Recycling of wastes for value-added applications in concrete blocks: An overview

Environmental concerns related to the disposal of various waste materials have escalated to a worrying level. Depending on the local industries, different types of waste are generated in huge quantities every year. Hence, the demand for more sustainable development has further increased the importance of green construction. In recent years, extensive study efforts have been made to recycle wastes for possible use in the production of concrete products. This is because concrete blocks seem to be the most popular option for the incorporation of recycled waste materials due to the lower quality requirements of materials. This paper reviews published research works on the use of various kinds of wastes (i.e. recycled concrete, crushed brick, soda lime glass, cathode ray tube glass, crumb rubber, ceramic and tile waste, etc.) in the production of concrete blocks. The common concrete block properties as well as the value-added properties of concrete blocks with incorporated waste materials are highlighted and discussed in this paper. Several unique characteristics of recycled crumb rubber, plastic waste and crushed brick enhance the fire resistance, toughness, functional and insulation properties of concrete blocks. Also, the quantity of these materials incorporated into concrete blocks can be maximized up to 100% as natural aggregate replacements, while their usage can also be limited to below 30% in certain applications in order to meet the standard requirements of concrete blocks. The compliance of concrete blocks with standard requirements and the value-added properties have demonstrated good potential for incorporating wastes as aggregate in concrete blocks.