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Engineering Properties and Optimal Design of Ultrahigh Performance Alkali-Activated Concrete
No full textThe low carbonization of ultrahigh performance concrete (UHPC) and the resource utilization of industrial solid waste have become research hotspots for sustainable development in the construction industry. This study prepared ultrahigh performance alkali-activated concrete (UHP-AAC) using industrial solid waste slag and silica fume as binders. Through experiments on 11 groups of UHP-AAC, the effects of water-to-binder ratio, water-glass modulus, alkali equivalent, and steel fiber content on the fresh and mechanical properties of UHP-AAC were investigated, and the results were compared with those of ordinary portland cement-UHPC (OPC-UHPC) control groups. The results indicate that, in terms of fresh properties, an increase in W/B, water-glass modulus, and alkali equivalent positively influenced the fresh properties of UHP-AAC, while an increase in steel fiber content led to poorer workability. Due to the alkaline environment and the presence of silicates, the flowability and setting time of all UHP-AAC mixtures were lower than those of OPC-UHPC. In terms of mechanical properties, there exists an optimal W/B and alkali equivalent, and an increase in water-glass modulus and steel fiber content enhanced the mechanical properties of UHP-AAC, with all UHP-AAC mixtures exhibiting higher compressive strength than OPC-UHPC. When 1% steel fiber was added, the mechanical properties of UHP-AAC after 7 days of standard curing reached approximately 90% of those at 28 days, demonstrating significant early strength development. Additionally, the tensile stress-strain curves of UHP-AAC under different parameters were analyzed, revealing strain hardening phenomena at steel fiber contents of 2% and 3%. Overall, the optimized mix design significantly improved the mechanical properties of UHP-AAC, with lower carbon emissions and energy consumption, making it a sustainable green building material with broad application prospects.</p
More than ‘Add Women and Stir’:Integrating Gender and Social Sciences into Agricultural Research-for-Development
No full textThe majority of the world’s poor are women and many of the world’s women are farmers. Whilst smallholder families play a central role in farming, food and health and natural resource management systems in low- and medium-income countries, women’s contributions are frequently undervalued or unrecognised—and they are disproportionately affected by poverty. In the agricultural sector, a focus on poverty reduction and livelihood improvement that addresses gender equity and empowers women and girls as a central pillar can narrow the gap between men’s and women’s access to resources and decision-making to increase agricultural production. This chapter captures the insights from such an approach by an agricultural research-for-development funding agency and uses the case study of the Family Farm Teams program in Papua New Guinea (PNG), to highlight key factors at both an institutional and program level.</p
Underpinning the impact of in-vehicle distractions on driving performance in Australia
No full textIntroduction: Give the significant and diverse impact of in-vehicle distractions on road crashes, this study examines the comparative impact of four inside-vehicle distractions (auditory, visual, behavioral/manual and cognitive) on driving performance. Method: A lab-based driving simulator study was conducted with Australian drivers (n = 103) to examine the impact of four types of distractions on driving performance. Results: Simulator-based study results confirmed that behavioral/manual and auditory distractions were the largest inside-vehicle distractions affecting driving performance adversely. Practical Applications: The study’s findings offer valuable insights for developing safe driving awareness campaigns, particularly by addressing auditory and behavioral distractions
Circumpolar Deep Water upwelling is a primary source of 10Be in Antarctic continental shelf sediments
No full textBeryllium-10 (10Be) has been proposed as a potential proxy for investigating ice shelf presence and absence, or meltwater discharge in coastal polar environments. However, the sources and distribution of atmospherically produced meteoric-10Be in the Antarctic marine realm are yet to be fully characterized, making any inferences about its concentration in sediments challenging. We present a dataset of 9Be and 10Be concentrations, and 10Be/9Be ratios in seafloor surface sediments from the Antarctic continental shelf - including from sub ice shelf cores - to assess the sources and processes contributing Be-isotopes to ice-sheet proximal marine settings. We show that upwelling waters (e.g. Circumpolar Deep Water) are a significant source of 10Be to continental shelf sediments. This limits the use of 10Be/9Be as a proxy for ice shelf environment or meltwater discharge, but instead provides a potential proxy for reconstructing Circumpolar Deep Water incursions onto Antarctic continental shelves
