Stabilization of fly APC ashes with Portland cement as encapsulating for their usage as aggregate material. Mechanical and environmental evaluation

Abstract

The rising generation of waste products signifies a big problem in today’s society. This is a direct result of an ever growing population. A possible solution for waste disposal can be found in an incineration plant by means of a revalorization process. This process would not only reduce the volume of waste produced but would function as a power generating system. The control of waste production involves a cleaning system to purify the resulting gases of the incineration. The cleaning process varies depending on the nature of the waste. Independently from the type of waste found in the incineration plant, two very different by-products can be obtained: ash and slag. These by-products have properties which resemble those of cement. On the one hand, depending on the cleaning process, the ash obtained can contain a high level of calcium resembling the pozzolanic behavior typically associated with cement; on the other hand, once the slag has been valorized it becomes a fine arid made mostly of concrete, ceramic materials and glass. This composition allows valorized slag to form embankments or to be used as a filler. Demographic growth has simultaneously caused an increase in CO2 emissions. This increase is a result of the necessity to build and join different communities. The creation of new urban nucleus’s entails the paving of new roads which consequently produces the need for more construction materials. Nowadays, the cement industry accounts for around 8 to 15 % of total world emissions. For this reason, investigation into the optimization of its use is of great interest. This investigation project intends to use the properties of the by-products obtained in the incineration process to incorporate the maximum quantity of fly ashes generated in the gas cleaning system, into a Portland cement, which, once mixed with the valorized slag, creates a material that can be used in the layering of roads with small traffic flows. This would contribute to a decrease in the use of cement and would use the by-products obtained from the incineration process, which would in turn reduce CO2 emissions. Through compliance with environmental regulations and through the performing of standard tests, different formulations will be studied in order to determine the best way of reusing the highest quantity of ash with the best mechanical properties. To reach the optimal formulation, different influential factors in the mortar will be determined and will be assigned different values through use of the DoE computer program. Finally, from the results of the standardized testing an optimal formulation will be found in accordance with its mechanical and environmental criteria.