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In the context of pavement evaluation, backcalculation is the process of estimation of elastic properties of pavement layers using measured structural responses. A number of backcalculation programs are available for estimating effective pavement layer moduli from surface deflections. Different optimization techniques have been used in the development of these backcalculation models. Genetic algorithm (GA) has been used successfully in the recent past for backcalculation of pavement layer moduli. Selection of appropriate GA parameters is important for the efficient performance of the GA-based algorithm. However, there are no general guidelines available at present for the selection of GA parameters. This paper presents a study conducted for the selection of optimal GA parameters to be adopted for backcalculation of pavement layer moduli. The parameters have been selected on the basis of the level of accuracy desired and the corresponding computational effort (CE). The performance of the GA-based program with the selected parameters was evaluated using some hypothetical and field problems. [ABSTRACT FROM AUTHOR]

In India, the aggregate gradation of bituminous mixes and acceptable limits of mix design parameters have evolved through experience in construction and performance, Emphasis, generally, is on the maximum attainable density and strength parameters. However, in view of the fact that pavement failure due to fatigue cracking is predominantly observed in bituminous toads in India, it is necessary to develop or revise suitable specifications for bituminous mixes so that the mixes have high fatigue strength while satisfying the Marshall stability requirement, The present work reports a comparative study of the engineering parameters of various bituminous mixes with aggregate gradations that are different from those recommended in the Ministry of Surface Transport (MOST) specifications for bituminous concrete (BC). New mix specifications for BC have been proposed in this paper, which showed better performance than the conventional gradation without compromising with the Marshall stability and other mix volumetric requirements. A model table is presented to show the economy in temps of reduction of design thickness of pavement compared to the conventional BC mix. [ABSTRACT FROM AUTHOR]