Sachi Kodippily

Detecting Flushing of Thin-Sprayed Seal Pavements Using Pavement Management Data

AbstractFlushing is a pavement surface defect that affects the structural integrity of thin-sprayed seal (chip seal) surfacings. Analysis was carried out on pavement performance data to determine the combination of factors that provides the best indication of flushing occurrence on in-service pavements. Data were sourced from the Long-Term Pavement Performance (LTPP) programme in New Zealand as well as from field testing. The LTPP data were analysed in four categories; pavement composition characteristics: traffic-related factors, climatic factors, and effects of other pavement defects. Factor and correlation analyses were used to determine and investigate the factors that showed significant relationships to flushing. Surface thickness, surface age, surfacing type, and rutting were found to have statistically significant correlations to flushing. Field testing provided data relating to the soil moisture environment under the pavement. The dry density and water content of soil were identified as having sig...

Evaluating pavement performance through smart monitoring – effects of soil moisture, temperature and traffic

This paper presents the findings from a research conducted to investigate the effects of moisture and environmental conditions on the mechanical behaviour of granular pavements. Analysis was conducted on data collected from state-of-the-art instrumentation on two field pavement sites located in Sunshine Coast, Australia. The sites were monitored over three years, and daily temperature, moisture and strain values were analysed. Large tensile strains in the basecourse occurred when moisture increased and temperature decreased at the end of day. This result indicated that the change in soil pore pressure due to moisture and temperature variations was causing the strains in the pavement. Heavy traffic volume had a minor effect on basecourse strain in comparison to moisture and temperature although, it was concluded that the combined effect of soil moisture, temperature and heavy traffic loading was a cause for large vertical strains in the pavement.

Improving Recycled Asphalt Mix Performance Through Rejuvenation

Developing technologies that provide sustainable solutions for future pavement construction is vital given the ever-increasing demand on the supply of bitumen and good-quality pavement construction materials. Recycled asphalt pavement (RAP) is a technology that presents many advantages in cost and environmental savings. This study investigated the performance of RAP mixes containing rejuvenation additives to determine the effects of those additives on the deformation (rutting) resistance, cracking resistance, and fatigue performance of RAP mixes. Laboratory testing was conducted on 11 RAP mixes that were manufactured with RAP proportions of 15% and 30%, as well as with the addition of different types of rejuvenating agents. Results produced useful performance indicators for the use of rejuvenation additives in RAP. The mixes that had rejuvenation additives preserved the high deformation resistance of RAP mixes, particularly at the higher RAP proportion of 30% when compared with a mix with no RAP, and concurrently the addition of rejuvenators counteracted against overstiffening effects of RAP. The addition of RAP, especially 30% RAP proportion, had poorer fatigue performance than when only 15% RAP was used, but with the use of rejuvenation agents, the fatigue performance of the high RAP mixes improved significantly. Use of a maltene fraction for RAP rejuvenation had marginally better fatigue performance than a chemical rejuvenation agent. The research results provide a valuable understanding of the behavior of RAP mixes and, in particular, the positive performance results that can be gained by using rejuvenation additives.

Using Multiple Investigative Techniques to Assess Flushing of Chip Seal Surfaces

Flushing is a defect that has a damaging effect on the functional performance of chip seal pavements. The reported study was conducted to develop techniques to identify and assess flushed pavements effectively. The main aims of the study were first to investigate the effects of chip seal volumetrics on development of flushing and second to develop a model to forecast flushing of chip seal pavements. The study methodology consisted of mechanical testing of chip seal pavement samples and analysis of pavement performance data. Laboratory testing was conducted on samples obtained from flushed chip seal pavements from four regions in New Zealand. Samples were loaded by using a wheel-tracking device, and imaging techniques were used to assess the effects of micromechanical changes on development of flushing. Data analysis was performed on pavement condition data to identify factors providing the best prediction of flushing, and regression analysis was performed to develop a model to predict the initiation and progression of flushing. Study results revealed a direct relationship between flushing and reduction in air void volume that occurred as a result of loading. Data analysis revealed that the combination of factors providing the best indication of flushing was surface thickness, surface age, rut depth, and grade of aggregates. The flushing initiation model had an accuracy of 76%, and the flushing progression model was robust at predicting the quantity of flushing. By using the study outcomes, a pavement condition assessment guideline was developed to aid with assessing and managing flushed chip seal pavements.

Using a multi-phase model to predict flushing of sprayed seal pavements

Flushing is a pavement defect that has a negative effect on the structural integrity and performance of a pavement surface. The aim of this study was to develop a model to predict the occurrence and progression of flushing on sprayed seal pavements. Data analysis and model development were performed using data sourced from New Zealands Long-Term Pavement Performance programme. The developed model consists of two phases to model (1) the probability of flushing initiating on a pavement and (2) the progression of flushing. The probability of flushing initiation was modelled using a logistic model format, and the progression of flushing was modelled using a linear model format. Testing of the developed model revealed that the logistic model predicted the probability of flushing initiation at 76% accuracy, whereas the linear model had statistically robust predictions of flushing. The developed model is recommended for use in sprayed seal pavement management processes.