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，MBT Woermaan地下工程公司以“2000年隧道建设”为题召开了一次专

业会议，并展示了该公司提供的混凝土喷射的产品和方法。通过展示干喷和混喷的方法，对这两种系统的优缺点进行了比较。

德国—采用湿喷少吗？

MBT国际地下建筑工程公司总经理汤姆-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是20:80，在斯堪底那维亚和意大利湿喷法则占100%，而在瑞士和法国湿喷法和干喷法的比例是80：20。

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The MBT Woermann Untertagebautechnik GmbH staged a special congress with demonstrations

of the products and methods it markets for

concrete spraying under the slogan Tunnelling

2000 upon entering the German market, a field, which it had long neglected. As both the

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 lies in wet-mix concrete. The overall costs

for placed wet-mix concrete, he insists are

30 to 40% less than for any kind of dry-mix concrete. Furthermore, in the case of dry-mix concrete, the dust nuisance exceeds the ultimate values laid down in all existing regulations.

With the experience gained from 12 km (of a total of 19 km) of monocoque lining with shotcrete in the Vereina Tunnel, F. Amberg,

案。最便宜的产品并不总是最经济的方案，所需要的应当是符合技术要求的经

济的方案。

汤姆-梅柏认为，德国未来将普遍采用湿喷混凝土。已浇注的湿喷混凝土的

总费用比任何形式干喷混凝土便宜30% 到40%。另外，干喷混凝土的粉尘量超

过所有规范的极限值。

F. Amberg，Amberg 工程咨询公司根据在弗莱娜隧道中的12公里(全长19 公里)采用喷射混凝土单层衬砌获得的

经验证实了湿喷混凝土方法在经济方面

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

预算表明，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]。这还没有考虑劳动保护及减少环境污染方

面的优点。

喷射混凝土——比添加剂、

水泥和水更重要

与干喷法相比，湿喷法有许多优点：回弹量较低，产生的粉尘少、水与水泥

比稳定，这样可保证混凝土质量，且喷

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

清洗量，所以当喷射混凝土量小时受到

限制。为了利用湿喷的优点并克服其缺点，开发出Delvocrete体系。

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，以0.2-2.0%的配比（相对于水泥重量）

加入到搅拌机里的新拌混凝土中。组分

A使水泥颗粒发生疏水作用并保持混凝

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

组分B加入粘流状态的混凝土中。组分

B能够终止组分A的缓凝作用，并使水泥开始凝结。

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Amberg Ingenieurburo AG, was able to confirm the economic advantages of the wet-mix method. The Vereina Tunnel originally called for securing the heading and inner shell via

the dry-mix method but provisional cost accounting showed that wet-mix concrete with a non-alkaline accelerator can be installed

up to 10% more cheaply than dry-mix concrete (2). Advantages relating to industrial safety

and reduced environmental nuisance are not taken into account here.

Sprayed Concrete-more than Aggregate, Cement and Water

The wet-mix method has a whole series of advantages compared with the dry-mix method: lower rebound, less dust development, constant W/C value and as a result, secured concrete qualities and higher spraying rates. The disadvantages of conventional wet-mix technique: limited flexibility when

processing small amounts owing to the restricted life of the concrete and the

amount of cleaning required after each spraying phase. In order to exploit the dvantages of wet-mixing and at the same time to eliminate its disadvantages, the

Delvocrete system was devised. This relates

to a 2-component system for regulating the cement hydration. Component A, the Delvocrete stabiliser is added to the

freshly mixed concrete in the mixer with a dosage amount of 0.2 to 2.0% (related to the cement weight). It hydrophobises the cement grain and keeps it fresh up to a maximum of

72 h. The component B, the Delvocrete activator, carried by air flow, is added at

the nozzle to the concrete, carried in a

viscous flow. This stops the retarding

effect of A and immediately causes the cement to start setting.

The Delvocrete system does not influence the concrete-technological features of the