Abstract
Steel production wastes (steel slags) are used more often in asphalt concrete pavements as a valuable replacement for natural aggregates, which are becoming increasingly rare. In this paper authors investigate the polishing characteristics of aggregates, and in particular of steel slags, used in bituminous road surfacing, are a major factor in determining the resistance to skidding. The main purpose of the study is the identification of a suitable degradation model, based on friction indicators, in the laboratory, as well as the comparison of in-situ pavement skid resistance with the cumulative number of passing vehicles over the years. The model predicts the expected resistance to skidding of the road surface based on the knowledge of the polished stone value (PSV) of the aggregates and the expected traffic on the road. In this study, several types of aggregates were compared: steel slag, limestone, limestone and slag mixture, diabase, Criggion stone and basalt. Using a standard PSV test, it was found that the aggregates did not reach the lower value of skid resistance (equilibrium value). The analysis of the British Portable Number (BPN) data versus polishing time allowed to empirically derive a regression model for each investigated aggregate. Hence, it appears possible to define both an investigatory level and threshold level to predict the actual residual life of the pavement from the examination of skid resistance.
Highlights
The by-product of steel production waste, named slag, whose chemical properties are similar to effusive rocks, is transformed into coarse aggregates and they are used for bituminous surfacing as a valuable replacement for natural aggregates, which are becoming increasingly rare
Several experimental studies [1] have suggested that the number of wet-pavement skid road accidents increases as skid resistance decreases and skid resistance depends on the road pavement surface characteristics: macrotexture and microtexture
Macrotexture refers to the irregularities in the road surface associated with voids between aggregate particles, which relate to the size, shape, and distribution of coarse aggregates used in pavement, as well as the construction method of the surface layer
Summary
The by-product of steel production waste, named slag, whose chemical properties are similar to effusive rocks, is transformed into coarse aggregates and they are used for bituminous surfacing as a valuable replacement for natural aggregates, which are becoming increasingly rare. Several experimental studies [1] have suggested that the number of wet-pavement skid road accidents increases as skid resistance decreases and skid resistance depends on the road pavement surface characteristics: macrotexture and microtexture. Macrotexture refers to the irregularities in the road surface associated with voids between aggregate particles, which relate to the size, shape, and distribution of coarse aggregates used in pavement, as well as the construction method of the surface layer. The magnitude of macrotexture can increase or decrease during pavement service life [2,3,4]. The size of microtexture varies over time during the pavement service life, depending on the initial roughness of the aggregate and the ability of the aggregate to maintain roughness against the polishing action of traffic and weather [5] whereas microtexture always has a decreasing trend over time
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