Grouting materials have undergone a considerable period of development and can be broadly categorized into the following four stages based on the raw materials used. The primitive clay slurry stage: In 1802, French civil engineer Charles Berigny successfully applied grouting technology by injecting clay slurry into the ground to repair and reinforce masonry walls for the port city of Dieppe, marking the beginning of grouting materials. During this stage, grouting materials primarily consisted of simple substances such as clay, volcanic ash, and quicklime. The early cement slurry grouting stage: After the advent of Portland cement in 1824, it was widely used in various civil engineering projects, including the improvement of grouting materials. In the United States, Watson*1 first injected cement mortar under the foundation of a spillway chute, heralding the start of the early cement slurry grouting stage. During this phase, the main raw material for grouting was ordinary Portland cement.
Characteristics of tunnel arch* formwork grouting process: The secondary lining formwork* is預(yù)留 with grouting pipes and grouting exhaust holes, which also serve as observation holes to check whether the arch* concrete is fully filled.
Using SM-RPC grouting pipes (hereinafter referred to as RPC pipes), micro-expansion slow-setting early-strength filling mortar, and integrated grouting equipment, the setup is simple, with convenient mobility and operation. The operation is straightforward, requiring only about 2 hours for grouting one section of the secondary lining, without occupying the normal secondary lining construction time. Formwork grouting can begin when the concrete initially sets, and the grouting pressure is far** greater than that of post-demolding grouting, enhancing the integrity of the lining concrete and the grouting treatment slurry, thereby repairing various concrete defects. During formwork grouting, the secondary lining concrete is protected by the trolley formwork and will not be damaged. Generally, the concrete pouring pressure* exceeds 6MPa, while the grouting slurry pressure typically does not exceed 1.0MPa.