JOURNAL OF TRANSPORTATION RESEARCH
Year:2018 | Volume:15 | Issue:56 |Papers Count:30

This paper examines the structure of traveler behavior and how it can be measured using a set of survey questions. In this context، senses of place factors were extracted using a three-tiered، structural equation model، which simultaneously estimated three factors: Attitude، Lifestyle and shopping orientation. Through this research we have been able to both transfer successful questions measuring well accepted behavior constructs and examine further place attributes contribution. However، it is necessary to further this research and the preliminary findings of this exploratory analysis. All three factors need to be verified in future studies for their ability to explain behavior، and should be examined in different everyday activity settings to compare the strength of the manifested factors across types of activities and settings. In parallel، qualitative analysis can be used to enhance the understanding of these concepts. Although several socio-demographic characteristics were shown to be attitudes، these indicators are only able to explain a small subset of the variation، and the rich nature of behavior may require more in-depth scrutiny of their formation as well as other determinants. This study is limited to behavior about one specific location studied (Bazar)، and within a short period of a day’ s activities. Future research should be conducted to determine if there are aspects of behavior and their development that might be predicted more completely using socio-demographic indicators. The idea of applying these variables in modeling the individual clothes shopping destination choice by using structure equation models was sourced from ethology studies on customers of shopping centers (novelty of paper). In this paper 213 samples are collected by internet-based questionnaire and individuals socio-economic، attitude، lifestyle and shopping orientation were asked. This integrated model is able to correctly predict the 68. 1 percent of observation has the highest percent correct.

Look at the History of Transportation shows that efficient transport system، an important factor for the preservation and conservation of cities from ancient times to modern age. Technological and economic development of human society، human evolution happened very fast. With skyrocketing demand in the Networks، the traffic is not carried out to meet the transport demand. In such Networks، management solutions in the field of supply and demand، generally using a temporary solution to the problems remain. That is why other methods known as Unconventional method، used. One of these methods is U-turns. U-turn maneuver is one of the most complicated maneuvers which recently welcomed researchers. In this study، the Kermanshah-Biston highway were studied. Data collection was performed in one day with normal weather conditions for 6 hours using video techniques. After Data analyzing، network was modeled in Aimsun micro simulation. Considering the U-turn’ s current condition in the study area، five scenarios were designed to find the best way to U-turn maneuver must be matched. Each scenario was simulated 5 times and each time for 1 hour. The simulations’ results revealed that replacing current U-turn with underpass is the best scenario in study area based on measure of effectiveness، so that network’ s delays and travel time improved. Considering the data collection،

In this paper the effect of Epoxy Resin polymer on moisture sensitivity of Asphalt mixtures containing Silica and limestone aggregates has been evaluated. Epoxy Resin without hardener and Epoxy Resin curing with hardener in 0، 1، 2، 3، 4، and 5 weight percentages for Asphalt Binder modification have been applied. The method used for evaluating moisture sensitivity of Asphalt mixtures is Surface Free Energy method. In this method، with Surface Free Energy measurements of Asphalt Binder using Sessile Drop method and by using of the extracted values of Surface Free Energy of aggregates of valid reports، the energy parameters related to moisture sensitivity of Asphalt mixtures containing Asphalt Binder and aggregates compound، have been calculated and analyzed. At the end، base and modified Asphalt Binders with Epoxy Resin curing with hardener have been examined with FTIR test. The results show that the Epoxy Resin curing with hardener decreases moisture sensitivity of Asphalt mixtures containing Silica and limestone aggregates. Epoxy Resin without hardener does not have important effect on Asphalt mixtures containing limestone aggregates، but decreases moisture sensitivity of Asphalt mixtures containing Silica aggregates.

The model presented in this research belongs to a class of vehicle routing problems with backhaul، which the pickup and delivery process is carried out simultaneously. This problem is formulated in a bi-objective model، whose objectives are to minimize transportation costs (including the fixed cost of using vehicles and the variable cost of travelled distances) and increase the driver’ s satisfaction by balanced distribution of the product. Due to the NP-hardness of the problem، a multi-objective differential evaluation (MODE) algorithm is proposed to solve of the VRP with simultaneous pickup and delivery (VRPSPD). To show the performance of the proposed MODE، its results are compared with the results obtained by a multi-objective harmony search. Additionally، a computational test is carried out on a number of test problems taken from the literature. The computational results show the good efficiency of the proposed MODE in terms of solutions quality and time.

