Statistical Clustering Performance in Pavement Condition Prediction as Decision Supporting System Tool

Mathematical methods and statistical patterns have always been considered by managers, designers and science and technology expert in order to develop technology and engineering objectives. During the development of data-gathering tools and increment of data-bases, data mining have made suitable tools in management and engineering. The assessment of roads' maintenance is highly important in order to prevent early deterioration of roads and performing maximum road capacity during the service-life. Pavement management of roads has also implemented this tool to make proper decisions and preferences of pavement repair methods, using decision tree. Through engineering management, cluster analysis is one of the basic tools of data mining and knowledge discovery and makes the decision making, easier in engineering. Data categorization is helpful for planning and is important in picking proper methods. This study was performed by using recorded data from other scientific sources considering data mining method and analyzing data with respect to statistical clustering. The results indicate that bitumen content in asphalt mix, pavement age, marshal strength and rate of passing vehicles have the most important effect on decrement of condition index of pavement, relatively. Also, the highest deterioration in asphalt happens in 5.5% and higher values of bitumen content and the progressive deteriorations take place when the pavement age exceeds 35 years

Effect of Drainage and Subgrade Compaction on Pavement Frosting Performance in Construction Zone

The roughness in the construction site surrounding condition and the pavement of the paths of the workzones makes a decrease in the efficiency in executive operation. Increasing the rolling resistance due to the roughness, is one of the reasons for reducing the speed of operation and delay in that. In this study first, the fields of roughness appearance are recognized including inflation due to frost of subgrade and executive operations areas, then frost depth are calculated which is affected by the density conditions and moisture amount of workzone area’s surface. The different percentages of moisture 2, 5, 7, 15 and 20 and compaction ratio 100, 90, 75, 65 percent were considered in this study for density of workzones' top surface. Frost depth calculations are carried out in the US - Army method and by Pavem-Calc software. The results show that an increase in the density of 40 % is caused by a 25 % increase in frozen strain. Furthermore, the increase of 15 % of pavement moisture causes a 20 % increase in the frost depth and the increase of surface roughness. Statistical analyses were carried out to investigate the effectiveness of the research variables and the classification of results in the classification method of CART algorithm

EFFECT OF FREEZING AND THAWING ON THE STRENGTH AND DURABILITY OF SANDY SUBGRADE CONTAINING FIBRILLATING NETWORK FIBER FOR PAVEMENT

One of the challenges of road construction is encountering soils with lack of required strength and durability. Nowadays, various stabilization techniques are applicable for improving the engineering properties of soils. In the present study, dune sand, as subgrade of pavements, was treated using various contents of fibrillating network (FN) fiber and cement. Dune sand has low bearing capacity that makes it unsuitable for construction activities such as pavement applications. The common solution is improving the strength properties of dune sand so that it can be used for civil engineering projects. Stability of subgrade is very important since the layer provides the stability for the whole pavement structure and the upper layers, namely subbase, base, and asphalt layers. In this regard, compression strength and California bearing ratio (CBR) tests were carried out. Freezing-thawing cycle is one of the most important factors affecting the mechanical properties of soils. Several researchers reported that freezing-thawing cycle could change the physical and mechanical behaviours of soils. The influence of freezing and thawing (up to 18 cycles) on the properties of samples was also studied. Based on the results, the inclusion of FN-fiber to the sand led to increasing the ductility and compressive strength. Also, the addition of cement reduced the ductility, and increased the compressive strength. By increasing the freezing-thawing cycles, the soil strength significantly decreased. Results showed that the stabilized sand soil as subgrade layer led to reducing the compressive strain under the applied wheel load, and therefore reduced the possibility of rutting failure of subgrade

Interaction of subgrade resistance and dimensions of asphalt pavement surface cracks on propagation of secondary distresses

