Lime Sludge–Based Geopolymer Concrete: Experimental Investigation and Life Cycle Assessment

The construction industry is a major source of CO2 emissions owing to its high cement usage. Geopolymer concrete is a type of concrete with zero per cent cement content. The adoption of industrial waste materials has been explored to decrease cement production. In this investigation, a control geopolymer concrete was prepared with fly ash and ground-granulated blast furnace slag as ingredients, and a detailed experimental study was conducted using lime sludge as a substitute for ground granulated blast furnace slag. The performance and microstructural properties of lime-sludge-based geopolymer concrete were comprehensively investigated. Experiments were undertaken to evaluate the mechanical properties of the newly developed geopolymer mix through compressive, flexural, and split tensile tests. The durability characteristics were examined through acid resistance, sulphate resistance, alkali-silica reaction, and water absorption. Microstructural examination using SEM and EDX revealed the internal composition and bonding characteristics of concrete. An environmental evaluation was undertaken using a life cycle assessment (LCA) to examine the impact. This study found that 30% lime sludge in geopolymer concrete was optimal for improving its mechanical, durability, and microstructural properties.