1、1 外文翻译 论 文 题 目： 力学性能和热性能评价超高纤维钢筋混凝土的工程应用 学 院 名 称： 建筑工程学院 专 业： 土木工程 学 生 姓 名： 学号： 08404010228 指 导 教 师： 2012 年 1 月 10 日 2 Mechanical and thermal evaluation of Ultra High Performance Fiber Reinforced Concretes for engineering applications Valeria Corinaldesi , Giacomo Moriconi Department of Materials an
2、d Environment Engineering and Physics, Universit Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy Abstract Ultra High Performance Fiber Reinforced Concrete (UHPFRC) is a cement-based material, which behaves like a low-porosity ceramic material with excellent mechanical performance.
3、This work was aimed to study soft cast (flowable at casting time) UHPFRC s and, in particular, the time development of compressive strength, flexural strength and elastic modulus was monitored for UHPFRC prepared by varying the water to cement ratio from 0.20 to 0.32. Silica fume, steel fibers and a
4、crylic-based superplasticizer were employed to prepare the UHPFRC mixtures. Optimum workability and mechanical performance were obtained with a water to cement ratio of 0.24. Thermal conductivity was determined for the same UHPFRC, in the presence and in the absence of steel fibers. The scope was to
5、 evaluate the effect of steel fibers on the thermal conductivity coefficient, in order to predict the UHPFRC capacity for heat loss. This information as well as its drilling characteristics, in order to test its suitability to be machined, could be essential for possible fields of application such a
6、s in mechanical engineering, where UHPFRC materials can be employed as high abrasion-resistant dies in the molding process of metal and polymer products. _ 2011 Elsevier Ltd. All rights reserved. Keywords Machine workability Mechanical performance UHPFRC Silica fume Thermal conductivity 3 1.Introduc
7、tion Ultra High Performance Fiber Reinforced Concrete is a special cement-based material which behaves like a low-porosity ceramic material with excellent mechanical performance. In particular, it is a superplasticized silica fume concrete, often reinforced with fibers, with improved homogeneity bec
8、ause traditional aggregates are replaced with very fine sand up to 400 lm 1. According to Richard and Cheyrezy 1, if soft cast and cured at room temperature, its compressive strength can achieve 200 MPa. In fact, UHPFRC represents the highest development of High Performance Concrete (HPC) and its ul
9、timate compressive strength depends on the curing conditions (either standard curing or steam curing or autoclave curing 2,3), on possible thermal treatments 4,5 as well as on the manufacturing technique adopted, and its value could rise up to 800 MPa in the case of compressive molding 6. Just to gi
10、ve an idea of the excellent mechanical performance of UHPFRC, the stressstrain curves of an ordinary performance concrete (OPC), of a High Performance Concrete (HPC) and of an Ultra High Performance Fiber Reinforced Concrete (UHPFRC) are shown for comparison in Fig. 1 7. In most industrial countries
11、 HPC materials are currently employed in infrastructural engineering works where heavy static and dynamic stresses or severe environmental aggression have to be counteracted, such as in sea platforms for oil extraction, long span bridges, undersea tunnels, and skyscrapers in seismic areas. However,
12、UHPFRC materials show, although in an experimental phase with some field tests, much higher performance than HPC. Particularly, besides extraordinary compressive and flexural strength (see Fig. 1), very high ductility as well as toughness and fracture energy 24 encourages new applications for these
13、materials, competing with innovative ceramics and structural metals in the field of mechanical and environmental engineering, as well as civil and building engineering 7. The following applications are promising in relation to UHPFRC materials utilization 8. In environmental and chemical engineering
14、, highly reliable containers can be advantageously produced to store hazardous (toxic, inflammable, etc.) fluids or solids, since the use of UHPFRC materials, in which negligible diffusion of ionic and molecular species occurs, can allow to make insignificant the release of toxic or radioactive wastes from the container to the environment. In civil engineering, construction of extraordinary buildings, whose sizes or location
