喷射混凝土：干喷还是湿喷

喷射混凝土：干喷还是湿喷 喷射混凝土:干喷还是湿喷? Sprayed Concrete:Dry or Wet? 为进入长期被忽视的德国市场， The MBT Woermann Untertagebautechnik GmbH MBT Woermaan地下公司以 staged a special congress with demonstrations “2000年隧道建设”为题召开了一次专 of the products and methods it markets for 业会议，并展示了该公司提供的混凝土 concrete spraying under the slogan Tunnelling 喷射的产品和方法。通过展示干喷和混 2000 upon entering the German market, a field, 喷的方法，对这两种系统的优缺点进行 which it had long neglected. As both the 了比较。 dry-mix and wet-mix methods were offered, the pros and cons of both systems were up for comparison. Germany-deficit in Wet-Mix application? Tom Melbye, director of MBT International Underground Construction and an active champion of the wet-mix method, quoted a ratio for the wet-mix to dry-mix methods of 20:80 in Germany, whereas in Scandinavia and Italy, wet-mix holds a 100% share, while in Switzerland and France the ratio stands at 80:20 in favour of wet-mix. The times when individual components were sold are over, tunnellers expect global solutions. The cheapest products do not always lead to the most economic solution. The target must be the economic solution for a defined technical requirement. Tom Melbye thus feels that Germany's future 德国—采用湿喷少吗, lies in wet-mix concrete. The overall costs for placed wet-mix concrete, he insists are MBT国际地下建筑工程公司总经理 30 to 40% less than for any kind of dry-mix concrete. Furthermore, in the case of dry-mix 汤姆-梅拜是湿喷法的积极拥护者。据 他介绍，在德国湿喷法和干喷法的比例 concrete, the dust nuisance exceeds the 是20:80，在斯堪底那维亚和意大利湿 ultimate values laid down in all existing 喷法则占100%，而在瑞士和法国湿喷法 regulations. With the experience gained from 12 km (of a 和干喷法的比例是80:20。 total of 19 km) of monocoque lining with 出售单个设备的时代已经过去，如 今隧道施工人员要求提供完整的解决方 shotcrete in the Vereina Tunnel, F. Amberg, 案。最便宜的产品并不总是最经济的方 Amberg Ingenieurburo AG, was able to confirm 案，所需要的应当是符合技术要求的经 the economic advantages of the wet-mix 济的。 method. The Vereina Tunnel originally called 汤姆-梅柏认为，德国未来将普遍采 for securing the heading and inner shell via 用湿喷混凝土。已浇注的湿喷混凝土的 the dry-mix method but provisional cost 总费用比任何形式干喷混凝土便宜30% accounting showed that wet-mix concrete with 到40%。另外，干喷混凝土的粉尘量超 a non-alkaline accelerator can be installed 过所有规范的极限值。 up to 10% more cheaply than dry-mix concrete F. Amberg，Amberg 工程咨询公司 (2). Advantages relating to industrial safety 根据在弗莱娜隧道中的12公里(全长19 and reduced environmental nuisance are not 公里)采用喷射混凝土单层衬砌获得的 taken into account here. 经验证实了湿喷混凝土方法在经济方面 Sprayed Concrete-more than 的优点。最初准备在弗莱娜隧道采用干 喷法进行掘进支护和内层衬砌，但费用 Aggregate, Cement and Water 预算明，浇注含有非碱性促凝剂的湿 喷混凝土比干喷混凝土便宜10%[2]。这 The wet-mix method has a whole series of 还没有考虑劳动保护及减少环境污染方 advantages compared with the dry-mix method: lower rebound, less dust development, 面的优点。 constant W/C value and as a result, secured concrete qualities and higher spraying rates. 喷射混凝土——比添加剂、 The disadvantages of conventional wet-mix technique: limited flexibility when 水泥和水更重要 processing small amounts owing to the restricted life of the concrete and the 与干喷法相比，湿喷法有许多优点: amount of cleaning required after each 回弹量较低，产生的粉尘少、水与水泥 spraying phase. In order to exploit the 比稳定，这样可保证混凝土质量，且喷 dvantages of wet-mixing and at the same time to eliminate its disadvantages, the 射率较高。传统湿喷技术的缺点:由于 混凝土的有限寿命及每次喷射后需要的 Delvocrete system was devised. This relates 清洗量，所以当喷射混凝土量小时受到 to a 2-component system for regulating the 限制。