Requirements of self-compacting concrete （SCC） applied in pre-stressed mass concrete structures include high fluidity, high elastic modulus, low adiabatic temperature rise and low drying shrinkage, which cannot be s...Requirements of self-compacting concrete （SCC） applied in pre-stressed mass concrete structures include high fluidity, high elastic modulus, low adiabatic temperature rise and low drying shrinkage, which cannot be satisfied by ordinary SCC. In this study, in order to solve the problem, a few principles of SCC design were proposed and the effects of binder amount, fly ash （FA） substitution, aggregate content and gradation on the workability, temperature rise, drying shrinkage and elastic modulus of SCC were investigated. The results and analysis indicate that the primary factor influencing the fluidity was paste content, and the main methods improving the elastic modulusof SCC were a lower sand ratio and an optimized coarse aggregate gradation. Lower adiabatic temperature rise and drying shrinkage were beneficial for decreasing the cement content. Further, based on the optimization of mixture, a C50 grade SCC （with binder amount of only 480 kg/ m3, fly ash substitution of 40%, sand ratio of 51% and proper coarse aggregate gradation （Vs.~0 mm： V10-16 ram： V16.20 mm= 30%： 30%：40%）） with superior workability was successfully prepared. The temperature rise and drying shrinkage of the prepared SCC were significantly reduced, and the elastic modulus reached 37.6 GPa at 28 d.展开更多
The influences of compositing mineral admixtures on the regularity of mechanical property, workability, durability and microstructure of C50 marine concrete were investigated. The results show that the incorporation o...The influences of compositing mineral admixtures on the regularity of mechanical property, workability, durability and microstructure of C50 marine concrete were investigated. The results show that the incorporation of mineral admixtures can improve the mechanical properties and workability of C50 marine concrete, 3 min-doped mineral admixture had excellent resistance to chloride ion permeability. The microscopic structure mixing mineral admixtures system was well-distributed and compact, little macroporeare can be found.展开更多
This study developed an optimal structural system for the hybrid cable-stayed bridge expected to have a durable lifetime of 200 years and of which major structural members are made of ultra high performance concrete (...This study developed an optimal structural system for the hybrid cable-stayed bridge expected to have a durable lifetime of 200 years and of which major structural members are made of ultra high performance concrete (UHPC) with 200 MPa-class compressive strength. This innovative cable-stayed bridge system makes it possible to reduce each of the construction and maintenance costs by 20% compared to the conventional concrete cable-stayed bridge by improving significantly the weight and durability of the bridge. Therefore, detail design is carried out considering a real 800 m cable-stayed bridge and the optimal structure of the hybrid cable-stayed bridge is proposed and verified.展开更多
为有效延长城市快速公交系统(BRT)站台铺装层的使用寿命并提升正交异性钢桥面板的抗疲劳性能,同时满足不中断交通的需求,提出了“正交异性钢桥面板+短剪力钉+预制超高性能混凝土(UHPC)板+TPO(薄层环氧抗滑铺装材料)”的复合桥面结构及...为有效延长城市快速公交系统(BRT)站台铺装层的使用寿命并提升正交异性钢桥面板的抗疲劳性能,同时满足不中断交通的需求,提出了“正交异性钢桥面板+短剪力钉+预制超高性能混凝土(UHPC)板+TPO(薄层环氧抗滑铺装材料)”的复合桥面结构及装配化施工工艺。以成都二环线高架桥BRT站台为工程背景,设计了BRT站台铺装层快速维修方案,通过有限元分析确定了最优方案,并开展了BRT站台钢桥面维修改造试验段的实施。有限元分析结果表明:10 mm UHPC灌浆料+50 mm预制UHPC板+10 mm TPO为最佳方案,维修方案的剪力钉受力性能、UHPC抗裂性能均满足结构受力需求,且具有较大的安全储备,改造后正交异性钢桥面板常见疲劳敏感细节的疲劳性能显著提升。结合试验段实施提出了涵盖UHPC板预制、原铺装层处理、预制UHPC板安装和磨耗层与沥青接缝施工4个流程的城市BRT站台铺装层维修施工工艺,为同类型公交站台铺装层维护提供了理论和技术支撑。展开更多
