Investigation of the mechanical properties and the influence of micro-structural characteristics of aggregates using micro-indentation and Weibull analysis

Influence of Loading History and Soil Type on the Normal Contact Behavior of Natural Sand Grain-Elastomer Composite Interfaces

“…This elbow shape of the unloading curve implies a non-linear response during unloading, which is expected for many material types [ 94 , 95 ], despite the fact that the most important part of the unloading curves in the PP tests can be considered linear. A similar behavior was reported in the recent study by Kasyap et al [ 72 ] based on micro-indentation experiments. Among the different types of geological materials/aggregates examined by [ 72 ], elbow-shape curves were observed for recycled concrete aggregate, which has rough surfaces with the presence of microparticles, and this behavior was explained based on the hypothesis of partial relaxation leading to a change of the slope (stiffness) during the unloading process.…”

“…A similar behavior was reported in the recent study by Kasyap et al [ 72 ] based on micro-indentation experiments. Among the different types of geological materials/aggregates examined by [ 72 ], elbow-shape curves were observed for recycled concrete aggregate, which has rough surfaces with the presence of microparticles, and this behavior was explained based on the hypothesis of partial relaxation leading to a change of the slope (stiffness) during the unloading process.…”

“…For rigid interfaces, the three major contributing factors on their normal contact response can be summarized as (i) microscale morphology (roughness); (ii) mesoscale morphology represented by the local shape of the grains in the vicinity of their contacts; and (iii) the presence of impurities on the surfaces of the grains. All the natural grains tested in the present study (despite their differences in terms of morphology and the presence of natural coating in some types of aggregates) are, predominantly, silica-based materials; thus, surface chemistry is important in terms of composition (i.e., elemental analysis) of the grains, as this would be expected to influence surface hardness [ 70 , 72 , 75 ]. As will also be discussed in the subsequent sections, there is a significant difference between the natural aggregates (as brittle-to-ductile materials) with that of granulated rubber, which belongs to the group of elastomers, and its behavior is viscoelastic, which plays a dominant role in the behavior of the composite interfaces.…”

“…Completely decomposed granite (denoted as CDG) originates from Hong Kong, and it consists of a weathered igneous rock of felsic composition, and its grains are crushable (i.e., weak grains) with irregular shapes and rough texture. LBS is a benchmark quartz sand previously studied in the Geomechanics Laboratory of City University of Hong Kong [ 69 , 70 , 71 ], BLS is a typical material (in crushed form) used as fill/backfill/ballast in infrastructure projects [ 72 ], while CDG may also find many potential applications as an earth material in tropical/subtropical regions such as Hong Kong [ 47 , 73 , 74 , 75 ].…”

Application of Nanoindentation in the Characterization of a Porous Material with a Clastic Texture

“…Specific material properties which are of major interest in tribology engineering are Young’s modulus and (micro-)hardness, as they strongly influence the frictional response and slip displacement of interfaces [ 9 , 10 ]. These properties can be assessed based on indentation experiments, a type of test which offers, apart from the quantification of basic material properties, insights into the microstructure of materials, which is particularly important in assessing materials of complex textures and fabrics [ 11 ]. However, the interpretation of indentation experiments is a challenging task, particularly in correlating surface/structural characteristics of materials with their viscoelastic or creep behavior.…”