Preparation of Shield Grouting Material with Recycled Fine Powder from Waste Concrete and Its Performance Evolution
Recycled fine powder(RFP)produced by the disintegration of waste concrete has high yield and certain activity,which is expected to partially replace cement,fly ash and bentonite to prepare RFP shield grouting material.However,RFP influence on the performance of shield grouting material is not clear,which is difficult to guide engineering application.In this paper,the initial fluidity,setting time,compressive strength and drying shrinkage of RFP shield grouting material were tested.The results show that the RFP replacement of cement is easy to decrease the theological properties of shield grouting material.When RFP replaces 12.5％(mass fraction,same below)cement,the fluidity of shield grouting material is 17.6 cm,which does not meet the specification requirements(21±3)cm.The replacement of bentonite by RFP results in the deterioration of slurry mance.When RFP replaces 30％bentonite,the shield grouting material bleeding rate is 5.2％,and the stratification phenomenon occurs.The replacement of fly ash by RFP is beneficial to improve the fluidity.When RFP replaces 30％fly ash,the fluidity of shield grouting material increases by 16.5％,the bleeding rate is low,and there is no stratification.The RFP'micro-aggregate'effect builds a rigid support skeleton,which can reduce the porosity of shield grouting material and effectively inhibit drying shrinkage.Based on the performance of all aspects,the optimum slurry ratio is:water-binder ratio 0.31,cement-sand ratio 0.66,cement 27％,bentonite 44.5％,fly ash 9.4％,RFP 19.1％,water reducer 0.3％.
recycled fine powderwaste concreteshield grouting materialbentonitedrying shrinkage
万方数据
维普
