Abstract: A water-dispersible amphoteric polyurethane and a preparation method therefor. The water-dispersible amphoteric polyurethane is prepared from a polyisocyanate compound, a polyol compound, a dial compound having an anionic group or a potential anionic group, a compound having a tertiary or quaternary amine cationic group at least having two active H functional groups and a polyamine compound having a polyoxyethylene group. During preparation, the feeding order of the dial compound and the compound having a tertiary or low-molecular quaternary amine cationic group is controlled, and then neutralization and chain extension are performed, to obtain the target product. Also disclosed is a use of the water-dispersible amphoteric polyurethane in reinforcing concrete, wherein the water-dispersible amphoteric polyurethane is present in an amount of 0.1% to 5%, based on the total weight of the concrete.

Abstract: Disclosed is a method for testing the self-drying effect of a cement-based material, capable of testing the change in humidity of the cement-based material after the final setting until the Id stage of adding water, so as to reflect the water consumption therein and the self-drying course. In the time period after the final setting of the cement-based material until the 1 d stage of adding water and forming, the dew-point temperature inside the cement-based material is tested, and then the relative humidity inside the cement-based material is calculated using a formula. The present invention can test the change in humidity of the cement-based material after the final setting until the Id stage of adding water, so as to reflect the internal water consumption therein and the self-drying course.