Abstract:

Singlecomponent cement mortar with a long cementing time is widely employed in the construction of shield tunnels in China. Due to the long cementing time of this mortar after injection, various engineering issues such as segment floating and cement mortar loss often occur in practical applications. To overcome these issues, a concept of "timecontrolling cement mortar" is proposed. By adding aluminum chloride solution and sodium silicate into single component cement mortar, the formulation of "timecontrolling cement mortar" was studied based on the cementing time, fluidity, and strength of 28 days. The results reveal the following: (1) The approach of adding aluminum chloride solution first and then sodium silicate can achieve cementing time control of cement mortar. (2) The addition of 0.50%~0.75% aluminum chloride solution and 1.00%~1.25% sodium silicate to cement mortar can achieve a good performance of cementing time control. (3) By simply modifying grouting equipment, doublecomponent cement mortar including cement mortar and sodium silicate can be pumped in one pipe.

Key words: shield tunnel, backfill grouting, fluid formula, aluminum chloride solution, sodium silicate, cementing time, floating