This research study evaluated the effects of adding Scottish canal sediment after calcination at 750 °C in combination with GGBS on hydration, strength and microstructural properties in ternary cement mixtures in order to reduce their carbon footprint (CO2) and cost. A series of physico-chemical, hydration heat, mechanic performance, mercury porosity and microstructure tests or observations was performed in order to evaluate the fresh and hardened properties. The physical and chemical characterisation of the calcined sediments revealed good pozzolanic properties that could be valorised as a potential co-product in the cement industry. The results obtained for mortars with various percentages of calcined sediment confirmed that this represents a previously unrecognised potential source of high reactivity pozzolanic materials. The evolution of the compressive strength for the different types of mortars based on the partial substitution of cement by slag and calcined sediments showed a linear increase in compressive strength for 90 days. The best compressive strengths and porosity were observed in mortars composed of 50% cement, 40% slag and 10% calcined sediment (CSS10%) after 90 days. In conclusion, the addition of calcined canal sediments as an artificial pozzolanic material could improve strength and save significant amounts of energy or greenhouse gas emissions, while potentially contributing to Scotland’s ambitious 2045 net zero target and reducing greenhouse gas emissions by 2050 in the UK and Europe.
Fibras poliméricas têm sido utilizadas com sucesso para o aumento da resistência ao dano de concretos refratários durante a secagem. Tal aplicação se baseia no aumento de permeabilidade ocasionado pela fusão ou degradação dessas fibras durante o primeiro aquecimento do concreto. Além desse benefício, as fibras poliméricas podem também atuar como reforço, aumentando tanto a resistência mecânica quanto a energia total de fratura, se suas propriedades se mantiverem íntegras até a temperatura de máxima pressurização. Este trabalho tem como objetivo avaliar a resistência mecânica e a energia total de fratura de concretos úmidos e secos, reforçados com diferentes tipos de fibras poliméricas. Verificou-se um grande aumento das propriedades mecânicas com a adição de fibras, sendo que a influência do tipo de fibra adicionado mostrou-se mais acentuada nos ensaios realizados com o concreto seco. Os resultados ajudam a explicar o comportamento dos concretos com fibras durante a etapa de secagem.
A large quantity of sediments is dredged continuously worldwide. They are generally dumped in landfill areas which ensue in the increasing cost of the dredging operations and in soil-groundwater pollution. The objective of this work is to study the beneficial reuse of dredged sediments in foam mortar and particularly by studying the influence of the substitution of sand by dredged sediments. Air foam mortars/concrtes is an alternative to ordinary concrete, which presents the advantages of lightweight and low thermal conductivity. In this study, the density required ranges from 1200kg/m3 to 1600kg/m3 to the development of foam concrete building blocks and slabs for load-bearing and non-load-bearing structures. Twenty foam mortar mixes were prepared. Sediments were introduced by replacing 15%, 30%, and 50% mass of the sand. The foam percentage was introduced from 0–100% volume of mortar. Workability, compressive strength, and flexural strength at the age of 7, 28, and 60 days were monitored. The size distribution of foam bubbles and the effect of sediments on their stability is also studied. The results demonstrate that sediment has a good general effect on foam concrete and this opens up very promising new types of concretes. However, for a high substitution rate, a decrease in performances is denoted.
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