Cement, Energy and Environment

In Place of Sand The construction industry is slowly recognising alternatives to sand. While some call for deriving sand from crushing stones or using fly ash, many see prospects in recycling construction waste or in using industrial waste. Copper s lag : Currentl y, about 33 million tonne (MT) of copper slag is generated annually worldwide, with India contributing 6-6.5 MT.A study by the Central Road Research Institute has shown that copper slag can be used as a partial replacement for sand, as fine aggregate in pavement grade concrete up to 40 per cent. Granulated blast f urnace slag: According to the report of the Working Group on Cement Industry for the 12th Plan, around 10 MT blast furnace slag is currently being generated in the country from iron and steel industry. M C Nataraja, in his study publ ished in the International Journal of Structure & Civil Engineering Research in May 2013, says that granulated blast furnace slag sand (GBFS) can be used as an alternative to natural sand from the point of view of strength. Fly ash : India currently produces over 100 MT of coal ash. Out of the total ash produced in any thermal power plant, approximately 15-20 per cent is bottom ash and the rest is fly ash. Fly ash is preferred for construction of durable housing as a lightweight aggregate. Foundry sand: India ranks fourth in terms of total foundry production (7.8 MT), according to the 42nd Census of World Casting Production of 2007. Foundry sand which is very high in silica is regularly discarded by the metal industry. Currently, there is no mechanism for its disposal, but international studies say that up to 30 per cent f\y Ash Ume foundry sand can be utilised for economical and sustainable development of concrete. C&D waste: There is no documented quantification of amount of construction and demolition (C&D) waste being generated in India. The Municipal Corporation of Delhi says it is collecting 4,000 tonne of C&D waste daily from the city - this amounts to almost 1.5 MT of waste annually in Delhi alone. If recycled , this waste can substitute natural sand. But the Bureau of Indian Standards stipulates that concrete can be made only with "naturally accessed material". This rule out the use of recycled material such as copper slag and construction waste, which is widely used in other parts of the world as aggregates. Courtesy: State of India's environment, 2014 Pg. No.: 132 A comprehensive water use audit will examine all of the major areas in which a facility uses water, including sanitation, maintenance, mechanical systems, building processes and irrigation By James Piper, P.E j J