Under normal circumstances, after the ordinary cement concrete paste hardens, there will be a lot of pores in the internal structure of the paste, and the pores are the main factors affecting the concrete strength. In recent years, with the further study of concrete, it is found that the bubble introduced in concrete mixing is the main reason for the formation of pores in the structure and on the surface after concrete hardening. After adding defoamer, the strength of concrete increased obviously.           
The formation of bubbles is mainly generated during mixing. The new air entering is wrapped up, and bubbles are formed when the air cannot run out. Generally, in the liquid with high viscosity, it is difficult for the introduced air to overflow from the slurry surface to generate a large number of bubbles.           
There are two main functions of concrete defoamer, one is to restrain the formation of bubbles in concrete, the other is to destroy the bubbles and make the air in the bubbles overflow.           
The addition of concrete defoamer can reduce the defects of concrete surface, such as porosity, honeycomb and pockmark, and effectively improve the apparent quality of concrete; it can also reduce the air content in concrete, improve the compactness of concrete, and thus improve the strength of concrete.