New Technique Producing Recycled Aggregate Concrete for Conservation of Resources and Energy
By M. Tsuji and T. Sawamoto
Concrete Journal, Vol.37, No.11, Nov.1999
- Synopsis
- Concrete waste is hardly recycled to be aggregate for concrete by only normal crushung, because the micro cracks remain in the crushed concrete and the particles consists of only mortar or cement paste are included. Thus many techniques to produce recycled aggregate are proposed and used, but these techniques need significantly much energy and may cause much CO2. In this paper, effects of the processes for recycled aggregate to absord a part of mixing water or Pozzolanic material, ex. colloidal silica, on the properties of concrete were reported. One of these processes can be achieved by soaking the recycled aggregate in mixing water or Pozzolanic liquid before mixing concrete. The other process is the mixing procedure for recycled aggregate to soak up a part of mixing water with or without Pozzolanic liquid. In this investigation, the vacuuming sequence before or during mixing of concrete is also evaluated. The absorbed water or Pozzolanic liquid is expected to fill up the micro cracks in recycled aggregate with cement gel by hydration or Pozzolanic reaction. Thus the strength of recycled aggregate concrete can be improved, even though the only crushed concrete wastes are used.
- Keywords:
- recycled aggregate, concrete, colloidal silica, concrete waste, mixing, recycle
