A methodology for long-range prediction of air transportation

A framework and methodology for long term projection of demand for aviation fuels is presented. The approach taken includes two basic components. The first was a new technique for establishing the socio-economic environment within which the future aviation industry is embedded. The concept utilized was a definition of an overall societal objective for the very long run future. Within a framework so defined, a set of scenarios by which the future will unfold are then written. These scenarios provide the determinants of the air transport industry operations and accordingly provide an assessment of future fuel requirements. The second part was the modeling of the industry in terms of an abstracted set of variables to represent the overall industry performance on a macro scale. The model was validated by testing the desired output variables from the model with historical data over the past decades

Forecast of future aviation fuels: The model

A conceptual models of the commercial air transportation industry is developed which can be used to predict trends in economics, demand, and consumption. The methodology is based on digraph theory, which considers the interaction of variables and propagation of changes. Air transportation economics are treated by examination of major variables, their relationships, historic trends, and calculation of regression coefficients. A description of the modeling technique and a compilation of historic airline industry statistics used to determine interaction coefficients are included. Results of model validations show negligible difference between actual and projected values over the twenty-eight year period of 1959 to 1976. A limited application of the method presents forecasts of air tranportation industry demand, growth, revenue, costs, and fuel consumption to 2020 for two scenarios of future economic growth and energy consumption

Mechanical and hygrothermal properties of hemp-silica bio-composites

This research investigated the development of a fast-drying silica-based binder for hemp concrete products with enhanced mechanical and thermal properties. Hemp-silica bio-composites were prepared by mixing hemp shivs with a two-component binder system composed of liquid sodium silicate and tributyl citrate (TBC). Compressive strength, thermal conductivity, moisture buffering value, cyclic moisture resistance and microstructure of hemp-silica composites were analysed, and the results were compared with those of hemp-lime concrete. Hemp-silica blocks with shiv-liquid sodium silicate mass ratio of 1:3.75 and TBC content of 37.5 wt% of sodium silicate dry matter produced a compressive strength of 0.56 MPa only after 3 days of drying and 1.92 MPa after 28 days. These were higher than hemp-lime blocks at the same density range. Hemp-silica panels showed a thermal conductivity of 0.101 W/mK and an excellent moisture buffering value of 3.49. Hemp silica formed an open porosity with large air gaps between the particles and a water-resistance silica-based layer on the shiv surface producing a higher moisture resistance compared to hemp-lime systems. This paper focuses on the development of a novel fast-drying binder system with a potential for use in conjunction with other lingnocellular plant aggregates to form low-carbon and efficient multifunctional building materials

Low-carbon cements: Potential for low-grade calcined clays to form supplementary cementitious materials

The use of low-carbon supplementary cementitious materials (SCM), such as calcined clays, to replace cement clinker has been recognized by the Cement Industry to achieve reductions in greenhouse gas emissions. This paper investigates eight low-grade clays, with <20% kaolinite, obtained from different geological formations, that have been calcined to produce potential SCMs. The clays were characterised before and after calcining at 750, 800, 850 and 900 °C, and the mineralogical changes and amorphous phase contents determined. The pozzolanic activity and the strength activity index of the different calcined clays were evaluated. The results show that calcined clays from the Oxford and Ampthill geological formations in the UK can produce SCMs with pozzolanic activity higher than conventional SCMs such as PFA. These clays were rich in illite and smectite and produced ∼60% amorphous phase when calcined at 850 °C. Mortars produced using calcined clays had higher compressive strengths than mortars containing pulverised fuel ash and achieved ∼90% of the compressive strength of 100% Portland cement mortar samples at 28 days. The research demonstrates that low-grade clay resources can be calcined to produce SCMs and that these can be used to form cementitious materials with reduced total associated CO₂ emissions

Acid activated smectite clay as pozzolanic supplementary cementitious material

This research has investigated the structural changes and pozzolanic activity produced in acid activated smectite clay. The activation treatment used HCl at different concentrations, using different times and at a range of temperatures. X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy were used to determine the acid dissolution mechanism and characterise the activated clay mineral structure. Acid activation causes dehydroxylation of smectite clay, followed by leaching of octahedral cations. This results in the formation of a silica-rich amorphous phase that exhibits substantial pozzolanic activity compared to the same clay sample that had undergone calcining treatment at 850. The optimum sample was activated for 8 h using 5 M HCl at 90 °C. This was 93 % amorphous. Mortar prisms prepared with 25 % replacement of Portland cement by acid activated smectite produced 93 % compressive strength of plain Portland cement mortar

