1. The more cement, the faster it solidifies and the harder the concrete is. Therefore, when using rich concrete to plug leaks, the required thickness can be thinner than when using lean concrete. But too much cement can also reduce the strength of concrete. In order to improve the early hardness of blocking concrete, flocculants such as calcium chloride, hydrochloric acid, sodium carbonate and sodium silicate lamps can be mixed in cement.

2. Concrete mixing and underwater watering: first lay a layer of sand on the flat plate, then lay a layer of cement, fully mix while drying, then add gravel and water, while thoroughly mixing with spade for five times, quickly put into the barrel (or cloth bag) and send it to underwater application. Divers open the bottom of the barrel or untie the knot on the cloth bag. If there is no bottom, they carefully turn the barrel upside down, pour the concrete into the place where leakage needs to be stopped. Finally, they gently levelled the surface of the concrete with their hands to avoid the loss of mortar as much as possible in order to prevent serious impact on the quality of the concrete. It is ineffective to fill with wooden wedges and cotton wool after concrete is poured. It is advisable to tidy up the damaged areas, remove dirt or loose matter, and then pour concrete.

3. Notices for concrete leak stoppage. In order to protect concrete from water erosion, the unconsolidated concrete can not be forced or washed by running water. The rust, oil stain and garbage on the ship steel plate contacted with concrete must be thoroughly removed. It is better to wash the metal luster, if some hook-shaped steel bars can be welded on the steel plate, then it is better to pour concrete on the part. Good walls, walls are made of wood and pools are made of bags filled with sand or concrete; concrete should be irrigated continuously from beginning to end, if not once, it must be separated by boards and constructed in sections so that each section can be reliably connected; when blocking leakage in places with large holes or where bending, tension and vibration occur, the thickness of concrete must be increased according to the situation. Degree or add steel bar, steel wire in concrete or add supporting pillar on concrete to reinforce it.