One of the very important issue of pedestrian traffic engineering is. Due to the typical characteristics of personality، reckless behavior expected of young pedestrians not far-fetched. In Iran، a large number of educational centers are located mainly used by teenagers are located on the periphery of suburban roads and pedestrian traffic is frequently seen with this type of institution. Study the interaction of vehicle and pedestrian flow these areas can improve traffic safety and pedestrian facilities to provide useful results. In this study، students as one of the most vulnerable pedestrians in suburban roads were analyzed and recorded video data from the past 3 school students in suburban road in the city of Mahmudabad، Mazandaran province، the three working days of the week were collected. The possibility of pedestrians crossing the street width using spss software and logistic regression were used. The results showed that the waiting time before passing away vehicle and the amount of headway on the possibility of crossing the line pedestrians across the road are very effective. Among the factors influencing the amount of headway had the greatest impact on the probability of passing pedestrians.

The main objective of this paper is to identify the factors that influence the practical process of designing port tariffs. The analysis is based on data from 40 ports worldwide. At first، Exploratory Factor Analysis was used to identify the factors influencing the choice of tariff design model. Subsequently، the Confirmatory Factor Analysis is used to examine the relationship between the variables. The findings show that، the port demand، knowledge about pricing theories، the dynamics of port and shipping segments (including ship size and competition)، pricing goals and costs associated with port services are factors that influence the design of infrastructure tariffs. Most ports use a combination of pricing approaches that include discriminatory pricing، cost based pricing and market-based pricing. Ports are aware of the fundamental pricing approach، but they know little about their use. Based on the results of the analysis، a strategy for port management in tariff design was established، at last research constraints and recommendations for future research are discussed.

This research investigated the possibility of predicting the fatigue life of reinforced asphalt by recycled polyethylene terephthalate (PET) fibers based on dissipated energy parameters. Fatigue tests were performed using 4-point bending test at three temperatures of-5، 10 and 20oC and two frequencies of 10 and 2 Hz. Fibers were incorporated at two lengths of 1 and 2 cm and average diameter of 30 micrometer. Furthermore، four fiber contents including 0. 5، 1. 0، 1. 5 and 2. 0% by weight of bitumen were used. Obtained fatigue laws showed an increase by increasing the test temperature. At a constant frequency، the fatigue lives of reinforced specimens were higher than the reference one. The beneficial effects of fibers were more pronounced at higher temperature and lower initial strain levels. Traditional fatigue models used the initial dissipated energy or cumulative dissipated energy to predict fatigue life. In newly established models the plateau value (PV1) parameter has been defined using the ratio of dissipated energy changes in plateau stage of dissipated energy curve obtained from 4-point fatigue test. In this research a new definition was presented to calculate the PV parameter (PV2). Based on statistical analysis power functions were presented to predict fatigue life based on PV1 and PV2 parameters. The relationships between PV and fatigue life was unique independent of the mix type and testing conditions (i. e. temperature، frequency and strain level). Furthermore، the fatigue model based on PV2 parameter was as precise as that presented using PV1.

In the present study، Behavioral Evaluation of drivers' performances is been considered. Based on different studies، High speed is known as one of most causes of accidents occurrences or the increase of accidents severity. Thus، transportation researchers are always looking forward the presentation of effective solutions about the decrease of vehicles speed. In this study، effect one type of pavement marking as a traffic calming system (Speed Limitation on pavement) was considered on drivers' performance in real and virtual (driving simulation) environments. Results of Simulation of 60 participants' performance (39 men، 21 women، at least 3 years driving، Age Average: 27. 2 and S. D: 5. 7) using driving simulator showed that drivers drove using safer behavior (less speeds) after the implementation of pavement marking. Based on results، speeds average decreased from 91. 87 km/h to 77. 21km/h. Also، the relative displacement of vehicle decreased from 44 cm to 31 cm. In the real environment، analysis of 1227 vehicles (before the study) and 1073 vehicles (after study) indicated that vehicles' speed average after the implementation of pavement driving decreased from 86. 38 km/h to 79. 12 km/h. Moreover، the result of the T-test showed a high similarity between the results of real and virtual environments.