“The great source” microplastic abundance and characteristics along the river Thames

This study focused on quantifying the abundance of microplastics within the surface water of the River Thames, UK. Ten sites in eight areas were sampled within the tidal Thames, starting from Teddington and ending at Southend-on-Sea. Three litres of water was collected monthly at high tide from land-based structures from each site from May 2019 to May 2021. Samples underwent visual analysis for microplastics categorised based on type, colour and size. 1041 pieces were tested using Fourier transform spectroscopy to identify chemical composition and polymer type. 6401 pieces of MP were found during sampling with an average MP of 12.27 pieces L⁻¹ along the river Thames. Results from this study show that microplastic abundance does not increase along the river

Manufacture and performance of lightweight aggregate from waste drill cuttings

This research investigated the technical feasibility of transforming waste drill cuttings into lightweight aggregate. Drill cuttings produced from the North Sea oil field were dried, ball milled, formed into pellets and fired at temperatures between 1160 and 1190 °C. Physical properties of the manufactured lightweight aggregate, including particle density, water absorption and compressive strength, were determined. The drill cuttings had a typical evaporite composition containing high concentrations of chloride salts. This limits the potential for using the as-received drill cutting samples in lightweight aggregate production as the products formed show high levels of leaching. The addition of a washing pre-treatment to reduce the leaching of chloride ions was necessary. Washing also reduced the initial sintering temperature and improved lightweight aggregate properties. Sintering at 1180 °C produced lightweight aggregate with particle density of 1.29 g/cm³, water absorption of 3.6% and compressive strengths of 4.4 MPa. The research showed that lightweight aggregate manufacturing represents a resource efficient option for the reuse of waste drill cuttings and provides significant material saving and landfill diversion

Forecast of Future Aviation Fuels. Part 1: Scenarios

A preliminary set of scenarios is described for depicting the air transport industry as it grows and changes, up to the year 2025. This provides the background for predicting the needs for future aviation fuels to meet the requirements of the industry as new basic sources, such as oil shale and coal, which are utilized to supplement petroleum. Five scenarios are written to encompass a range of futures from a serious resource-constrained economy to a continuous and optimistic economic growth. A unique feature is the choice of one immediate range scenario which is based on a serious interruption of economic growth occasioned by an energy shortfall. This is presumed to occur due to lags in starting a synfuels program

Low-carbon cements: potential for low-grade calcined clays to form supplementary cementitious materials

The use of low-carbon supplementary cementitious materials (SCM), such as calcined clays, to replace cement clinker has been recognized by the Cement Industry to achieve reductions in greenhouse gas emissions. This paper investigates eight low-grade clays, with <20% kaolinite, obtained from different geological formations, that have been calcined to produce potential SCMs. The clays were characterised before and after calcining at 750, 800, 850 and 900 °C, and the mineralogical changes and amorphous phase contents determined. The pozzolanic activity and the strength activity index of the different calcined clays were evaluated. The results show that calcined clays from the Oxford and Ampthill geological formations in the UK can produce SCMs with pozzolanic activity higher than conventional SCMs such as PFA. These clays were rich in illite and smectite and produced ∼60% amorphous phase when calcined at 850 °C. Mortars produced using calcined clays had higher compressive strengths than mortars containing pulverised fuel ash and achieved ∼90% of the compressive strength of 100% Portland cement mortar samples at 28 days. The research demonstrates that low-grade clay resources can be calcined to produce SCMs and that these can be used to form cementitious materials with reduced total associated CO2 emissions

Acid activated smectite clay as pozzolanic supplementary cementitious material

This research has investigated the structural changes and pozzolanic activity produced in acid activated smectite clay. The activation treatment used HCl at different concentrations, using different times and at a range of temperatures. X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy were used to determine the acid dissolution mechanism and characterise the activated clay mineral structure. Acid activation causes dehydroxylation of smectite clay, followed by leaching of octahedral cations. This results in the formation of a silica-rich amorphous phase that exhibits substantial pozzolanic activity compared to the same clay sample that had undergone calcining treatment at 850. The optimum sample was activated for 8 h using 5 M HCl at 90 °C. This was 93 % amorphous. Mortar prisms prepared with 25 % replacement of Portland cement by acid activated smectite produced 93 % compressive strength of plain Portland cement mortar