Polyurethane (PU) can be used as a road material binder, and its mechanical properties, durability, temperature stability, and other road performance metrics are good. However, the interlayer bonding between PU mixtures and asphalt mixtures is poor. The influence of the pavement structure, interlayer treatment scheme, load, and environmental factors on the interlayer shear characteristics of PU mixture composite pavement is analysed. Further, dynamic modulus, Hamburg rutting, accelerated loading, and inclined shear tests were conducted, and the typical PU mixture pavement shear stress was calculated. The interlaminar shear stress of double layer PU mixture pavement, polyurethane–asphalt composite pavement, and typical asphalt pavement were calculated. The results showed that the PU mixture has a low rutting deformation rate, stable mechanical properties, and strong resistance to the coupled action of temperature, water, and loading. The double-layer PU mixture structure has good water-temperature stability and fatigue resistance; however, freeze–thaw and accelerated loading cause great damage to the double-layer PU mixture structure. The residual shear strength ratio after freeze–thaw cycles and accelerated loading is only 50.3% and 35.6%, respectively, while the influence on the double-layer asphalt mixture structure is less. The theoretical calculation results of different pavement structures show that when the temperature increases from 10 °C to 50 °C, the interlaminar shear stress of polyurethane–asphalt composite pavement increases by about 20%. Additionally, the shear stress of pavement PU mixture pavement and typical asphalt pavement is mainly affected by load, and the temperature changes have an obvious effect on the interlayer shear stress of polyurethane–asphalt composite pavement. The calculated maximum shear stress of the three pavement structures with different working conditions is less than the interlaminar shear strength measured by the inclined shear test, indicating that the interlaminar treatment scheme of composite specimens can meet the shear resistance requirements of the three typical pavement structure types.

A polyurethane mixture (PUM) is an energy-saving and emission-reducing pavement material with excellent temperature stability; however, the fatigue properties and fatigue damage models of PUM still require further research. Therefore, four-point bending static load tests, fatigue tests, and digital speckle correlation method (DSCM) tests with different load levels of PUM and styrene butadiene styrene (SBS)-modified asphalt mixture (SMA) were carried out. The fatigue life, stiffness, midspan deflection, and maximum tensile strain were obtained and compared. The fatigue damage factor calculation method of PUM based on stiffness degradation was proposed, and the fatigue damage function of PUM at different load levels was fitted. The results show that the fatigue life of PUM was much larger than that of SMA, and the static loading failure and fatigue failure modes of PUM were both brittle. The fatigue damage of PUM exhibits an obvious three-stage damage law: the rapid development stage (accounting for about 10–20% of the fatigue life), the deformation stability expansion stage (accounting for about 70–80% of the fatigue life), and the instability development stage (accounting for about 10–20% of the fatigue life). The fatigue damage factors (D_B) were calculated based on stiffness, according to $D_B=\frac{E{I}_0-E{I}_{nr}}{E{I}_0-E{I}_{Nr}}$, and the fatigue damage functions of PUM were fitted based on the stiffness degradation, according to $f\left(\frac{n}{N}\right)=1-\frac{1-{(n/N)}^a}{{(1-n/N)}^b}$. The fatigue damage fitting curves have good correlation with the calculation results of the damage factor based on test data, which can predict the stiffness degradation of PUM at different load levels. The results can help further the understanding of the fatigue characteristics and damage mechanism of PUM, which will provide theoretical support for the application of PUM in pavement structures.

In order to obtain the law of the fatigue damage development of reinforced concrete hollow beams that has been in service for 24 years, its solid hollow beams were removed and transported to the laboratory for loading test. Two beams were selected for static loading to obtain the ultimate flexural bearing capacity, and three beams were, respectively, subjected to constant‐amplitude fatigue loading with different load amplitudes. The static and dynamic behaviors of the beams were monitored in the fatigue test. The fatigue failure of the beams showed that the outermost rebar at the butt weld fractured at first, and the crack width at the fracture position of the steel bar was about 0.3 mm, which was largest in all cracks. After a rebar was broken, midspan deflection and flexibility increased by approximately 20% and 10%, respectively, relative to the initial state. The damage developed rapidly in the following range: (1) the first 10,000 fatigue cycles; (2) after fatigue fracture of the rebar; and in the intermediate stage of fatigue test, the damage development was relatively stable. As the loading amplitude increased, the stiffness degradation and the cumulative damage that occured under the same loading cycle were more significant.

The performance, durability and safety of prestressed concrete bridge were directly affected by the compaction of prestressed pipe. However, the pipe was hidden in the beam, and its grouting density was difficult to detect. The paper had modified three different status of gouting quality through making test model. After that, the impact-Echo method was adopted to detect the grouting quality of tendon ducts, the study was sunmmarized as follow. If the reflect time of slab bottom and nominal thickness of slab increased, the degree of density will increase; testing from half-hole of web, the reflect time and nominal thickness of slab was biggest. At the same time, the reflect time of compacted and uncompacted tendon ducts were mainly. At last, the method was verified by the engineering project, which provided reference value.

The residual bearing capacity of existing bridges has been a controversial topic for engineers and technicians. In order to accurately evaluate the actual bearing capacity of a 24‐year‐old RC hollow beam bridge, its components with different thickness concrete leveling layer were removed and transported back to the laboratory. The representative static and dynamic responses of the two beams were monitored during the whole procedure. A quick assessment of loading capacity of bridge using crack height and a parameter correction method for the crack width prediction formula in the code were proposed. In addition, comparison of measured and current design codes GB 50010 and ACI 318 predicted behaviour of existing beams was also presented. The results showed that the bending process of the RC hollow beam went through the elastic phase to the elastic‐plastic phase and to the final failure. The actual flexural capacity of two beams was 10% larger than the calculated values. The natural vibration frequencies of the beam changed slightly before plastic stage, but the modal amplitude increased with the increase of degree of damage, once the beam entered plastic stage. The predicted deflections according to GB50010 were consistent with the experimental values at about 200 kN; for the code ACI, as the loading force increased, the difference between the two gradually decreased.

Thiopve asphalt mixture has the advantages of reducing construction temperature, saving asphalt consumption and improving high temperature stability. The formula substitution method is used to calculate the optimum binder amount and the optimum asphalt content of different grading types and different Thiopve mixture. And through the rutting test, low-temperature bending and freeze-thaw splitting tests to evaluate the performance of various asphalt mixtures comprehensively, on the basis of analysis of the test data, various types of asphalt mixture suitable for the climate zone nce modulus and Thiopve asphalt mixture with different content and different grading types are given. It provides suggested. Combined with uniaxial compression test (Cylinder method), the regression equation of compressive resiliees a reference for the selection of design parameters when Thiopve asphalt mixture is popularized and used.