Study on the Suitability of Reclaimed Asphalt Pavement Aggregate (RAPA) in Hot Mix Asphalt Production

The main objective of this study was to evaluate the suitability of recycled asphalt aggregate with fresh aggregate in hot mix asphalt production by using experimental laboratory investigation. Also, Non-probable sampling techniques were adopted to collect a sample. The engineering properties of extracted Reclaimed asphalt pavement aggregate and the fresh crushed aggregate were identified based on standard specification before starting the Marshall Mix design, Then the Marshall Stability test was conducted on crushed aggregate with three different aggregate gradation sizes 5.0%, 5.5% and 6.0% by weight of aggregates and with five different bitumen content 4.0%, 4.5%, 5.0%, 5.5% and 6.0% by weight of total mix. Depending on the selected aggregate gradation Marshall Stability test was conducted for reclaimed asphalt pavement aggregate with a replacement rate of 5.0%, 15%, 25%, 35%, 45%, 55%, and 65% by weight of crushed aggregate to determine its optimum bitumen content according to National Asphalt Pavement Association method (NAPAM). A total of 64 mix designs and 190 specimens were prepared. Hence, Marshall Stability and Moisture Susceptibility test with 3-trials, hence rutting test with 2-trials. From 190 specimens, 45 were for the control mix, 105 were for replacement proportion, 36 were for Moisture Susceptibility and 4 were for Rutting Based on the Marshall Test results and their performance tests such as Moisture Susceptibility and Rutting was performed to maximum allowable replacement percentage was compared with standard specification. The optimum bitumen content result obtained in percent was 5.1, 5.04, 4.98, 4.87, 4.81, 4.74, 4.67 and 4.53 for 0 % (control), 5.0%, 15%, 25%, 35%, 45%, 55% and 65%, respectively. The experimental value of Tensile Strength Ratio, proportional rut depth and mean rut depth on 45% RAPA replacement was 85.42% and 4.48 %, 2.24 mm respectively. Finally, the test result obtained from the marshal stability and the performance testes indicates that up to 45% replacement of aggregate is reclaimed asphalt pavement aggregate in hot mix asphalt production satisfies the standard specification.

Evaluation of a Filtering Facepiece Respirator and a Pleated Particulate Respirator in Filtering Ultrafine Particles and Submicron Particles in Welding and Asphalt Plant Work Environments

Manufacturing sites, such as welding, casting, and asphalt production (fumes), generate vast numbers of ultrafine particles of <0.1 µm in size and submicron particles close to the ultrafine range (0.1–0.5 µm). Although cumulative masses of these particles are negligible in comparison to the larger particles, the health effects are more severe due to the higher penetration in the human lower respiratory tract, other body parts crossing the respiratory epithelial layers, and the larger surface area. This research investigates the effectiveness of two common commercially available N95 filtering facepieces and N95 pleated particulate respirator models against ultrafine and submicron particles. Two specific types of respirators, the N95 filtering facepiece and the N95 pleated particulate models, in both sealed and unsealed conditions to the manikin face, were tested at various commercial and academic manufacturing sites, a welding and foundry site, and an asphalt production plant. Two TSI Nanoscan SMPS nanoparticle counters were used simultaneously to collect data for particles of 10–420 nm in size from inside and outside of the respirators. While one of them represented the workplace exposure levels, the other one accounted for the exposure upon filtration through the respiratory surfaces. The results showed the particles generated by these manufacturing operations were mostly within the range of from 40 to 200 nm. Results also indicated that while the percentage of filtration levels varied based on the particle size, it remained mostly within the desired protection level of 95% for both of the N95 respirator models in sealed conditions and even for the N95 pleated particulate model in the unsealed condition. However, in the case of the N95 filtering facepiece model, unsealed respirators showed that the percentage of penetration was very high, decreasing the protection levels to 60% in some cases. Although the number of workplace airborne particle levels varied considerably, the filtration percentages were relatively consistent.

Manufacturing of Wear Resistant Iron-Steel: A Theoretical and Experimental Research on Wear Behavior

In this study, four different alloys of steel blocks with a thickness of 15mm were manufactured in order to develop an alternative to steel plates used in wear exposed areas of construction machines, trucks, and asphalt production plants. To further increase the wear resistance of the manufactured steel blocks, their thickness was reduced to 10mm by the hot-rolling method. Wear specimens were obtained from rolled blocks. These specimens were abraded at 20N, 40N, and 60N loads in reciprocating linear motion module ASTM G-33 standards to determine their wear resistance. SEM and EDX analyses were also conducted to see modifications on the worn surfaces. In addition, a theoretical model of wear behaviors was created, calculations were made with Archard wear equation and ANSYS software, and the theoretical and experimental results were compared

THE INFLUENCE OF WASTE WATER SEDIMENT AS A COMPONENT OF ASPHALT CONTAINING HEAVY METALS AND DETECTING ITS EFFECT ON SOILS UNDER MODEL EXPERIMENTAL CONDITIONS

