Research on damping properties and microscopic mechanism of polyurethane cement-based composites

The normal concrete is widely used in bridge, high speed railways and high-rise buildings. However, the low damping properties cannot provide enough energy dissipation. Therefore, it is of great significance to improve the damping properties of normal concrete. Polyurethane has the characteristics of high damping and high strength, which maybe a useful method to improve the damping properties of concrete. In this paper, eleven groups of polyurethane-based concrete (PUCC) mix proportions were designed. The different contents of basalt aggregate (BA), polyethylene fiber (PF) and rubber powder (RP) were added. The mechanical properties of PUCC were tested by universal testing machine. Moreover, the damping properties of PUCC were investigated by data acquisition & signal processing (DASP) vibration and control test system on the base of free vibration attenuation method and INV damping meter method. The mechanism of the different admixtures on PUCC damping were analyzed. The results show that the compressive strength of reference group (RF) reaches 43.3 MPa and the tensile strength reaches 6.89 MPa. Moreover, the damping ratio of PUCC reaches 3.168 %. Compared with RF, the damping ratio of PUCC after adding basalt (30 %) was increased by 51 %. A huge number of interfaces were introduced into the matrix after adding the basalt. The damping was increased because of friction slip between basalt and matrix. The damping ratio of PUCC after adding polyethylene fiber was only slightly improved. Although the interface transition zone between the polyethylene fiber and the matrix is large, which is prone to slip friction. The surface of polyethylene fiber is smooth, the energy dissipation efficiency will be reduced. The damping ratio of PUCC after adding rubber powder (40 %) was significantly increased, which was 262 % higher than that of RF. Rubber powder has strong deformation ability. When subjected to external force, the rubber powder dissipates energy through its own contraction and expansion. In addition, a model is proposed to describe the acceleration-time curve of polyurethane cement-based composites. The constitutive model has a good correlation with the test results, and the simulation is accurate.