碳纖維等FRP在土木工程中的應用,為我國碳纖維應用的發展探索出一條新路徑,即依靠應用端的發展,來帶動整個材料的產業化。
在今年1月舉行的國家科技獎勵大會上,中冶建筑研究總院作為第一完成單位完成的“土木工程用高性能纖維復合材料制備及應用關鍵技術”榮獲國家科技進步獎二等獎。
據了解,高性能纖維復合材料(簡稱FRP)具有輕質、高強、耐腐、可設計等優點,可顯著提高土木工程結構的性能,延長其使用壽命。而上述獎項的頒發,也讓作為高性能纖維復合材料之一的碳纖維,再次進入人們關注的視野。
中冶建筑研究總院院長岳清瑞在近日舉行的一次學術交流會上指出,從我國碳纖維的應用來看,航空領域市場尚未打開,能源領域尚未形成穩定市場,體育休閑領域對成本要求很高。而在土木工程領域,據統計,國產碳纖維每年有40%用于結構的加固和補強上,因此是重要的應用方向。
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發展困境
據相關市場研究機構數字,2015年前,全球碳纖維市場需求將保持13%的增長,我國對碳纖維的需求增速則快于全球。預測到2015年,我國碳纖維總體需求將達1.6萬噸。
事實上,從研發角度看,我國碳纖維的起步并不晚。早在20世紀60年代,中科院長春應化所便率先開始聚丙烯腈基碳纖維的研究,并于上世紀70年代初完成了連續化中試裝置。此后,中科院山西煤炭化學研究所、北京化工大學等也開始了相關研究。
產業化方面,進入21世紀后,國產碳纖維發展開始加速,產能大幅提高。2012年,我國已有30多家企業從事碳纖維的研發和生產,建成產能已經突破1萬噸。此外,國內還有大量的在建和規劃建設的碳纖維生產線。
不過在賽迪方略總部經濟研究中心總經理冀志宏看來,國內碳纖維項目遍地開花背后,也存在著不少問題。
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首先是產能利用率低。雖然國內的建成產能已經突破1萬噸,但實際產量僅為2000噸左右,產能利用率僅有0.2%。而國際上大多數企業的產能利用率為0.7%~0.9%。
冀志宏指出,國內碳纖維生產線產能利用率低,并不是因為下游市場需求不足,而是因為難以生產出合格的產品。他進一步指出,生產碳纖維工序復雜,從聚合、紡絲,到氧化、碳化、表面處理等,任何一個生產環節出了問題,都可能影響碳纖維的性能。“國產原絲大多雜質含量高、質量穩定性差、變異系數大,沒有好的原料,怎么生產出好的產品?”
其次,我國碳纖維在高端產品方面也有待突破。冀志宏指出,以占碳纖維產量90%以上的丙烯腈基碳纖維為例,在世界范圍內,工業應用和體育休閑的比例分別為75.7%和24.3%,而在中國,這個比例卻分別是20%和80%。此外,冀志宏認為,國內碳纖維產業缺乏完善、權威的評價體系,這也是制約國產碳纖維發展的原因之一。
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尋找突破點
在上述背景下,雖然我國近年來碳纖維產能快速擴張,但大多為相對低品質的產品,與國外相比差距明顯,因此這種產能的擴張,也在一定程度上加劇了碳纖維的結構性過剩。
在岳清瑞看來,碳纖維在土木工程領域的應用,有望改變上述局面。他指出,與航空、能源和體育休閑領域相比,碳纖維在土木工程領域的應用更具前景。
而岳清瑞也帶領自己的團隊與其他高校合作,對碳纖維在土木工程領域的應用進行了一系列的探索,并開發出板材、筋材、布材等產品。
同時,由于碳纖維的特點是強度較高,延伸性較差,岳清瑞和其團隊便嘗試將碳纖維和其他纖維混合,增加材料的斷裂延伸率。“混雜纖維可以充分發揮不同纖維的優勢,揚長避短,在提高結構延伸性、耗能能力和變形恢復能力等方面有可能優于單一品種的纖維,且降低成本。”岳清瑞說。
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在岳清瑞看來,碳纖維等FRP的一個重要領域就是結構加固和改造。比如,可以將纖維網格型材固定于混凝土構件表面,然后噴射或手工鏝抹聚合物水泥砂漿與原有混凝土一體化,從而提高結構的承載能力及耐久性。
碳纖維另一個重要應用方向是海洋(海港)環境。當前我國正著力開發海洋資源,將FRP和混凝土組合,則能有效解決開發過程中防止海水腐蝕這一重要問題。
以應用帶動產業化
碳纖維等FRP在土木工程中的應用,也為我國碳纖維應用的發展探索出一條新路徑,即依靠應用端的發展,來帶動整個材料的產業化。
“此次中冶建研總院的突破值得肯定,這不僅標志著我國科技研發實力的大幅提升,還有助于帶動碳纖維產業科研攻關、設備制造等工作的有效開展。”中投顧問高級研究員賀在華對《中國科學報》記者指出。
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事實上,我國發展碳纖維的思路也正在發生轉變。“以前國家主要支持碳纖維產品的生產,現在則更支持應用的發展,希望把應用領域做大之后,反過來促進生產企業的發展。”岳清瑞說。
此外,碳纖維機器復合材料產業技術創新戰略聯盟也于2013年10月被科技部納入國家產業技術創新戰略試點聯盟。在2013年12月該聯盟舉行的第一屆理事會上,工信部高新司副司長胡世輝指出,聯盟要以提高國產碳纖維競爭力為己任,將市場需求作為指定行業發展戰略的重要參考,以市場為導向,結合產學研力量,圍繞共性關鍵問題,組織全行業力量推動國產碳纖維行業的技術創新。
冀志宏也充分強調了碳纖維產品與應用的銜接。他指出,碳纖維上下游產業關聯度非常緊密,比如要開發一個碳纖維下游的新產品,光靠碳纖維生產商很難完成。因此,政府要充分發揮協調配置能力,通過聯盟等行業組織,圍繞下游產業發展重點,構建產、學、研、用多方面協調發展的完整產業鏈。
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賀在華則認為,各項扶持政策亟須制定并落實到位。“土地、稅收、補貼、電價、科研等政策若能及時實施,企業進行科研創新的積極性便會被調動起來。”
應用設計案例:
The first-ever building to have a carbon fibre structure is a mobile studio-cum-stage by Japanese architects Atelier Bow-Wow, which just opened in New York.
