Recycle and Replacement of Concrete Waste Products

In the last decade, construction industry has been conducted research on the utilization of waste products in concrete. Some of waste products are fly ash, rice husk, saw dust, and discarded tires, plastic, glass rock, steel slugs, stone dust and ceramic. Each waste product has its specific effect on properties of fresh and hard concrete. The use of waste products in concrete not only makes it economical but also solves some of the disposal problems. The crushed rock flour can be used to replace the natural sand in concrete. The use of crushed ceramic aggregate can be used to produce lightweight concrete, without affecting strength. The stone dust can be used as alternative material in place of sand in concrete based on grain size data. Sand can replace by rock flour up to 40% without affecting strength and workability. The sand can be replaced fully with rock flour. However a slight loss in workability has been noticed with increase in replacement of san by rock flour. Sand can be replaced fully by rock flour without much loss of workability.

Nearly 20% of rock is converted into rock flour while crushing rock into aggregate at stone breaking plants. In ceramic insulator industry, there is a mass failure of about 30 to 50% of the total production due to improper mixing of raw materials, excess water, improper drying and too much of heating. No work has been reported using stone dust and ceramic scrap together in concrete so far. Hence the present work has been planned to evaluate suitability of these waste materials in concrete production.

The quantities of the constituents of the concrete were obtained from the Indian Standard Mix Design method. The variation of strength of hardened concrete using stone dust as fine aggregate and ceramic scrap as partial / full replacement is studied by casting cubes, cylinders and prisms. The concrete was prepared in the laboratory using mixer and . The cement, fine aggregate and coarse aggregate were first mixed in dry state to obtain uniform color and calculated amount of water obtained from workability test was added and the whole concrete was mixed for five minutes in wet state. Meanwhile the moulds are screwed tightly to avoid leakage; Oil was applied on inner surface of the moulds. The concrete after mixing using the was poured into moulds in three layers by poking with a tamping rod. The cast specimens were removed from moulds after 24 hours and the specimens were immersed in a clean water tank. After curing the specimens for a period of 28 days, the specimens were removed from the water tank and allowed to dry under shade.