Department of Civil Engineering

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Author: search.filters.author.Bhargava, NishantSubject: search.filters.subject.Mix design

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    State of the art review on design and performance of microsurfacing
    (Taylor & Francis, 2019-04) Bhargava, Nishant
    Over the years, microsurfacing had gained popularity owing to the effectiveness, economic and environmental benefits as a pavement preventive maintenance treatment. The review study explores the merits and demerits of mix design procedures along with modifications suggested by various studies. Subsequently, studies on the performance of microsurfacing had been extensively reviewed and significant parameters contributing to variation in performance were identified. Literature review indicated that the microsurfacing mix design, unlike conventional hot mix asphalt, was complicated due to chemically controlled curing system and additional components involving microsurfacing production. Despite simple test procedures, most commonly adopted mix design parameters such as mixing and setting time, and torque-measurements exhibit operator specific variability in test results. In order to overcome such issues, mechanical modifications for mixing and automated measurements of parameter values were proposed by several researchers. Laboratory investigations on microsurfacing performance highlighted that the inclusion of process control parameters and environmental conditions to mimic field conditions could further improve the evaluation of microsurfacing durability. In terms of field performance, even though microsurfacing contribute to road safety, issues related to noise and reflective cracking would require further research for better understanding and possible solutions. Hence, the evaluation of synergistic influence of parameters on microsurfacing performance by simulating production and environmental conditions in a laboratory would allow better quantification of the associated failures and help to find probable solutions.
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    Systematic approach to address challenges in microsurfacing mix design
    (Elsevier, 2021-02) Bhargava, Nishant
    This paper presents a systematic laboratory approach for microsurfacing mix design to address the challenges faced due to multiple components and associated chemical complexity. A comprehensive laboratory study was undertaken to understand the variation in microsurfacing mix performance with respect to filler characteristics, mineral filler and emulsion components including emulsifier dosage, asphalt binder type and solvent. First, replacement of filler was done to address the issue of pre-mature breaking which was related to very high reactivity of aggregates. Next, the type and dosage of mineral filler was selected using cohesion test. Interestingly, the combination of cement (2%) and fly ash (1%) imparted highest cohesion highlighting the benefits associated with incorporation of waste materials having pozzolanic characteristics in the mix. In terms of emulsion components, use of higher emulsifier dosage showed a delay in the curing process which in turn, resulted in inferior cohesion, raveling and rutting resistance. Further, incorporation of harder asphalt binder and the use of solvent during emulsion production resulted in reduction in rutting by>61%. Raveling resistance was also found to be dependent on the use of solvent indicating the importance of maintaining equiviscous temperature during emulsion production. From the results, a narrow range diagram illustrating the acceptable range of emulsion content considering all design parameters was recommended to determine optimum emulsion content (OEC). The mid-point of acceptable emulsion content range was termed as OEC which, in the present study, was found to be 14% by dry weight of aggregates.