Schmidt hammer exposure-age dating of periglacial and glacial landforms in the Southern Swiss Alps based on <i>R</i>-value calibration using historical data

As a contribution to the palaeoenvironmental history reconstruction of the Alpine periglacial domain, this study focuses on the Schmidt hammer exposure-age dating (SHD) of (peri-)glacial landforms using rebound-value (R-value) calibrations for 10 stations in the Scaradra glacier forefield (north-eastern part of the Ticino Canton, Lepontine Alps) and for 13 stations in the Splügenpass region (located between Switzerland and Italy, Rhaetian Alps). Linear calibration based on the known age of several moraines of the Scaradra glacier assessed by historical cartography allowed the reconstruction of the glacier fluctuations around the end of the Little Ice Age. Timing of deglaciation and of rock glacier development was defined in the Splügenpass region using the calibration of exposure ages based on two mule tracks built in 300 CE and 1250 CE, respectively. Discussion on R-value analysis and calibration improves the knowledge on the potential use of SHD for numerical-age dating in Alpine geomorphological studies.

Rock properties and rock-controlled landforms

Rock properties are a crucial control of landform development. The purpose of this chapter is to examine the progress that was made in studying rock properties in general and then to discuss developments in the study of landforms in three main rock types: granite, limestone and sandstone. From the mid-1960s onwards, geomorphology witnessed an increasing concern with the quantification of rock properties and their relationship to landforms and landscape evolution. Japanese geomorphologists led in this endeavour. Studies crossed a range of scales from those of a large size, that were susceptible to field measurements, and those of small size that involved laboratory studies. Among the basic characteristics of rocks that have been studied are fracturing and jointing, rock mass strength, hardness as determined by the Schmidt Hammer, resistance as determined by laboratory simulations, slaking susceptibility, porosity, water absorption capacity, water content and permeability, and petrological thin section analyses. The investigation of forms and processes in granite, limestone and sandstone areas has shown the value of combined geological and geographical approaches, and the increasing internationalization of studies.

The Assessment of Strength of Cementitious Materials Impregnated Using Hydrophobic Agents Based on Near-Surface Hardness Measurements

Recently, the surfaces of concrete structures are impregnated to protect them against the environment in order to increase their durability. It is still not known how the use of these agents affects the near-surface hardness of concrete. This is especially important for experts who use the near-surface hardness of concrete for estimating its compressive strength. The impregnation agents are colorless and, thus, without knowledge of their use, mistakes can be made when testing the surface hardness of concrete. This paper presents the results of investigations concerning the impact of impregnation on the subsurface hardness concrete measured using a Schmidt hammer. For this research, samples of cement paste with a water–cement ratio of 0.4 and 0.5 were used. The samples were impregnated with one, two, and three layers of two different agents. The first agent has been made based on silanes and siloxanes and the second agent has been made based on based on polymers. The obtained research results allow for the conclusion that impregnation affects the near-surface hardness of concrete. This research highlights the fact that a lack of knowledge about the applied impregnation of concrete when testing its near-surface hardness, which is then translated into its compressive strength, can lead to serious mistakes.

Geomechanical and Fracture Network Interpretation of a Devonian Outcrop

Summary The Duvernay Formation is an unconventional reservoir characterized by induced seismicity and fluid migration, with natural fractures likely contributing to both cases. An alpine outcrop of the Perdrix and Flume formations, correlative with the subsurface Duvernay and Waterways formations, was investigated to characterize natural fracture networks. A semiautomated image-segmentation and fracture analysis was applied to orthomosaics generated from a photogrammetric survey to assess small- and large-scale fracture intensity and rock mass heterogeneity. The study also included manual scanlines, fracture windows, and Schmidt hammer measurements. The Perdrix section transitions from brittle fractures to en echelon fractures and shear-damage zones. Multiple scales of fractures were observed, including unconfined, bedbound fractures, and fold-relatedbed-parallel partings (BPPs). Variograms indicate a significant nugget effect along with fracture anisotropy. Schmidt hammer results lack correlation with fracture intensity. The Flume pavements exhibit a regionally extensive perpendicular joint set, tectonically driven fracturing, and multiple fault-damage zones with subvertical fractures dominating. Similar to the Perdrix, variograms show a significant nugget effect, highlighting fracture anisotropy. The results from this study suggest that small-scale fractures are inherently stochastic and that fractures observed at core scale should not be extrapolated to represent large-scale fracture systems; instead, the effects of small-scale fractures are best represented using an effective continuum approach. In contrast, large-scale fractures are more predictable according to structural setting and should be characterized robustly using geological principles. This study is especially applicable for operators and regulators in the Duvernay and similar formations where unconventional reservoir units abut carbonate formations.