Effect of sintering and coldbonding techniques onlightweight aggregates fromindustrial waste – a review

Concrete is a building material which consist major portion of hard inorganic materials called aggregates such as crushed stone aggregate. Due to continuous usage of natural resources within a short length of time these get depleted. Production of concreteby using waste materials from industries is important in this era. The production of light weight aggregate from waste material is done by pellatization and hardened by sintering or cold bonding techniques. Depending upon the hardening methods the properties of concrete is also varied. From previous research works it can be concluded that it is possible to produce structural concrete using sintered fly ash aggregate which are spherical in shape having specific gravity varying from 1.33 to 2.35. According to the literature, the specific gravity of these aggregates was 16 to 46 percent lower than that of standard of weight aggregates, and they might be employed as aggregates in structural concrete production depending on the constituent qualities and the production environment. Cold bonded aggregate concretewith compressive strength 48% lesser compared to normal concrete mix, it exceeds the value of 17 MPa that has been fixed as minimum criteria for concrete to be used as a structural material. This paper mainly focuses on review of artificial light weight aggregate from cold bonding and sintering methods and how these methods affect the concrete properties. From different studies, it is concluded that Cold bonding is an energy saving method and Sintered sludge pellets have a stronger aggregate strength, larger porosity, and lower aggregate density than cold bonded aggregates, exhibiting qualities that are superior to those required of building aggregates. Sustainable development is indeed achievable in this developing era and lightweight aggregate in construction sector is key to achieve this