Advanced Materials Research Vols. 1120-1121

Abstract: To prepare high strength, low cost concrete interface treatment agent, by chemical synthesis, obtained by varying the experimental conditions suitable temperature, stirring speed, emulsifiers and the like modifier content. When the initial reaction temperature is 70 °C, reaction steady temperature 80 °C, reaction to maintain the temperature 85 °C, stirring speed of 400 rpm / min, emulsifier ( polyvinyl alcohol and nonylphenol ether complex) content of 35% (by mass scores) , modifiers (methyl trimethoxysilane) content of 8% , the interface treatment agent synthesized better performance .

Abstract: In view of the phenomenon that the curved duct in anchorage zone of cable-stayed bridges result in non-uniformity of each of steel strand, we analyzed the position change law of the prestressed steel strand in curved duct. Simulating real bridge design, a simple method was proposed to compute non-uniformity level of prestressed steel strand in the process of tensioning. Results showed that the rearrangement caused the additional length difference result in stress non-uniformity of each steel strand. Because each of steel strand cannot participate in force at the same time, the actual elongation value of the tendon is greater than theoretical value.

Abstract: This paper deals with flexural performance of thin concrete members reinforced with continuous carbon fibers in the form of filament yarns. The laboratory specimens were tested under static loading conditions to investigate the effects of three different strengthening techniques on flexural stress, mid-span deflection and modes of failure. The specimens were strengthened in flexure using carbon fiber yarns as near-surface mounted, externally bonded and placed in the geometric center of the specimen, respectively. Based on this investigation, the advantages and shortcomings of individually strengthening technique can be drawn.

Abstract: The high temperature characteristic of asphalt is closely associated with the performance of asphalt pavement. In this paper, repeated creep and recovery experiments are conducted for 2 kinds of base asphalt and 4 different kinds of modified asphalt. According to the pavement situation of China, two temperature levels (i.e., 60 °C and 70 °C) and two stress levels (120Pa and 300Pa) are selected in the test. We observe improved performance of the modified asphalt than the base asphalt, owing to the fact that the modified asphalt is a linear viscoelastic material, with special delayed elastic deformation and recovery properties. The high temperature performance of the modified asphalt is vulnerable to changes in temperature, stress and loads. We further perform rutting test and find that result is highly correlated with the viscous composition of creep stiffness (Gv), with the correlation coefficient being 0.9838 and 0.9813, respectively, indicating that Gv can well judge the merits of high temperature performance of different asphalt.

Abstract: The spall fracture of steel fiber reinforced concretes (SFRC) is investigated with the strain wave profiles in buffer bar behind the specimen bar in a large size Hopkinson pressure bar equipment. The experimental results indicate that the spall strength of SFRC is related to the steel fiber volume ratio, the compressive strength of concretes and the load rate (impact velocity). The spall strength of SFRC empirical formula shows the relationship between these factors. The conclusion that the steel fiber has the effect to improve the ability to prevent spall fracture is of real importance in the correlative numerical simulation and protective engineering design.

Abstract: This paper focuses on the the relationship between strength and ductility of high-strength concrete (HSC) columns with high-strength aseismic transverse reinforcement under concentric compression and its influencing factors. Some confining models for HSC with high-strength aseismic transverse reinforcement are introduced. Based on 10 groups of high-strength aseismic stirrup confined high-strength concrete square columns are tested under concentric compression, the influence of stirrup in binding strength and the ductility of concrete columns on different stirrup strength, different volume ratio of reinforcement, different stirrups type and different stirrup spacing form is studied by using finite element software ABAQUS. The results indicate that a good agreement is obtained between calculated results and experimental ones. The high-strength stirrup confined concrete columns can improve the bearing capacity and deformation performance of components effectively, laying the foundation of the applications of high-strength stirrups in concrete structures.

Abstract: This paper addresses the usage of new construction materials made of natural fibre reinforced polymer and concrete composite for future earthquake-resistant structures. The structure considered is a simple circular bridge pier. To evaluate the seismic performance of the structure shake table experiments were performed. To reveal the consequence of the magnitude of the ground excitation for the structure the effect of a gradual increase of the peak ground displacement is investigated. The results show that although external damage to the structure cannot be observed the bond between polymer and concrete is a significant factor that determines the performance of the structure.

Abstract: Aiming at the environmental property and damage mechanism of ancient adobe buildings, the material components, compressive strength and freezing-thawing resisting performance of ancient adobe bricks were tested and analyzed. Based on test data, the power function relation between nondestructive rebound value and compressive strength of adobe bricks was established, and the nonlinear correlation curve between mass loss rate and freezing–thawing cycles of adobe bricks was also determined. The study shows that the compressive strength of ancient adobe brick is greater than that of adobe in traditional rammed earth wall, and ancient adobe brick is inferior to fired brick at the waterproofing quality and freezing resisting performance, it needs to adopt surface waterproofing measures for ancient adobe buildings to improve the resisting capacity to environmental erosion.

Abstract: Influence of fiber on workability and mechanical property of ultra-high strength concrete (UHSC) were studied. Results show that, when amount of steel fiber (Equivalent diameter is 0.2mm; nominal length is 13mm; Tensile strength is 2850MPa )substituting fine aggregate is 120kg/m³, UHSC could have the best mechanical properties of 139.0MPa compressive strength, 18.0MPa flexural strength, and 10.0MPa Splitting strength; steel fiber cannot improve volume stability of UHSC.

Abstract: In order to reduce the temperature and drying shrinkage cracking in cement concrete pavement, setting up cracks which becomes the weakest part of the cement concrete pavement. Load transfer behavior of cracking has a great influence on road performance and used lifetime in cement concrete pavement. The improvement of load transfer behavior of cracking is conducive to maintain effective load transfer between the pavement and to enhanced bearing capacity of pavement structure, also to reduce the damage of the structure, which is an important technical approach to extend the used lifetime of pavement. This paper describes the mechanism of load transfer and research status of crack, and points out the problems existing in the crack load transfer ability of research and development trend.