The dynamic characteristics of different structures have led to the development of various analytical methods for analyzing the seismic behavior of structures. The existence of a predominant period in the structure is one of the features that can be used in analytical simplifications. Steel arch bridge is one of the systems for covering relatively long span. Mass distribution of steel arch bridge is the most important reason complexity of their seismic analysis. In this study a 300m span steel arch bridge has been investigated as a sample in the longitudinal direction. A comprehensive study has been carried out on the application of a capacity and demand prediction procedure based on incremental dynamic analysis with 17 seismic records for seismic performance evaluation of that bridge. Also results of IDA have been compared with nonlinear pushover analysis, and incremental dynamic analysis with sinusoidal record. Load pattern of pushover analysis is considered in two cases: inertia force distribution and modal force distribution. Nonlinear material effects are considered in the form of a concentrated plastic joint. The results show that Mass distributions of steel arch bridge due to this structure have not a predominant period and their seismic behavior is different under different accelerations because different mode shapes of structure are incitement. Also, by removing the mass of the arch element of the bridge and creating a model with predominant mode in the longitudinal direction, the results of its incremental dynamical analysis and nonlinear pushover analysis are investigated. Finally, a new approach is used for IDA by selecting harmonic base acceleration functions. This method is able to reduce the calculation cost of IDA with same accuracy of ground motion time histories.

Despite the high application and proper properties of bitumen in Consumptions of road construction، damages and disadvantages of asphalt mixing are created. Including rutting، cracking، necessitate the repair of bitumen that are used in road construction with additives. Some additives reduce the hardening of the bitumen by reducing mixing and compaction temperature، resulting in a modification of the mixing behavior of the asphaltic against the loads. in addition، will reduce air pollutants and energy consumption. Therefore the aim of this research is to study rheological properties of modified bitumen via investigating and comparing sasobit، paraffin wax with unmodified bitumen as well as their composition considering the effect of this additive on aging and performance temperature. For this purpose، base bitumen (AC 60/70) was selected and used as a laboratory method based on common bitumen tests، which including penetration degree and، softening point، and Sharp tests including Dynamic shear rheometer Rotational viscosity and aging tests. The results of the experiments indicated the effectiveness of the mentioned waxes in increasing the bitumen efficiency by reducing the viscosity. In this case، the mixing and compaction temperature can be reduced، which reduces the aging and stiffness of the bitumen. Also the use of combination sasobit waxes and paraffin can improve the high performance of bitumen compared to the samples which consist of paraffin. By comparing the effects of this combination with other waxes along with considering to the cost and effectiveness degree، it is possible to have good choice for improving properties and behavior of bitumen.

By assigning a part of state ownership and participating private sector at assignable sections، the Iran’ s railway is going to reduce its costs’ burden. In this study، by inspiring from the strategies’ prioritizing models and 20-year landscape document the scholars have tried to measure the 44th institute of the constitution and the 5-year development plan of privatization’ s strategies under the influence of policy. The research mythology is survey and analytical method in which for accepting or rejecting the variables، binomial and Friedman statistical tests and strategies’ prioritizing model within the public expedient (rail transportation industry) are used. In the opportunity and capacity which are based on Iran’ s position، the private sector participation is so high for developing the Rail transport industry and in the railway، such as any organizational profound transformation، it is required to adopt strategic decisions. The countries’ economic situation is the first main factor which is determining the using scope of the privatization strategies. The second main factor is performing the basic rules which are a guarantee to proper the implementation of chosen strategies، exactly and fundamentally because for implementing any policy، respectable and direct treatment of law is essential. Supplying Edalat-stock and the operation reporting from process of choosing and privatization strategies within the public expedient are essential، so the relevant authorities should provide people with clear reports and information، also، they generally should pay more attention to capital market.

