ABSTRACT



Now days in modern construction industries, concrete is commonly used as construction material. It is believed that concrete is the second most widely used material after water. Every day human needs are changing and need of new construction and replacement of old structure is unavoidable, wh ich results in potential quantum of the construction waste. This waste is increasing problem s of reducing natural aggregates and adverse impacts on human environment mostly in developing countries. The best practice of managing th is waste is by uti lizing the same in the construction as recycled concrete aggregates. The utilization of th is waste
has a positive effect on the economy and the preservation of natural aggregates.

ln this research work, evaluation of compressive strength of green concrete with used concrete of Nawabshah as recycled coarse aggregate is studied. Old concrete is collected from city area of Nawabshah from demolished residential building at Mohni bazaar(slab and staircases waste of the buildings is utilized) .7 batches of concrete are prepared with replacement of 0%, 5%, 15%, 25%, 35%, 45% and 50% recycled coarse aggregates. Mix ratio of I :2:4 with 0.45 - 0.60 w/c ratio is used for the purpose. Total number of 54 cylinders with virgin aggregates and 324 cylinders with recycled aggregates using d ifferent percentages are prepared and cured for 7, 14 and 28 days. Laboratory tests have been conducted for basic properties and compressive strength . According to the resu lts of this study, it is concluded, with increased percentage of recycled coarse aggregates compressive strength decreases.
Even replacing 50% recycled coarse aggregate 26% reduction was observed. However, it can be used effectively in the construction works, i.e. for construction of
C. C flooring outside the building , footpaths , part ition walls, sun shade. column for
boundary wall!>, top roof slabs etc.