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| Experimental study of quick setting enhancement effect of shotcrete in tunnel surrounding rock and its engineering application |
| ZHANG Luchen1，LI Shuchen1，LU Wei1，2，LI Shucai1，LI Yuhui1 |
| (1. Geotechnical and Structural Engineering Research Center，Shandong University，Jinan，Shandong 250061，China；2. Research Institute of Highway，Ministry of Transport，Beijing 100088，China) |
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Abstract In tunnel construction，sprayed concrete as a necessary means of primary support plays an important role on the stability of tunnel surrounding rock control，and the quality and dosage of accelerator directly affect the shotcrete strength and the construction environment. Based on the accelerating mechanism of aluminate accelerator，a new high performance and low dosage of liquid accelerator is developed，The accelerator has good properties. for examples，the caustic ratio is less than 1.2，pH value is 9–1，the amount of solid is 65% and the solution is stable without precipitation. Through the analysis of the XRD and SEM and the related performance tests，the accelerator can effectively improve the degree of hydration of cement，and in a short time，form a large number of calcium silicate，which overlap each other to form crystal structure，and hence reduces the setting time. The suitable dosage of the liquid accelerator is 1.5%–3% of cement quality，while the sprayed concrete late strength loss within 10%. In the field application，a high precision and small flow rate of liquid accelerator adding device is developed to ensure the precise control of the dosage of liquid accelerator. The corresponding matching spraying technology was improved，which can effectively improve the shotcrete strength，reduce the dust and rebound in the construction，and therefore have good popularization and application value.
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2016, Vol. 35 
