Utilization of waste materials in non-autoclaved aerated concrete blocks: State of art review

Abstract

In the modern construction industry, there are many advanced materials used as a replacement for conventional bricks considering their advantages. Lightweight concrete blocks, Autoclaved Aerated Concrete Blocks (AAC), gypsum panels, etc. are some of the popular materials used for wall construction. They are preferred because of their easy workability and low density. Lightweight concrete blocks have high water absorption which reduces their durability. AAC blocks are extensively used but they are very costly and require a large quantity of water for autoclaving, thus the embodied energy increases significantly. NAAC is a lightweight concrete in which efforts are regularly made by researchers to incorporate waste material as a partial replacement of fine aggregate; this completes the definition of sustainable development to “meet the requirements of the present generation without risking future generations' ability to meet their own needs.” Waste materials such as fly ash, geopolymer, phosphogypsum, and rice husk have been used but waste marble dust, granite dust, and rubber which cause damage to the environment haven’t been yet incorporated as waste material in NAAC blocks. This review paper will focus on the advantages of using NAAC blocks and all the waste materials used in NAAC blocks to improve their mechanical properties. The characteristics which form the basis of comparison are Density, Water Absorption, Compressive Strength and Thermal Conductivity. A case study is mentioned for a single-storied bungalow in which the cost and time parameters of using NAAC block as a wall material were compared against AAC blocks and conventional red clay bricks using Primavera Software.