2. Re use of Demolished concrete in
construction
Re-use of demolished concrete in
construction
 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.

3. Problem statement

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
structures.

We are going to re-cycle demolished concrete, to reduce cost of new construction and
environmental pollution.

To reduce consumption of natural aggregate and depletion of natural coarse
aggregate by utilizing demolished concrete in new construction.

4. Objectives

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.

5. Methodology
Making samples of Natural coarse aggregate (NCA) concrete and re-cycled coarse
aggregate (RCA) concrete in different proportions.
Re-cycled coarse
Natural coarse aggregate
aggregate (%)
(%)
0
100
25
75
50
50
75
25
100
0

6. Methodology
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.

7. Methodology

8. Methodology
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.
3-point

9. Methodology
 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
aggregate material.
 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.

10. Methodology
Bulk density of hardened concrete :
 This test involves the determination of unit weight and voids of concrete in hardened
form.
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.

11. 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.

12. 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.

13. References
 Recycled Aggregates in New Concrete by Cement & Concrete Association of New Zealand
(CCANZ)
 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 )
 www.astm.org