Abrasion is one of the key mechanisms by which coke undergoes degradation in the blast furnace. Abrasion in coke refers to its surface breakage, and it occurs when lumps of coke move against each other as they descend the furnace. In industry, abrasion is assessed using tumble drum testing. However, tumble drum indices do not provide a measure of pure abrasion; rather, different breakage mechanisms occur during the test, including volume breakage and asperity breakage. To this end, we previously developed an approach using tribological testing of coke specimens to examine their resistance to pure abrasive wear and linked the mechanisms by which abrasion took place to coke microstructural and microtextural features, and thereby the properties of the parent coal(s) used to make the cokes. The key objectives of this present study were to: (i) investigate whether correlations exist between abrasion resistance measured using tribological testing and conventional coke quality indices, namely tumble drum indices-which is one of the novel aspects of this work; (ii) link the mechanisms of wear to coke microtextural components and the rank and maceral composition of the parent coal or blend; (iii) conduct a preliminary evaluation of whether partially pre-reacting coke samples with H2O affects their abrasion resistance compared to pre-reacting samples with CO2. This last objective contributes to a broader research aim of improving understanding of the coke quality requirements for effective operation of hydrogen-enriched blast furnaces. Key findings of the present study include: Some positive correlation was observed between the coefficient of friction (COF) of a coke at the end of tribological testing under ambient conditions and its measured ASTM Hardness or I600. This trend is a tentative observation requiring further validation. In addition, the mechanisms of abrasive wear under ambient conditions were correlated with parent coal rank. For coke from mid-rank coal, the reactive maceral derived components (RMDC) appeared to have a high fracture toughness based on SEM image analysis. For coke from the high-rank coal, which showed a higher degree of RMDC anisotropy, the main mechanisms of abrasion were delamination and ploughing. Finally, increased abrasive wear was observed for the samples pre-reacted with H2O than for those pre-reacted with CO2. The impact of the different gasification conditions on all six cokes will be subject of a follow-up paper.
Abstract This study experimentally investigates the flexural behavior of ultrahigh performance ferro-geopolymer (UHPFG) panels constructed using self-compacting ultrahigh performance geopolymer concrete (SCUHPGC) reinforced with stainless steel wire mesh (SSWM) and stainless steel fiber (SSF). A total of six UHPFG panels, 400 mm in length, 100 mm in width, and 25 mm in depth, were cast and tested under four-point loading until failure. The influence of adding SSF to the SCUHPGC and varying the number of SSWM layers on the flexural behavior of the UHPFG panels was examined. The moment capacities of the UHPFG panels were evaluated experimentally and analytically. The experimental results showed that the moment capacity of the panels increased by 131.9% for the addition of 2% SSF (by volume). The moment capacity of the UHPFG panel with two layers of SSWM was 301.1% higher than that of the plain UHPFG panel. The experimental moment capacity was compared to that calculated using existing models and code-based equations. ACI 549.1R–18, ACI 318–19, and ACI 544.4R–18 provisions were found to be conservative in calculating the moment capacity of both plain panels (without SSWM) and panels reinforced with SSWM. The flexural toughness of the UHPFG panels was evaluated. The increase in flexural toughness between successive deflection points is more pronounced in the UHPFG panel reinforced with two layers of SSWM compared to those with one layer of SSWM. Up to the deflection of L/100 (3 mm), the fiber-reinforced UHPFG panel without SSWM exhibits higher flexural toughness than the UHPFG panel reinforced with one layer of SSWM. The incorporation of SSF into SCUHPGC resulted in a substantial increase in the flexural strength of UHPFG panels.
Reconstructing terrestrial palaeoenvironmental change during the Middle Pleistocene is essential for understanding ecosystem stability and resilience under long-term climatic forcing. However, well-dated, quantitative records from Australia remain limited. Fossil deposits at Mount Etna Caves, central eastern Queensland, preserve two taxonomically distinct faunal assemblages that have been interpreted as a substantial ecological transition from a diverse rainforest system to an arid-adapted faunal community. Previous interpretations of this transition have relied primarily on faunal evidence, with limited site-specific geochemical validation. Here, we integrate oxygen isotope (δ18O) analyses of fossil macropodid enamel with refined in-situ U-Th geochronology to reconstruct changes in hydroclimatic conditions across this transition. New U-Th ages better constrain deposition of the arid-adapted assemblage to a narrow interval between 199 ± 5 and 205 ± 4 ka. Fossils from older deposits (pre-280 ka) exhibit consistently low δ18O values (−2.59 ± 0.54 ‰), suggesting relatively humid conditions, whereas the younger deposit is markedly enriched (4.59 ± 1.92 ‰). Random Forest classification models trained on modern macropodine δ18O data suggest that pre-280 ka assemblages show strongest similarity with humid temperate forest environments analogous to modern temperate oceanic (Cfb-like) systems of southeastern Australia and highland New Guinea. In contrast, the post-205 ka assemblages show the strongest affinity with arid, hot desert (BWh-like) conditions characteristic of central Australia. This transition coincides with broader Middle Pleistocene climatic reorganisation centred on ∼270 ka, which may have contributed to sustained regional drying. These findings suggest that long-term climatic forcing may push ecosystems beyond hydroclimatic thresholds, resulting in major ecological reorganisation, altered species distributions, and reduced biogeographic connectivity. By providing a directly dated, multi-proxy terrestrial record, this study highlights how substantial environmental change during the Quaternary offers an important analogue for understanding ecosystem vulnerability under ongoing and future climate change.
Shoreline deposits bordering ephemeral lakes can record large flood events, historical lake level variations, and temporal variations of climate patterns. Yet, the hydrological history of the Lake Eyre Basin, one of the world's largest endorheic basins, is mostly limited to records from its southern and eastern areas, such as Kati-Thanda Lake Eyre (KT-LE), Lake Frome and Cooper Creek. Here, we present the first modern-hydroclimatic history of Lake Machattie in KT-LE's most northern catchment, the Georgina, based on sedimentological data and spatial analysis of shoreline features. Barrier spit deposits on the northern margin of the lake are dominated by a series of landward-prograding overwash deposits generated during extreme lake fillings. Historical and modern flood events were identified from these sedimentary units, with those between 1974 and 2001 coinciding with the largest lake fillings observed from Landsat spectral data. All modern floods that interacted with the barrier spit reached the Diamantina River, confirming waters from the Georgina River can contribute to modern- and palaeo-KT-LE fillings. Our analysis also shows that modern Lake Machattie high stands are generally tied to La Niña events combined with negative phases of the Interdecadal Pacific Oscillation (IPO), suggesting precipitation over the northern Lake Eyre Basin could be strengthened by IPO-La Niña modulations.
This study examines the career trajectories of tertiary education teachers in Australia using 24 years of longitudinal data that capture changes in employment and career paths over time. The results reveal substantial early-career attrition, with higher exit risks observed among younger teachers, VET subsector staff, individuals in regional and remote areas, and those in insecure roles. Lower wages, reduced job satisfaction, higher job stress, lower perceived job complexity, and limited perceived skill development are also associated with an increased likelihood of teacher exit. Longitudinal analyses further indicate clear divergence in career experiences, with early-career leavers reporting declining job satisfaction and increasing stress prior to exit, while long-term stayers maintain more stable and positive perceptions of their work over time. These findings highlight the importance of strengthening early-career support, improving employment stability, enhancing job quality, and addressing structural disparities across subsectors to sustain a stable and resilient tertiary education workforce.
