Implementation of the Linear Amplitude Sweep Test to Evaluate Fatigue Resistance of Highly Polymerized Asphalt Binders

Highly polymerized asphalt binders (HPABs) such as PG 64-40 have been increasingly used in cold regions such as Alaska in recent years. However, there are currently considerable data gaps when it comes to the characterizations of the HPABs, especially their fatigue behaviors. The objective of this study is to apply the linear amplitude sweep (LAS) test with the viscoelastic continuum damage (VECD) model to assess the fatigue resistance of HPABs. Three HPABs (PG 52-40, PG 64-40, and PG 52-46) and one unmodified binder (PG 52-28) were used in the study. The fatigue failure during LAS tests on HPABs was defined, and an analysis protocol using the VECD model was proposed based on the experimental results. The analysis protocol was validated by the agreements of the predicted and measured number of cycles to failure in the time sweep (TS) test. The results indicated that the LAS test with the selected analysis protocol can effectively predict the fatigue lives of HPABs. Both the LAS and TS test results showed that the HPABs had higher fatigue resistance than the unmodified asphalt binder. Among the four binders, the PG 64-40 binder exhibited the longest fatigue lives under repeated loadings

Integrating Quality Assurance in Balance Mix Designs for Durable Asphalt Mixtures: State-Of-The-Art Literature Review

Delivering durable asphalt concrete within a reasonable cost is one of the great ambitions of pavement material engineers. This state-of-the-art review article documents the efforts spent in the past two decades to ensure the durability and performance of asphalt mixtures in mix design and production. A perspective with the attempt to integrate laboratory mix design, plant production quality assurance, and field place acceptance is applied in the review. The development of the performance specification and performance mix design is summarized. The paper categorizes performance specification into index-based performance specification and predictive performance specification that include performance-related specification and performance-based specification. The approaches to developing index-based performance mix design/balanced mix design and predictive performance mix design are also compared in the review. The challenges and solutions in incorporating performance tests in asphalt productions are documented and discussed. The challenges include selecting performance testing methods, determining index threshold limits, estimating and incorporating testing variability and uncertainty, determining sampling position and testing frequency, and so forth. The paper also provides suggested areas of future research and implementation activities

Evaluation Of Thermal And Rheological Properties Of Phase Change Material-Incorporated Asphalt Mastic With Porous Fillers

Incorporating phase change material (PCM) into paving materials can regulate the pavement temperature, improve the pavement durability, and mitigate the heat-island effects. In this research, porous fillers were used as the PCM carrier, and the thermal and rheological behaviors of the asphalt mastic with the PCM were evaluated. Two different carrier materials (diatomite and expanded perlite) and four types of PCMs were used in the study. The candidate filler, PCM, and proper blending ratios were determined based on the results of scanning electron microscope image analysis, the filter paper test, and the temperature sweep test. The thermal and rheological behaviors of the mastics with PCMs were further evaluated with different filler replacement ratios. Thermal analysis through a differential scanning calorimetry test, thermal conductivity and volumetric heat capacity test, and real-time temperature performance test were performed on the asphalt mastics. Rheological tests, including the complex shear modulus test, the bending beam rheometer test, and the linear amplitude sweep test, were also conducted. The modified mastics were found to have high heat capacity with the latent heat storage ability. The rheological analyses showed that with the addition of polyethylene glycol, while the low-temperature performance of the asphalt mastics was improved, the performance at intermediate and high temperatures was not adversely affected by the PCM

Improving Rheological And Thermal Performance Of Gilsonite-Modified Binder With Phase Change Materials

Gilsonite, as a type of natural asphalt binder, has been used to improve the high-temperature performance of regular asphalt binders. However, the addition of Gilsonite may compromise binders\u27 low-temperature thermal cracking resistance. In this research, polyethylene glycol (PEG), as one type of the phase change materials (PCMs), was used as an innovative material to balance the impacts of Gilsonite on high and low performance of asphalt binders. The dosages of Gilsonite and PEG were first determined based on the materials\u27 rheological behaviors at low temperatures. The performance of the PEG-Gilsonite-modified binder was then fully evaluated in terms of the resistance to cracking and rutting at various temperatures. Thermal tests were also conducted to assess the thermal behaviors of the modified binders. The testing results indicate that with the proper dosage of Gilsonite and PEG, the rutting resistance of the binder can be improved without sacrificing its low-temperature performance. With the addition of the PCM, the binder was tested to have high volumetric heat capacity, which indicates PCM can reduce the rate and the magnitude of the temperature changes in pavements

Evaluation Of Feasibility And Performance Of Foamed Fire-Resistant Coating Materials

A preliminary study found high-performance cement mortar, geopolymer mortar, and magnesium phosphate cement mortar (MPCM) have the potential as new fire-resistant materials. In this study, foam was added to these three fire-resistant materials to further improve their rheological, mechanical, and fire-resistant performance and reduce costs. Systematic design and experimental programs were conducted. The results showed the addition of foam enhanced workability, adhesiveness, and fire resistance, allowing the materials to withstand higher temperatures and further delay heat transfer. A mixture of 70% MPCM and 30% foam was identified as the optimum design, which could withstand 1000 °C with low heat transfer rates

