Effect Of Alumina Micropowders On The Installation Performance And Mechanical Property Of CAC-Bonded Castables

Studies have found that alumina micropowders have great effect on hydration of calcium aluminate cement.Performance of castable bonded by calcium aluminate cement is closely related to calcium aluminate cement(CAC).However,there is no systematic study on the effect of different alumina micropowders on hydration,installation performance and mechanical property of CAC-bonded castables.In this work,four kinds of alumina micropowders with different grain size were chosen.We do reasearch on the effect of alumina micropowders on hydration of CAC,flowability,green strength,and strength of castables after firing at 800?,1100? and 1450?.The main conlusions are as follows:(1)Alumina micropowders accelerate the hydration of CAC and castables matrix bonded CAC.Therefore,alumina micropowders accelerate the flowability decay of castables.(2)Different alumina micropowders have different effect on rheology of castables.When the content of alumina micropowder A and C with smaller particle size is 3%-7%,castable matrix achieves the maximum torque of rheometer in a relatively short period.This suggests that the addition of A and C at 3%-7% accelerates the hydration of CAC at a high speed.Alumina micropowder B and D have a similar effect on the torque change of castable matrix.This suggests that alumina micropowder A and C with smaller size accelerate the hydration of CAC in castable matrix,alumina micropowder B and D with bigger size have a little effect the hydration of CAC.(3)Alumina micropowders with different grain size have different effect on green strength of castables.The green strength of castables with alumina micropowder A and C which have smaller size is higher than that of castables with alumina micropowder B and D which have bigger size.The reasons as follows: micropowders with small size can fill in the gap between particle of castables,which makes castables have higher bulk density.Meanwhile alumina micropowders with smaller size accelerate the hydration of CAC in castables matrix.(4)The strongest strength of castables after firing at 1450? is achieved at 5%,when samller alumina micropowders are added to castables.However,the strongest strength of castables is achieved at 7%,when bigger alumina micropowdesr are added to castables.That is because the particle sizes of alumina micropowders affect the generation and growth of CA6.