基金Funded by National Natural Science Foundation of China(Nos.U1134008 and 51302090)the Fundamental Research Funds for the Central Universities(No.2015ZJ0005)
文摘Requirements of self-compacting concrete （SCC） applied in pre-stressed mass concrete structures include high fluidity, high elastic modulus, low adiabatic temperature rise and low drying shrinkage, which cannot be satisfied by ordinary SCC. In this study, in order to solve the problem, a few principles of SCC design were proposed and the effects of binder amount, fly ash （FA） substitution, aggregate content and gradation on the workability, temperature rise, drying shrinkage and elastic modulus of SCC were investigated. The results and analysis indicate that the primary factor influencing the fluidity was paste content, and the main methods improving the elastic modulusof SCC were a lower sand ratio and an optimized coarse aggregate gradation. Lower adiabatic temperature rise and drying shrinkage were beneficial for decreasing the cement content. Further, based on the optimization of mixture, a C50 grade SCC （with binder amount of only 480 kg/ m3, fly ash substitution of 40%, sand ratio of 51% and proper coarse aggregate gradation （Vs.~0 mm： V10-16 ram： V16.20 mm= 30%： 30%：40%）） with superior workability was successfully prepared. The temperature rise and drying shrinkage of the prepared SCC were significantly reduced, and the elastic modulus reached 37.6 GPa at 28 d.
基金Funded by the Science Foundation of the Science and Technology Department of Hubei Province (No.2004ABA100)
文摘The influences of compositing mineral admixtures on the regularity of mechanical property, workability, durability and microstructure of C50 marine concrete were investigated. The results show that the incorporation of mineral admixtures can improve the mechanical properties and workability of C50 marine concrete, 3 min-doped mineral admixture had excellent resistance to chloride ion permeability. The microscopic structure mixing mineral admixtures system was well-distributed and compact, little macroporeare can be found.
文摘This study developed an optimal structural system for the hybrid cable-stayed bridge expected to have a durable lifetime of 200 years and of which major structural members are made of ultra high performance concrete (UHPC) with 200 MPa-class compressive strength. This innovative cable-stayed bridge system makes it possible to reduce each of the construction and maintenance costs by 20% compared to the conventional concrete cable-stayed bridge by improving significantly the weight and durability of the bridge. Therefore, detail design is carried out considering a real 800 m cable-stayed bridge and the optimal structure of the hybrid cable-stayed bridge is proposed and verified.
文摘为有效延长城市快速公交系统(BRT)站台铺装层的使用寿命并提升正交异性钢桥面板的抗疲劳性能,同时满足不中断交通的需求,提出了“正交异性钢桥面板+短剪力钉+预制超高性能混凝土(UHPC)板+TPO(薄层环氧抗滑铺装材料)”的复合桥面结构及装配化施工工艺。以成都二环线高架桥BRT站台为工程背景,设计了BRT站台铺装层快速维修方案,通过有限元分析确定了最优方案,并开展了BRT站台钢桥面维修改造试验段的实施。有限元分析结果表明:10 mm UHPC灌浆料+50 mm预制UHPC板+10 mm TPO为最佳方案,维修方案的剪力钉受力性能、UHPC抗裂性能均满足结构受力需求,且具有较大的安全储备,改造后正交异性钢桥面板常见疲劳敏感细节的疲劳性能显著提升。结合试验段实施提出了涵盖UHPC板预制、原铺装层处理、预制UHPC板安装和磨耗层与沥青接缝施工4个流程的城市BRT站台铺装层维修施工工艺,为同类型公交站台铺装层维护提供了理论和技术支撑。