Level of compaction and its uniformity is an important parameter to specify mechanical quality of road layers. Compaction is an expensive and time consuming procedure therefore without applying decent compaction control tools; the results could be unsuitable and cause premature local and general distresses. Compaction quality control، as is common in Iran، can be based on end-product specifications or combination of method specifications and end-product specifications. In situ test method results have relatively low accuracy on assessing materials properties. Some limitations associated with these test methods are: random quality control of compaction، unreliable results in some of this method due to presence of oversized particles، moisture content dependency in stiffness based methods، measurement depth limitation in some of in situ test methods and lack of lift thickness control. Using several means including controlographe (in order to record daily roller operation like speed control، traveled distance، frequency، vibration)، roller performance tables، and test section construction it is possible to have primary control over compaction procedure that can lead to higher uniformity and quality of compaction. By introduction of continuous compaction control (CCC) systems، most of conventional in situ test method limitations were solved. The main goal of this technology is to produce uniformly compacted pavement and high quality products. This method makes it possible to monitor compaction control and construction simultaneously and 100 percent coverage on the compacted area. The objective of this study is to investigate CCC systems and evaluation of conventional in situ compaction verification tests and specifications for compaction control of embankments and pavement layers in order to propose a solution to modify existing situation in Iran.

Long-term planning requires the use of new approaches، such as future studies، to be able to withstand future uncertainties. Identifying policies that will result in a sustainable transportation system is a major challenge for policy makers since it involves a high level of uncertain. The objective of this paper is “ prioritize transport strategies based on robust criteria on the 20-years horizon” using “ Global Business Network” . Statistical population is of 30 experts in the field of urban affairs which were selected by snowball sampling method. Data gathering tool was documentation study، literature review، panel and questionnaire. Validity of the questionnaire assessed using the judgment of experts and the Cronbach's alpha was used for validation. Two driving forces included “ government support for private sector” and ” society merits” were identified as main driving forces shaping transport futures of Hamedan and four scenarios included “ green transportation” ، “ dependence to private cars” ، “ chaos” ، "strict controls" based on two factor were developed. A fuzzy logic approach was used to identify robust strategies. Two strategies included “ promotion of culture and traffic behavior and increase participation of citizens in transportation” and “ parking management and organize parking space” were identified as robust strategies which have acceptable performance regardless will happen in future. Finally، in order to achieve two robust strategies، proposals were presented.

In order to decrease the growing trend car ownership precipitate، supporting public transport is an essential matter. Analyzing experimental data shows that increasing the level of offered services can be an effective way to increase supporting of public transport. Public transport users are divided in two groups: those who use public transport and own private car and those who use public transport but they don’ t own private car. One of the main issues in travel demand management (TDM) is identifying and separating effective factors on service quality based on these two group’ s viewpoint and following that، attracting and encouraging them for using these services. The question we follow to answer in this research is that، Is there a meaningful difference between these two groups in terms of effective factors on service quality of transport. In this research 26 factors for analyzing services quality of railway transport have been identified which by using factor analysis have been summarized and classified in 7 factors and then by using statistical tests between these two groups of users، a comparison has been made regarding effective factors on service quality. The results of this research show that there is no meaningful difference in the importance of each index of public transport in these two groups.

Bridges are the most important and influential infrastructures in urban transportation networks. Isfahan transportation network has many bridges having important role in the performance of the network. Felezzi Bridge is one of the most important bridges at this network because of transferring traffic flow from north of the city to south and vice versa. Construction of this bridge was finished at 1959. At this study the impact area (10% traffic flow change range at the peak hour in 1393) was determined by omitting this bridge from the network in TransCAD software. Then scenarios and indicators were introduced to evaluate. Scenarios were assigned to the model. Then indicators was calculated for each scenario and converted to costs to compare with each other. Indicators were divided to 3 groups according to payers. These payer groups contain users، public and agency. User indicators are travel time، fuel and vehicle operation cost. Public indicators include crash costs، air pollution and noise pollution. Agency indicators are maintenance and construction costs، traffic service and facilities costs. The analysis period is until the end of bridge operation life (2029). Scenarios increasing supply reduce travel time but increase fuel and vehicle operation costs. Results show that summation of costs for users increase at these scenarios and demand management scenarios have lower costs for this group. On the other hand in public costs، crash and air pollution costs are reduced by operating supply enhancement scenarios and noise pollution are increased. It is clear that supply enhancement scenarios have more cost for agency than demand management scenarios.

