自密实混凝土的发展、应用与调查土木工程专业毕业设计外文翻译-中英文对照.doc

济南大学毕业设计外文资料翻译毕业设计外文资料翻译题 目 自密实混凝土的发展、应用与调查学 院 土木建筑学院 专 业 土木工程 班 级 学 生 学 号 指导教师 二一 年 月 日- 15 -Journal of Advanced Concrete Technology Vol. 1, No. 1, 5-15, April 2003 / CoSELF-COMPACTINGCONCRETEDEVELOPMENT,APPLICATIONSANDINVESTIGATIONSMasahiro OUCHIAssistant Professor, Dr. Eng.Kochi University of TechnologyTosa-yamada, Kochi, 782-8502 JAPANm-ouchiinfra.kochi-tech.ac.jpJournal of Advanced Concrete Technology Vol. 1, No. 1, 5-15, April 2003 / CoSELF-COMPACTINGCONCRETEDEVELOPMENT,APPLICATIONSANDINVESTIGATIONSMasahiro OUCHIAssistant Professor, Dr. Eng.Kochi University of TechnologyTosa-yamada, Kochi, 782-8502 JAPANm-ouchiinfra.kochi-tech.ac.jpABSTRACTSince the development of self-compacting concrete in 1988, the concrete has been used in practical structures in Japan. Investigations have been carried out from the viewpoint of making it a standard concrete. Recommendations and manuals for self-compacting concrete were also established.Key words: self-compacting concrete, development, application,Investigation1. DEVELOPMENT OF SELF-COMPACTING CONCRETEFor several years beginning in 1983, the problem of the durability of concrete structures was amajor topic of interest in Japan. To make durable concrete structures, sufficient compaction byskilled workers is required. However, the gradual reduction in the number of skilled workers inJapans construction industry has led to a similar reduction in the quality of construction work.One solution for the achievement of durable concrete structures independent of the quality ofconstruction work is the employment of self-compacting concrete, which can be compacted intoevery corner of a formwork, purely by means of its own weight and without the need forvibrating compaction. The necessity of this type of concrete was proposed by Okamura in 1986.Studies to develop self-compacting concrete, including a fundamental study on the workabilityof concrete, were carried out by Ozawa and Maekawa at the University of Tokyo 1.The prototype of self-compacting concrete was first completed in 1988 using materials alreadyon the market. The prototype performed satisfactorily with regard to drying and hardeningshrinkage, heat of hydration, denseness after hardening, and other properties. This concrete wasnamed “High Performance Concrete.” and was defined as follows at the three stages of concrete:(1) fresh: self-compactable(2) early age: avoidance of initial defects(3) hardened: protection against external factorsAt almost the same time, “High Performance Concrete” was defined as a concrete with highdurability due to low water-cement ratio by Professor Aitcin. Since then, the term highperformance concrete has been used around the world to refer to high durability concrete.Therefore, Okamura has changed the term for the proposed concrete to “Self-Compacting HighPerformance Concrete.”2. APPLICATIONS OF SELF-COMPACTING CONCRETESince the development of the prototype of self-compacting concrete in 1988, the use of self-compacting concrete in actual structures has gradually increased. The main reasons for theemployment of self-compacting concrete can be summarized as follows:(1) to shorten construction period(2) to assure compaction in the structure:especially in confined zones where vibratingcompaction is difficult(3) to eliminate noise due to vibration: effective especially at concrete products plantsThat means the current condition of self-compacting concrete is a “special concrete” rather than standard concrete. Currently, the percentage of self-compacting concrete in annual product of