Preparation of municipal waste incineration fly ash artificial aggregate using CO₂ curing and its properties

Abstract

With the acceleration of urbanization and the continuous growth of population, the treatment of municipal solid waste incineration fly ash (MSWI-FA), a product of municipal solid waste incineration, has become an important issue. In this study, MSWI-FA, fly ash, and cement were used as raw materials to prepare artificial aggregates by CO₂ curing technology and to study their properties. The results showed that the best performance of aggregates was obtained under CO₂ curing conditions with a water-solid ratio of 0.26, a cement content of 30 %, and fly ash content of 15 %. The formulation of raw materials affects the strength of aggregates. The appropriate amount of cement and fly ash can improve the strength, while excessive cement and fly ash can hinder the absorption and fixation of carbon dioxide, affect the carbonation reaction and strengthening effect, and even lead to the deterioration of performance. The CO₂ curing increased the average compressive strength of the artificial aggregate at the age of 28 days by approximately 80 %, and reduced water absorption, and improved durability. The produced aggregates have good stabilization ability for heavy metals, and the leaching concentration is lower than the national standard, which can be used safely in the construction field. In this study, MSWI-FA waste was successfully converted into artificial aggregates for use in construction using CO₂ curing technology, achieving the dual goals of waste recycling and carbon sequestration.