Waste water sediment (WWS) is an ecological hazard to the environment and the search for its effective disposal is an urgent task. The main limitation of the WWS use is associated with the presence of the different ingredients - heavy metals, which can have a negative impact on the environment. There is asphalt production technolologies using WWS. This work considers the possibility of using asphalts with the WWS additives from car washes. This technology will reduce the negative influence on the environment due to the WWS recycling, as well as due to the possibility of using WWS instead of pure sand by replacing it in the standard asphalt production technology. In this work, a heavy metal content was determined by the ICP-OES method using an Agilent 5110 spectrometer; in the course of a model experiment, the effect on the soil of three model objects was studied: WWS from car washes in Moscow; the standard technology for asphalt production; asphalt fused with car wash WWS. We studied the change in the content of various forms of heavy metals penetrating the soil from wash-offs of these objects, and by comparing the results and assessing their absolute content, we assessed the possibility of using fused asphalt. The studies have shown that during the model experiment, the total content of heavy metals increased up to 7-10 times for Zn, Ni and Cr. In all variants of the experiment, the content of mobile forms of all Cr, Cu, Mn, Ni, Pb, V and Zn significantly decreased by the third stage of the experiment to 50--95%, which indicates the transition of mobile forms of heavy metals to the total content due to the processes of sorption and precipitation.

A Novel Integrated Interval Rough MCDM Model for Ranking and Selection of Asphalt Production Plants

Asphalt production plants play an important role in the field of civil engineering, but also in the entire economic system since the construction of roads enables uninterrupted functioning within it. In this paper, the ranking of asphalt production plants on the territory of the Autonomous Province of Vojvodina has been performed. The modern economy needs contemporary models and methods to solve complicated MCDM problems and, for these purposes, it has been developed an original Interval Rough Number (IRN) Multi-criteria decision-making (MCDM) model that implies an extension of two methods belonging to the field with interval rough numbers. After forming a list of eight most significant criteria for assessing the efficiency of asphalt production plants, the Interval Rough Number PIvot Pairwise RElative Criteria Importance Assessment (IRN PIPRECIA) method was developed to determine the significance of the criteria. A total of 21 locations with asphalt mixture installation were considered. For that purpose, seven asphalt production plants were included, and for their ranking, the IRN EDAS (Evaluation based on Distance from Average Solution) method was created. The aim of this paper is to develop a novel interval rough model that can be useful for determining the efficiency of asphalt production plants. Averaging in group decision-making (GDM) for both methods was performed using an IRN Dombi weighted geometric averaging (IRNDWGA) aggregator. The obtained results show that (A15) Ruma (SP)–Mačvanska Mitrovica–Zasavica has the best characteristics out of the set of locations considered in this study. However, Alternatives A6 and A19 are also variants with remarkably good characteristics since there is very little difference in values compared to the first-ranked alternative. Also, the obtained results have shown that the developed model is applicable, which is proven through a comparative analysis.

Life Cycle Assessment of Hot Mix Asphalt Production with Reclaimed Asphalt Pavement in Washington State

This study is an attempt to create a framework, using the best available inventory data, to perform lifecycle assessment (LCA) on asphalt pavement production. In particular, the use of reclaimed asphalt pavement (RAP) as an end-of-life product of deteriorated pavements is under consideration. Following ISO 14000 series standards, the framework constitutes the four major LCA steps in defining goal and scope, lifecycle inventory analysis, environmental impact assessment, and results interpretation. Three different scenarios in which varying portions of RAP are incorporated into hot mix asphalt production are to be compared. The system boundary of this study is limited to the construction and rehabilitation phases and ignores the vehicular use phase. It was found under this study that since high RAP mixtures require more frequent and aggressive maintenance activities, the overall footprint of asphalt pavements constructed with higher RAP contents is also higher. This would necessitate more efficient design procedures and protocols for mixtures produced with high RAP contents to compensate for their lack of long-term performance.

Impact Analysis Using Life Cycle Assessment of Asphalt Production from Primary Data

Road construction and maintenance have a great impact on the environment, owing to the huge volumes of resources involved. Consequently, current production procedures and technologies must be properly investigated, for identifying and quantifying the life cycle environmental impacts produced. In this paper, primary data, i.e., site-specific data directly collected or measured on a reference plant, are analyzed for calculating the impact of the production of a hot mix asphalt. The analysis is performed in a from “cradle to gate” approach to estimate the environmental burdens of the production process in an average plant, representative of the existing technology in Italy and Southern Europe. The research outcomes are useful to increase reliability in quantification of asphalt production impacts and the contribution of each component. The results represent a reference basis for producers, designers, and contractors in the decisional phases, identifying the most critical aspects in the current practice and the possible improvements for reducing impacts of road industries. In this regard, efficient energy technologies for reducing the production temperature (such as warm mix asphalt) and burned fuels are proven to assure relevant improvements in the environmental performance.