HAO Zengheng; TAN Yiqiu; ZHANG Xiaoning; ZHANG Feng
The normal asphalt index test,DSR test,FTIR and the GPC distribution analysis of molecular weight on the extraction and recovery of asphalt of the gussasphalt,SMA extraction and recovery of asphalt and the rotary-thin-film-oven-aged asphalt above 240℃were introduced.The results indicate the rutting factor and fatigue factor of the extraction and recovery of asphalt of the gussasphalt are greatly improved,and an obvious absorption peak of carbonyl and a further decrease of the SBS molecular weight of the gussasphalt are found.
Using a Hamburg wheel-traek test device, the resistance to rutting of Gussasphalt is tested and compared.Gussasphalt with hard bitumen has good resistance to rutting. The related resistance abilities to cracking at low temperature of Gussasphalt are tested and compared through flexural experiments and the composite structure fatigue test with temperature dropping. Gussasphalt with high pedormanee polymer modified bitumen has a longer fatigue life and a lower breaking temperature; they can be used in the future sudaces for steel bridge decks in Germany.
WU Wenjun; HE Zhaoyi; HAO Zengheng; ZHANG Hua
Four-point flexural fatigue test for Gussasphalt mixture specimen was carried out at a strain-controlled mode system. The results showed that the development of the tested stiffness modulus and phase angle of the mixtures with increasing load cycles exhibited three periods, initial generation, slow development and failure period. The fatigue crack generation zone formed in the third period, in which the macro mechanical properties were significantly decreased. Moreover, we also analyzed the effects of asphalt content and mixing temperature on the fatigue life of the mixture. The results showed that the first period when the specimen’s initial stiffness modulus was reduced to 80%accounted for 5%-10%of the total fatigue life;the second period in which the reduction became slow and demonstrated a liner relationship with load cycles occupied 70%-85%of the fatigue life;and the third period was about 5%-10%. The results indicated that the lower the mixing temperature, the longer the fatigue life of Gussasphalt mixture. Besides, the increasing of asphalt content has a minor effect on the fatigue life of Gussasphalt mixture
杨宇明; 钱振东; 胡靖
对浇注式沥青混合料进行了3种温度和3种荷载水平下的三轴重复荷载试验，利用B ur-gers模型推导了浇注式沥青混合料在重复荷载作用下的总应变公式。对理论应变公式和实验数据进行非线性拟合得到了浇注式沥青混合料在3种温度下的黏弹性参数，并分析了浇注式沥青混合料的永久变形和黏弹性变形的发展特性。研究结果表明：在半正弦重复荷载作用下，浇注式沥青混合料的变形规律与Burgers模型变形公式吻合较好，其永久变形随荷载作用呈线性增长，黏弹性变形先增长后趋于稳定，永久变形比例逐步上升；流动黏度随温度上升而迅速下降，延迟时间随温度上升而增加。%The triaxial repeated load test is conducted on gussasphalt under three stress levels at three temperatures.The Burgers model is used to deduce the deformation formulae of gussasphalt under re-peated load.The values of viscoelastic parameters at three temperatures are obtained by nonlinear re-gression analysis between theoretical formulae and experimental data.The characteristics of perma-nent deformation and viscoelastic deformation of gussasphalt are then analyzed.The research results show that the deformation law of gussasphalt under half sine repeated load agrees well with the de-formation formula of the Burgers model.The permanent deformation grows linearly with the increase of load times while the viscoelastic deformation increases at first and then becomes stable.The per-centage of permanent deformation keeps increasing under repeated load.And with the increase of temperature,the flow viscosity decreases rapidly while the retardation time increases.
南京长江第四大桥是世界上首座主跨1418 m的三跨连续弹性支承体系钢箱加劲梁悬索桥，首次采用了弹性支承体系以及缆索的分布传力锚固系统，克服了复杂地质条件下超大“∞”形地下连续墙（以下简称地连墙）及超大规模沉井深基础的设计施工技术难题，提出了主缆缆索混编技术及富氩气体保护焊技术，采用了复合浇筑式沥青钢桥面铺装技术，运用综合技术手段严格控制大体积混凝土施工质量。本文从建设管理及关键技术创新方面进行了综述。%The Fourth Nanjing Yangtze River Bridge is the first suspension bridge of three-span steel box girder using continuity and flexible bearing system with a main span of 1 418 m,and makes use of the flexible bearing system and distributional force transmission system with main rope for the first time. It overcomes the deep foundation design and construction technical problems of oversized“∞”shape diaphragm wall and ultra-large well-sinking under complicated geological conditions,proposes the technologies of main rope mixed-knit and argon-rich gas shielded arc welding,and uses the pavement technique of compound gussasphalt at steel bridge deck. Additionally,it utilizes synthetical technique to control construction quality of bulk mass concrete. This text summarizes the construction management and key technical innovation.