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Perceiving moisture damage of asphalt mixes containing RAP using survival analysis based on Kaplan-Meier estimator and Cox proportional hazards model
Highlights Moisture induced stress tester (MIST) has been recently developed which aims to simulate stripping due to repeated pore pressure generation. Due to the technical, economical, and environmental benefits of utilising recycled asphalt pavement (RAP) in asphalt mixes, RAP mixes are gaining popularity. Varying stress cycles of MIST were applied on the control and RAP mixes to simulate the dynamic loads due to traversing traffic. To overcome the inherent drawbacks associated with conventional indirect tensile (IDT) strength test for evaluating the moisture damage resistivity of asphalt mixes, survival analysis has been adopted to analyse the results. Survival analysis is the collection of longitudinal analysis methods for examining data which possess “time” as an outcome variable. Over the years, two methods primarily contributed to the development of the field of survival analysis: a) Kaplan and Meier (KM) estimator for estimation of survival probabilities; and, b) Cox proportional hazards (CPH) Model which is a regression model and enables for adjustment of explanatory variables (or predictors).
Abstract Moisture induced stress tester (MIST) has been recently developed which aims to simulate stripping due to repeated pore pressure generation. In the current work, asphalt mixes containing recycled asphalt pavement (RAP) (in proportion of 0, 10, 20, 30 and 40% by weight) were subjected to varying stress cycles of MIST (0, 1000, 2000, 3500, 5000, 10,000 cycles) and indirect tensile (IDT) strength test was conducted on such mixes. AC30 was used for control mix whereas AC10 was adopted for RAP mixes. The results of IDT strength tests assisted in computing the failure times and such times were analysed using survival analysis based on Kaplan Meier (KM) estimator and Cox Proportional Hazards (CPH) model. The results indicated that survival analysis can be effectively utilised to analyse the IDT strength test results. It was observed that increasing stress cycles of MIST increase the time to failure whereas RAP is expected to reduce the time to failure. Moreover, KM estimator indicated that RAP reduces the survival of asphalt mixes. Hazard ratio () computed using CPH model shows a decrease with the increase in RAP proportion. Both MIST tensile strength ratio (M−TSR) and revealed that RAP leads to an improvement in moisture damage resistivity of asphalt mixes. Hence, has the potential to be an effective indicator of moisture damage susceptibility of asphalt mixes. Also, “Good” and negative correlation was observed to exist between M−TSR and . The current study is expected to further enhance our understanding regarding moisture induced damage of asphalt mixes and assist in effectively screening good mixes from poor ones.
Perceiving moisture damage of asphalt mixes containing RAP using survival analysis based on Kaplan-Meier estimator and Cox proportional hazards model
Highlights Moisture induced stress tester (MIST) has been recently developed which aims to simulate stripping due to repeated pore pressure generation. Due to the technical, economical, and environmental benefits of utilising recycled asphalt pavement (RAP) in asphalt mixes, RAP mixes are gaining popularity. Varying stress cycles of MIST were applied on the control and RAP mixes to simulate the dynamic loads due to traversing traffic. To overcome the inherent drawbacks associated with conventional indirect tensile (IDT) strength test for evaluating the moisture damage resistivity of asphalt mixes, survival analysis has been adopted to analyse the results. Survival analysis is the collection of longitudinal analysis methods for examining data which possess “time” as an outcome variable. Over the years, two methods primarily contributed to the development of the field of survival analysis: a) Kaplan and Meier (KM) estimator for estimation of survival probabilities; and, b) Cox proportional hazards (CPH) Model which is a regression model and enables for adjustment of explanatory variables (or predictors).
Abstract Moisture induced stress tester (MIST) has been recently developed which aims to simulate stripping due to repeated pore pressure generation. In the current work, asphalt mixes containing recycled asphalt pavement (RAP) (in proportion of 0, 10, 20, 30 and 40% by weight) were subjected to varying stress cycles of MIST (0, 1000, 2000, 3500, 5000, 10,000 cycles) and indirect tensile (IDT) strength test was conducted on such mixes. AC30 was used for control mix whereas AC10 was adopted for RAP mixes. The results of IDT strength tests assisted in computing the failure times and such times were analysed using survival analysis based on Kaplan Meier (KM) estimator and Cox Proportional Hazards (CPH) model. The results indicated that survival analysis can be effectively utilised to analyse the IDT strength test results. It was observed that increasing stress cycles of MIST increase the time to failure whereas RAP is expected to reduce the time to failure. Moreover, KM estimator indicated that RAP reduces the survival of asphalt mixes. Hazard ratio () computed using CPH model shows a decrease with the increase in RAP proportion. Both MIST tensile strength ratio (M−TSR) and revealed that RAP leads to an improvement in moisture damage resistivity of asphalt mixes. Hence, has the potential to be an effective indicator of moisture damage susceptibility of asphalt mixes. Also, “Good” and negative correlation was observed to exist between M−TSR and . The current study is expected to further enhance our understanding regarding moisture induced damage of asphalt mixes and assist in effectively screening good mixes from poor ones.
Perceiving moisture damage of asphalt mixes containing RAP using survival analysis based on Kaplan-Meier estimator and Cox proportional hazards model
Showkat, Burhan (author) / Singh, Dharamveer (author)
2021-12-25
Article (Journal)
Electronic Resource
English
Micro-Structural Analysis of Moisture-Induced Damage Potential of Asphalt Mixes Containing RAP
| British Library Online Contents | 2016
| Taylor & Francis Verlag | 2022