Rail transportation is seen every bit unitary of the bulk transport modes along with valuable advantages such as Economic savings in fuel consumption، reducing air pollution and approaching environmental standards the importance of this piece of the transportation has increased and the continuation and development of the rail transportation sector has passed in the country. And proper and timely utilization of this section it can also make the necessary investment in transit، the rail transportation sector of the country is effective. The main purpose of this research using panel data econometric technique on Investigative demand for transit in Iran's rail transport sector and estimating demand function using the gravity model. In the estimated model، five variables are considered: 1-The amount of transit goods transported on the railways of the country، 2-Tariff Transit Rate in Rail Transport، 3-Time transportation of transit cargo in the rail transport sector، 4-Gross domestic product (GDP) of Russia، India، Turkey، Kazakhstan، Turkmenistan and Uzbekistan، 5-Geographic distance between Iran and these selected countries: Russia، India، Turkey، Kazakhstan، Turkmenistan and Uzbekistan. Furthermore In this paper، the effects of shocks of variables on the amount of goods transported in the rail transport sector، Tariff Rate، Shipping Time، GDP Countries Studied and Geographic distance between these countries over time been investigated. The results of the estimation show that the variable tariff rate is statistically Meaningful and its coefficient is 0. 27. The time variable also has a coefficient of 1. 27 has been meaningful. Both of these variables produce results as expected and express with a one percent increase in tariff rates and transit time، the transit demand in the rail transport sector is reduced by 0. 27% and 1. 27%. A direct and meaningful relationship with a coefficient of 0. 24 Gross domestic products of Russia، India، Turkey، Kazakhstan، Turkmenistan and Uzbekistan، There is a demand for transit in the rail transport sector of Iran. Also، the results of the geographic distance variable states that There is a negative and significant relationship with the coefficient of 15. 73 Geographical distances of the countries surveyed And Transit request In the rail transportation sector of the country are exist.

Although Global Navigation Satellite Systems (GNSS) provide precise and accurate services، it is technically possible that any delay in sending signals or sending them incompletely or interruption of services cause damage. Navigation of aircrafts by Global Navigation Satellite Systems creates a variety of questions about the liability of service providers which international air and space law conventions are not sufficient for the answers. Maybe at first، attempting to ratify an international Convention in Global Navigation Satellite Services is the best option but at the same time، experience of time-consuming efforts to drafting an international convention regarding to liability of Air Traffic Control، makes clear the difficulties. Author believes that International Civil Aviation Organization (ICAO) as one of the active international organizations in the aviation industry can play a major role in various aspects of the implementation of satellite systems like liability of service providers by creation an appropriate legal framework.

Todays، there are many submerged vessels in the ocean and sea environments that must be salvaged very soon. Salvaging these wrecks is of great importance for many reasons as maritime safety، bio-environmental pollutions، and material interests from their scrubs، archaeological discussions، and avoiding morphological changes. There are also many conventions regarding to salvaging submerged ships throughout the world that are approved by the considered international maritime organizations and the Persian Gulf and Oman Sea states. In this study، we are going to investigate the strategic and status importance of Arvand River (Arvandrood). In addition to clarifying the status importance of this border river between Iran and Iraq countries regarding to its geographical status and special strategic situation، we will deal with problems are subjected to Arvand river reconstruction. The general goal of this research is to solve the problems which vessels especially large ships are dealing with during navigation in this river and present a proper strategic for restoring Arvand River which ultimately will lead to economic، politic and social development. This is a descriptive-survey research، so a questionnaire includes of questions regarding to the problems are dealt with in Arvand river is used. This questionnaire is delivered to the experts in Ports and Shipping Organization and also shipping companies. The statistical population includes of 55 individuals. According to the field study and survey، the questionnaire validity is confirmed with alpha kronbakh that means a questionnaire of high reliability. SPSS software version. 19، is used to validate research hypotheses، and Kolmogorov– Smirnov test is used for defining the research sample distribution. Because of non-normal distribution of questionnaires، so a Binomial Test is used in this research.

