Performance study and tunnel waterproofing application of polyurethane prepolymer prepared by prepolymer and acetone combination

Abstract

Waterproof measures are an important guarantee to protect the tunnel structure and maintain its safe and reliable operation. With the continuous progress of science and technology, waterborne polyurethane (WPU) is widely used in various applications such as coatings and adhesives due to its excellent mechanical properties. With the presence of hydrophilic groups, it is necessary to chemically modify PU due to its reduced performance. The PU prepolymer was prepared using the prepolymer acetone combination method and was emulsified by the high gravity strengthening technology for a better synthetic process. The modified PU composite lotion (CL) was then prepared. When the acrylate content increased, the two parameters, i.e., the size and particle size distribution of PU CL, showed opposite trends. For instance, the size changed from 61.45 nm to 106.5 nm, and the particle size distribution index changed from 0.255 to 0.11. Furthermore, the compressive strength of the material is 13.7 Mpa. When the acrylate content gradually increases, the material tensile strength changes from 11.9 MPa to about 6.5 MPa, and the overall elongation at break remains within 200%–250%. In the actual test of tunnel waterproofing (TW), the water absorption rate of the modified polyurethane changes slightly and is generally kept in the range of 4%–4.5%. It has a good waterproof effect, providing a new method reference for PU CL modification and TW.