INNOVATIVE BUILDING MATERIAL

摘要

Phosphogypsum is the waste product of the fertilizer industry, i.e. phosphoric acid production. It is also produced by the mining of phosphate rock. It has been reported that for every ton of phosphoric acid produced 4.5 to 5.5 tonnes of phosphogypsum is generated which amounts to 5 million tonnes annually in India. Phosphogypsum is the third major waste product of India, the other two being fly ash and blast furnace slag respectively. Phosphogypsum is being used in the manufacture of wall boards and partition panels after appropriate treatment. It has also been used in concrete in the form of slag aggregate, in roller compacted concrete, etc. Phosphogypsum is a very fine material and possesses good binding properties under compaction. Typical analysis of phosphogypsum shows that the major constituent of phosphogypsum is gypsum, and the other constituents viz. phosphate, fluoride, sand and soluble salts are in minor quantities. The pH of phosphogypsum varies between 2 to 5 and its specific gravity is about 3.5. It provides retardation and workability to cement based mixtures. In the present study investigations have been carried out on replacement of cement by phosphogypsum for producing High Strength Concrete. Furthermore, laboratory investigations reveal that at 5% replacement by weight of cement, the strength increases and also economy is achieved. The principal objectives of the investigation are to study the strength characteristics of cement containing phosphogypsum and early age behaviour. The implication of the study is that, due to the escalating production of phosphoric acid the quantum of phosphogypsum produced is increasing leading to accumulation of heaps of phosphogypsum around the areas of production, causing air, water and land pollution. Thus its utilization in concrete would not only increase the strength and helps to achieve economy, but would also help in reducing the pollution load on environment.