Re use of Demolished concrete in
Re-use of demolished concrete in
It involves breaking, crushing and removing irrelevant
and contaminated materials from existing concrete and
then using it new construction work.
When a structure demolishes due to any disaster like
earthquake, flood etc or a structure completes its life span
and we demolish it ourselves, then the demolished concrete
is re-cycled for its re-use.
The re-cycling and re-use of demolished concrete seems feasible solution in
rehabilitation and new constructions after the natural disaster or demolition of old
We are going to re-cycle demolished concrete, to reduce cost of new construction and
To reduce consumption of natural aggregate and depletion of natural coarse
aggregate by utilizing demolished concrete in new construction.
To find different physical and mechanical properties of re-cycled
coarse aggregate (RCA) concrete like, workability, compressive
strength, tensile strength, flexure strength, modulus of elasticity etc
and to compare it with the natural coarse aggregate (NCA) concrete.
To obtain the desired properties of Re-cycled coarse aggregate
concrete by adding admixtures, Air Entrainment, Super plasticizers,
Retarders, Accelerators, Fly Ash etc.
Making samples of Natural coarse aggregate (NCA) concrete and re-cycled coarse
aggregate (RCA) concrete in different proportions.
Natural coarse aggregate
Tests to be performed:
Compressive strength test:
Finding compressive strength of natural coarse aggregate (NCA) and re-cycled coarse
aggregate (RCA) samples at 2, 7 and 28 days strength.
Tensile strength test: (at the age of 28 days)
Finding tensile strength of NCA and RCA samples, by placing it horizontally in
compression testing machine and applying compressive load diametrically along its length.
Failure of the sample takes placer along the vertical diameter.
Flexure strength test: (at age of 28 days)
Material’s ability to resist deformation under loadings.
A rod specimen having either a circular or rectangular cross-section is bent until
fracture using a center-point or third-point loading test technique.
Provides values of modulus of elasticity, flexural stress, flexural strain and the
flexural stress-strain response of the material.
Workability (slump test) : To check consistency
of concrete immediately after
mixing and after 30 minutes.
Bulk density of fresh concrete : To find out the Bulk Density of aggregate (i.e. unit
weight and voids in aggregate). Bulk Density indicates the %age of voids present in the
Air content: This test involves the determination of the air content of freshly mixed
concrete from observation of the change in volume of concrete with a change in pressure.
Bulk density of hardened concrete :
This test involves the determination of unit weight and voids of concrete in hardened
Fatigue test :
A beam of concrete is tested under repeated loads until failure.
Load is applied slowly and in small increments.
Load may be repeated tensile, compressive or flexural.
Research significance / benefits
Re-cycling of demolished concrete reduces the use of natural aggregate and thus
depletion of natural resources in prevented.
Reduces the environmental pollution as concrete is re-cycled and production of new
aggregate for construction is avoided.
Research significance / benefits
As disposal of demolished concrete requires a big area to get disposed, recycling allows to utilize that area for other meaningful purposes.
Construction cost can be reduced by a big amount by utilizing re-cycled demolished
concrete instead of using natural coarse aggregate for whole new construction.
Can be used as a construction material in new concrete for pavements, shoulders,
median barriers, sidewalks, curbs and gutters, and bridge foundations.
Recycled Aggregates in New Concrete by Cement & Concrete Association of New Zealand
Use of Recycled Aggregates in Construction by Cement Concrete & Aggregates Australia.
Recycled Concrete as Aggregate for Structural Concrete Production
( Mirjana Malešev , Vlastimir Radonjanin and Snežana Marinković )