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Cement is the strength-forming component of concrete. It has been a major building material for more than a century. However, its production is accountable for a considerable percentage of global CO2 emissions and is very energy-intensive. The Ordinary Portland Cement (OPC) production is a thermal process at around 1450 °C. This study shows that the reactivation of Hydrated Cement Powder (HCP) can be successful at a much lower temperature. Therefore, the possibility of using HCP to replace parts of OPC in concrete reduces the energy consumption and the CO2 emissions associated with OPC production. HCP, which may ultimately stem from recycled concrete, needs treatment to produce new concrete of the required mechanical strength. Using reactivated HCP in concrete, an optimum strength is achieved by heating the HCP in the range of 400–800 °C. Among other factors, the type of cement used influences the optimum heating temperature and attainable strength. This paper shows that 600 °C is an optimum heating temperature using the OPC type CEM I 52.5R. The crystalline phase transitions resulting from the thermal treatment were analyzed by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetry (TG). The heat released during hydration was investigated, and scanning electron microscopy (SEM) displays the microstructure evolution. OPC can be partially replaced by thermally treated HCP in mortar, attaining similar mechanical strength values.

Bitumen is a material used in many industrial applications. It is the primary binding material for road pavements in asphalt. To improve sustainability, it is important to be aware of the finite nature of conventional oil reserves. As a cost and energy saving material, reclaimed asphalt pavement can help preserve our resources. Virgin binder ages significantly during its service life time yielding declining mechanical properties. As material properties of bitumen are responsible for the endurance of asphalt pavements, adding rejuvenators is supposed to restore the mechanical properties like the original bitumen properties. In this paper, three different rejuvenators were studied using one common polymer modified bitumen PmB 25/55-55 A. The virgin binder was aged in two different aging steps (short and long-term) and rheological properties were determined by traditional bitumen tests and dynamic shear rheometer (DSR) tests. For a better understanding of rejuvenation on the microscale, virgin, aged, and modified bitumen samples were measured using Optical Microscopy and Atomic Force Microscopy (AFM). Aging has significant influence on the macro- and micro-Rheology of bitumen. It causes changes in viscosity and at the same time clear changes in its surface structure. All Rejuvenators positively influence the rheological properties to different extents. Atomic Force Microscopy revealed considerable changes of the morphology between virgin, aged, and rejuvenated binders. The combination of rheological properties and micro structure imaging is an important tool in advancing and optimizing reclaimed asphalt pavement.

As part of the 2019 Southern oCean seAsonal Experiment (SCALE) Winter Cruise of the South African icebreaker SA Agulhas II first-year ice was sampled at the advancing outer edge of the Antarctic marginal ice zone along a 150 km-Good Hope Line transect. Ice cores were extracted from four solitary pancake ice floes of 1.83–2.95 m diameter and 0.37–0.45 m thickness as well as a 12 × 4 m2 pancake ice floe of 0.31–0.76 m thickness part of a larger consolidated pack ice domain. The ice cores were subsequently analyzed for temperature, salinity, texture, anisotropic elastic properties and compressive strength. All ice cores from both, solitary pancake ice floes and consolidated pack ice, exhibited predominantly granular textures. The vertical distributions of salinity, brine volume and mechanical properties were significantly different for the two ice types. High salinity values of 12.6 ± 4.9 PSU were found at the topmost layer of the solitary pancake ice floes but not for the consolidated pack ice. The uniaxial compressive strength for pancake ice and consolidated pack ice were determined as 2.3 ± 0.5 MPa and 4.1 ± 0.9 MPa, respectively. The Young’s and shear moduli in longitudinal core direction of solitary pancake ice were obtained as 3.7 ± 2.0 GPa and 1.3 ± 0.7 GPa, and for consolidated pack ice as 6.4 ± 1.6 GPa and 2.3 ± 0.6 GPa, respectively. Comparing Young’s and shear moduli measured in longitudinal and transverse core directions, a clear directional dependency was found, in particular for the consolidated pack ice.

Frazil ice, consisting of loose disc-shaped ice crystals, is the very first ice that forms in the annual cycle in the marginal ice zone (MIZ) of the Antarctic. A sufficient number of frazil ice crystals forms the surface grease ice layer taking a fundamental role in the freezing processes in the MIZ. As soon as the ocean waves are sufficiently damped, a closed ice cover can form. In this brief communication we investigate the rheological properties of frazil ice, which has a crucial influence on the growth of sea ice in the MIZ. Grease ice shows shear thinning flow behavior.