为了利用湿喷的优点并克服其缺 cement hydration. Component A, the 点，开发出Delvocrete体系。 Delvocrete stabiliser is added to the freshly mixed concrete in the mixer with a 这个体系是调节水泥水合作用的双 组分体系。组分A是Delvocrete缓凝剂， dosage amount of 0.2 to 2.0% (related to the 以0.2-2.0%的配比(相对于水泥重量) cement weight). It hydrophobises the cement 加入到搅拌机里的新拌混凝土中。组分 grain and keeps it fresh up to a maximum of A使水泥颗粒发生疏水作用并保持混凝 72 h. The component B, the Delvocrete activator, carried by air flow, is added at 土新鲜，最长可达72小时。组分B 是 Delvocrete促凝剂。在喷嘴处用气流将 the nozzle to the concrete, carried in a 组分B加入粘流状态的混凝土中。组分 viscous flow. This stops the retarding B能够终止组分A的缓凝作用，并使水泥 effect of A and immediately causes the 开始凝结。 cement to start setting. The Delvocrete system does not influence the Delvocrete体系不影响喷射材料的 混凝土技术特性，特别是不影响早期和 concrete-technological features of the 最终抗压强度的变化，但影响反应时间。 sprayed material, especially the development 这样，湿喷射混凝土可以在设定的缓凝 of the early and final compressive strengths 期内的任何时间凝结。每次喷射后不需 but it does affect its processing time. In 要清洗。Delvocrete使得施工工地不受 this way, the wet-mix concrete can be 混凝土预拌厂和施工工地搅拌设施的送 processed at any desired point-in-time 料时间影响。 within the set retardation period. There is 在国外于数年前成功地使用 no need for cleaning after each spraying Delvocrete之后，德国第一次将该体系 phase. Delvocrete makes the construction 用于阿尔特娜附近的迪齐哈德隧道。承 site independent of opening times for 包商使用该体系是为了从车行约30分钟 ready-mix concrete works and construction 远的预拌混凝土厂一周七天昼夜不停地 site mixing plants. 将混凝土运往工地。迪齐哈德隧道联合 After Delvocrete succeeded in breaking 体在外层衬砌共使用了18000立方米采 through years ago elsewhere, the system was 用Delvocrete缓凝和促凝的喷射混凝土。 used for the first time in Germany in the 用于控制新拌混凝土粘度的TCC体 Ditschhardt Tunnel near Altenahr. The 系由3个组分组成。将Woerment TCC651 contractor used the system there in order 加入到搅拌机里的混凝土中。TCC651能 to be in a position to have concrete 增加混凝土的流动性，即使是在较高的 available round-the-clock, 7 days a week, 温度下也能长时间地稳定混凝土的粘度。 from a ready-mix concrete factory, some 泵送助剂MeycoTCC780能提高混凝土的 30 min drive away. Altogether, the 泵送能力，即使配方小颗粒量少时也是 Ditschhardt Tunnel consortium used 18,000 m3 如此。 of shotcrete retarded and accelerated with 在喷嘴处加入Meyco TCC766。 Delvocrete for the outer shell. TCC766是一种硅酸盐聚合物促凝剂，用 The TCC (Total Consistency Control) system 于引发水泥颗粒凝结。该体系组分间的 for controlling the fresh concrete 相互作用引起粘度突然下降，这称作 consistency comprises 3 components. Woerment "粘度衰减效应".添加Meyco TCC766, TCC 651 is added to the concrete in the 使混凝土具有可塑性和触变性。因为滞 mixer. which increases the slump and 后一段时间后才发生促凝效应，所以表 stabilises the consistency over a long 面的混凝土软，能与以后喷射的混凝土 period even given higher concrete 料较好地粘合，回弹量降低。用TCC处 temperatures. The pumping aid, Meyco TCC 780 理的混凝土具有足够的早期凝结强度， enhances the pumpability of the concrete 并在强度变化方面明显高于铝酸盐基促 even given a recipe which is low in micro 凝剂，28天的抗压强度通常只稍低于未 particles. 促凝的混凝土。 At the nozzsle, Meyco TCC 766 is added, a TCC体系促凝剂的PH值约为11.5。 polymer silicate accelerator, which 因此，在劳动卫生保健方面比通常的铝 initiates the setting of the cement grain. 酸盐促凝剂问题要小。TCC体系已引入 The inter-action of the system components 德国，并在一些施工试验中得到证实。 brings about a sudden slump loss, known as 传统的促凝剂使喷射混凝土的28天抗压 the "slump killing effect". The adding of 强度降低，与未添加促凝剂的喷射混凝 Meyco TCC 766 makes the concrete plastically 土相比，降低30%以上。传统的促凝剂 formable and thixotropic. As the 在劳动卫生保健方面还存在问题，并有 acceleration effect first takes place after 一种不利的沥滤性质。在一些欧洲国家 a time delay, the concrete on the surface 已禁止使用这类促凝剂。