@article{ragni_sudarsanan_canestrari_kim_2022, title={Investigation into fatigue life of interface bond between asphalt concrete layers}, volume={23}, ISSN={["1477-268X"]}, DOI={10.1080/10298436.2021.1894420}, abstractNote={A proper interface bond between adjacent asphalt concrete layers ensures the layers to act monolithically to withstand traffic and thermal loading. The presence of a weak interface results in delamination, slippage and fatigue cracks thereby affects the pavement performance; hence, requires careful evaluation. The objectives of this investigation are three-fold. The first objective is to develop a test protocol to investigate the damage characteristics of the interface bond. The proposed test applies a 5 Hz cyclic shear load on a double-layered asphalt concrete specimen using a Modified Advanced Shear Tester at 23°C. The second objective is to determine the effect of interlayer shear modulus on the pavement response of typical pavement sections using numerical simulations. The interface material model property used in this study is a set of arbitrary values that lies within the typical range of interlayer shear modulus values observed during cyclic shear tests. The third objective is to propose a failure criterion for shear fatigue testing that is based on the critical tensile strain obtained during pavement response analysis. The test outcomes show that specimens with a tack coat at the interface exhibit a significant increase in shear fatigue life resistance compared to specimens with no tack coat.}, number={10}, journal={INTERNATIONAL JOURNAL OF PAVEMENT ENGINEERING}, author={Ragni, Davide and Sudarsanan, Nithin and Canestrari, Francesco and Kim, Y. Richard}, year={2022}, month={Aug}, pages={3371–3385} }
 @article{gedela_kalla_sudarsanan_karpurapu_2021, title={Assessment of load distribution mechanism in geocell reinforced foundation beds using Digital Imaging Correlation Techniques}, volume={31}, ISSN={["2214-3912"]}, DOI={10.1016/j.trgeo.2021.100664}, abstractNote={The pressure distribution below geocell reinforced foundation beds depends on several factors like height of geocell, weld distance (pocket size), infill material, etc. This paper describes a method to determine the load dispersion mechanism through a geocell layer using a non-contact Digital Image Correlation technique. Series of plate load tests were performed in a test tank having plan dimensions of 0.6 m × 0.6 m and height of 0.65 m. The loading was applied through a strip footing of width 120 mm. Two miniature geocells having heights of 60 mm and 75 mm were used for reinforcing the base layer of the foundation section. The studies were performed with two types of geocells having smooth and rough surfaces. The relative density (RD) of the base and subgrade layers were maintained as 80% and 40%, respectively during the tests. The movement of soil particles was recorded by capturing images at different stages of the test. The images were processed using a Digital Image Correlation (DIC) software to obtain displacement contours and vectors. The results show that the geocells distribute the load over a wide area of the foundation soil. The dispersion angle was found to depend on the height of geocell and the roughness of the geocell surface. The load dispersion angles obtained from Digital Image Correlation analyses of unreinforced and reinforced sections have been compared with similar published results.}, journal={TRANSPORTATION GEOTECHNICS}, author={Gedela, Ramesh and Kalla, Swetha and Sudarsanan, Nithin and Karpurapu, Rajagopal}, year={2021}, month={Nov} }
 @article{yaghoubi_yaghoubi_guerrieri_sudarsanan_2021, title={Improving expansive clay subgrades using recycled glass: Resilient modulus characteristics and pavement performance}, volume={302}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2021.124384}, abstractNote={The scarcity of sound soils, especially in urban areas, often forces engineers to construct the pavement on problematic subgrade soils such as expansive clays. The associated cost involved in replacing the existing problematic soil is avoided by adopting treatment techniques. In this study, a type of high plasticity expansive clay was mixed with 10, 20, and 30% sand-size recycled glass (RG) as a non-chemical soil treatment approach. An extensive investigation comprising experimental works, numerical modeling, and pavement performance analysis was undertaken. After determination of the physical properties of clay and RG, resilient modulus characteristics of clay and the three clay-RG mixtures were carried out through an experimental program. Subsequently, the obtained resilient modulus data sets were incorporated into a finite element analysis program in order to analyze the stress-strain response of pavement models founded on clay and RG-treated subgrades. The compressive and tensile strains achieved through the analysis of the pavement models under traffic loads were next used to compare each pavement model with respect