Reactions created in road construction and secondary distresses made in pavement are dependent on dimensions and geometry of cracks, resistance of subgrade and existing pavement layers. Thus, this essay assessed the effect of changes in crack’s geometry and also the amount of subgrade resistance on settlement in the cracking place. Since pavement layers thickness has a drastic effect on the resistance of the layers, cracks propagation and secondary distresses, in this essay, different types of strong, semi-strong, and weak pavements have been considered according to combination of different thicknesses for the pavement layers which are respectively wearing layer with the thickness of 5, 10, 20 centimeters, base course with thickness of 10, 20, 40 centimeters and sub base with thickness of 15, 30 and 60 centimeter. Also, as pavement can be constructed in grounds with different resistance and so subgrade resistance has an important role in pavement settlement  and distresses, in this essay, subgrade have been studied in three types of dense sand (strong soil), fine sand (semi-strong soil), and soft clay (weak soil) with different geotechnical properties. So, for preventing the mentioned problems, layers’ behavioral properties are considered as Mohr Coulomb-plastic and by three-dimensional modeling with finite element software of ABAQUS, we studied the degree of subgrade and cracked pavement surface settlement with different forms of cracking in different types of pavement and subgrade situations, like different thickness and behavioral properties. Then, to check results and validating software, by field observation, level of settlement in different cracking places was gathered and compared to the numerical results of the software. Results of finite element software show that by 25% increase in crack opening, the level of settlement of the surface layer and  the surface of subgrade would increase by 49% and 38% respectively. Also the level of the surface and subgrade settlement would rise by increase in crack depth; and the measurements for 25% increase in crack depth are 16% for surface and 13% for subgrade. In addition, by increasing in the width of crack in soils with different resistance, width line slope of crack-settlement in weak soil would be about triple compared to strong soil, and by increase in depth of crack in soils with different resistance, depth line slope of crack-settlement in weak soil would be about twice compared to strong soil. By the use of probabilistic analysis, It was determined that in 95% confidence interval, cracking on deformation of surface and subgrade, is significantly under the influence of subgrade type and as the subgrade weakens, the amount of deformation will increase more

The feasibility of using specialized sand for making mosaic of ready mixed mortar

Studies show that mortar and concrete are used as the main materials in more than 80% of technologies. Therefore, pay attention how to increase workability and improve performance required of mortar and concrete. Mortar can be made in numerous ways, but studies have shown that the ready mixed mortar has many advantages compared to others, but without quality control and production monitoring, the customer confidence would be missed. The aim of this study is to investigate the possibility of using specialized sand in the factory for making mosaic mortar mix and controlling mortar properties. In this study, mortar specimens were created by specialized sand for making mosaic, and ordinary sand in different ratio of cement to sand. Also, specimens were produced by the ready mix mortar. The results of the compressive strength and water retention of mortar, the comparisons of fracture specimens and scanning electron microscope (SEM) images showed the possibility of using specialized sand mosaic in the production of dry mortar

Teaching and Learning of Practical Skills: Learning From the Pavement Laboratory Course

Having the necessary technical skills is one of the issues faced by the community of graduates. Assessing the current status of engineering education at universities and adapting to other countries can provide policies and solutions to improve current programs and processes. Laboratory classes are an integral part of an engineering course designed to improve technical skills, provide opportunities for developing thinking skills and promote experience-based learning. The objective and topics discussed in this study are not limited to a specific topic of civil engineering laboratory course and include other technical disciplines as well. In order to achieve this objective, this study provides a framework of study that can also be used in other disciplines and laboratory courses. In this study, while evaluating the experiences of different countries in the application of laboratory training at universities, a primary proposed solution and strategy is provided. The present study is descriptive-analytical in nature using library and field methods together with questionnaire for data collection. The results show that the use of active teaching methods in the process of teaching a skill can promote effective teaching and increase students’ satisfaction. Finally, some strategies are suggested to improve training and prepare the eligible graduates for working in industry

Application of Mathematical Models for Optimizing Inspection Frequency in Maintenance and Management of Pavement

Mathematical optimization, also called mathematical programming, is the process by which the best answer (according to a set of criteria) is selected from a set of possible answers to a particular problem. Today, optimization problems are used in all quantitative fields such as computer science, engineering, operations research, economics, and more; one of the engineering disciplines in which optimization is very important is road and transportation engineering. Road repair is one of the most important components of pavement management that requires regular road inspection by road specialists. One of the most important measures to prevent failure is maintenance inspection; Assessment of the condition of road surfaces to ensure their performance, while the road still provides maximum safety for existing traffic, should be done to ensure timely and effective repair and reconstruction operations. But exactly when these inspections should take place and when they are effective is an issue that is addressed in this study. The aim of this study is to optimize the frequency of maintenance inspections for a high-traffic suburban road by optimizing the frequency of inspections with a certain degree of reliability; so, the breakage function was considered as a pavement condition index (PCI). The results show that in order to pave the suburban road with high traffic in order to perform the desired pavement with 95% reliability, 218 inspections should be carried out annually (on average once every two days)

