Properties of Self-Compacting Concrete in Corporating Bottom Ash as a Partial Replacement of Fine Aggregate

Ratchayut Kasemchaisiri* and Somnuk Tangtermsirikul

ABSTRACT: This article presents the test results of fresh and hardened properties of self-compacting concrete (SCC) incorporating bottom ash as partial replacement of normal sand at 0 %, 10 %, 20 % and 30 % by weight. Mix proportion of the investigated powder-typed SCC was determined by fixing the water to powder ratio at 0.31 and the ratio of paste volume to void volume of compacted aggregate phase (γ) at 1.5. The effects of bottom ash on properties of SCC were investigated by comparing the test results of SCC mixed with bottom ash with those of the control SCC made of river sand. Test results revealed that slump flow and L-box passing ability of the SCC mixtures with bottom ash reduced, while 500-mm slump flow time (T500) increased with the increase of bottom ash replacement level. The use of bottom ash resulted in the reduction of compressive strength and caused increase of porosity of hardened concrete. However, in long term these properties were improved by pore refinement due to pozzolanic reaction when bottom ash was used to replace 10 % of total fine aggregate and water curing was performed. In term of durability, chloride penetration, carbonation depth, drying shrinkage of most of the bottom ash SCC mixtures except for the mixture with 10 % bottom ash were larger than those of the control SCC, mainly due to higher porosity. On the other hand, the resistance against sodium sulfate was enhanced with the increase of bottom ash content. By considering overall performances of the tested SCC mixtures with bottom ash, the optimum replacement percentage of bottom ash was found to be about 10 % by weight of total fine aggregate.

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School of Civil Engineering and Technology, Sirindhorn International Institute of Technology, Thammasat University, Patumthani 12121, Thailand.

* Corresponding author, E-mail: ratchayk@cementhai.co.th

Received 18 Apr 2007, Accepted 21 Nov 2007