Application Of CFB Ash From Gangue Power Plant In Cement And Concret

With the increasing number of Gangue power plants, CFB ashes are becoming more and more, which are pilled up or landfilled. In order to make full use of the CFB ashes, this paper researched the properties of different kinds of ashes in HuaYu gangue power plant and studied their influences on cement and concrete, came up with the a solution that, we can utilize CFB ash to produce concrete as the alternative of mineral powder and fly ash. And we developed a new type road base stabilized cement with high dosage of CFB ash, we also conducted its influence on the anti-cracking properties of road base course materials. The results are listed as follows :(1)Changes of coal and desulfuration type result in the variation of the content of Loss、CaO and SO3 in CFB ash. The water demand ritio of original CFB ash is high, and its pozzolanic activity is low, which is related to its porous microstructure. The water demand of CFB ash decrease sharply and pozzolanic activity has great improvement after mechanical activation, the pozzolanic activity can reach 95%.(2)By the analysis of different kinds of CFB ashes, we found that: the water demand ratio of cinder is less than fly ash, but its grindability is poor and has low pozzolanic activity. Temperature has much influence on pozzolanic activity, The pozzolanic activity of 900℃ type fly ash can reach 95%, but the activity of 980℃ type is just 75%. The order of all kinds of CFB ahses’ pozzolanic activity is : XF2≈F2>C2>C1>F1.(3)When CFB ash is used in cement as admixture, the standard consistency water requirement rises rapidly, and CFB ash has strong adsorption of water reducer, resulting in the soon loss of fluidity of cement paste, but the large molecular weightpolycarboxylate superplasticizer can improve the fluidty with its steric hindrance. The mechanical strength of CFB ashes-cement has great growth after 28 days, the compressive strength of F2 and XF2 can reach 55 MPa. When CFB fly ash takes the place of P.O42.5 cement、fly ash and some mineral powder in concret, the early strength decreases slightly, but the late strength is high which can reach the strength standard of C30 concrete.(4)We have developed a new special road base cement with CFB fly ash, which has high pozzolanic activity and micro-expansion property, by the standard of mechanical properties, expansion and shrinkage properties and economic performance. The basic ratio of the special cement J4 is: 30% clinker, 3%gypsum(the content of SO3 is 5.2%), 67% XF2, of which the special surface area of XF2 is more than 700 m2.kg-1. When we applied J4 in cement stabilized macadam, the results showed that the 7 d unconfined compressive strength of J4 was slightly lower than P.C 32.5, but the strength of 28 d and 90 d was obviously higher than that of the latter, and the micro expansion of large dosage of CFB fly ash compensated the shrinkage of cement paste, compacted the internal space, greatly improved the crack resistance of cement-stabilized material.