Improved concrete via upgraded oil shale ash

Oil shale combustion produces large amounts of bottom ash residue that currently adds a storage problem due to a lack of efficient utilization modes. Oil shale is an abundant potential energy source, but its low calorific value and high ash content have limited its large-scale economic utilization as a fossil fuel. In Israel, there is only one industrial user which utilizes oil shale as fuel for process heat (steam production), producing so far more than a million tons of useless oil shale bottom ash (OSBA) in large piles under atmospheric conditions, raising environmental concerns. Previous studies show that OSBA can be a good substitute for cement due to its good pozzolanic reaction, in concrete without reducing strength, but its cementitious properties are limited. This study explores several chemical treatment methods to upgrade OSBA so that it can be used as a partial substitute for cement or aggregates in concrete. The study proved that the chemical-treated OSBA has improved reactivity and suitability as a concrete ingredient. Thus, upgrading OSBA could provide a productive use for the ash while reducing the need for cement production which is a polluting process. It could also cut off the environmental risks of long-term storage of large ash piles. The results may demonstrate a way for fruitful economic environmentally safe utilization of oil shale combustion as a fossil fuel. This also has the benefit of producing useful building materials without the need for large quarries while harnessing an abundant energy source with less waste.