# Experimental Study on Flexural Properties of Polyurethane-Cement Composites under Temperature Load
###### Abstract
At the same time, the heteroatomic groups in polyurethane strengthen the polarity and aromaticity of asphalt, thus improving the adsorption capacity of aggregates and the resistance to water damage of polyurethane composite-modified asphalt mixes is also significantly enhanced [18]. Polyurethane cement composite is a new type of high-strength, and high toughness organic-inorganic composite material by mixing polyurethane glue and cement evenly, and the performance of the composite material can be improved significantly after solidification. It can be applied in rapidly repairing materials in building structures, bridge structure reinforcement [19], and bridge deck pavement layers. Many researchers have studied and explored the ratio of polyurethane cement. A series of compressive and flexural tests have been carried out to arrive at the most reasonable ratio [20, 21]. Polyurethane materials contain active cations that can improve the mechanical properties of cementitious materials, and the addition of polyurethane significantly reduces the early brittleness of cementitious materials [22]. The product obtained by mixing polyurethane and silicate cement is similar to ordinary silicate cement but has much higher plasticity than ordinary silicate cement [23]. The mechanical properties have been significantly improved and enhanced. A comparative study of the response of polyurethane cement composite and carbon-fiber-reinforced material reinforced RC frames shows that a polyurethane cement composite makes the structure more ductile and has a more straightforward construction method and lower material cost. Polyurethane cement composites enable more accessible, higher quality, and lower-cost structural performance modifications than carbon-fiber-reinforced materials [24]. The polyurethane and the cement can form a polyurethane cement foam material, which has good mechanical properties, such as lightweight and high strength and is suitable for seismic components of structures. It also has good heat and sound insulation, water vapor permeability, and fire resistance [25]. In bridge reinforcement,traditional concrete reinforcement methods have the disadvantages of long construction times, complex maintenance, and severe environmental pollution [26]. Due to the good tensile properties of polyurethane elastomers, polyurethane cement for reinforcement does not require an internal configuration of reinforcement, and the short curing time of polyurethane cement makes the construction process relatively difficult and easy [27]. In pavement engineering, the performance of pavement materials depends on the construction quality and later maintenance level of the road [28,29]. Current common pavement materials, such as petroleum asphalt and cement concrete, can hardly meet the requirements of some special projects, such as airport runways, tunnel pavements, and coastal highways [30,31]. Due to its good properties, polyurethane cement materials have been widely used in pavement engineering. They can partially or entirely replace traditional pavement materials in the pavement layer of roads [32]. Compared with common cement-based materials in engineering, polyurethane-cement composite materials have the following characteristics: (1) Polyurethane, as a highly adhesive substance, can firmly adsorb cement particles, while cement particles can be uniformly distributed inside the polyurethane colloid so that the internal pores of polyurethane cement composites are filled densely, forming an organic-inorganic composite network structure [33], which ensures that the properties of the material are the same and have good homogeneity. (2) High toughness is an essential feature of polyurethane composite materials [13]. High toughness is an essential feature of polyurethane composites.