By Mr. Hanafi Bin Yusop
| 1 | Question from Assoc. Prof. Ts. Dr. Ch'ng Huck Ywih | The research presents an environmental friendly and sustainable material for cable trench backfill to replace the natural sand, and at the same time reduce the unwanted coal ash production. What is the material used for the cable trench backfill in other countries? Are they using sand as the main component also? Can CFA and CBA withstand extreme weather condition and maybe earthquake? | Answer from presenter | 1. Normally high flow backfill concrete infill would consist of the normal cement, sand and coarse aggregate, with sometime addition of coal fly ash, and concrete admixtures (additives) to improve flow. The current test we conducted, we replaced the natural sand 100%, and do not use any admixtures. 2. There are some studies and utilizing coal bottom ash around the world for various application. But the constituents of coal bottom ash & coal fly ash is very dependent on the a. type of coal used b. firing technology at the boiler Thus, every plant may have different ash properties 3. CFA has been used as cement additive to increase concrete strength worldwide, so I suppose yes, CFA addition in concrete can be used to withstand extreme weather condition and earthquake. For CBA, it depends on how you use it, because full replacement using CBA would reduce the strength of the concrete because of the brittleness of the particles compared to natural sand / stones. However, there have been some studies which managed to produce high strength concrete using partial replacement of the aggregate with CBA. Thus, I suppose the answer would be yes its possible, provided the concrete is designed properly, with consideration on the properties of CBA (positives and negatives). |