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Effect of Functional Admixtures on the Performances of Mortars Filling behind Tunnel Vault Secondary Lining
(1 Shaanxi Engineering Laboratory of High Performance Concrete, Weinan 714099; 2 School of Surveying and Testing, Shaanxi Railway Institute, Weinan 714099; 3 Shaanxi Zhuoxin Engineering Testing Co., Ltd. of China Railway First Group Co., Ltd., Xi′an 710199)
Abstract As for the vault voids and other issues of tunnel secondary lining, based on the basic performance re? quirements for filling mortars of secondary lining of railway tunnels, and under mixture formula of OPC∶SAC = 0.65∶0.35, cement∶sand = 0.55∶0.45, water: aggregate = 0.18 and 10% fly ash admixture, this paper studies the effect of functional admixtures on the performance of mortars in terms of the fluidity, bleeding rate, strength, expansibility and dry shrinkage, etc. The results show that: under the mixing dosages of 0.3% tartaric acid, 0.2% lithium carbonate, 0.06% plastic expander, 0.15% defoamer and 0.12% water-retaining thickener, the filling mortar can be prepared with properties of self-compacting, no bleeding, no segregation, high early and long-term strength, and micro expansion; through the bonding test of filling mortar and lining concrete, field radar nondestructive testing and vault core drilling, the results show that there is a good bonding capability between the filling mortars and the tunnel secondary lining, which could mitigate voids behind tunnel secondary lining and avoid the separation between filling materials and secondary lining concrete.
Abstract：
As for the vault voids and other issues of tunnel secondary lining, based on the basic performance re? quirements for filling mortars of secondary lining of railway tunnels, and under mixture formula of OPC∶SAC = 0.65∶0.35, cement∶sand = 0.55∶0.45, water: aggregate = 0.18 and 10% fly ash admixture, this paper studies the effect of functional admixtures on the performance of mortars in terms of the fluidity, bleeding rate, strength, expansibility and dry shrinkage, etc. The results show that: under the mixing dosages of 0.3% tartaric acid, 0.2% lithium carbonate, 0.06% plastic expander, 0.15% defoamer and 0.12% water-retaining thickener, the filling mortar can be prepared with properties of self-compacting, no bleeding, no segregation, high early and long-term strength, and micro expansion; through the bonding test of filling mortar and lining concrete, field radar nondestructive testing and vault core drilling, the results show that there is a good bonding capability between the filling mortars and the tunnel secondary lining, which could mitigate voids behind tunnel secondary lining and avoid the separation between filling materials and secondary lining concrete.
PENG Lei1,
2 HE Wenmin1,
2 HUI Haitao3 LI Bingliang1 etc
.Effect of Functional Admixtures on the Performances of Mortars Filling behind Tunnel Vault Secondary Lining[J] MODERN TUNNELLING TECHNOLOGY, 2021,V58(5): 244-251
2021, Vol. 58 