An overview of eco-friendly alternatives as the replacement of cement in concrete

Due to the global urbanization, economic development, and increasing rate of the world's population, the construction of new buildings and infrastructure is increasing. The manufacture of concrete has become an essential part of our life all over the world. Emitting 5-8% of carbon dioxide (CO2), the production of concrete becomes the main obstacle to reach global climate action under the Paris 2050 Agreement. Reuse of waste or recycled waste materials in concrete as an environmentally friendly construction material has become highlighted as a feature of achieving sustainability, because of its potential environmental and economic benefits. The focus of this paper is to assess the application of alternative eco- friendly substitutes of cement for an innovative, economically attractive, and environmentally friendly alternative, and the transition towards of circular economy by reducing the number of natural resources consumed. Based on the existing studies, waste material (fly ash, bottom ash, coal ash, tire, steel slag, construction and demolition waste, glass, ceramic) incorporated with concrete accepted performance in the environment and economic perspective by reducing energy consumption, greenhouse gas emissions, costs, and other indicators.