ready-mixed concrete in Japan is around 0.1% (Fig. 1) 2.A typical application example of Self-compacting concrete is the two anchorages of Akashi-Kaikyo (Straits) Bridge opened in April 1998, a suspension bridge with the longest span in the world (1,991 meters) 3 (Fig. 2). The volume of the cast concrete in the two anchorages amounted to 290,000 m3. A new construction system, whichmakes full use of the performance of self-compacting concrete, was introduced for this.The concrete was mixed at the batcher plantbeside the site, and was the pumped out of theplant. It was transported 200 meters throughpipes to the casting site, where the pipes were arranged in rows 3 to 5 meters apart. The concrete was cast from gate valves located at 5meter intervals along the pipes. These valves were automatically controlled so that a surface level of the cast concrete could be maintained. In the final analysis, the use of self-compacting concrete shortened the anchorage construction period by 20%, from 2.5 to 2 years. Self-compacting concrete was used for the wall of a large LNG tank belonging to the Osaka GasCompany, whose concrete casting was completed in June 1998 3. The volume of the self-compacting concrete used in the tank amounted to 12,000 m3. The adoption of self-compacting concrete means that (1) the number of lots decreases from 14 to 10, as the height of one lot of concrete castingwas increased.(2) the number of concrete workers was reduced from 150 to 50.(3) the construction period of the structure decreased from 22 months to18 months.Self-compacting concrete is often employed in concrete products to eliminate the noise ofvibration 3. This improves the working environment at plants and makes it possible for concrete product plants to be located in the urban area. The annual production of concreteproducts using self-compacting concrete exceeded 200,000 tons in 1996 2.3. INVESTIGATIONS ON SELF-COMPACTING CONCRETEVarious investigations have been carried out in order to make self-compacting concrete astandard one. The items to be solved are summarized as follows:(1) self-compactability testing method(2) mix-design method including evaluation method for materials(3) construction method including acceptance test at jobsite(4) new construction system to make full use of the performance of SCCThe investigations were carried out at each university, large construction company and material maker.Committee activities were also carried out. As the result, Architectural Institute of Japan and Japan Society of Civil Engineers established “Recommendations for Mix Design and Construction Practice of Highly Fluidity Concrete” in 1997 and “Recommendation for Construction of Self-Compacting Concrete” in 1998 respectively. The national ready-mixed concrete industry association, Japan, established “Manual for Manufacturing of Self-Compacting Concrete” in 1998 3.3.1 Self-compactability testing methodThere are two purposes for self-compactability testing methods. One is to judge whether theconcrete is self-compacatable or not, and the other is to evaluate deformability or viscosity forestimating proper mix-proportioning if the concrete does not have sufficient self-compactability.Of the many testing methods proposed for evaluating self-compactability, the U-type test proposed by the Taisei group is, at this stage,the most appropriate (Fig. 3) 4. In this test,the degree of compactability can be indicated by the height that the concrete reaches afterflowing through an obstacle. Concrete with the filling height of over 300 mm can be judged as self-compacting.A modification