The large increase in the volume of demolition concrete waste and its impact on the
environment has led to reconsider of using concrete demolition rubble as a partial or a
whole alternative of natural aggregates to produce new concrete which has th
e required
properties to use in engineering constructions[1]. With the possibility of improving the
mechanical properties of this concrete by processing this aggregates before using it or
support this concrete with fiber to improve its structural behavior.
This research deals with the study of the replacement the natural aggregates used in
concrete with recycled concrete aggregates resulting from the demolition rubble ,
according to different replacement ratiosranging between 0 % -25 % -50 % -75 % -100%
and the impact on the concrete behavior with a natural aggregates and determine the
optimal replacementpercentage.
The results showed a relative decrease in the concrete resistance on the simple
pressure , limited decrease in the volumetric mass also, and a slight adjustment to the
behavior of concrete under the loading effect by increasing the replacement proportion of
the natural aggregateswith recycled concrete aggregates..
The accelerated structural expansion in most countries has resulted in a major problem related to providing the necessary concrete for these buildings. Besides, the buildings that have become out of service recently has posed a real problem represent
ed in demolishing them creating a large amount of hard-to-manage aggregate.
The necessity to get rid of the aggregate have opened up the possibilities for attempting to use it as a relative substitute for the natural aggregate. The research focuses on recycling these aggregate in an attempt to use them in producing concrete and other construction materials. The research deals with one of the mechanisms of benefiting from these recycled aggregate through using them in producing concrete through treating the aggregate produced from demolition, and mixing them in quantities that reflect their actual ratio. The results are of great importance economically and environmentally.
Concrete considers as the most popular building material because of the many advantages that it has. This come up with a huge amount of concrete waste. As a way to produce a concrete which is friend to environment, four percentages 0%, 50%, 75%,
100% of coarse recycled aggregate as replacement of natural coarse aggregate in concrete mix are used in this research. The work ability and wet and dry density are presented in this study. The compressive strength at age of 7, 28, 56 days are estimated, also splitting tensile strength and modulus of elasticity are founded at 28 day. The study shows that when The percentage of recycled aggregate exceeds 50% in concrete mix the mechanical properties reduce. When 100% of recycled aggregate is used the compressive strength, splitting tensile strength and elastic modulus decrease by 14%, 22%, 25% respectively, so it is possible to use recycled aggregate concrete in production of non-structural elements.