Iran is one of the countries where there are a lot of traffic accidents and the number of people killed and injured in road accidents is high compared to other countries in the world. On the other hand، one of the main carriers of accidents is the human factor، which is a very risky factor. The research has introduced six driver assistant systems to reduce driver workload and human error in order to reduce accidents، including navigation system، lane keeping system، forward collision avoidance، adaptive speed control، priority tracking system and emergency call system In order to carry out the above research، police and traffic police reports، forensic centers of the country، library resources، Internet searches، statistics and information about the number of casualties، injuries and damages caused by accidents in 2014 in Tehran province were collected and according to research and Various articles of cause of accidents and the share of each cause were determined in the total number of accidents. Then، with the introduction of each of the six driver assistant systems، the performance and role of each system were evaluated in the amount of crash reduction. In the next step، considering the cost of each of the six driver assistant systems and the benefits that each system makes in reducing accidents، using the economics of engineering، Benefits-Cost، were evaluated technically and economically. Then، according to the results of the economic evaluation obtained from the system that has the highest value for Benefits-Cost to the least amount was prioritized. In the end، the prioritized results were corrected with regard to the technical assessment and manufacturing technology and compared with the existing conditions and attitudes of car makers and legislators abroad and the accuracy of the prioritization was confirmed.

The performance of a pavement is not only a function of its design، but the success of each project depends on the construction، systematic and effective supervision، and the technical and qualitative control of the construction، maintenance and repair of the next time. Therefore، the establishment of a quality system and quality control system in project-based organizations، which was previously a choice، has become a belief and a requirement today. The Office of Project Quality Management has now become increasingly accepted as an organizational solution for more effective project management in project-based organizations in the world، and currently، on average، 87% of organizations in the world have a Project Management Office they are the main custodians of quality in the organization. The necessity and importance of quality in projects، the need for accurate and timely information، the analysis of critical conditions during implementation، the examination and analysis of laboratory results and the provision of timely reminders and resolution of problems identified by technical and expert committees. Therefore، in this paper، we examine the effect of executive performance of the Office of Quality Control of the projects of the Directorate of Railway and Road Transport of Yazd province and present a general overview of the establishment and method of analysis of project information. Establishment of QC office in this department with the attention and trust of all managers is based on two principles of quality control and technical control of projects with the aim of organization profitability and optimization and return of national capital through control and quality assurance of projects. In this case the benefits and benefits of creating this organizational unit are explored.

Every year، millions of people are affected by natural disasters like flood and earthquake and unnatural (man-made) disasters like road accidents. In Iran، The rapid growth of motor vehicle ownership in recent years، along with the youngness of the population and the variety of the vehicles has led to an increase in the need for massive relief operations in man-made events. Therefore، the preparation for the quick reactions and doing operations of the emergency management including providing relief centers and creating relief chains to reduce its losses and transfer the victims from the crisis regions to the predefined relief centers seem necessary. On the other hand، in determine location of the relief centers، there are different stakeholders that have different viewpoints، capabilities، and needs. Road users and accident victims are one group of the stakeholders that minimizing the relief time with the maximum capacity of the relief center is from their needs. In this paper، it was attempted to model the problem of finding the relief hub locations with the priority of the road victims’ requirements. In this model، time has been considered as fuzzy number and deterministic solving methods and Meta heuristic NSGAII algorithm have been used.

Travel is one of the most important aspects of human life and is one of the most important periodic (or non-periodic) activities. For this reason، over the years، various ways have been devised to meet this need of communities. Similar many industrial systems، the transportation system are affected by supply and demand relations، and any action in this area should be planned according to existing relationships and future trends of supply and demand. In this research، using 3 Models: simple linear regression، multivariate regression and multi-layered perceptron neural network models for forecasting traffic demand of Qom-Tehran (freeway) axis was studied. The data used in this research include the Iranian Statistical Center، statistical manuals and Qom traffic information. Independent variable in multivariate regression and neural network including population، working population، income level and simple linear regression model of population. The results of this study show that Pearson correlation between variables considered in neural network methods، multivariate regression، linear regression was 0. 995، 0. 933، and 0، 723 respectively، and the success rate of each of these models in estimated dependent variable (travel demand) were 0. 99، 0. 885، and 0. 541، respectively. Comparison of methods has shown that the neural network method has the highest correlation and accuracy and simple linear regression method has the least correlation and precision in demand estimation.

