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  • Publication
    Development of calcium sulfate - ggbs - Portland cement binders
    Binders manufactured using a blend of gypsum, ground granulated blast furnace slag and Portland cements are technically viable and possess considerable environmental and economic advantages when compared to binders manufactured using Portland cement alone. As such, the evaluation of binders made from these materials offers a promising research focus in the quest to produce technically sound, environmental and economical binders for specialist uses as an alternative to traditional concrete binders of higher carbon footprint. The aim of the test programme was to investigate the viability of a series of binders designed to fulfil particular user needs while having significantly decreased carbon footprints. Two distinct series of binders were designed; the dominant ingredient in the first was calcium sulfate while in the second it was ggbs. Potential applications for both series of binders were considered and the strength development of each binder was analysed. In addition, the effect of water on the gypsum-based binders was analysed, as was the sulfate resistance of the ggbs-based binder. The results of the laboratory tests carried out were varied. For the calcium sulfate-based binders, those manufactured using anhydrite II as the dominant ingredient were found to achieve highest strengths. However these binders were found to be particularly susceptible to moisture-induced deterioration. For the ggbs-based binders, it was found that the early strength development was improved by the addition of small quantities of anhydrite II and gypsum. The strengths and sulfate resistance at later ages remained unaffected. These binders may have significant potential in situations where early strength development is a requirement.
      4140ScopusĀ© Citations 54
  • Publication
    Estimated nitrous oxide emissions from nitrogen fertilizer use on multispecies grassland compared to monocultures
    Grassland agriculture faces increasing demands in terms of sustainability; economic, social, and environmental. Soils are critical to sustainable agriculture, in terms of maintaining soil fertility and quality, protecting water quality and mitigating greenhouse gas (GHG) emissions. There is evidence to suggest that greater sward diversity may have benefits in this regard. We report results from SmartGrass; a three year field study at two sites in Ireland investigating grass sward diversity along a gradient from perennial ryegrass (Lolium perenne L.) monoculture to grass-legume mixes to more complex grass-legume-herb mixes of up to nine species. Results reported include estimates of nitrous oxide (N2O) emissions from fertiliser nitrogen (N), soil temperature and moisture conditions, plant-available soil N, changes in soil organic carbon (C) and plant-available phosphorus (P). Estimated direct N2O emissions from N fertiliser (g N2O-N t DM-1 ha-1 yr-1) decreased from 146 for the monoculture at 250 kg fertiliser N ha-1 yr-1 to 35 for the monoculture at 90 kg fertiliser N ha-1 yr-1, to approximately 16 for the grass-legume and grass-legume-herb mixes, also at 90 kg fertiliser N ha-1 yr-1. This was due to a combination of the grass-clover and mixed swards maintaining high DM yields at low fertiliser N input, and the fact that the fertiliser N for these treatments was applied entirely as urea. These results indicate significant potential for more diverse swards to mitigate GHG emissions from fertiliser N use in grassland agriculture.