INVESTIGATE PERFORMANCE OF POLYMER MODIFIED ASPHALT MIXTURES

: In recent years, traffic loads have increased, and the sizes and loads of vehicles have become greater, thereby affecting the performance of asphalt pavements. Modified bituminous materials assist to add benefits to performance, maintenance and construction, in terms of better and longer lasting road, and saving in total road life cost. This study attempts to identify the influence of polymer modification in improving asphalt mixture performance. Three types of polymer resins were used, namely, Epoxy resin, Phenol resin, and Polyester resin. The physical properties of asphalt cement were tested by penetration and softening point. Apart from mix performance, the effect of modification on Marshall properties was studied. To estimate the tensile strength and evaluate the mixture’s susceptibility to temperature variations, three test temperatures were used (15, 30, and 45°C). Furthermore, modified mixtures were tested by measurement of static creep. Based on the study results, it was found that increasing the phenol or epoxy resin quantities in asphalt cement lead to an increase softening point and reduce penetration. Material properties can be improved by the incorporation of phenol and polyester resins, since recovery property can be improved. Moreover, using phenol resin in asphalt mixes can increase the resistance to deformation when exposed to traffic loading

Evaluation of structural properties of Baghdad-Baquba road pavements

Structural evaluation of the road pavements is an essential concept to ensure their efficiency to carry traffic loads and to archive the data for future usage especially in major highways. Baghdad-Baquba is an important interstate highway as it connects the capital of Iraq with Diyala governorate which is one of the biggest governorates in Iraq. In addition, this highway connects Baghdad city with several governorates in the north of Iraq. However, this highway exhibits low serviceability due to poor condition of its pavements. Therefore, the structure of the pavements must be evaluated to specify the causes those lead to the decrease in its serviceability and to propose the suitable rehabilitation methods. This study aims to adopt a field survey to extract a number of samples from selected section in this highway to evaluate the structural properties of the pavements based on laboratory testing. Four cores and one pit with 1×1 m dimensions were extracted from the pavements in the field. Several tests were implemented on these tests based on standard methods. The results of the tests were adopted to evaluate the capacity of the pavement based on AASHTO 1993 method. The results exhibited that the estimated applied traffic load exceeded the calculated allowable traffic load by more than 12 times which reflect the disastrous situation. Therefore, the study proposed to rehabilitate the pavements by reconstruction. The study proposed to construct three layers: asphaltic layer with thickness of 240 mm, granular base with thickness of 250 mm, and granular subbase with a thickness of 250 mm. The study stated that all layers must have superior quality with high elastic modulus to resist the predicated traffic load

Evaluation of Elasticity Modulus of Clayey Soil from Undrained Shear Strength

The modulus of elasticity represents the soil stiffness; it was used to design and analyze the foundation, slope stability, retaining structure, etc. It is one of the main input parameters used in the finite element method for analyzing soil behavior. The scope of this study is to evaluate the correlation between the modulus of elasticity (E) and the cohesion of the soil (cu) for the remolded and undisturbed samples of clayey soil so it can assess the effect of lateral confining pressure on the soil modulus of elasticity. The unconfined test is chosen for remolded soil to identify the stress-strain behavior. After the experimental utilized is done, the test is modeled using the finite element method to study several states of soil. The PLAXIS program is utilized, and the results are compared with the practical results. The mohr-Coulomb model is chosen for this study because it is commonly used. Based on the results throughout this study, it can be concluded the simulation using the Mohr-Coulomb model of PLAXIS software gives good results for representing the unconfined compression test, so that for soft clay, the ratio between modulus of elasticity and cohesion is equal to (Eu = 30 cu) for remolded clay and (Eu = 55 cu) for undisturbed clay. While for stiff clay, it was equal (Eu = 65 cu) for remolded and (Eu = 120 cu) for undisturbed clay. The modulus of elasticity for the undisturbed is higher than for remolded clay, so the difference is almost double in the case of stiff clay. The lateral confining pressure affects the modules of soil; however, for soft clay, the range of soil modulus in the case of the drained test was (5 to 25 MPa), while the range is higher for the undrained case (18 to 54 MPa). Moreover, for stiff clay, the range was equal (11 to 100 MPa) for a drained test and between (18 to 100 MPa) for an undrained case

