Advanced Materials Research Vol. 900

Abstract: Polyimide (PI) has good mechanical properties, heat resistance and low temperature performance, and thus shares a wide range of applications. Atmospheric pressure plasma jet was designed for polyimide films surface modification in this paper. The impacts of exposure time and gas ratio on the film surface morphology and property were studied. Scanning Electron Microscope (SEM) results prove that the treated film surface becomes rough and the contact angle decreases rapidly with exposing to plasma. The contact angle did not decrease anymore after extending plasma exposing time to 20 seconds Moreover the intensity of C=O absorption band increases as shown in the Fourier transform infrared spectroscopy (FTIR).

Abstract: The uniform and transparent Zn₂TiO₄ series thin films were successfully deposited on medical glass slide by magnetron sputtering. The influences of the Zn-doped quantity and annealing treatment on films properties were investigated. Film structure, surface morphologies and optical properties were measured with XRD, SEM and UV-VIS transmittance spectroscope. The results show that the Zn-doped quantity and annealing treatment have influence on the absorption edges. The absorption edges of the films can increase 10nm after annealing treatment. The intensity of c-series ZnTiO₃ diffraction peaks is higher, which may be that the grain size is bigger and the crystallization is complete. The annealing treatment not only growing up grain size of composite films, but also the surface films have tiny crack phenomenon.

Abstract: A microstructure kinetic model is introduced for the hydration of cementitious materials.The hydration degree is mainly controlled by chemical reaction or diffusion rate in hydrate process of cement. According to evolution of characteristic parameters in two main processes, the hydrated kinetic equations is given in the paper. The kinetic equations can simulate the main hydrated processes, and an understanding on the hydration mechanism of cement can be emphasized. Chemical reaction dominates in the early stage of hydration, diffusion rate becomes the dominating factor gradually as the hydration degree increases.

Abstract: In consideration of the light weight, high strength, corrosion resistance and construction is convenient of carbon fiber reinforced polymer (CFRP), using CFRP to strengthen structure is becoming more and more widely. However, there is no commonly accepted understanding of the constitutive relationship of the bonding shear stress and slip between concrete and CFRP bonded interface, especially the decline of the constitutive relation is more difficult to measure accurately. An aim of this paper is to improve the experiment to explore bond stress and slip (τδ) constitutive relation of the bonding interface, strive for the experiment to measure the τδ constitutive relation curve of CFRP-concrete interface. Double pull test was proposed with the improved specimen, using the horizontal load, eliminate additional bending moment influence and improve the experimental accuracy. 17 specimens were tested to measure the τδ curves, according to the features of the constitutive relation curves, the mechanical characteristics of the bonding interface was further analysised.

Abstract: The paper shows the approach toward the construction of a very large Pultruded Fibre Reinforced Polymer (PFRP) temporary structure realized to accommodate future restoration work and to cover a historic church stroked and partially collapsed by 2009 LAquila earthquake. The aim regards the analysis and evaluation of seismic performance of that structure made by very light and elastic-brittle material, as FRP material, in a moment in which there is a loss of technical recommendation for specific calculation in seismic field, indeed actually some deepening already present in literature allows only static field. The covering structure is an all FRP spatial-reticular with elements made by pultrusion process, connection plates by bag molding process and steel bolts. The PFRP structure covers more than 1050 meters squares surface with 32 meters height and only 100 kN weight. Detail performance of first part of PFRP structure through mode vibrations and involved percentage mass deduced by numerical approach with discussion of employments perspectives of PFRP material in seismic zones than traditional material are showed.

Abstract: This paper evaluated an effect of dowel looseness on response of jointed concrete pavement using 3D finite-element analyses of rigid pavement systems that relies on an embedded formulation of a beam element. This embedded element allows the efficient modelling of dowel looseness using nodal contact approach and permits the dowels to be exactly located irrespective of the slab mesh lines. These studies indicate that significant reduction in load transfer efficiency and increase in both slab and base course stresses can be expected due to small gaps varies from 0.25 to 1.25mm between the dowels and the slabs. For the worst case the LTE were reduced to 11.3% and 11.6% respectively for single wheel loading and odd dual wheel loading case while there were voids present at the base course layer for 1.25 cases 4.

Abstract: As the high concrete faced rockfill dams construction, grain breakage gradually become the factors that influence the high dam construction which can not be ignored. This text based on the master of rockfill of shuibuya dam as the experimental material, getting and analyzing the particle breakage data under different confining pressure through the large-scale triaxial test, and the results show that the particle breakage index increases with the increase of confining pressures. The relationship between particle breakage index and confining pressure can be expressed by formula;Particle breakage increase leading to reduced internal friction angle and the shear strength of rockfill, and the author newly introduced two broken variable to describe the relationship which can be expressed by the formula between the particle breakage and internal friction angle, it has certain reference value for establishing constitutive model considering particle breakage.

Abstract: The present work proposes and analyses the solution for seismic behaviour of GFRP (Glass Fiber Reinforced Polymers) applications to evaluate the performances respect to dynamic actions considering the global effect on historical structures. The good strength-self-weight relationship defines the GFRP pultruded profile as an efficacious and innovative solution for structural rehabilitation of historical buildings. The composite material with polymeric matrix, FRP (Fiber Reinforced Polymers), is widely used in civil engineering as sheets, bars and strips. Recently a new technology was adopted to improve the structural response with limited increment of dead load with reversible and independent solution.

Abstract: The aim of this research regards the evaluation of mechanical performance of a prototype panel made by steel fiber reinforced concrete, SFRC, on the top, and fiber reinforced pultruded sandwich panel, GFRP, on the bottom, subjected to combined moment-shear actions through four-bending test. Two different mechanical solutions were used for the connection of the panels. A first steel connection previously designed and a second one with resin applied uniformly on the surface of GFRP panel. The SFRC-G panel involves the analysis of the weakness of GFRP material due to its very low deformability, the risk of the local instability and the elastic brittle behaviour till the collapse, while steel is obviously characterized by elastic-plastic curve. However in the test proposed the ultimate limit state (SLU) involves first of all the loss of bond strength between materials. The panels length/thickness ratio has been previously designed to give prominence to flexural-shear combined actions and in verifying the connections capacity.

Abstract: This paper analyzes the pavement performance of colored asphalt mixture of its high-temperature stability, water, stability low-temperature cracking resistance, and color characteristics, etc.; evaluates the technical capability, economic and social benefits, discusses the constriction technology and points for consideration for its ratio design, mixing, spreading and rolling of colored asphalt mixture pavement, which play an active role on application, extension and development of this technology.