Ethylene - vinyl acetate copolymer (EVA)-modified mortar is widely used in China because of better adhesion strength and flexibility as compared to traditional one. This paper, based on a laboratory program, evaluated the effects of EVA-cement and different fillers on interface properties of EVA-modified cement mortar such as adhesive strength and dynamic cracking resistance, and the mechanism was also analyzed by scanning electron microscopy (SEM). The results showed that under laboratory condition, adhesion strength and dynamic cracking resistance of EVA-modified cement mortar increased with EVA-cement rising. Interface performance of the EVA-modified mortar improved greatly as EVA-cement increased from 0% to 12% and amplification slowed down when it increased further. EVA-cement around 12% was the optimal proportion considering all factors in this study. Fillers of different particle grade contributed to interface properties of EVA-modified cement mortar, A/fillers around 1/6~2/3 is the optimal proportion in this study.
Polishing powder based on CeO2 is synthesized by a neutral precipitation method under the action of an additive, with Ce2(CO3)3 as starting material and NH4HCO3 as the precipitant. The size distribution of CeO2 particles is narrow-ranged and their morphology show a shape of polyhedral globules. They have a satisfied dispersion in water. The optimum characteristics are obtained under the conditions of followings: the mass ratio of F (in H2SiF6 ) to CeO2 7%, the molar concentration of additive A4 0.85mol/L, calcined at 850°C for 2 hours.
The expansion of cement mortar mixing expansive agent under standard curing and membrane curing conditions and compressive strength in constrained conditions are studied in this paper. Results show that the early expansion effect of calcium sulphoaluminate hydrate-calcium hydroxide expansive agent is obvious, mid-to late effect of magnesia expansive agent increase clearly. Compare with standard curing, the shrinkage of the basic cement mortar increase and expansion effect of expansive agent reduce under membrane curing. The expansion effect of expansive agent B is good and persistent under membrane curing, its applicable to used in the closed environment, such as concrete filled steel tubes. The compressive strength of mortar with expansion agent is a little more than the basic mortar under the condition of limit.
To discuss prevention of sulfate attack, especially thaumasite form of sulfate attack (TSA), sulfate resistance cement based material (SRM) were designed and prepared, and properties of which were investigated systematically. Micro-analytical techniques were introduced to identify erosion substances especially thaumasite, namely Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with X-ray energy dispersive spectrometer(EDS). Results show that SRM have better sulfate resistance, as well as TSA resistance, when exposed to aggressive environment with 33800 ppm mass concentration of SO42- in magnesium sulfate solution at 5°C±2°C. When immersed in magnesium sulfate solution for 40 weeks, compressive strength and tensile strength of SRM are still higher than their initial, and those of control specimen are lower by 33.7%, 36.5% compared to its initial. Surface erosion substances of SRM named S1 are ettringite and gypsum, while those of control specimen are ettringite, gypsum, thaumasite and brucite.
In this study, Tin Oxide (SnO2) inverse opal was fabricated by infiltrating SnO2 sol-gel precursor solution into Poly Styrene (PS) spheres crystal template which was generated via evaporative deposition self-assembling, then was heat treating at 500°C for two hours in controlled atmosphere box furnaces. PS spheres crystal template was characterized by Scanning electron microscope and Ultraviolet-visible-near infrared absorption spectrometer. The SnO2 inverse opal was characterized by Scanning electron microscope, Energy Diffraction Spectrum, X Ray Diffraction. The large-area, highly ordered SnO2 inverse opal was achieved in this paper.
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