Advanced Materials Research Vols. 374-377

Abstract: Researches of spray pure polyurea technology for hydraulic concrete protection in water conservancy facilities to ensure long term security operation has a great significance. With an emphasis upon mechanical properties and surface morphology of spray pure polyurea coatings comparing before and after aging by means of the artificial accelerated xenon arc lamp(AAXAL) and scanning electron microscope(SEM) in this paper. Besides, the dry-wet circulation resistance performance of coatings wre analyzed through experiment. It is shown that tensile strength, elongation at break and tear strength of coatings increased by 0.2%, 0.5% and 1.7% respectively after AAXAL aging 720h. By contrast, after aging 3000h the results were 22.6%, 3.8% and 17.4% respectively, the tendency of increasing at first and then reducing can be obtained. The mechanical properties reduced slightly for adding defects of coating surface after aging, however, the resistance performance of ultraviolet ray was excellent. The similar development trend of mechanical properties were gained from dry-wet circulation experiment. After aging 200 cycles, the tensile strength and tear strength descended by 4.1% and 1.7% severally but the elongation at break ascended by 5.0%. In a word, it is suggested that the aging of coatings were negligible in dry-wet circulation in short term.

Abstract: Firstly, this paper presents an overview of DoD code [1] against progressive collapse and points out the shortcomings of the current design approaches. After that, seven experimental tests of common types of bolted steel beam-column joints under a middle-column removal scenario are presented. This study provides the behaviour and failure modes of different types of connections, including their resistances and rotational capacities in catenary action. The test results indicate that the web cleat connection has the best performance in the development of catenary action. The flush end plate, fin plate and top and seat with web angle (TSWA) connections could also deform in a ductile manner and develop catenary action prior to failure. Numerical simulations have also been conducted. Both static and explicit dynamic solvers were employed to overcome problems of non-convergence, contact, large deformation and fracture simulations. It is demonstrated that the finite element analyses give reasonable accuracy compared to the test results. In addition, an extensive parametric study was undertaken using these validated models to obtain the rotation capacities of various types of connections under catenary action. Finally, some practical design implications have been drawn up from the experimental tests and the parametric study. A new tying resistance expression is proposed to consider the effect of large rotation. If large rotation capacity is not considered in the design stage, the joints with poor rotation capacities would fail to achieve the design tying resistances. In addition, four new connection acceptance criteria of rotation capacities have been proposed to incorporate catenary action under a middle column removal scenario. The work shows that current acceptance criteria of rotation capacities for steel joints such as web cleat, fin plate, flush end plate and TSWA connections, are probably too conservative as they only consider pure flexural resistance.

Abstract: It was the much more variation through the development of technology of housing construction and the change of life cycle of occupation and it is the same to construct the apartment. In early age to adopt the apartment, the rahmen method was main course but the RC bearing wall method is the main course nowhere. However, the RC bearing wall method was the course to increase a wet method and to increase a wet method was a longer a construction duration & input an abundant labor and it is the actual condition to drop a qualification for increasing the unit cost of construction & oncoming age of a skilled worker & a skill falling. So, it is going to be higher the demanding of dry wall method to be changeable throughout being the higher of social demanding on the long-life housing of demanding recently. Therefore, in this study, it would compare & analyze the productivity of lightweight concrete dry wall method (LDWM) and the RC bearing wall method (BWM).

Abstract: according to the road use functions, the article for asphalt mixture of high temperature stability, the low temperature crack performance is analyzed, the results for further study on the asphalt mixture has important significance.

Abstract: In this paper, the research of Low-Noise Asphalt Pavement（LNAP）mix design with the crumb rubber has been studied, including materials selection, gradation selection, asphalt content selection, performance tests, and so on. To verify the high-temperature performance and the effect of noise reducing, the new test methods are studied in the lab. The On-board Sound Intensity (OBSI) is developed to measure the tire-pavement noise and evaluate the noise reducing effect of trial pavement. The QC and QA of LNAP is researched by the trial pavement and the tire-pavement noise is measured by the OBSI，the LNAP has not only the good performance but also low noise than the conventional asphalt pavement.

Abstract: Through test on influence of water reducer agent YC on properties of alkali activated slag cement mortar, it is shown that water reducer agent YC has favorable plasticizing effect on alkali activated slag cement. When the alkali component is NaOH, the water reducer agent YC gives a water reduction rate of 22.0% to the alkali activated slag cement mortar and the flow ability loss with time is small. The water reducer agent can be adsorbed on the surface of slag and enhance theξpotential of the alkali activated slag cement system.

Abstract: This report mainly studied rheological property and phase separation of modified asphalt by waste crumb rubber with some methods including common performance test, frequency sweep test, multiple stress creep recovery test and Cole-cole rule detection. All these experiment result shown that waste crumb rubber can upgrade apparently high temperature stability and elastic performance of modified asphalt, but modified asphalt by rubber is not a homogeneous system and has obvious phase separation state, so it is important to keep an appropriate rubber content in modified asphalt for good product stability

Abstract: Vanadium dioxide (VO₂) films were prepared on quartz glass and TiO₂-coated quartz glass substrates by reactive RF-magnetron sputtering. The VO₂ thin film with film thickness of 50 nm deposited on quartz glass substrates showed two kinds of regions with different color visible to the naked eye, i.e., the earth yellow region and the cyan region. Both XRD and Raman spectroscopy showed that the different color regions of the films had the different crystallinity quality and phase composition. Whereas, the VO₂ thin films with film thickness of 50 nm fabricated on TiO₂-coated quartz glass (with TiO₂ film thickness of 50 nm) had uniform color and exhibited a larger change in transmittance at near infrared region than the VO₂ thin films deposited on quartz glass did. A TiO₂ buffer layer improved the crystallinity and uniformity of the VO₂ film. Such very thin VO₂ films with a TiO₂ buffer layer have high potential for practical application in smart thermal glazing of windows.

Abstract: This paper presents an effective model which can equivalently regard the pores in the porous concrete as a series of capillary bundles with the same diameter due to the complexity of the pores in the porous concrete. The proposed model was used to calculated the total flows of all capillary bundles in the test piece by the single capillary bundle calculation approach from the Hagen-Poiseuille theorem, and together with the well known Darcy theorem to determine the relationship among the flow of the porous concrete, the diameter of pore and the minus of up and down water pressures. The experimental results show that the permeability of the porous concrete mainly depends on the pores with diameter more than 4.12mm, and the pore structure changes obviously when the valid porosity of the porous concrete is greater than 25%.

Abstract: An extensive research programme was set up to investigate the efficiency of scrap rubber particles on strength of cementitious materials. The index of strength loss rate of paste and mortar sample caused by increasing 1% volume rubber particles was proposed to analyze the efficiency of rubber particles in cementitious materials. And the corresponding mechanism was also discussed in this paper. Results indicate that in the investigated area, the loss rate in compressive strength both for paste and mortar almost ranges from 2% to 5% caused by increasing 1% rubber particles depending on the total volume of rubber particle added into sample. However, the loss rate in flexural strength of mortar by increasing 1% volume rubber particles is obviously different from that. Three roles of scrap rubber particles played in cementitious materials, named as deformation effect, equivalent-pore effect and hydrophobic effect, are responsible for the efficiency of scrap rubber particles on strength of cementitious material. The efficiency of rubber particles on strength of paste and mortar differs from each other due to the different microstructure between paste and mortar.