Re use of demolished concrete in construction

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Re use of demolished concrete in construction

  1. 1. 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.
  2. 2. 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.
  3. 3. 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.
  4. 4. 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
  5. 5. 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.
  6. 6. Methodology
  7. 7. 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
  8. 8. 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.
  9. 9. 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.
  10. 10. 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.
  11. 11. 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.
  12. 12. 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

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