Construction is both in construction and in maintenance discussions، except for the most costly parts of the civilization of any country. The traffic has increased dramatically in recent years، and road traffic has also increased. One of the most common ways to reduce road failures is to increase the asphalt resistance of asphalt modifiers. In the meantime، modifying materials that improve bitumen and asphalt tracing simultaneously are more lucrative. In this research، asphalts modified with two types of high-consumption fibers، one imported and another is made inside، is considered. To prevent the promotion of products، their brand was not used، and the imported fibers were named Fiber No. 1 and the inner fabric was named as Fiber # 2. Modified asphalt with these fibers were tested using dynamic creep tests، grooving، moderate temperature failure and indirect tensile loading fatigue. Asphalt samples corrected with fiber number 1 with consumption values? ? of 0. 05، 0. 075 and 0. 1 weight percent of asphalt mixture and asphalt samples corrected with fiber number 2 were also used with values? ? of 0. 1، 0. 15 and 0. 2 The weight percentages of asphaltic mixtures were made and the experiments were performed on them. The results showed that، except for the dynamic creep test، in all experiments، fiber number 1 performance was better than fiber number two. According to the results، it was found that fiber number 1 had a better performance than fiber number 2، although both fibers improved the performance of the asphalt.

Polymer modified asphalt binders have been used for years to produce asphalt mixes with improved resistance to rutting، fatigue cracking، and thermal cracking. Special equipment and technique، which may not be always available، are required to produce polymer modified binders with desired engineering properties. Recently، a new approach is introduced to facilitate the use of polymers in asphalt mixtures. Polymer-binder additive، with 40% Styrene Butadiene Styrene [SBS]، produced in pellet form can be directly incorporated to the mix during production in asphalt plant without the need for any special equipment. Logistically، this new form of mix additive simplifies and expands the use of polymers even for small paving projects. However، due to the novelty of technology more research is required to assess its efficacy. In this paper stiffness، rutting، fatigue، and thermal cracking resistance properties of asphalt mixes modified with polymerized pellet are compared to the mixes containing unmodified and polymer modified binders. The effects of long-term oxidative aging on stiffness and strength of mixes were also evaluated. Result of this study showed that the polymerized pellet mix additive had similar effects as the SBS polymer modified binder in improving asphalt mix performance-related properties.

This study deals with the development of an environmentally sustainable roller compacted concrete (RCC). Response surface methodology (RSM) has been used to design and optimize the mixtures. The variables used were; high volume fly ash (HVFA) at 50%، 60%، and 70% replacement by volume; crumb rubber at 10%، 20%، and 30% replacement by volume of fine aggregate; nano silica at 0%، 1%، and 2% addition by weight of cementitious materials. Multi-objective optimization was carried out to determine the optimized mixtures by maximizing the 28 days compressive، flexural and splitting tensile strength. An optimized HVFA RCC mix can be achieved by partially replacing 10% fine aggregate with crumb rubber by volume، replacing 53. 72% of cement with fly ash by volume، and the addition of 1. 22% nano silica by weight of cementitious materials. To further study the effect of crumb rubber and nano silica on the properties of HVFA RCC، new mixtures were prepared using a constant fly ash content as replacement to cement (50%) and varying the percentage replacement of fine aggregates with crumb rubber (at 0%، 10%، 20%، and 30%)، and the percentage addition of nano silica at (0%، 1%، 2%، and 3%). Compared to conventional RCC pavement، HVFA RCC exhibited lower fresh density، Vebe time، compressive strength، splitting tensile strength and flexural strength compared to conventional (control) RCC pavement. However، at after 1 year، HVFA RCC pavement shows higher compressive strength than the conventional (control) RCC pavement. Partially replacing fine aggregate with crumb rubber leads to a reduction in fresh density، Vebe time، compressive strength، flexural strength and splitting tensile strength. The addition of nano silica increases the Vebe time، fresh density، compressive strength، flexural strength، splitting and tensile strength of HVFA RCC.