Effect of fiber expansion agent on the properties of tunnel lining concrete
In this study,the effect of fiber expansion agents on the working performance,compressive strength and deformation properties of concrete with different water-cement ratios and strength grades was investigated.The results of the study indicate that,for a given water-cement ratio,the variation in the content of fiber expansion agent does not significantly affect the slump of the concrete mixture.Additionally,the content of fiber expansion agent is the main factor affecting the limited expansion rate of concrete.Increasing the amount of fiber expansion agent from 7%to 11%can effectively compensate for shrinkage.However,this increase also negatively impacts the compressive strength of the concrete.Taking into account the influence of fiber expansion agent on concrete compressive strength and limited expansion rate,the mix ratio of tunnel lining expansion concrete with C30 and C40 strength grades was determined.This mix ratio was found to meet the strength design requirements and provide good early crack resistance while maintaining good working performance.