to fatigue and rutting performances. The experimental results showed up to a 113% increase in resilient modulus of clay by the addition of 30% RG. The outcomes of the analysis on pavement systems modeled using the experimental input showed a considerable reduction in compressive and tensile strains by treating the clay subgrade with RG. Consequently, the strain reduction exhibited a significant increase in fatigue life and rutting life of pavements founded on RG treated clay subgrades. The outcomes of this research aim to encourage the construction industry to consider the utilization of environmentally clean recycled aggregates, such as RG, for improving subgrades with problematic soils and hence, promote sustainable construction materials and approaches.}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Yaghoubi, Ehsan and Yaghoubi, Mohammadjavad and Guerrieri, Maurice and Sudarsanan, Nithin}, year={2021}, month={Oct} }
 @article{yaghoubi_sudarsanan_arulrajah_2021, title={Stress-strain response analysis of demolition wastes as aggregate base course of pavements}, volume={30}, ISSN={["2214-3912"]}, DOI={10.1016/j.trgeo.2021.100599}, abstractNote={The sustainable construction approach by utilizing recycled aggregates has increasingly been the focus of highway construction industries and local road authorities in recent years. The efficient usage of recycled aggregates for sustainable construction is owed to more than a decade of extensive experimental research aiming to remove uncertainties in the properties and performance of recycled aggregates in transport infrastructures. Nevertheless, a lack of knowledge exists about the stress-strain response of the pavement structures constructed using recycled aggregates. The main goal of this study was to propose a response analysis approach to incorporate the repeated load triaxial (RLT) test results as a Level 1 MEPDG input parameter in a well-established pavement analysis software named FlexPAVE TM . In this approach, the aggregate base course was divided into ten sublayers of equal thickness. Three different constitutive resilient modulus (Mr) models were utilized to determine the Mr of each sublayer corresponding to the stress levels achieved at that sublayer. Modeling the pavements in FlexPAVE TM by assigning the corresponding Mr to the sublayers resulted in a more accurate stress-strain response compared to the conventional linear elastic analysis approach. This approach provides a more realistic and, accordingly, more accurate analysis of the behavior of unbound aggregates in pavements. The secondary goal of this study was to investigate the stress-strain response of pavements with aggregate base courses made of three types of recycled construction and demolition wastes, being recycled concrete aggregate (RCA), crushed brick (CB), and waste excavation rock (WR). The resilient properties of the demolition wastes were determined through repeated load triaxial (RLT) testing. A typical pavement profile consisting of asphalt surface course, aggregate base course, and an A6 type of natural soil as subgrade was modeled using FlexPAVE TM . The response analysis was undertaken following the proposed sub layered approach. Under the loading conditions adopted in this research, with bulk stresses <185 kPa, CB and RCA exhibited a superior Mr response compared to the conventional virgin materials, while WR showed an inferior behavior.}, journal={TRANSPORTATION GEOTECHNICS}, author={Yaghoubi, Ehsan and Sudarsanan, Nithin and Arulrajah, Arul}, year={2021}, month={Sep} }
 @article{sudarsanan_fonte_kim_2020, title={Application of time-temperature superposition principle to pull-off tensile strength of asphalt tack coats}, volume={262}, ISSN={["1879-0526"]}, DOI={10.1016/j.conbuildmat.2020.120798}, abstractNote={Abstract Flexible pavements are multilayered structures that are designed to withstand vehicular traffic and thermal loading. Tack coat provides the bonding between these multilayers, which is a critical mechanism to provide a pavement with the monolithic action of asphalt layers to resist traffic and thermal loading, thereby dictating the pavement’s service life. Asphalt binder bond strength (BBS) is an indicator that can be used to evaluate the interlayer bonding ability of tack coat and changes as a function of temperature and loading rate. The focus of this paper is to prove that the time-temperature superposition principle is applicable to the BBS of various tack coat materials. In order to achieve this goal, BBS and dynamic shear rheometer (DSR) tests were conducted on four different tack coats, CRS-2, CRS-1h, NTCRS-1hM, and Ultrafuse. The Pneumatic Adhesion Tensile Testing Instrument (PATTI) was used to determine the BBS at 13 different temperatures ranging from 5 °C to 53 °C. The BBS data showed that adhesive failures between the binder and pull stub of PATTI caused the drop of BBS below 5 °C to 15 °C for hard (CRS-1h) and Non-tracking (NTCRS-1hM, Ultrafuse) tack coat. In addition