Abstract: The effective initial steam-curing and water-curing duration on concrete with lower water-binder ratio were investigated with XRD, TG-DSC, X-ray CT, SEM-BSE and MIP techniques. According to the effects of initial curing on the micro-structural characteristics of the pre-cast concrete, the effective steam curing duration is 10-14 hours and the effective water curing time was determined not to be over 7 days.
Abstract: Profiled steel sheet-concrete composite slab is a common structural elements in composite structure, mechanical properties in high temperature and thermal characteristics of the steel-concrete structure are the basis to analyzing structural response while in fire, bonding properties of profiled steel sheet and concrete play a key role in exerting the composite effect of steel and concrete in composite slabs.
Abstract: The influence of admixture on concrete pore structure was analyzed by using the mercury intrusion method and the rapid frozen-thaw method under the condition of the same water/binder ratio in this paper, and thus the relationship between pore structure and frost resistance of concrete were analyzed. When the compound mineral ad-mixture is mixed, the porosity rate of concrete can be decreased and the harmful hole is in-creased, the less-harm hole and the no-harmful hole are decreased. The early strength of concrete is not decreased. But the strength has the increasing trend in the late, which is more favorable for the impermeability and corrosion resistance. But the improvement of the freezing resistance is not obvious. The admixture of air entraining agent can increase the porosity and more-harmful hole, and the concrete strength will be decreased, which will be not favorable for the freezing resistance of concrete. If these two substances are admixed at the same time, the concrete porosity is increased, and the pore size distribution of concrete can be reasonable. The decrement of concrete strength is not obvious, but it is favorable for the freezing resistance of concrete.
Abstract: It is very difficult to evaluate risk of sulfate attack and diagnose the form of sulfate attack of cement mortar and concrete because of the diversity of attack form and complexity of erosion phases during sulfate attack, which affect repair of concrete component damaged by sulfate attack mostly. From the sulfate ions, ambient temperature and humidity of service environment as well as local climate characteristics, key components of building structures suffered great risk of sulfate attack should be inspected well and master the property of cement-based material, and then evaluate the risk of sulfate attack. In this foundation, three main erosion phases which are ettringite, gypsum and thaumasite are distinguished by micro-analysis and so the form of sulfate attack can be identified.
Abstract: The negative factors of the colored asphalt mixture extremely correlate to its high-temperature behavior. With the Grey Relation Analysis, this paper makes a thorough analysis of the affective factors on the high-temperature behavior of the colored asphalt mixture, the result of which shows that the affective factors can be classified as the softening point of colored asphalt and the aggregate ratio of mixture. The research findings will provide a beneficial reference for the design of colored asphalt mixture.
Abstract: The symplectic method is applied to study analytically the deﬂection field of bi-directional functionally graded piezoelectric materials in this paper. And the material properties varies exponentially both along the axial and transverse coordinates.The dual equations were presented by variation principle and introducing separation of variables used. Then in the symplectic space which consists of the original variables and their dual variables, the problem can be solved via symplectic expansion. This comparisons with experimental data were carried out to verify the validity of the symplectic method.
Abstract: A brick material was prepared with marble wastes as main raw material by pressure forming and water-curing at room temperature. With the increases of the amounts of water additions, the compressive strength increased gradually and obtained a highest value of 34.8MPa in the sample of the ratio of cement: wastes=20:100 at 17.0% water addition, above which the strength had an adverse change and decreased. The addition of glass fiber had small effects on the strength, water absorbing rate and density comparing with that of wood flour. The strengths of sample had changed obviously with the increment of the forming pressures. However, the strength would fall because of the lamination caused by the recovering effects of the wood flour in the sample with replacement of the wood flour to marble wastes, as the forming pressures were higher than 5.0 MPa.
Abstract: Aqueous CdTe quantum dots(QDs) with different colors were synthesized. Fluorescence spectroscopy analysis showed that synthesized CdTe QDs possessed narrow size distribution. TEM image indicated that the average size of CdTe QDs was 4nm. Fluorescent fibers were prepared by electrospinning mixed solution of CdTe QDs and CA. SEM and TEM photographs showed that the diameters of fibers were 300-700nm, QDs were well dispersed in CA fibers. Fluorescence micrograph showed the fluorescence color and brightness of QDs were not significantly changed after compounding QDs into fibers. The addition of QDs resulted in improvement of crystallinity of the composite fibers by XRD observation.
Abstract: This paper studied the influence of water to binder ratio to time dependent diffusion coefficients in concrete exposed to marine environments. And a refined diffusion model which considered the time dependent apparent diffusion coefficients and time dependent surface chloride concentration was established. It was found that both apparent diffusion coefficients and surface chloride concentration are time dependent and both are significantly influenced by water to binder ratio. Apparent diffusion decrease with time while surface chloride concentration increase with time. but water to binder ratio has similar influence to the constant of time dependent diffusion coefficients and the parameter of time dependent surface chloride concentration.
Abstract: As the most common material, concrete shows one of the most essential beauty, with the natural appearance of calm charm, innate, some heavy and elegant modern building materials can not be replicated and comparable. Material itself has a soft feel, rigid sense of warmth, cold and flu, and not only the spirit of the human impact on the senses, and can express the emotion building. So architects believe that this is a noble simplicity, seems to be simple, in fact, more than the magnificent artistic effect.