Extension Of Immersion Time Research Articles

基于垂直振动试验方法有机聚合物稳定碎石水稳定性研究

通过与静压法成型试件和实体工程芯样的物理力学性能的对比，证明了垂直振动试验方法(VVTM)的适应性，并采用垂直振动试验方法研究了有机聚合物稳定碎石饱水强度和干化强度，分析了其水稳定性。结果表明：静压成型法存在着确定的ρdmax偏小、最佳含水率偏大、压实度处于100.2%~100.7%超百等现象，而垂直振动法确定的压实度一般处于98.3%~98.8％，最佳含水率更加接近实际，抗压强度与劈裂强度和现场芯样的强度吻合度在90%以上；随着浸水时间的延长，有机聚合物稳定碎石的相对含水率不断增大，抗压强度不断减小，当浸水时间达到32小时饱水时，抗压强度基本不再变化，且此时有机聚合物稳定碎石的抗压强度约为最大抗压强度的60%以上，浸水时间(t)与某一浸水时间下抗压强度与最大抗压强度比值(R)满足：R=-0.135Int+1.097；有机聚合物稳定碎石试件在重复饱水、干化后测定的干化强度，其残留强度比均大于90%，水稳定性良好。 The paper proved the adaptability of Vertical Vibration Test Method (VVTM) by comparing the mechanical strength with the core sample of practical engineering, taking the organic polymer (SRX) stabilized crushed stone base as the research object and exploring its water stability by studying its saturated strength and dry strength. The research shows that: the compaction degree determined with the static method was between 100.2% - 100.7%; there existed over 100% phenomenon; the compaction degree determined with VVTM was between 98.3% - 98.8%, and degree of anastomosis was more than 90% between the strength of the specimen and the strength of field core sample. The relative water content of SRX stabilized crushed stone constantly increased with the extension of immersion time; the compressive strength constantly decreased, when the immersion time was up to 32 hours after saturation, the compressive strength did not change, and the soaking time (t) and the ratio(R) of compressive strength and maximum compressive strength meet: R=-0.135Int+1.097 ; the residual strength ratio of SRX stabilized crushed stone specimen was more than 90% under the worst conditions; water stability was good.

Effect of Stress Ratio and Loading Frequency on the Corrosion Fatigue Behavior of Smooth Steel Wire in Different Solutions.

In this work, the effects of loading condition and corrosion solution on the corrosion fatigue behavior of smooth steel wire were discussed. The results of polarization curves and weight loss curves showed that the corrosion of steel wire in acid solution was more severe than that in neutral and alkaline solutions. With the extension of immersion time in acid solution, the cathodic reaction of steel wire gradually changed from the reduction of hydrogen ion to the reduction of oxygen, but was always the reduction of hydrogen ion in neutral and alkaline solutions. The corrosion kinetic parameters and equivalent circuits of steel wires were also obtained by simulating the Nyquist diagrams. In corrosion fatigue test, the effect of stress ratio and loading frequency on the crack initiation mechanism was emphasized. The strong corrosivity of acid solution could accelerate the nucleation of crack tip. The initiation mechanism of crack under different conditions was summarized according to the side and fracture surface morphologies. For the crack initiation mechanism of anodic dissolution, the stronger the corrosivity of solution was, the more easily the fatigue crack source formed, while, for the crack initiation mechanism of deformation activation, the lower stress ratio and higher frequency would accelerate the generation of corrosion fatigue crack source.

Research on Resistance to Moisture Damage of Warm Mix Rubber Asphalt Mixture

To verify the resistance to moisture damage of warm mix rubber asphalt mixture, the splitting strength test of warm mix rubber asphalt mixture (WMRAC-13) was conducted under different immersion time and immersion temperature. Test results show that freeze-thaw splitting strength of warm mix rubber asphalt mixture meets the requirement of moisture stability. The immersion splitting strengths in 60°C and 4°C decline with the extension of immersion time. The immersion splitting strengths in 60°C decline faster than those in 4°C. The best fitting function of immersion splitting strengths with immersion time obeys second-order polynomial and power function respectively, and their correlations are the best. The inflection point of attenuation curves is 3th day and 20th day respectively.

Semiconducting Behavior of Epoxy Resin/Carbon Steel in Sulfuric Acid Solution

Semiconductor behavior of epoxy resin coated on carbon steel immersed in 0.5 mol·L-1 sulfuric acid aqueous solution during its degradation was investigated. Potential (U)-capacitance (C) measurement and Mott-Schottky analysis technology were utilized to understand the coat′s conduction mechanism during its degradation in the electrolyte. The epoxy resin film was still an insulator in the initial immersion stage (10 min), but its outer layer (the side that contacts with solution) gradually changed into n type semiconductor due to the corrosion with growing immersion time. Charge carrier density of this semiconductor film increased by degrees with extension of immersion time from 1010 cm-3 at 7 h to 1012 cm-3 at 48 h approximately. Between 7 h and 48 h, the organic film had not entirely transformed into semiconductor but only the outer side, and the inner was still insulator. Therefore, an MIS structure (metal-insulator-semiconductor) was generated. The result indicated that this MIS structure was in inversion state between -0.5 V and 0.5 V, and carrier charges were electron holes in inversion layer. The measured space-charge capacitance was series capacitance of inversion layer capacitance and depletion layer capacitance at relatively low frequency. The capacitance value decreased with growing polarization potential. The measured capacitance at relatively high frequency was only the depletion layer capacitance and remained constant in the total scanning potential region. An anodic drift occurred about the C-U characteristic curve of the MIS structure.