Compaction Quality Assurance Specifications of Unbound Materials

Compaction quality control/assurance of unbound geomaterials is one of the crucial components in pavement and embankment construction to ensure their performance, stability, and sustainability. Conventional density-based methods such as nuclear density gauge to determine the compaction quality have been widely used due to the straightforward relationship between the readings and targeted material property. Recent modifications in construction standards and the introduction of the Mechanistic-Empirical Pavement Design Guide have inspired a growing interest in developing and implementing strength/stiffness-based compaction control quality assurance (QA) specifications. Numerous studies have been dedicated to investigating the efficiency and effectiveness of the stiffness-based compaction QA tools. This paper presents a comprehensive review of the recent compaction QA relevant literature and surveys. Findings of different approaches for studying QA devices, and the main results of the existing models, experiments, and engineering practices were summarized. Several in situ spot QA technologies, including the latest compaction QA technologies [e.g., the lightweight deflectometer (LWD)], were highlighted, and their efficiency and effectiveness were compared. The review also summarized the intercorrelations between different devices, the correlations between in situ QA device readings and mechanical properties of unbound material, findings of the numerical simulations, and case studies and current practices using different QA tools. The recommendations for future research needs and practical implementations were identified and discussed

Impact of Deicers on Low-Temperature Performance of Missouri Pavements

The use of deicer chemicals for highway winter maintenance operations is an essential strategy for ensuring a reasonably high level of service. It\u27s critical to quantify their effectiveness and potentially detrimental effects on transportation infrastructure (i.e., asphalt and concrete pavements). In this study, nine deicer chemicals used in the state of Missouri were collected. The ice-melting test was conducted to quantify the performance characteristics of deicer chemicals. Freeze-thaw (F-T) test of concrete in the presence of deicer was conducted to quantify the negative effects of deicers to concrete. Low-temperature behavior of asphalt mixture affected by deicers was quantified by asphalt mixture indirect tensile (IDT) tests. The results showed that the calcium chloride (liquid) treated rock salt had the best ice melting capacity among all the studied products, while the calcium chloride (flake/pellet) treated rock salt showed the lowest ice melting capacity. The IDT creep compliance and strength of asphalt mixture results indicated brine treated rock salt and Top Film treated rock salt had insignificant effects on the creep compliance of asphalt mixture, regardless of testing temperatures. The deicer chemicals had different scaling effects on concrete beams after F-T cycles. The calcium chloride (liquid) treated rock salt had little scaling effect on the concrete beams. However, concrete beams with the presence of brine treated rock salt showed the highest mass loss values

Development of Holistic Methodologies for Improving Asphalt Mix Durability (Yr 1)

69A3551947137Asphalt mix durability has always been one of the major concerns of all highway agencies. To have a durable mix, one needs to address three aspects: durable mix design, production, and placement. The objective of this project is to develop holistic methodologies for addressing all three aspects with an ultimate goal to improve asphalt mix durability. As a minimum, this project will develop a systematic balanced mix design (BMD) methodology for designing durable mixes in the laboratory, recommend a performance-related methodology for production quality control and quality assurance (QC/QA) at asphalt plants, and identify innovative practices for placement acceptance in the field. This report summarizes the findings from the research efforts in Year 1

Implementation of the Linear Amplitude Sweep Test to Evaluate Fatigue Resistance of Highly Polymerized Asphalt Binders

Highly polymerized asphalt binders (HPABs) such as PG 64-40 have been increasingly used in cold regions such as Alaska in recent years. However, there are currently considerable data gaps when it comes to the characterizations of the HPABs, especially their fatigue behaviors. The objective of this study is to apply the linear amplitude sweep (LAS) test with the viscoelastic continuum damage (VECD) model to assess the fatigue resistance of HPABs. Three HPABs (PG 52-40, PG 64-40, and PG 52-46) and one unmodified binder (PG 52-28) were used in the study. The fatigue failure during LAS tests on HPABs was defined, and an analysis protocol using the VECD model was proposed based on the experimental results. The analysis protocol was validated by the agreements of the predicted and measured number of cycles to failure in the time sweep (TS) test. The results indicated that the LAS test with the selected analysis protocol can effectively predict the fatigue lives of HPABs. Both the LAS and TS test results showed that the HPABs had higher fatigue resistance than the unmodified asphalt binder. Among the four binders, the PG 64-40 binder exhibited the longest fatigue lives under repeated loadings

An Efficient and Explainable Ensemble Learning Model for Asphalt Pavement Condition Prediction based on LTPP Dataset

Accurate prediction of asphalt pavement condition is important to guide pavement maintenance practices. The existing models for pavement condition predictions are predominantly based on linear regressions or simple machine learning techniques. However, additional work on these models is needed to improve their basic assumptions, training efficiency, and interpretability. To this end, a new modeling approach is proposed in this manuscript, which includes a ThunderGBM-based ensemble learning model, coupled with the Shapley Additive Explanation (SHAP) method, to predict the International Roughness Index (IRI) of asphalt pavements. The SHAP method was applied to interpret the underlying influencing factors and their interactions. Twenty features were initially identified as the model inputs, and 2,699 observations were extracted from the Long-Term Pavement Performance (LTPP) database. Three benchmark models, namely the Mechanistic-Empirical Pavement Design Guide (MEPDG) model, the ANN model and the RF model, were used for comparison. The results showed that the developed model achieved a satisfactory result with a R-squared (R² value of 0.88 and Root Mean Square Error (RMSE) of 0.08, both better than three benchmark models. It ran 86 times and 2.3 times faster than the ANN and RF model, respectively. Feature interpretation was performed to identify the top influencing factors of IRI. The 20-feature model was further simplified based on the analysis result. The simplified model only required six features to efficiently and effectively predict IRI using the proposed ThunderGBM-based approach, which can reduce the workload in data collection and management for pavement engineers