The BMW Guggenheim Lab comprises a black mesh-clad box, elevated by the lightweight framework that makes it easily transportable.
Nestled between two existing buildings, the structure shelters a courtyard studio that is open to the street at both ends.
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A rigging of lighting, screens, audio equipment and other tools is suspended behind the mesh and can be lowered into the studio for different activities.
A timber hut provides a cafe for visitors where picnic benches are sheltered beneath a fabric canopy.
The lab is hosting a series of programs around the theme of comfort in the city, including talks, exhibitions, discussions, screenings, workshops and games.
As part of a six-year tour of mobile studios, the lab will later be relocated to Berlin and Mumbai, before being replaced by a new structure and theme.
The project was commissioned by the Solomon R. Guggenheim Foundation and is sponsored by automotive company BMW.
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Two other projects by Atelier Bow-Wow from the Dezeen archive include a townhouse renovation and a gallery of stacked concrete boxes - see both projects here.
Architecture and Graphic Design
The mobile structure for the first cycle of the BMW Guggenheim Lab has been designed by the Tokyo-based Atelier Bow-Wow as a lightweight and compact “traveling toolbox.” The 2,200-square-foot structure can easily fit into dense neighborhoods and be transported from city to city. In New York, the two-story structure is nestled between two buildings on a three-quarter-acre T-shaped site; at its southern end, it opens out onto an inviting landscaped public space and cafe.
The lower half of the BMW Guggenheim Lab structure is an open space that can be configured to meet the particular needs of the various programs, shifting from a formal lecture setting with a stage to the scene for a celebratory gathering or a workshop. The upper, “toolbox” portion of the structure is loosely wrapped in two layers of semitransparent mesh, which creates a shimmering moiré effect and allows visitors to catch glimpses of the extensive apparatus of “tools” that can be raised or lowered on a rigging system to configure the lower space for the different programs. Remarkably, the BMW Guggenheim Lab is the first building designed with a structural framework composed of carbon fiber. Videos and images of the structure and the construction process can be viewed at youtube.com/bmwguggenheimlab and flickr.com/bmwguggenheimlab.
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“Rather than architects educating the public on how to behave within spaces, it is the public who should have the autonomy of spatial practice in their cities,” stated Yoshiharu Tsukamoto and Momoyo Kaijima of Atelier Bow-Wow. “We have always been advocates of people regaining ownership in order to shape the city around them, and are very pleased to participate in the launch of the BMW Guggenheim Lab. We always conceived the Lab as a public space without enclosure.”
The inaugural BMW Guggenheim Lab will leave behind permanent improvements to the once-vacant East Village lot on which it sits, including the stabilization and paving of the site, replacement of sidewalks, and new wrought-iron fencing and gates.
The graphic identity of the BMW Guggenheim Lab has been developed by Seoul-based graphic designers Sulki & Min.
BMW Guggenheim Lab Team
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The BMW Guggenheim Lab is organized by David van der Leer, Assistant Curator, Architecture and Urban Studies, and Maria Nicanor, Assistant Curator, Architecture, Solomon R. Guggenheim Museum. Selected by an international Advisory Committee composed of experts from various disciplines, the members of the New York Lab Team are: Omar Freilla, a Bronx, New York–based environmental justice activist, cooperative developer, and founder and coordinator of Green Worker Cooperatives; Charles Montgomery, Canadian journalist and urban experimentalist, who investigates the link between urban design and well-being; Olatunbosun Obayomi, Nigerian microbiologist and inventor and 2010 TEDGlobal Fellow; and architects and urbanists Elma van Boxel and Kristian Koreman of the Rotterdam-based architecture studio ZUS [Zones Urbaines Sensibles].
Public Information and Amenities
The BMW Guggenheim Lab and all programs are free and open to the public on a first-come, first-served basis during operating hours. Advance registration for selected programs will be available online. Hours of operation are 1 to 9 pm on Wednesdays and Thursdays, 1 to 10 pm on Fridays, and 10 am to 10 pm on Saturdays and Sundays. The 42-seat BMW Guggenheim Lab cafe, operated by the Brooklyn-based restaurant Roberta’s, is open 1 to 9 pm on Wednesdays to Fridays and 10 am to 9 pm on Saturdays and Sundays.
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Future Venues
Following the New York presentation, the BMW Guggenheim Lab will move on to Berlin in the spring of 2012, where it will be presented in collaboration with the ANCB Metropolitan Laboratory in Pfefferberg, a former industrial complex. In winter 2012–13, the first three-city cycle will be completed when the BMW Guggenheim Lab travels to Mumbai. The Mumbai presentation will be organized in collaboration with the Dr. Bhau Daji Lad Museum.