MECHANISTIC EVALUATION OF LIME-MODIFIED ASPHALT CONCRETE MIXTURES

Frequently, Load associated mode of failure (rutting and fatigue) as well as, occasionally, moisture damage in some sections poorly drained are the main failure types found in some of the newly constructed road within Baghdad as well as other cities in Iraq. The use of hydrated lime in pavement construction could be one of the possible steps taken in the direction of improving pavement performance and meeting the required standards. In this study, the mechanistic properties of asphalt concrete mixes modified with hydrated lime as a partial replacement of limestone dust mineral filler were evaluated. Seven replacement rates were used; 0,0.5, 1, 1.5, 2, 2.5 and 3 percent by weight of aggregate. Asphalt concrete mixes were prepared at their optimum asphalt content and then tested to evaluate their engineering properties which include moisture damage, resilient modulus, permanent deformation and fatigue characteristics. These properties have been evaluated using indirect tensile strength, uniaxial repeated loading and repeated flexural beam tests. Mixes modified with hydrated lime were found to have improved fatigue and permanent deformation characteristics, also showed lower moisture susceptibility and high resilient modulus. The use of 2 percent hydrated lime as a partial replacement of mineral filler has added to local knowledge the ability to produce more durable asphalt concrete mixtures with better serviceability

Characteristics of Traffic Accidents in Baghdad

Road traffic accidents (RTAs) are events that suddenly, inadvertently and unexpectedly occur under unforeseen circumstances that involve at least one moving vehicle and result in one or more road users being killed or injured. Unfortunately, Iraqi governorates suffer from higher rates of traffic accident casualties compared with the rates of casualties from terrorist attacks; this situation reveals a serious and growing problem. Road traffic accidents are not easy to eradicate. However, their prevalence can be reduced to the barest minimum via periodic assessments of traffic accident characteristics and the most important aspects for road authorities to consider when designing and evaluating the performance of a road to improve traffic and road users’ safety.Therefore, the primary objective of this paper is to evaluate traffic accidents in Baghdad using a retrospective analysis of accidents that occurred from 2006–2016 taking into consideration the following parameters: the cause of the accident, the genders of the victims, the number and type of vehicles involved in the accident, the time of the accident, the severity of the accident, the type of accident and the age group of the driver(s). The data were been obtained from the Central Statistical Organization in the Ministry of Planning. The results reveal that 12,019 RTAs occurred in the city of Baghdad; on average, 1,092 RTAs occurred each year. Twenty-two percent of the RTAs resulted in death, 67% resulted in injury and 6% resulted in both deaths and injuries. Only 4% of the RTAs resulted in property damage without victims. To this end, Baghdad has the highest prevalence of RTAs of all Iraqi governorates. These results provide scientific evidence to mobilize road authorities to effectively and urgently develop adequate traffic strategies and policies to reduce the epidemic of RTAs in Baghdad as well as other Iraqi governorates

Assessment the Impact of Different Hydrated Lime Addition Methods on Fatigue Life Characteristic

The purpose of this study is to evaluate the effect of hydrated lime addition methods as filler replacement on fatigue performance of Hot Mix Asphalt (HMA). Three types of addition methods of hydrated lime were introduced namely dry HL on dry aggregate and saturated surface aggregate above 3% and slurry HL on dry aggregate, ordinary Lime stone powder was reduced by three HL percentage (1.0, 2.0 and 3.0 %). The effect of different methods were investigated on the fatigue properties of HMA using, third-point flexural fatigue bending Test. Pneumatic Repeated Load System (PRLS) was carried out to establish the effect of hydrated lime on the fatigue failure criteria and to select the proper hydrated lime application methods on fatigue behavior of HMA mixtures. The fatigue functions for asphalt mixture with hydrated lime are obtained and compared, and it confirm that the fatigue property of asphalt mixture can be improved using all methods and the addition methods were exhibited different optimality for the result due to its effect . The test results were carried out through the performance analysis using Vesys 5W (2003) to study the long term effectiveness of hydrated lime effect

A Review of Interface Bonding Testing Techniques

Interface bonding between asphalt layers has been a topic of international investigation over the last thirty years. In this condition, a number of researchers have made their own techniques and used them to examine the characteristics of pavement interfaces. It is obvious that test findings won't always be comparable to the lack of a globally standard methodology for interface bonding. Also, several kinds of research have shown that factors like temperature, loading conditions, materials, and others have an impact on surface qualities. This study aims to solve this problem by thoroughly investigating interface bond testing that might serve as a basis for a uniform strategy. First, a general explanation of how the bonding strength function works and how it affects the pavement is given. The construction of various setups is then examined, and their functions are contrasted, followed by an explanation of various interface bond test procedures according to loading situations. A concept for a systematic approach to a standard assessment of asphalt interface is proposed, based on previous findings