to the BBS test, DSR tests were performed on the emulsion residue to measure the time-temperature shift factors at the reference temperature of 20 °C. It was found that the time-temperature shift factors determined from the DSR tests could be successfully used to shift the BBS vs. stress rate curves to construct the mastercurve for all four tack coat materials at a residual application rate of 0.14 L/m2 (0.03 Gal/yd2) as long as the BBS test exhibited cohesive failure between the binder and pull-off stubs. A simple method based on the BBS values at two temperatures is proposed to predict the mastercurve for routine characterization of the BBS mastercurve. No definite trend in the BBS mastercurve emerged among the different tack coat application rates for the different tack coats.}, journal={CONSTRUCTION AND BUILDING MATERIALS}, author={Sudarsanan, Nithin and Fonte, Benjamin Robert and Kim, Youngsoo Richard}, year={2020}, month={Nov} }
 @article{sudarsanan_arulrajah_karpurapu_amirthalingam_2020, title={Fatigue Performance of Geosynthetic-Reinforced Asphalt Concrete Beams}, volume={32}, ISSN={["1943-5533"]}, DOI={10.1061/(ASCE)MT.1943-5533.0003267}, abstractNote={One of the common distresses observed in asphalt concrete (AC) pavements under repeated vehicular and thermal loadings is cracking. Overlay placement is a quick remedy to rehabilitate these distressed surfaces. Unfortunately, this practice without treating the cracks will not resolve the cracking issue because the existing cracked surface soon propagates the cracks through the new layer, resulting in a phenomenon known as reflective cracking. Different types of geosynthetic interlayers have been used to retard the reflective cracks, thereby enhancing the overlay’s service life. The preliminary step in quantifying the service life improvement is measuring the fatigue life enhancement in the laboratory. This paper developed a test procedure to conduct four-point beam (4PB) fatigue tests, adapted a permanent deformation evolution model (PDEM) to predict the fatigue life of the 4PB specimens under laboratory testing conditions, and compared the fatigue life of beam specimens reinforced with three types of geosynthetics at 10°C, 20°C, and 30°C. The improvement factor measured using the PDEM model indicated that the geosynthetic reinforcement in AC beams increased the fatigue life on the order of 1.2–12 times depending upon the temperature at which the test was performed and the choice of the geosynthetic type. The best fatigue life outcome is expected when the improvement factor calculated for the geosynthetic-reinforced asphalt concrete’s bond strength and fracture energy meets the right combination of threshold values. The limitation of the study is that the improvement factors evaluated from the laboratory fatigue life require calibration factors to predict the field performance. Further field studies of the geosynthetic-reinforced pavements will help establish these calibration factors.}, number={8}, journal={JOURNAL OF MATERIALS IN CIVIL ENGINEERING}, author={Sudarsanan, Nithin and Arulrajah, Arul and Karpurapu, Rajagopal and Amirthalingam, Veeraragavan}, year={2020}, month={Aug} }
 @article{sudarsanan_karpurapu_amirthalingam_2019, title={Investigations on fracture characteristics of geosynthetic reinforced asphalt concrete beams using single edge notch beam tests}, volume={47}, ISSN={["1879-3584"]}, DOI={10.1016/j.geotexmem.2019.103461}, abstractNote={Reflective cracking is a major cause for premature deterioration of asphalt pavements. Different varieties of geosynthetics are used at the interfaces of surface layers to control the reflective cracks. The significant factors influencing their efficiency are the flexural strength and interfacial bonding. Fracture energy that leads to development of cracks and their propagation can be investigated by single-edge notched beam (SENB) tests with sufficient accuracy. Double layered asphalt samples were extracted from pavement sections purposely built as part of this investigation for conducting quasi-static SENB tests. The goal of this paper is two-fold (a) to present a methodology for conducting SENB tests to measure the fracture properties of geosynthetic reinforced samples at temperatures of 10 °C, 20 °C and 30 °C and (b) evaluation of the flexural and the fracture characteristics of unreinforced and geosynthetic reinforced samples. The geosynthetic reinforcement did not show much improvement of the Asphalt Concrete (AC) in the pre-cracking phase but slowed down the crack propagation. The failure pattern of reinforced specimens has changed from quasi-brittle to ductile. An equation is proposed to predict the crack initiation force of SENB sample knowing the bond strength of the corresponding reinforced AC layers at their respective temperature.}, number={5}, journal={GEOTEXTILES AND GEOMEMBRANES}, author={Sudarsanan, Nithin and Karpurapu, Rajagopal and Amirthalingam, Veeraragavan}, year={2019}, month={Oct}, pages={642–652} }