Grouting mortar for annular injection

Abstract

In conditions of cramped urban development, trenchless methods of laying engineering communications are used for environmental protection. Currently, the most widespread is shield driving with tunneling complexes. However, during construction work voids and crevices may form between the shell of the shield and the tunnel lining. In order to fill these voids and create a durable waterproof screen around the lining, the technology of injecting grouting mortars in the annular space is applied. The article shows the results of laboratory tests and gives a comparative analysis of applied grouting mortars based on mineral binders. A new composition of a grouting mortar with improved characteristics including Portland cement and bentonite clays is proposed. The results of laboratory tests of a new material are presented. Data are given that indicate the advantages of using bentonite powders for the preparation of grouting compositions over other materials used as protective injection mortars. The article contains information about field tests of the developed material, which show that the proposed grouting mortar is characterized by high rheological properties and allows obtaining a high-quality waterproof shell in the annulus.