在德国，使用 remains soft and binds better with 这类促凝剂也遇到了日益增加的批评。 subsequent sprayed material, the rebound 新的干喷技术和进一步发展的干喷 decreases. Concrete processed in conjunction 技术[3,4]促进了喷射混凝土的工艺。 with TCC possesses an adequate early setting 这种工艺包括，当喷射混凝土中石膏量 strength and considerably higher values with 少时不添加促凝剂，或者使用生理上无 regard to strength develop than accelerators 害的喷射混凝土时添加粉末状非碱性促 on a aluminate basis. 凝剂。这两种不同的方法日益受到欢迎， The 28-day compressive strengths usually are 尤其是建设较小型的隧道。与湿喷法相 just slightly less than those for a 比，优点是操作简单，缺点是粉尘量大， non-accelerated concrete. 回弹性较高。 The setting accelerator in the TCC system 多年以来，MBT公司一直致力于研 has a pH value of approx. 11.5. As a result, 制用于湿喷法和液体形式干喷法的非碱 it is less doubtful in terms of working 性促凝剂。含有Meyco SA160的产品是 hygiene than conventional aluminate 一种生态上性产品，在劳动医学上 accelerators. The TCC system is currently 无害，可以液体形式提供。与传统的铝 being introduced in Germany and has already 酸盐促凝剂相比，早期凝结强度的变化 proved itself during a number of site tests. 显示促凝剂开始作用较慢。不过， Conventional setting accelerators reduce Meyco SA160的28天值显示了相当有利 the 28-day compressive strengths compared 的结果，与没有加促凝剂的喷射混凝土 with unaccelerated shotcrete by 30% and 相比，只稍微差一些，产生的粉尘少， more, they are disputed in terms of working 回弹量低。 hygiene and reveal an unfavourable leaching behaviour. In some European countries, their use is already banned. In Germany too, their application is being met with increasing criticism. New and further developments in dry-mix technology [3,4] facilitate the processing of a shotcrete, which contains either - in the case of shotcrete cement that is low in gypsum-no accelerators or in the case of physiologically non-disputed shotcrete, non-alkaline accelerators in powder form. Both variants are becoming increasingly popular, especially when it comes to smaller tunnelling measures. The advantage of easier handling compared with the wet-mix method finds itself opposed with the disadvantage of higher dust development and higher rebound. For a number of years, MBT has been engaged in developing a non-alkaline setting 文献: accelerator for the wet-mix sand dry-mix [1] Melbye,T.: Neue Zusatzmittel fuer methods in liquid form. With Meyco SA 160, spritz-beton/New advanced shotcrete for the first time an ecologically neutral Admixtures. Tunnel 3/1994 , product, which is approved in terms of seite/page 38 industrial safety, is available in liquid [2] Hentschel, H.: Vereinatunnel: form. Compared with conventional aluminate Beide Vortriebe mit hoher accelerators, the early setting strength Geschwindigkeit auf der Zielgeraden/ development, the early strength development The Vereina Tunnel: Both Drives on the reveals a slower start for the accelerator, finishing straight-full speed ahead. however, when it comes to the 28-day values, Tunnel 4/1996, seite/page 7 Meyco SA 160 provides considerably more [3] Eichler, K.: Umweltfreundlicher favourable results and when compared to spritz-beton/Environmentally-friendly unaccelerated shotcrete, the results are shotcrete. Tunnel 1/ 1994 seite/ page 33 only slightly poorer. Dust development and [4] Aschaber, M., Balbach, W., Rombold, rebound are low. A.:Verarbeitung von umweltfreundlichem spritzbeton im Trockenspritzverfahren/ Processing environmentally friendly shotcrete using the dry-spraying method. Tunnel 3/1995, Seite/page 21 BACK HOME