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Preservation of the appropriate quality of road assets needs timely rehabilitation of high-level design and construction. Since the actual life cycles of Hungarian road rehabilitation projects are often much lower than expected, research activities of the authors were concentrated on the development of an updated design technology of road pavement rehabilitation using scientifically based algorithms. The paper outlines the elements of a pavement rehabilitation design based on Hungarian and foreign literature survey, detailed own laboratory test series and trial section monitoring. The main steps of the design methodology comprise the Client’s data supply and disposition, site condition evaluation by the designer, deflection measurement in carefully selected points, eventual additional laboratory tests, choosing design subsections, correction of the equivalent thickness of the new asphalt layer, calculation of strain in wearing course. Besides, relationships are presented between various condition parameter data like bearing capacity values, unevenness measuring data and rut depth values. The pavement rehabilitation design technique suggested here – if widely in Hungary – can significantly contribute to attaining a much longer life cycle of rehabilitated roads than by now, and it is (would be) extremely efficient due to the very limited funds available for highway purposes.
India has world’s second largest road network in terms of length with a total road length of 4.24 million km. Hot mix bituminous pavement contributes around 50% road length to this vast road network. Large scale highway construction in India, emanating from rapid development, has caused massive depletion of scarce natural aggregate. This paper addresses this problem by investigating the influences of the utilization of steel slag as a coarse aggregate on the properties of hot mix bituminous concrete. Physical characteristics of bituminous mix ingredients i.e natural aggregate, steel slag aggregate and bituminous binder were determined to find out their compliance with Ministry of Road Transport and Highway Specification for Road and Bridge Works in India. Mechanical characteristics of bituminous mixes i.e Unmodified (having natural aggregate) and Modified (having steel slag as coarse aggregate) were determined using Marshall Method of mix design.
Unmodified and Modified mixes were subjected to an array of performance tests to check out the suitability of steel slag aggregates for the preparation of high performance bituminous concrete mix. The performance tests includes, retained Marshall Stability, indirect tensile strength, static creep test, wheel-tracking test and resilient modulus test. The laboratory study confirmed the improvement in various mechanical properties of steel slag modified mixes besides reduction in temperature and moisture susceptibility.
Iraq has been experiencing tremendous development in the national infrastructure road network over the last decade. Iraqi economic growth in rural areas has been triggered by good and safe roads and a good highways network system. Studies have shown that climate, traffic conditions, characteristics of the asphalt binder and the aggregate are the main factors that can contribute to premature pavement failures. The ability of hydrated lime to improve the fatigue and rutting resistance of Hot Mix Asphalt (HMA) as well as moisture sensitivity, has led to observed improvement in the field of lime modified HMA pavements, and significant decreases in maintenance and repair costs of the highway network. In this study, the mechanistic properties of asphalt concrete mixes modified with hydrated lime as a partial replacement for limestone dust mineral filler were evaluated. Four replacement rates were used; 1, 1.5, 2, and 3 percent by weight of aggregate beside two kinds of addition methods, namely dry and wet. Asphalt concrete mixes were prepared at their optimum asphalt content and then tested to evaluate their engineering properties which include moisture damage, resilient modulus, and permanent deformation and fatigue characteristics. These properties have been evaluated using indirect tensile strength, uniaxial repeated loading and repeated flexural beam tests. The experimental results, in general, showed that the mixes modified with hydrated lime were found to have improved fatigue and permanent deformation characteristics, also showing lower moisture susceptibility and higher resilient modulus. The use of 1.5 percent of hydrated lime in the wet addition method as a replacement for limestone dust mineral filler has shown a significant improvement in asphalt concrete behavior and has added to the local knowledge the possibility of producing more durable mixtures with higher resistance to distress.
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