with the abrasion standard of EN 1338 it was in appropriate range in terms of wearing. In addition, the results of the composite pavement shear strength test showed that with increasing the rate of tack coat application, the shear strength increased to reach the optimum point and then gradually decreased. The optimum rate of applying tack coat was varied from 0.6 to 0.9 liters per square meter depending on the type of tack coat. Considering the optimum rate of the shear strength ranking for different bitumen between composite layers was as follows: emulsion bitumen< control bitumen< crumb rubber with zeolite modified bitumen.

Warm mix asphalt (WMA) is a mixture with a mixing and compaction temperature 30–40 degree less than conventional asphalt mixture. Lower product temperature of WMA leads to increase use of this but this temperature reduction has raised concerns about rutting and fatigue performance. The object of this study is to in to investigate the effect of type of warm mix additives on moisture susceptibility and rutting resistance. For this purpose, limestone and steel slag, two type of filler and Zycotherm and Asphalten-B as warm additive were used for samples preparation and evaluating performance. Indirect tension, resilient modulus and Dynamic creep tests were performed on prepared samples for evaluating the effect of aggregate type, filler and additives on moisture susceptibility and rutting resistance. Results indicate that mixture containing Asphalten-B improve the performance of WMA as compared to HMA in ITS, MR, rutting by 10, 15 and 5%, respectively and in moisture susceptibility, asphalt mixture contain Zycotherm can increase the moisture resistance by about 10%. Also, result show that asphalt mixture containing steel slag aggregate and cement filler the highest durability and rutting resistance.