Composition Design and Application of CFB Ash-Slag Concrete
With the large-scale application of clean combustion technology of circulation fluidized bed(CFB)boiler,the disposal CFB ash-slag has become an urgent problem to solve.CFB ash-slag concrete was prepared by using crushed stone as coarse aggregate,CFB slag as fine aggregate and CFB ash as mineral admixture.The effects of CFB slag sand rate and CFB ash content on workability and mechanical properties of CFB ash-slag concrete were discussed,and the mix proportion of CFB ash-slag concrete was optimized.The Cl-permeability resistance,freeze resistance and dry shrinkage of CFB ash-slag concrete and machine-made sand concrete were compared.The results show that compressive strength of CFB ash-slag concrete first increases and then decreases with the increase of CFB slag sand rate.With the increase of CFB ash content,the slump of CFB ash-slag concrete gradually decreases,and the compressive strength first increases and then decreases.The optimal mix proportion is cement 280 kg/m3,CFB ash 120 kg/m3,mineral powder 40 kg/m3,CFB slag 620 kg/m3,gravel 1 013 kg/m3,water 223 kg/m3,water reducing agent 8.8 kg/m3.Compared with machine-made sand concrete,CFB ash-slag concrete has better Cl-permeability resistance,freeze resistance and less drying shrinkage,and the small precast components prepared by CFB ash-slag concrete have better application effects in practical engineering.
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