Reinforcement and Modification Effect of CFB Fly Ash and Bottom Ash on Cement Stabilized Red Sandstone Aggregate
The homogeneity of red sandstone is poor,meanwhile the performance of red sandstone aggregate and cement stabilized red sandstone aggregate are not clear.Based on cement stabilized limestone aggregate,the substitution rates of coarse and fine red sandstones are studied respectively.The influence rules of circulating fluidized bed(CFB)bottom ash and fly ash contents on 7 d unconfined compressive strength,long-term strength,drying shrinkage resistance and frost resistance of cement stabilized red sandstone aggregate are studied.In addition,SEM is used to reveal the modification mechanism of CFB bottom ash and fly ash on cement stabilized red sandstone aggregate.The result indicates that there is a significant correlation between the composition and physical properties of red sandstone aggregate and its particle size.The smaller the aggregate particle size is,the higher the clay mineral content is.The lower the crushing value is,the higher the plasticity index is,which indicates that the different types of red sandstone can be separated by crushing and screening for improving the homogeneity of red sandstone aggregate.The compressive strength,crack resistance and frost resistance of cement stabilized red sandstone are less affected by the replacement rate of red sandstone coarse aggregate,but greatly affected by the replacement rate of red sandstone fine aggregate.Using CFB bottom ash and fly ash as composite fine aggregate can significantly improve the road performance of cement stabilized red sandstone aggregate.Compared with the cement stabilized limestone aggregate with the same cement content,the 7 d unconfined compressive strength of modified cement stabilized red sandstone aggregate is 0.8 MPa higher,the drying shrinkage strain is 49.5%lower,and the frost resistance is equal.With the SEM test result,needle-like ettringite and flocculent C—S—H gel can be observed,which indicate that the hydration products of CFB bottom ash and fly ash play a role in cementing enhancement.The expansion caused by needle-like ettringite formation and the porous internal curing effect of CFB bottom ash can synergistically reduce drying shrinkage and prevent freeze-thaw damage.
road engineeringreinforcement and modificationcrushing and sortingCFB bottom ash and fly ashred sandstonemicroscopic property
NETL
NSTL
万方数据