Investigation of Emulsion Bitumen Adhesion to Aggregates in Chipseal at Various Temperatures for Low-Cost Pavement Management

Preventive maintenance is recommended by economic models in pavement management. One of the issues that the Chipseal mix is currently dealing with is the degree of separation of the material from the mixture's surface due to a lack of proper adhesion between the emulsion(green) bitumen, and the aggregate. Have and cause an accident. In this study, it was attempted to reduce material separation by increasing the percentage of bitumen in the mixture as well as the percentage of sand as a filler. The results of this study showed that with increasing the percentage of emulsion bitumen in the chipseal mixture and with it increases the percentage of filler in the mixture, the separation rate of aggregates to less than 10% in the temperature range of -15 to +45 ° C, and a Created a more cohesive mixture

The Effect of Slope Geometry and Shoulder on Rutting Depth of Flexible Pavement

The slope and width of the road shoulder are important parameters in geometry of the road pavement. Therefore, it is important to comply with the requirements relating to the slope and width of the shoulders. So that by using the minimum width and slope of the shoulders according to regulations not only stresses and strains transferred to the lower layers will decrease, but also reduces damages in asphalt layers, base, and sub-base. Therefore, it is vital to conduct analyses which can bring good amount of accuracy in assessment of the stress and settlement due to shoulder width and slope. The aim of this study is to investigate the effect of geometry of the shoulder on the performance and behavior of weak or strong pavement. For this purpose, numerical two-dimensional modeling of the road pavement (asphaltØŒbaseØŒsub-base) on which the axel load is placed was done using finite element method, ABAQUS, and the effect of the shoulder width and slope on the stresses and settlements caused by the strong and weak pavement have been studied. Also for verification of the software, several obtained field values are compared to each other. The results indicate that the increase in the width of the shoulders and the decrease in the slope will cause in decrease of the stress and settlements in different layers of the roadways. Thus, creating less steeper shoulder and wider pavement can reduce damages and will contribute to the increased safety and sustained life of the pavement.  &nbsp

Investigation of Mechanical Properties of Quicksand Stabilized with Bitumen Emulsion and Reinforced with Waste Polypropylene Fibers and The Effect of Freeze and Thaw on Its Performance

The existing quicksands in the desert are among the problematic soils whose stabilization has been considered by experts. Emulsion bitumen is one of the environmentally friendly stabilizers of these sands. Also, the method of reinforcement with (fibers) has many advantages due to the increase in soil strength in the same way and the formation of thickness in the soil mass. The aim of this study was to investigate the effect of polypropylene fibers and emulsion bitumen on improving sandy soil properties and the effect of freeze-thaw cycles on the behavior of soils stabilized by these two substances; For this purpose, samples of aeolian sand soil with 0%, 0.25%, 0.5%, 0.75% and 1% waste polypropylene fibers of 0, 5, 10, 15% bitumen emulsion were made and tested for California load-bearing capacity and uniaxial compressive strength. Also, to evaluate the effect of the freeze-thaw cycle, the samples were subjected to uniaxial resistance test after enduring 3 and 7 freeze-thaw cycles. The results show that the addition of fibers and bitumen to the sand first increases the specific gravity and CBR and decreases from one percent onwards by increasing the fibers of these two parameters; It has compressive strength and ultimate strain with increasing fiber percentage; In general, increasing the percentage of fibers from 0 to 1% on average increases the compressive strength by 91% and the final strain by 54% and increasing the percentage of bitumen from 5 to 15% on average increases the compressive strength by 4% and the final strain by 13%. In addition, the results show that the compressive strength of the samples decreases by an average of 15% and 19% after withstanding 3 and 7 freeze-thaw cycles, respectively; however, after enduring 3 and 7 freeze-thaw cycles, the compressive strength increases with increasing the percentage of fibers to 75%. &nbsp