ABSTRACT
Lot of construction debris are generated during the construction and demolition of any concrete structure like buildings, roads, bridges etc. and sometimes, even during catastrophes like wars and earthquakes. Discarding these wastes is a very serious problem because it requires huge space for its disposal and very little demolished waste is recycled or reused. The aim of this study is to examine the use recycled aggregates concrete as replacement for natural aggregates in fresh concrete for Construction use. Experimental investigation was carried out to gauge the Strength Potentials of Concrete from Natural Coarse Aggregates (NCA) and Recycled Coarse Aggregates (RCA) using the Compressive Strength Test, Slump (workability) Test and Flexural Strength Test of recycled concrete. Grade 20, 25, 30, 35,40 of NCA were replaced with RCA respectively and the results obtained from compressive strength test and flexural test were compared with the conventional concrete using different mix ratio manually designed according to British Standard. From the study, the samples were first crushed into smaller particles manually with hammer. They were sieved into various sizes, the ones retained on the 20mm sieve were used for the laboratory work. The results obtained showed that compressive strength of concrete for the Natural Coarse Aggregates after 28 days were 19.57, 23.03, 28.73, 34.60 and 39.3KN/mm2 respectively while Recycled Coarse Aggregates for Grades 20, 25, 30, 35, and 40 were 19.33, 23.10, 29.17, 34.80 and 39.10KN/mm2 respectively. The flexural strength of concrete from the Natural Coarse Aggregates after 28 days were 1.109, 0.9747.1.2482, 1.2825 and 1.5231KN/mm2 respectively while Recycled Coarse Aggregates for Grades 20, 25, 30, 35, and 40 were 1.109 0.9747, 1.2482, 1.28245 and 1.5231KN/mm2 respectively. The Recycled Aggregates were almost of the same strength with that of Natural Aggregates; the insignificant variation in the values may be attributed to the fact that the recycled aggregate was soaked and washed after crushing before casting.
