Qingdao Jiaozhou Bay subsea tunnel is the second self-built tunnel in China with the designed service life over 100 years.The durability of lining concrete are one of an important factors to determinate the service li...Qingdao Jiaozhou Bay subsea tunnel is the second self-built tunnel in China with the designed service life over 100 years.The durability of lining concrete are one of an important factors to determinate the service life of tunnel.Considering the main environmental loads and mechanical loads of subsea tunnel,the durability properties of lining concrete under combined action of compressive load and carbonation has been studied through the critical compressive load test,accelerated carbonation test,natural carbonation test and capillary suction test.The tests results show that critical compressive load apparently accelerates the carbonation and deteriorates the anti-permeability of concrete.Under the combined action of critical compressive load and carbonation,the durability of lining concrete decreases.Based on the carbonization life criteria and research results,for the high-performance concrete with proposed mix ratio,the predicted service life of lining concrete for Jiaozhou bay subsea tunnel is about 80 years which fails to reach the required service life.It is necessary to adopt other measurements simultaneously to improve the durability of lining concrete.展开更多
Recently, the use of steel fiber at high rates has been introduced as the sole method of reinforcement for fully elevated-suspended slabs having long span such as 5 m to 8 m each way, with a span to depth ratio of up ...Recently, the use of steel fiber at high rates has been introduced as the sole method of reinforcement for fully elevated-suspended slabs having long span such as 5 m to 8 m each way, with a span to depth ratio of up to 33 [1]. As a result of long practical experience the total replacement of traditional rebar is a new routine. Now it is also used in the designing of SFRC pavements over conventional concrete pavements. Within the project framework a demonstration of a steel-fiber-reinforced roller-compacted concrete (SFR-RCC) pavement was constructed in a rural as well as urban area. In order to assess the economical condition of the demonstration pavement, life cycle assessment (LCA) and life cycle cost analysis (LCCA) studies were undertaken. This is the advancement study of the various papers which is already published in many publications which serve as the main and important source of study for the research. Many applications of steel fiber are listed in the paper but the main output of this paper is that SFR-RCC is more economically sustainable than others and also helps in reducing the thickness of the pavement up to 20 to 25 percent, due to the excessive strength of steel fiber. The roads of the present system required high cost investment. And the life period is almost 20 years theoretically but the actual life of the road is depending on the maintenance and the applied load. The constructions of road have been done since the 3500 BC but the method does not change fully. Also the cost of the construction is increased continuously;as a result, the construction of roads is more and more complicated and time taken. For the better and economical construction of the roads, we use steel fibers in the composite pavement. The theoretical plan of the construction of composite pavement is given in the methodology, which gives the appropriate idea about the construction of road using steel fiber. Here we use the composite pavement in which the steel fiber is mixed in the concrete layer, after which the bitumen layer is laid for the smooth and suitable riding of the vehicles.展开更多
近年来,超高性能混凝土(UHPC)得到了推广应用,但在UHPC生产过程中超量水泥消耗以及UHPC自身耐久性强、寿命长的特点,对UHPC的碳排放水平认识尚不清楚。因此,研究采用生命周期评价(LCA)方法构建了UHPC碳排放定量分析模型,对比分析钢-UHP...近年来,超高性能混凝土(UHPC)得到了推广应用,但在UHPC生产过程中超量水泥消耗以及UHPC自身耐久性强、寿命长的特点,对UHPC的碳排放水平认识尚不清楚。因此,研究采用生命周期评价(LCA)方法构建了UHPC碳排放定量分析模型,对比分析钢-UHPC桥面板与常规钢-混桥面板结构在全生命周期内的碳排放。结果表明:虽然生产阶段UHPC的碳排放量约1 245.84 kg CO_(2)eq/m^(3),是普通混凝土的1.58倍,但从性能上来说,UHPC碳强度是普通混凝土的62.25%,是一种更绿色的建材;在整个生命周期内,与常规钢-混桥面板相比,钢-UHPC桥面板的年均碳排放量下降了35.76%,具有巨大的碳减排潜力,有助于基础设施的可持续性发展;钢-UHPC桥面板方案具有工程比选优势,经济性合理,同时其单位产值碳排放为0.89 t CO_(2)eq/万元,是常规钢-混桥面板的86.41%,具有更好的减碳效果。研究对结果的可靠性和碳减排措施进行了讨论,最后提出了有待进一步研究的内容。展开更多