method for mix-proportion incase of insufficient self-compactability was also proposed, in which flow and funnel tests are used for estimating proper water-powder ratio and superplasticizer dosage by evaluating the deformability and viscosity of mortar in concrete 3.3.2 Mix-design methodSelf-compactability can be largely affected by the characteristics of materials and the mix-proportion. A rational mix-design method for self-compacting concrete using a variety ofmaterials is necessary. Okamura and Ozawa have proposed a simple mix-proportioning systemassuming general supply from ready-mixed concrete plants 4. The coarse and fine aggregatecontents are fixed so that self-compactability can be achieved easily by adjusting the water-powder ratio and superplasticizer dosage only.3.3 Evaluation method for materialsInvestigations on establishing evaluation method of materials, especially powder materials andsuperplasticizer have been carried out from the viewpoint of establishing a rational mix-proportioning method, that is, especially adjusting method for water-powder ratio andsuperplasticizer dosage, and of developing suitable material for self-compacting concrete.Ouchi et. al proposed evaluation method for the effect of superplasticizer and water independentof each other on the flowability of mortar by using flow and funnel tests 3.Some general construction companies employ a segregation-inhibiting agent so that the self-compactablity can be kept constant independent of the variation of unit water content, especiallydue to the variation of surface water content in the sand. There are various agents proposed andavailable in Japan. The evaluation method for the effect was also proposed 3.3.4 Acceptance test at jobsiteSince the degree of compaction in a structure mainly depends on the self-compactability of concrete and poor self-compactability cannot be compensated by the construction work, self-compactability must be checked for the whole amount of concrete just before casting at the jobsite.However, conventional testing methods for self-compactability require sampling and this can be extremely laborious if the self-compactability acceptance test is to be carried out for the whole amount of the concrete. A suitable acceptance test method for self-compactability has been developed by Ouchi et. al 3:(1) The testing apparatus is installed between agitator truck and pump at the job site. Thewhole amount of the concrete is poured into the apparatus.(2) If the concrete flows through the apparatus, the concrete is considered as self-compactable for the structure. If the concrete is stopped by the apparatus, the concrete isconsidered as having insufficient self-compactability and mix-proportion has to be adjusted.This apparatus was successfully used at the construction site of the Osaka Gas LNG tank, andsaved a considerable amount of acceptance test work (Fig. 4) 3.3.5 New structural design and construction systemsBy employing self-compacting concrete, the cost of vibrating compaction can be saved and thecompaction of the concrete in the structure can be assured. However, the total cost for theconstruction cannot always be reduced, except in large scale constructions. This is because theconventional construction system is strongly based on the necessity of the vibrating compactionof concrete. Self-compacting concrete can greatly improve construction systems previouslybased on conventional concrete requiring vibrating compaction. This sort of compaction, whichcan easily cause segregation, has been an obstacle to the rationalization of construction work.Once