The aim of this article is to present the current knowledge and experiences related to wear and fragmentation resistance tests and to indicate those of their aspects that require further research. ...For this purpose, a review of the literature was performed. Results show that tests of resistance to wear (the MDE/DS test) and fragmentation (the LA test) are performed worldwide according to different standards (and thus following different test methods), which prevents a comparison of the obtained results. Comparative research into the MDE/DS and LA tests indicates that the MDE/DS test is more effective. The disadvantage of both tests lies in the dimension range of the aggregate. In addition, the use of steel balls in the LA test may not reflect the actual influence that the internal properties of the material have on the fragmentation process. A final review of the available knowledge allowed the formulation of proposals regarding further research directions, such as proposed changes of test methods, extensive analysis, and selection of optimal dimensions for tested aggregates, analysis of short-term and long-term tests, as well as extensive research into and an analysis of the impact of crushing on the physical, mechanical, and geometric properties of aggregates.
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The performance of unbound base materials, exclusively of the upper base layers, besides compaction level and layer thickness, depends on unbound material type, aggregates shape, fine content and ...mechanical properties of aggregates. The response of the pavement structure to loading is expressed through stress and strain magnitudes, accumulation of which leads to layer permanent deformations. One of the key factors for designing unbound base layers is resilient modulus, which can be found from triaxial tests. The aim of the research is to analyse the effect of the aggregate particle shape, structure and the resistance to crushing properties on resilient modulus of the upper layers of the unbound base layers. The following properties have been determined during the tests: aggregate particle size distribution, particle shape and flakiness, percentage of crushed and broken particle surfaces, density, water absorption, resilient modulus under low stress level loading. According to the performed research with tested aggregate mixtures, it is assumed that most influence on resilient modulus is exerted by aggregate whole granular size distribution, water absorption and the largest aggregate particle surface angularity. Resilient modulus in the tested dolomite fraction mixtures differing from 32 mm to 56 mm showed any reasonable difference with mean nominal pressures being higher than 300 kPa.
A lot of research centres in the world deal with developing the reuse of waste technology. The processed waste is applied in many industries, especially in the infrastructure construction. The ...European standards allow to apply recycled materials in implementation of buildings and the road engineering. In most cases, the detailed classifications for recycled aggregates are the subject of domestic standards, in which this topic is studied and developed deeply (Germany, Austria). In Poland, at the stage of applying the recycled aggregate, contractors are forced to rely on German or Austrian guidelines. In many cases, the application of the recycled materials is based on the contractors’ experience or intuition. That is why each additional development expansion of the knowledge on the recycled aggregates is added value and is very helpful for designers and contractors. The paper presents the comparison of mechanical resistance to fragmentation in a Los Angeles abrasion machine of selected crushed-stone and recycled aggregates (crushed concrete rubble) from demolished road structures.
Physical and mechanical properties of asphalt mixtures have a significant impact on a condition of fitted pavement, its stability and reliability during the entire period of its operation. These ...properties not only depend on bituminous binders chosen for an asphalt mixture and properties of mineral filler, but also on geometric and physical properties of the aggregate. An analysis of these indexes showed physical and geometrical indexes of aggregate of different origins (granite, dolomite and gravel). While researching mineral materials used for asphalt mixtures, the values of flakiness and shape index (FI and SI), impact value SZ and Los Angeles coefficient LA were determined. After calculations, the hypotheses for the average of flakiness and shape indexes of researched rocks (granite, dolomite and gravel) and proximity of dispersions were tested in order to determine the authenticity of geometric quality parameters and similarity of their sampling dispersion. Results of statistical data calculations determined a correlation between geometric parameters of researched aggregate FI and SI and geometrical, strength parameters of the aggregate. The hypotheses, whether research data of these indexes were distributed by normal distribution, were tested by drawing frequency histograms of granite, dolomite and gravel flakiness and shape indexes.
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In Lithuania dolomite is the third most excavated by the amount mineral resource, which is mostly used in subbase layer and hot asphalt mixtures for asphalt binder and base courses. Although, for ...asphalt wearing layer are often used granite aggregates, but this magmatic rock is imported from foreign countries. In one of the quarries of JSC "Dolomitas" higher quality dolomite is produced, which has similar mechanical properties to granite. To determine changes in mechanical properties of the different type of aggregates while using in the road, high-quality dolomite and two types of granite were chosen for laboratory testing. In this study, for evaluation of physical and mechanical properties of aggregates by laboratory tests for determining resistance to freezing-thawing, resistance to fragmentation, and polished stone value were carried out. Also, according to the results of laboratory testing, high-quality dolomite aggregate showed equal performance comparing to granite aggregates.
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