Paper by PRAKASH KRISHNASWAMY from ISCR 8th 1998 Lisbon Portugal
Piubably, in the years to come, the use of recycled aggregates in concrete may become the need of the day. This is becasue of the nonavailability of natural aggregates in some urban areas. Also, the enviromental laws may force for the closing down of aggregate plants. Apart from this, in the present days, there has been enormous increase in the quantity of demolished rubble. The quantity of demolished concrete discarded every year has reached staggering figures of about 60 millon tonnes in USA, 50 million tonnes in the East European Countries, 10-12 million tonnes in Japan and 8-10 million tonnes in developing countries like India. Iherefore, disposal of such demolished concrete is posing a threat to the environmental authorities besides the shortage of dumping grounds. Under such pressures, it will be a wise decision to use the demolished concrete as aggregate for the production of new concrete viz - recycled aggregate concrete. Recycled aggregate concrete do have some shortcomings with respect to workability and strength. But one can overcome these shortcomings by using modern admixtures. This paper presents the results of an experimental investigation carried out on the suitability of recycled aggregate concrete for the road construction. The strength and workability of conventional natural aggregate concrete obtained from high grade cements (43 grade & 53 grade) is compared with recycled aggregate concrete obrained from high grade cements. Also, it is shown that, the shortcomings of recycled aggregate concrete in strength and workability can be overcome by the use of superplasticizers. Thus, in this paper the suitability of recycled aggregate concrete with Superplasticizers in the construction of conrete roads is highlighted.