Small-caliber suspension rolls are made of pebble or crushed pebble to reduce the frictional resistance of the stone surface and make the concrete simple and compact.Large-caliber suspension rolls should be machine-crushed. Use of the rough surface of the stone is easy to embed each other to reduce the concrete. Collapse possibility.
Ordinary portland cement with the number of 425 should be selected. Because dry hard concrete is used for the suspension roll system. The mixed water ash is relatively small. The dry shrinkage volume of the cement is small. Because the amount of cement alone is not high, it generally does not occur. Shorten cracks. Because the initial setting time of the cement is relatively short. The early strength is high. Regarding the stability and density of the concrete, avoiding the collapse of the inner wall, and improving the steam curing has advantages.
Generally, medium sand is used, and the concrete has good workability and good impermeability, while the strength of the concrete is low, and the pipe is easy to slump; the sand is thick, the concrete is not easy to work, the impermeability is good, and the mixed strength is high. It is not easy to slump in the pipe, and the selection of the sand rate is also important. The sand rate is high, the concrete is easy to work with, the formability is good, and the anti-seepage function is good, while the concrete in the pipe is easy to slump; the sand rate is low, the concrete and the Poor performance, poor formability, poor impermeability, and concrete is not easy to collapse in pipe making.