Cement: Ordinary Portland Cement (425R) should be used. Due to the use of dry hard concrete for suspension rolls. Mixed ash is relatively small. The dry shrinkage volume of the cement changes little. Because the amount of unilateral cement is not high. Therefore, shortening cracks are generally not present. Because the initial setting time of the cement is relatively short. Early stage strength is high. Concerning the stability and compactness of concrete \ It is advantageous to avoid inner wall collapse and improve steam curing.
Sand: Generally, medium sand is used. The concrete has good workability and impermeability, while the strength of the concrete is low, and it is easy to slump in the pipe making. The sand is too thick, the concrete has poor workability, good impermeability, and high mixing strength. It is not easy to slump in the pipe making, and the selection of the sand rate is also very important. The sand rate is high, the concrete is easy to work with, the formability is good, and the impermeability is good, but the concrete in the pipe is easy to slump. Poor workability, poor formability, and poor impermeability, while concrete is not prone to slump in pipe making.
Pebble: Small-caliber suspension rolls are made of pebbles or crushed pebbles to reduce the frictional resistance of the surface of the stones and make the concrete easy to compact. Large-caliber suspension rolls should be machine-crushed. The rough surface of the stones is easy to embed each other. May reduce concrete collapse.