Eco-friendly geopolymer prepared from solid wastes: A critical review.

Solid wastes are generated from human activities which could cause damage to the ecological environment and human beings. In recent years, there has been extensive research on solid wastes utilized as precursors, aggregates, fibers, etc. to prepare the geopolymers, which has invariably been a research hotspot. This review classifies the solid wastes utilized for geopolymers into three main categories: industrial waste, agricultural waste, and municipal waste. Accordingly, we systematically dissert solid wastes-based geopolymer from the perspectives of structure, properties, and application. The chemical composition, morphology, particle size, thermal conductivity, and other characteristics of solid wastes can trigger changes in the specific properties of geopolymers. On this account, solid wastes-based geopolymers have great potential in the domain of concrete, fireproof materials, impermeable materials, catalysts, adsorbents, and energy storage materials, etc. More importantly, geopolymers have obvious advantages in immobilizing heavy metals in solid wastes. Therefore, it can demonstrate geopolymer is a sustainable and environmentally friendly "green material". However, it still confronts the challenges of solid wastes utilized in geopolymer (technology, economy, administration). It requires the government, enterprises, and the public to work together for co-governance to accomplish industrialization and commercialization of solid wastes-based geopolymer.