基金Funded by the National Key Basic Research and Development Plans-973 Plans(2009CB623203)the Key Project of National Natural Science Foundation of China (50739001)+2 种基金the National Natural Science Foundation of China (50878109)the National Key Technology R & D Program (2007BAB27B03)the Education Ministry Doctor Foundation of China (20070429001)
文摘Qingdao Jiaozhou Bay subsea tunnel is the second self-built tunnel in China with the designed service life over 100 years.The durability of lining concrete are one of an important factors to determinate the service life of tunnel.Considering the main environmental loads and mechanical loads of subsea tunnel,the durability properties of lining concrete under combined action of compressive load and carbonation has been studied through the critical compressive load test,accelerated carbonation test,natural carbonation test and capillary suction test.The tests results show that critical compressive load apparently accelerates the carbonation and deteriorates the anti-permeability of concrete.Under the combined action of critical compressive load and carbonation,the durability of lining concrete decreases.Based on the carbonization life criteria and research results,for the high-performance concrete with proposed mix ratio,the predicted service life of lining concrete for Jiaozhou bay subsea tunnel is about 80 years which fails to reach the required service life.It is necessary to adopt other measurements simultaneously to improve the durability of lining concrete.
文摘Recently, the use of steel fiber at high rates has been introduced as the sole method of reinforcement for fully elevated-suspended slabs having long span such as 5 m to 8 m each way, with a span to depth ratio of up to 33 [1]. As a result of long practical experience the total replacement of traditional rebar is a new routine. Now it is also used in the designing of SFRC pavements over conventional concrete pavements. Within the project framework a demonstration of a steel-fiber-reinforced roller-compacted concrete (SFR-RCC) pavement was constructed in a rural as well as urban area. In order to assess the economical condition of the demonstration pavement, life cycle assessment (LCA) and life cycle cost analysis (LCCA) studies were undertaken. This is the advancement study of the various papers which is already published in many publications which serve as the main and important source of study for the research. Many applications of steel fiber are listed in the paper but the main output of this paper is that SFR-RCC is more economically sustainable than others and also helps in reducing the thickness of the pavement up to 20 to 25 percent, due to the excessive strength of steel fiber. The roads of the present system required high cost investment. And the life period is almost 20 years theoretically but the actual life of the road is depending on the maintenance and the applied load. The constructions of road have been done since the 3500 BC but the method does not change fully. Also the cost of the construction is increased continuously;as a result, the construction of roads is more and more complicated and time taken. For the better and economical construction of the roads, we use steel fibers in the composite pavement. The theoretical plan of the construction of composite pavement is given in the methodology, which gives the appropriate idea about the construction of road using steel fiber. Here we use the composite pavement in which the steel fiber is mixed in the concrete layer, after which the bitumen layer is laid for the smooth and suitable riding of the vehicles.
文摘近年来,超高性能混凝土(UHPC)得到了推广应用,但在UHPC生产过程中超量水泥消耗以及UHPC自身耐久性强、寿命长的特点,对UHPC的碳排放水平认识尚不清楚。因此,研究采用生命周期评价(LCA)方法构建了UHPC碳排放定量分析模型,对比分析钢-UHPC桥面板与常规钢-混桥面板结构在全生命周期内的碳排放。结果表明:虽然生产阶段UHPC的碳排放量约1 245.84 kg CO_(2)eq/m^(3),是普通混凝土的1.58倍,但从性能上来说,UHPC碳强度是普通混凝土的62.25%,是一种更绿色的建材;在整个生命周期内,与常规钢-混桥面板相比,钢-UHPC桥面板的年均碳排放量下降了35.76%,具有巨大的碳减排潜力,有助于基础设施的可持续性发展;钢-UHPC桥面板方案具有工程比选优势,经济性合理,同时其单位产值碳排放为0.89 t CO_(2)eq/万元,是常规钢-混桥面板的86.41%,具有更好的减碳效果。研究对结果的可靠性和碳减排措施进行了讨论,最后提出了有待进一步研究的内容。