Using soft soil models in geotechnical engineering: a review paper

Soil is considered a complicated material as, in general, the behavior under loading is non-linear in addition it is anisotropic material and its behavior is time-dependent. Various models were developed in the method of finite element for modeling the behavior of soil under different loading cases, and it must be known that no constitutive model is available that can simulate completely the actual soil behavior under all conditions. This paper attempts to investigate the soft soil model and present a discussion about the advantages and disadvantages for the purpose of giving an overview, and discussing the main finding of the previous studies regarding using the Soft Soil model in the numerical analysis of geotechnical engineering problems and applications. In this research, it was observed from the previous studies that the relation between the modified compression index (λ*) and unloading index (κ*) is from (5 to 10). The Soft Soil model gives a stiffer stress-strain behavior compared to Hardening model. Using this model for compressible soils needs a longer calculation time than other models as the material stiffness matrix was included in each calculation step. It shows satisfactory results in the analysis of the settlement of immediate and consolidation cases of foundation in clayey soil than the model of Mohr-Coulomb

Performance of Chemical WMA Mixtures – A review

In recent years, a new approach called WMA technology is developed, which include reduces binder viscosity and accordinglyallows lower temperatures for mixing and compaction. This technology gives several benefits, such as reduce emission, less odor,and energy saving. This study gives a comprehensive review on the use of WMA with chemical technology. In addition, give anintroduction to use chemical additives into the bitumen, in order to understand the application of these additives, the problems,benefits and how they act are reviewed

Service evaluation of urban public transportation in Baghdad City

Public transport performance is an important tool for users and operators. It generally allows them to verify whether the service is provided efficiently and effectively, identify areas where performance improvement may be needed, ensure that the community and users are satisfied; and support decision-making. In this research, the public transport routes located in different areas in Baghdad were studied. Public transport lines are used daily by people because they pass through vital areas and serve all passengers, students, employees, and others for several purposes. Data were taken on different days and at peak hours for four routes. The service level of public transport relied upon Transit Cooperative Research Program (TCRP) Report 100 scales was adopted to determine the level of service for each route. The most important problems faced by each line were identified, and based on these problems, appropriate solutions were proposed as they are important lines that serve a large group of people

Evaluation of Elasticity Modulus of Clayey Soil from Undrained Shear Strength

The modulus of elasticity represents the soil stiffness; it was used to design and analyze the foundation, slope stability, retaining structure, etc. It is one of the main input parameters used in the finite element method for analyzing soil behavior. The scope of this study is to evaluate the correlation between the modulus of elasticity (E) and the cohesion of the soil (cu) for the remolded and undisturbed samples of clayey soil so it can assess the effect of lateral confining pressure on the soil modulus of elasticity. The unconfined test is chosen for remolded soil to identify the stress-strain behavior. After the experimental utilized is done, the test is modeled using the finite element method to study several states of soil. The PLAXIS program is utilized, and the results are compared with the practical results. The mohr-Coulomb model is chosen for this study because it is commonly used. Based on the results throughout this study, it can be concluded the simulation using the Mohr-Coulomb model of PLAXIS software gives good results for representing the unconfined compression test, so that for soft clay, the ratio between modulus of elasticity and cohesion is equal to (Eu = 30 cu) for remolded clay and (Eu = 55 cu) for undisturbed clay. While for stiff clay, it was equal (Eu = 65 cu) for remolded and (Eu = 120 cu) for undisturbed clay. The modulus of elasticity for the undisturbed is higher than for remolded clay, so the difference is almost double in the case of stiff clay. The lateral confining pressure affects the modules of soil; however, for soft clay, the range of soil modulus in the case of the drained test was (5 to 25 MPa), while the range is higher for the undrained case (18 to 54 MPa). Moreover, for stiff clay, the range was equal (11 to 100 MPa) for a drained test and between (18 to 100 MPa) for an undrained case

Equity of transit need in Baghdad City

Public transportation plays a significant role in urban areas, transporting a large percentage of people. There is no existing study dealing with the balance between transportation demand and supply in Baghdad city; thus, there is a need to assess service equity before implementing any major services. The aim of the present research is to study the equity of transit need. The methodology uses geographic information systems (GISs) and spatial multi-criteria analysis to determine equity. Nine criteria were used in this study (land use, population density, commercial activities, medical locations, bus stops walkability, educational activities, bus terminal, and income) to determine a transit need map. Expert opinion surveys are conducted to determine pairwise comparisons between these criteria to estimate the weight of each criterion. Spatial analysis in ArcGIS 10.8 is utilized to apply methodology. The transit need map is obtained, and the need for transit service is represented by a value for each cell. In addition, the map output is important to public transit planning, as it maximizes the optimal transit route selection depending on the transit need. The output of this study (a transit need map) represents a powerful tool for the decision-makers to prioritize transportation programs and ranking alternatives. Gap analysis is used to measure equity between various zones. The results show that the transit supply provides higher service coverages in the Central Business District (CBD) and decreases as the distance to CBD increases