Traffic Noise in Arterial Streets: Case of Kirkuk City

Loud noise can be extremely harmful to the auditory system as well as to human health. Noise pollution is primarily caused by traffic noise. The study's goal was to determine how various vehicle types and speeds affected the amount of noise generated by traffic. The two factors were investigated at seven different arterial streets throughout Kirkuk city to measure the noise levels. The measurements were performed during peak hours to compare the result with WHO standards for noise specification. Traffic volume and vehicle speed are shown to be the key elements that determine an increase in noise level.

Equivalent Modulus of Asphalt Concrete Layers

A flexible pavement structure usually comprises more than one asphalt layer, with varying thicknesses and properties, in order to carry the traffic smoothly and safely. It is easy to characterize each asphalt layer with different tests to give a full description of that layer; however, the performance of the whole; asphalt structure needs to be properly understood. Typically, pavement analysis is carried out using multi-layer linear elastic assumptions, via equations and computer programs such as KENPAVE, BISAR, etc. These types of analysis give the response parameters including stress, strain, and deflection at any point under the wheel load. This paper aims to estimate the equivalent Resilient Modulus (MR) of the asphalt concrete layers within a pavement structure by using their individual MR values. To achieve this aim, eight samples were cored from Iraqi Expressway no. 1; they had three layers of asphalt and were tested to obtain the MR of each core by using the uniaxial repeated loading test at 25 and 40 °C. The samples were then cut to separate each layer individually and tested for MR at the same testing temperatures; thus, a total of 60 resilient modulus tests were conducted. A new approach was introduced to estimate the equivalent MR as a function of the MR value for each layer. The results matched the values obtained by KENPAVE analysis

Effect of Surface Pavement Type on Traffic Noise

This paper investigates the issue of surface-type effects on traffic noise in Baghdad. Since the raw materials for both flexible and rigid paving are available from local sources, the decision on selecting the type of paving which depends on the budget of the project and the road's importance and function. Knowing that for high traffic volumes and a high percentage of heavy vehicles, rigid pavement is more suitable compared to flexible pavement. In Baghdad, some highways consist of flexible pavement and others of combined pavement (flexible segments and rigid segments), so the study of the effect of surface type on traffic noise becomes an important matter. This study selected three highways: one with flexible pavement and two with the combined pavement. The results showed that the traffic noise generated by traffic on rigid pavement generates more noise than traffic on flexible pavement by about 2 dBA. A prediction model was generated to predict traffic noise depending on five variables (vehicle speed, traffic volume, skid number, distance between the edge of the inner lane and the sound level meter, and surface type). The measured traffic noise levels ranged from 73.23 to 82.86 dBA, which exceeded the permitted limits compared to the permissible Iraqi standards.

THE TRANSITION TO A PG GRADING SYSTEM FOR ASPHALT CEMENT IN IRAQ

In Iraq, as well as many other developing countries the performance graded (PG) based System is not yet implemented to evaluate the currently used asphalt cernents for paving works. It appears that not only the unavailability of test equipments is resulting in this delay but also the lack of clear understanding of what steps could be taken to incorporate this system. This research is an attempt to highlight the important aspects of a (PG) system that can be readily implemented without the need for expensive equipments. It includes the development of a Performance based System employing the conventional test methods and available nomographs from literature. It also, shows how climatic data, traffic data, and asphalt binder properties can be combined to propose a possible major improvement for the specifications of asphalts in Iraq. To achieve the objective of this research, an extensive air temperature data for a period of 18 years was reviewed for five cities (Mosul. Kirkuk. Rutba, Baghdad, and Basrah) to establish the required PG asphalt binder for each city. Also, the currently used asphalt cements with penetration grades (40-50) and (60-70) were tested by both of conventional test methods and Superpave methods to determine the equivalent performance grade for each type of the penetration graded asphalt and to evaluate the capability for these two types of asphalt cement to satisfy the required performance of pavement for each city, The results indicate that both the new proposed method and Superpave method give the same final performance grade. The asphalt with penetration grade 40-50 is equivalent to PG70-16 while that with penetration grade 60-70 is equivalent to PG64-16