Enhanced Acceptance Specification of Asphalt Binder to Drive Sustainability in the Paving Industry

Testing small amounts of extracted and recovered asphalt binder as used in construction allows for the acceptance of materials in accordance with traffic and climate requirements. This approach facilitates the sustainable use of resources and thus prepares the paving industry for the true circular economy. Oscillatory, creep, and failure tests in a rheometer are compared for the performance grading of 32 asphalt binders extracted and recovered from real-world contract samples. Films 8 mm in diameter and 0.5 mm thick were tested from 35 to −5 °C in dynamic shear, followed by shear creep at 0 and 5 °C, and finally in tertiary tensile creep at 15 °C. The enhanced protocol uses a very small amount of material in contrast to current methods, yet it provides comparable results. Phase angle measurements appear to be optimal for performance grading, but further field study is required to determine if additional binder properties such as stiffness and/or failure strain would be required for the control of cracking.

Asphalt Binder Performance Grading for the Republic of Yemen Based on Superpave Asphalt Mix-Design

Background: The asphalt binder is considered a temperature-sensitive viscoelastic material. Temperature can cause some common distress of asphalt pavement, such as rutting (permanent deformation), which correlated with high-temperature environments, and thermal cracking, which correlated with low-temperature environments. Objective: This study aimed to establish asphalt binder Performance Grades (PGs) in the Yemeni region to ensure that the asphalt pavement design can effectively resist the distresses of rutting and cracking that occurred due to seasonal temperature changes. Methods: In order to determine the performance grades, the temperature zoning was performed by obtaining the last 10 years temperature data of 19 cities in Yemen gathered by the Yemeni Meteorological Authority. The collected data were analyzed based on the trend and statistical reliability. Three air-pavement temperature prediction models of Superpave, LTPP, and Oman model were used to predict air pavement temperatures. The local performance grades were computed using reliability levels of 50% and 98%. Since the dependent variables of latitude in the Superpave equation can more reflect the geographical locations of Yemeni regions rather than the other models, this study strongly approved the SHARP Superpave model to be used to determine the performance grades. Results: Based on the Superpave model with reliability analyses, performance grade maps were drawn. The most common performance grades recommended in this study for low traffic volume roads were PG64-10, and PG52-10. Conclusion: The findings of this study are highly significant and provide valuable decision support for pavement management and improve the transportation system in the Republic of Yemen.

Feasibility of using Mastic for Performance Grading in Place of Extraction using SPS10 Mixtures

Because of the increased use of reclaimed asphalt pavement, reclaimed asphalt shingles, rejuvenators, and other additives, performance of asphalt mixtures can no longer be guaranteed by controlling properties of the binder. To determine the effect of additives on asphalt performance, the current procedure is to extract the binder from the mixture using solvents and recover the binder by removing the solvent. This is a two-step procedure, which can be time consuming and costly and which requires chemicals considered hazardous unless used with special care. Another issue is the quality of the extracted binder, as the process of dissolving the binder and recovering it from chemicals may affect the properties of the extracted binder. In this study, we suggest the use of mastic separated from the mixture, in place of extraction. The fine portion of the mixture (particles less than 0.25 mm) is physically separated from the mixture without use of solvents. This material is called composite mastic since it includes effects from all additives on the binder. The process of preparing composite mastic is significantly faster and less costly than extracting the binder. The separated mastic is tested following the Unified Performance Tests by incremental Method (UPTiM) using a dynamic shear rheometer to determine the high-, low-, and intermediate-temperature performance grades, similar to those of asphalt binder. This study shows strong correlations between properties of composite mastic, extracted asphalt, and asphalt mixture. Therefore, testing mastic could be a reliable alternative to testing extracted binder and compacted mixture.

Development of Performance Grading Map of Nepal Based on Superpave System

The Performance of the bituminous binder plays important role in the overall performance of the pavement system. One of the major cause of pavement failure is the bitumen grade, i.e selection of suitable grade of bitumen. Therefore, performance grading of bituminous binder is inevitable for the specific temperature and climatic zones. This study is focused on the determination of performance grading of bituminous binder for various temperature zones in Nepal. In this study, twenty one years’ daily maximum and minimum secondary temperature data of 70 meteorological stations were collected and were analyzed for temperature zoning. Performance grading of bituminous binder was conducted with the help of Strategic Highway Research Program (SHRP) and Long-Term Pavement Performance Program (LTPP) prediction models. The concept of Superpave has been adopted for the analysis, which stands for superior performing asphalt pavement. The Superpave mix design includes a new analysis system based on performance characteristics of the pavement layer. The bituminous binder grades for Nepal have been determined on the basis of air temperature thereafter predicting the pavement temperatures. The study has determined seven different performance grade zones based on SHRP and four different performance grade zones based on LTPP model. The study synthesized the Performance Grade (PG) map of the country.

Waterproofing Performance Grade Proposal through Standard Test Result Comparison of Self Adhesive Rubberized Asphalt Sheet

This study reviewed new concept waterproofing performance gradation to respond to the limit of unified single standard performance standard used in each country from the past until now. This study was carried out using the standard test data from 34 products tested and evaluated by Korea’s national quality test institution for 2 years (2018~2019) based on national standard specification (KS F 4934, Self-Adhesive Rubberized Asphalt Sheet). Major proposal contents utilized the result values of 9 waterproofing performance evaluation criteria included in the national standard specification. Major study contents and results are as follows. Existing widely used domestic and overseas standard grading (Stanine, Sten Scores, Grade 5 Scale, energy consumption efficiency, and other grading) theories were investigated and analyzed. Based on the analysis contents, standard Grade 5 Scale system suitable for waterproofing material performance grading was selected and applied. Grade sections were set according to the application ratio for each grade section of Grade 5 Scale (grade 1 with 10%, grade 2 with 20%, grade 3 with 40%, grade 4 with 20% and grade 5 with 10%). According to the set sections, performance grades were derived for 9 test criteria of 34 products. Section setting standard for grade section was derived centered on the performance result values of 9 criteria. As a result, average value of waterproofing performance of each of 9 test criteria for 34 products was verified to have 1.2 times to 7.52 times higher performance value than the minimum quality standard (based on grade 5). Such results sufficiently showed the limit of the current unified single standard performance application. Also, as a solution for waterproofing quality degradation problem, possibility to apply the waterproofing performance grading of this study was verified. Therefore, through this study, it is decided that new concept quality standard to pursue future waterproofing industry development can be set, quality reinforcement is possible by performance grading for each product and sustainable waterproofing performance maintaining effect at the waterproofing construction site can be expected with the use of such gradation.