Researchers have conducted some researches from 10 years ago, related to recycled aggregates to be used in concrete roads, pavements, bridges, etc. however, they have not applied recycled aggregates for structural concrete. The purpose of this research is to use recycled aggregate for structural concrete. This chapter focuses on previous research studies about environmental issues, waste management and Recycled Aggregate Concrete (RAC).
Environmental rules and regulations are made to improve the environment in order to create suitable condition (healthful water, air, land, etc.) for human and organisms as well as to fix the problems of polluted sites. Protecting from further degradation, preserving the present situation, and enhancing the environment are the main tasks of environmental engineering. There are several divisions in the environmental rules including environmental impact assessment and mitigation, waste-water conveyance and treatment, contaminated land management and site remediation, solid waste management, etc.
ECONOMICS AND BEST PRACTICABLE OPTIONS FOR RAC
The main alternative to using recycled aggregates is, of course, natural aggregate and these are still relatively low cost materials. However, in a purely economic balance, the cost of processing to recycled aggregates in the UK is becoming less than that of disposing of the demolition waste and purchasing new aggregates, due to increases in landfill tax and the newly introduced aggregates levy. If recycled aggregates have to be transported a significant distance from the place of production to the place of use, then both the cost and environmental benefits may become more questionable. In India, the cost of construction materials is increasing incrementally. As a result, in India, the informal sector and secondary industries recycle 15–20% of solid wastes in various building components.
It has been estimated that approximately 180 million tones of construction & demolition waste are produced each year in European Union. 10% of recycled aggregates in UK are RAC. 78,000 tons of RAC were used in Holland in 1994. The Netherland produces about 14million tons of buildings and demolition wastes per annum in which about 8 million tons are recycled mainly for unbound road base courses. The 285 million tons of per annum construction waste produced in Germany, out of which 77 million tons are demolition waste. Approximately 70% of it is recycled and reused in new construction work. It has been estimated that approximately 13 million tons of concrete is demolished in France every year. In Japan total quantity of concrete debris is in the tune of 10-15 million tons each year.
The central pollution control board (CPCB) estimates the current quantum of solid waste generation in India to be 48 million tonnes per annum, out of which the waste from construction industry accounts for about 12 to 14.7 million tonnes. These waste materials produced by demolished structures are disposed off by dumping them as landfill. Dumping of wastes on land is causing shortage of dumping place in urban areas. Therefore, it is necessary to start recycling and re-use of demolition concrete waste to save environment, cost and energy.
Realising the future & national importance of recycled aggregate concrete in construction, SERC, Ghaziabad had taken up a pilot R&D project on Recycling and Reuse of Demolition and Construction Wastes in Concrete for Low Rise and Low Cost Buildings in mid nineties with the aim of developing techniques/ methodologies for use recycled aggregate concrete in construction.
The properties of RAC has been established and demonstrated through several experimental and field projects successfully. It has been concluded that RAC can be readily used in construction of low rise buildings, concrete paving blocks & tiles, flooring, retaining walls, approach lanes, sewerage structures, subbase course of pavement, drainage layer in highways, dry lean concrete(DLC) etc. in Indian scenario. use of RAC will further ensure the sustainable development of society with savings in natural resources, materials and energy.