Applied Mechanics and Materials Vols. 744-746

Abstract: It’s easy to cause asphalt aging in the production, storage, transportation and construction sectors; the polar compounds of asphalt in the aging process were studied by using negative-ion electrospray ionization (ESI) Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry (MS).Test results showed that, with the deepening of aging process, molecular weight of asphalt samples was increasing. Ox class compounds had the biggest content change; Content of Nx class compounds were basically stable; Content changing range of class NxOy compounds was affected by types of compounds. Aging degree of heteroatom compounds was affected by molecular condensation degree, and oxidation rate of low DBE compounds was higher than that of high DBE compounds. The result is of value to analysis of asphalt production and asphalt recycling.

Abstract: This paper presents the synthesis of a new type of flexible epoxy curing agent and an approach to improve the toughness of epoxy resin by curing without reducing the strength and modulus of the resin-cured material. The results show that the degree of toughness reaches maximum values when the flexible curing agent is applied at weight percentages (wt.%) between 10% and 15%. When the amount of flexible curing agent added to epoxy resin weight is 10wt.%, the impact toughness and fracture toughness increases by 33.3% and 96.3%, respectively, compared with the pure epoxy resin. When the amount of flexible curing agent added to epoxy is 10wt.%, the resulting impact thoughness of the material is 19.5 kJ•m-2 at-50°C, the impact toughness of pure epoxy resin is only 7.96 kJ•m-2.

Abstract: For the study of fracture characteristics of ultra-high performance cementitious composites(ECC),16 different sizes of three-point bending beams were made and ultimate load, ultimate deflection and crack mouth opening displacement ,the curve andcurve of ECC were contructed,with the method of fracture work recommendedby RILEM , the external work was respectively calculated by the curve ofand, which determined the fracture energy of ECC.Results show that two kinds of calculation result are roughly equal;The influence of size effect on fracture character was: fracture energy increased with the increasing of the crack-depth ratio, the fracture energy of concrete specimen is the maximum when the crack-depth ratio is 0.4 ; is proportional to the initial crack-depth of the specimen, but there is no relationship betweenand crack-depth ratio. This paper would have great significance for the study of fracture characteristics of ECC.

Abstract: In this paper, the method to adjust the production process of polycarboxylic admixtures mother liquid is researched according to the production of polycarboxylic admixtures. One polycarboxylic admixture cannot be adapted to all cements because of the influence of the mother liquid, although it could be adjusted by composite stabilizer. This paper studies the method of parameter adjustment on the level of factor analysis according to the process of polycarboxylic admixtures. The fluidity of cement slurry test is carried out when the type of cement is changed. On the basis of the test results the parameters are analyzed to design the molecular structure of the polycarboxylic admixtures, which could solve the problem of compatibility between polycarboxylic admixture and cement fundamentally.

Abstract: Waste glass is an industrial waste and household garbage, having a "flash color pollution" notoriety. Although some white glass can be processed into glass again, however, low utilization. But much of the waste glass still cannot be recycled. The key to improve the utilization of waste glass is how to effectively use colored and mixed waste glass. Waste glass aggregate concrete as a new material, the study of its basic performance is not mature. Taking into account the impact of different glass replacement rate on their basic mechanical properties, this paper tests carried out static compressive elasticity modulus test with glass concrete. Study the mechanical properties and deformation performance of glass concrete columns the basis of its basic mechanical properties, in order to obtain the glass concrete column of structure performance parameters.

Abstract: Green ecological concrete is a new type of building material. It is important to study the relationship of the green ecological concrete between stresses and strains. In the paper, some constitutive models which are suitable to the green ecological concrete are introduced. These models include the linear elastic constitutive model, cauchy model, kuper-gerstle model, constitutive model based on the rheological theory, constitutive model based on plastic fracture theory etc. The constitutive model based on the rheological theory well describes the mechanical properties of the green ecological concrete.

Abstract: The reduction mechanism, characteristics of molecular structure, and main factors affecting the reduction ability are reviewed in brief. The research progress of poly carboxylic acid concrete SRA are also reviewed. And based on the structure characteristics of poly carboxylic acid SRA, more functional poly carboxylic acid SRA is the main development direction in concrete shrinkage agent reducing in the future.

Abstract: The discussion in the paper is focused on energy transition efficiency, stiffness and intensity of common piezoelectric transducers in the following aspects. Firstly, we have found out that bridge piezoelectric transducers possess high energy transition efficiency and the similar stiffness to asphalt pavement through comparing and analyzing road performance of several common piezoelectric transducers. Thus, we hold the view that it is applicable for energy collection of asphalt pavement and will be analyzed subsequently. Secondly, we have analyzed energy transition efficiency and stiffness characteristics of arc bridge piezoelectric transducer and rectangular bridge piezoelectric transducer in laboratory test. The results show that, under the same load stress, arc transducers are better than rectangular transducers in terms of energy transition efficiency; but comparing with rectangular transducers, arc transducers are more prone to be destroyed, which is not helpful for bearing traffic load.

Abstract: This paper studied the development of stress and strain influences by different cooling rates based on the concrete thermal stress tests. furthermore, discussed the temperature control measures for early concrete placement.

Abstract: This paper studies characteristics optimization of shearing viscoelastic damp of the SDOF system. Theoretical analysis included geometry and nechenical property of viscoelastic material and characteristics of connecting bars. Studies indicate varied thickness,shearing area and plies of viscoelastic material cause changes in modulus of shearing storage mudulus and shearing loss modulus and next experimetns shows effect of destortion, exciting frequncy and repeated cycles. The stiffness of connecting bar effect the effeciency of damp and the internal force of the structure, so the selection of connecting bar is very important in characteristic optimization. Contrast by the no simplified model and the simplified model indicated stronger connecting bars effect the inner force of the whole frame more notably, so the negative effect should be considered when using the simplified model. A procedure to find the optimal characteristics of shearing viscoelastic damp for SDOF system is proposed then. This procedure targets maximum damp ratio and minimum section of connecting bar. A predefined damp ratio excite the procedure and every step set an increment in damp ratio simultaneously stiffness of the connecting bar is computed. The procedure repeated until the damp ratio approaches an ideal value and the stiffness declined to a relative lower point then. All the characteristics can be determined according to the damp ratio and manufacture conditions at last. And an exanded procedure used in n-DOF system including both optimization of characteristcs and arrangement is expected in the end.