CT Image-based Analysis on the Defect of Polypropylene Fiber Reinforced High-Strength Concrete at High Temperatures

With the application of X-ray computed tomography（CT） technology of C80 high-strength concrete with polypropylene fiber at elevated temperatures, the microscopic damage evolution process observation and image building could be obtained, based on the statistics theory and numerical analysis of the combination of concrete internal defects extension and evolution regularity of microscopic structure. The expermental results show that the defect rate has changed at different temperatures and can determine the concrete degradation threshold temperatures. Also, data analysis can help to establish the evolution equation between the defect rate and the effect of temperature damage, and identify that the addition of polypropylene fibers in the high strength concrete at high temperature can improve cracking resistance.

Detection of Thermophysical Properties for High Strength Concrete after Exposure to High Temperature

Using the detection principle of infrared thermal imaging technique and the detection principle of DRH thermal conductivity tester laboratory,we investigated the infrared thermal image inspection,coefficient of thermal conductivity,apparent density,and compressive strength test on C80 high-strength concrete（HSC） in the presence and absence of polypropylene fibers under completely heated conditions.Only slight damages were detected below 400 ℃,whereas more and more severe deterioration events were expected when the temperature was above 500 ℃.The results show that the elevated temperature through infrared images generally exhibits an upward trend with increasing temperature,while the coefficient of thermal conductivity and apparent density decrease gradually.Additionally,the addition of polypropylene fibers with appropriate length,diameter,and quantity contributes to the improvement of the high-temperature resistance of HSC.

三色PP-BCF的均匀混色技术探讨

在国产膨体纱(BCF)设备上,增加预网络器和混丝罗拉,通过主网络装置改造和工艺优化,生产出混色均匀的三色丙纶-膨体纱(PP-BCF)。结果表明:改进主网器装置,调整主网络器压力0.45～0.60 MPa,网络器前张力100～150 cN,卷绕张力150 cN,试制的三色PP-BCF网络节均匀,网络节为(25±3)个/m,网络节最大间距小于10 cm,符合行业优等品标准。

聚丙烯粉料纺制高强丙纶色丝

研究了聚丙烯粉料在低熔融指数（ ＭＩ） 下防制高强丙纶色丝的生产工艺。结果表明， 采用低熔融指数的聚丙烯粉料， 选择合理的工艺， 可制得有色高强丙纶长丝， 其产品可获得优良的物理机械性能和良好的上色率。