this obstacle has been eliminated, concrete construction can be rationalized and a newconstruction system, including formwork, reinforcement, support and structural design, can bedeveloped (Fig. 5).One example of this is the so-called sandwich-structure, where concrete is filled into a steelshell. This sort of structure has already been completed in Kobe, which could not have beenachieved without the development of self-compacting concrete (Fig. 6)3.4. CONCLUSIONSIt is considered that the main obstacles for making self-compacting concrete widely used havebeen solved. The next task in Japan is to distribute the technique for manufacturing andconstruction of self-compacting concrete rapidly. In addition, new structural design andconstruction systems making full performance of self-compacting concrete should beintroduced.REFERENCES1 Ozawa K, et. al. Development of high performance concrete based on the durability designof concrete structures: Proceedings of the second East-Asia and Pacific Conference onStructural Engineering and Construction (EASEC-2), Vol. 1, pp. 445-450, January 1989.2 Kodama, Y. Current condition of self-compacting concrete (written in Japanese), CementShimbun, No. 2304, Dec 1997.3 Ozawa K (editor), et. al. Proceedings of the International Workshop on Self-CompactingConcrete (CD-ROM), Kochi, Japan, March 1999, including state-of-the art report on self-compactability evaluation, materials & design, construction, manufacturing & concreteproducts and summary of recommendations & manuals for self-compacting concrete in Japan.Also available from Concrete Engineering Series, No. 30, Japan Society of Civil Engineers,March 1999. http:/www.infra.kochi-tech.ac.jp/scc-net/4 Hayakawa M, et. al. Development & application of super workable concrete, RILEMInternational Workshop on Special Concretes: Workability and Mixing, Paisley, 1993.5 Okamura H, et. al. Mix-design for self-compacting concrete, Concrete Library of JSCE, No.25, pp.107-120, June 1995.Civil Engineers London 1999 Session pp. 53 - 54.自密实混凝土的发展、应用与调查正弘藕池高知大学摘要 自1988年以来，自密实混凝土在日本获得了很快发展，并已经广泛应用于实际结构中。为了制定自密实混凝土制作方面的标准而进行了调查。自密实混凝土的使用建议和手册也已经建立。关键词 自密实混凝土、开发、应用、调查.自密实混凝土的发展从1983年开始的几年中，混凝土的耐久性问题在日本是一个重要的课题。为了使混凝土结构充分压实需要大量的技术工人。然而，技术工人的数量在逐渐减少，从而导致了日本建筑行业的工程质量相应的下降。为了解决这一问题，冈村宁次在1986年提出了一个解决方案，采用自密实混凝土这一技术。该技术是仅依靠混凝土的自重是混凝土压缩成型而不需要振动压实。为了发展自密实混凝土这一技术，东京大学的小泽一郎和前川进行了一个可行性的基本研究。自密实混凝土与1988年首次应用于实际建设中。并且，自密实混凝土干燥后的收缩率、水硬性和密实度及其他属性等指标都令人满意。因此，这种混凝土也被称为“高性能混凝土”，并具有一下三个特点（1）新特性：自密实性（2）早期龄期：没有初始缺陷（3）硬化：不受外部因素干扰几乎在同一时间，埃克森教授把“高性能混凝土”定义为一种水灰比很低而耐久性很好的混凝土。从那时起，高性能混凝土在世界各地广泛应用，特指这种高耐久性混凝土。因此，冈村改变了最初的名称，而改称这个课题为“自密实高性能混凝土”。2.自密实混凝土的应用由于自密实混凝土自1988年以来的发展，自密实混凝土在实际结构中的使用已经逐渐发展。自密实混凝土的大力发展原因可以概括如下：（1）缩短了施工工期（2）可以保证结构的密实性。尤其是在不便于采用振动施工操作的密闭区域。（3）不会产生振动噪音，尤其是在混凝土制品厂效果明显。这意味着自密实混凝的目前状况是一种“特殊混凝土”,而不是普通意义上的混凝土。目前，在日本自密实混凝土占每年准备预搅拌混凝土的0.1%左右。（如图1）。图1.日本每年生产的自密实混凝土总量1997年日本预拌混凝土总量是167,6201,000一个关于自密实混凝土应用的典型实例是建成于1988年4月具有两个泊位的明石海峡大桥。它是世界上跨度最大的大桥（1991米）。大桥的两个锚地耗费的混凝土量达290,000立方米。为了应用自密实混凝土而建立了一个新的系统。混凝土在混凝土工厂搅拌并在现场泵送。混凝土背排列成间距3到5米的管道泵送到200米以外的浇筑现场。混凝土被从间隔5米的管道向外浇筑。这种泵送管道的阀门可以自动控制，使混凝土的表面可以维持平整。后来的分析表明使用自密实混凝土使锚地的施工工期缩短了20%，从2.5年缩短到2年。（图2）图2明石海峡大桥的4A锚地自密实混凝土首次应用于墙体工程是在属于大阪煤气公司的一个大型液化天燃气储存罐上，该工程浇筑完成于1998年6月。这个罐体耗用的自密实混凝土量达12000立方米。自密实混凝土的应用意味着：（1）混凝土搅拌站的数量随着浇筑高度的增加从14个减少到10个。（2）搅拌混凝土工人的数量由150个减少到50个。（3）结构的建设工期从22个月下降到18个月。混凝土制品大多采用自密实技术以减少振动噪音。这也提高了混凝土制品厂的工作环境，并使混凝土制品厂在市区生产成为了可能。在1996年自密实混凝土的使用量超过了20万吨。3.自密实混凝土的调查为了制定自密实混凝土的标准一，已经进行了广泛的调查。要解决的项目概括如下:（1）自密实试验方法（2）组合设计方法，包括材料的评价方法（3）施工方法，包括在现场的验收试验（4）充分利用自密实混凝土的新的建筑体系这项调查在每所大学、大型建筑公司和材料制造商进行，委员会也进行了活动。作为结果，日本建筑学会和土木工程师学会分别于1997年推出了“高流动性混凝土配合比设计和施工的建