纤维微表处混合料性能试验

针对微表处混合料的抗裂、抗变形不足等问题,采用加纤技术并运用纤维分散试验、纤维微表处混合料拌合试验、路用性能试验及低温抗裂试验对其性能进行研究。结果表明:采用自主研制的专用设备进行纤维分散,可保证加纤微表处混合料中纤维的均匀分布;纤维微表处混合料中纤维的适宜长度为6 mm;纤维添加量为0.2%时,加纤微表处混合料1 h及6 d时的湿轮磨耗值最小;纤维添加量为0.1%时,混合料黏附砂量最小,但和纤维添加量为0.2%时混合料粘附砂量差别不大;纤维添加量为0.3%时,加纤微表处混合料低温劈裂强度最大。综合各指标结果,确定纤维添加量为0.2%时,纤维微表处混合料总体路用性能最佳。

稀浆混合料配合比设计流程及试验

近年来,稀浆混合料已成为路面养护及修复的主要手段被广泛应用,一个良好的稀浆混合料配合比设计更是发挥其作用的前提,结合参与的稀浆混合料配合比设计,介绍稀浆混合料配合比设计流程和主要试验工作,对试验的关键点和注意事项进行了总结。

水固化型聚合物改性乳化沥青混合料性能研究

为提高常温拌合乳化沥青混合料的工作性能和路用性能,采用拌合试验、劈裂试验及间接拉伸疲劳试验研究了水固化型聚氨酯预聚体改性乳化沥青混合料的拌合和易性及力学性能。试验表明,水固化型聚氨酯预聚体改性乳化沥青混合料具有良好的拌合和易性,以及优于SBR改性乳化沥青混合料的拌和效果,同时水固化型聚氨酯预聚体的加入也有利于乳化沥青破乳后混合料早期强度的形成,从而提高乳化沥青混合料的早期劈裂强度及水稳定性。此外,为使该沥青混合料具有良好的抗疲劳性能,推荐聚氨酯预聚体改性材料的掺量为总用水量的40%~50%。研究表明,临界应变能密度与抗疲劳评价指标具有显著的相关性,在有限的试验条件下,可以通过综合力学性能评价指标(临界应变能密度)可以快速分析乳化沥青混合料的抗裂能力及抗疲劳性能,有利于指导室内评价研究。

Formability analysis of dissimilar tailor welded blanks welded with different tool pin profiles

An attempt has been made to study the tailor welded blanks （TWBs） made by friction stir welding （FSW） with five different tool pin profiles. The formability of welded blanks was evaluated at constant FSW process parameters. It has been found that the welded blanks with square pin profile tool produced better formability properties as compared to other tool pin profiles. It was found that the pulsating action of the square pin profile is said to be the reason for this improvement. A microstructural evaluation performed on the blanks revealed that the stir zone created by taper cylindrical and stepped cylindrical tools was less homogeneous than that of the square tool, resulting in less formability. The limiting dome height （LDH） of square pin profile tool was found to be 14 mm while those of taper cylindrical and stepped cylindrical tools are 12.5 mm and 12.4 mm, respectively.