Browsing by Author "Kakade, Vijay"

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Evaluation of dynamic modulus predictive equations for asphalt mixtures with recycled asphalt pavement material
(Springer, 2025-06) Kakade, Vijay
The NCHRP 1-37A and NCHRP 1-40D models have been incorporated into the PMED program to predict dynamic modulus (|E*|) of asphalt mixes for Level 2 and Level 3 inputs to design and analyze flexible pavement structures. These empirical predictive equations were developed using databases that did not include asphalt mixes with reclaimed asphalt pavement (RAP) material. The objective was to evaluate the predictive capability of the existing |E*| predictive equations for Indian asphalt mixes with RAP. Fourteen mixes were used in the study; two dense-graded mixtures containing 0%, 15%, 25%, and 35% RAP and two gap-graded mixes containing 25%, 35%, and 45% RAP. The concordance correlation coefficient was used as an index to evaluate the predictive capability of existing |E*| equations compared to measured |E*|. The NCHRP 1-37A and Hirsch models showed very good precision in predicting |E*|. However, the prediction bias was very high, resulting in a poor overall agreement of predicted |E*| with measured values. The NCHRP 1-40D model showed very high precision and low bias, which resulted in reasonably good overall |E*| predictions compared to measured values. A new |E*| prediction equation was developed; the validation data showed a good overall agreement at all test temperatures and frequencies. The newly developed |E*| model was used to predict the phase angle of asphalt mixtures using the first-order derivative of the |E*| master curve, this method showed a good overall agreement with measured values at all test temperatures and frequencies, except for high temperatures and low frequencies.
Evaluation of Lateral Distribution of Heavy Vehicles on Multilane Roads Using a Strip-Based Approach
(ASCE, 2023-08) Kakade, Vijay
Most highway agencies use the default values of the lane distribution factor (LDF) as suggested by their pavement design guidelines. However, the use of the default value of the LDF results in over- or underestimation of the number of standard axle repetitions, especially for multilane roads, which have a larger variation in the movement of vehicles across the entire carriageway compared with one- and two-lane roads. Therefore, this study focused on the accurate measurement of the LDF for multilane roads. Currently, the LDF is estimated as the ratio of the number of heavy vehicles in a design lane to the total number of heavy vehicles moving on the carriageway. However, in the case of multilane roads, the same vehicle can occupy more than one lane, which ultimately results in inaccurate measurement of the LDF. To overcome this issue, a strip-based approach is introduced for a microlevel analysis of the LDF of multilane roads. The vehicle damage factor (VDF) and LDF were obtained by extracting the traffic data collected through the video recording method. The results of the LDF indicate that the channelization of trucks occurred in the intermediate lane instead of the outer lane, which commonly is assumed for the estimation of the number of standard axle repetitions for flexible pavement design. A significant variation was observed in the number of standard axle repetitions estimated using actual LDF and the default LDF values suggested by the Indian Roads Congress. The study finding suggests that the estimation of the actual LDF from field study is essential for the estimation of the number of standard axle repetitions on multilane roads for the design of flexible pavement.
Investigating the efficacy of curing methods on concrete containing reclaimed asphalt pavement aggregates
(Sage, 2025-06) Kakade, Vijay
Curing is adopted to prevent moisture loss and promote hydration in concrete. It influences the concrete up to a depth known as a curing affected zone (CAZ), while the remainder of the concrete remains unaffected. The quality of the CAZ indicates the effectiveness of a curing method. The aim of this study is to investigate properties of concrete that are sensitive to changes in curing method; these properties can subsequently be utilized to assess the effectiveness of different curing media. Moist curing and acrylic and wax-based curing compounds were adopted in this work. Conventional concrete mixes and concrete mixtures with partial replacement, by volume, of natural aggregate by reclaimed asphalt pavement (RAP) aggregate were studied. RAP aggregate is covered with a thin hydrophobic bituminous film, which affects the interfacial transition zone properties and the local water–cement ratio of the concrete. The mechanical properties, moisture-modified maturity, and durability properties of concrete were investigated for different curing regimes. The tests of strength parameters and moisture-modified maturity showed contrasting results with respect to the curing method and concrete mix. Meanwhile, durability properties displayed a consistent trend with respect to concrete mixes; they were prone to vary for different curing methods and should thus be considered in assessing a curing method’s effectiveness. Moreover, by adopting a two-stage mixing approach, improved strength characteristics were observed for RAP mixes, compared with the control mix.