JPH0514068B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for applying shotcrete to spring or wet surfaces such as tunnels and underground structures. In this specification, "concrete" includes both cases where fine aggregate and coarse aggregate are used as aggregates and cases where only fine aggregates are used. [Conventional technology] Conventionally, when spraying concrete that has not yet hardened onto a spring or wet surface such as a tunnel using a spray nozzle, it has been necessary to increase the proportion of quick-setting agent added or to spray concrete at the nozzle. Measures have been taken to adjust the amount of water added to the spring water depending on the amount of spring water, but it is difficult to take appropriate measures, so measures such as conducting drain borings and installing water collection pipes and water collection sheets have been taken to reduce the amount of spring water. require supplementary measures to reduce
There were problems in terms of economy and workability. Japanese Patent Application Laid-Open No. 57-201498, filed by the same applicant, describes a method for directly applying shotcrete onto a spring surface or wet surface without taking such supplementary measures.
In the publication, in the route from the spray machine to the spray nozzle, the weight ratio of the thickening agent to the cement is 0.1.
We have proposed a shotcrete construction method that prevents spalling or washing away at the surface of spring water by adding ~4.0%, and have carried out numerous implementations. [Problems to be solved by the invention] According to the method proposed in the above-mentioned Japanese Patent Application Laid-Open No. 57-201498, thickening agent is removed in the path from the spray machine to the spray nozzle (including the spray machine). When adding a thickening agent, it is not appropriate to add the powdered thickening agent as it is in the route during pressure feeding, so it is necessary to mix the thickening agent with water or an accelerating agent before adding it. . In addition, when adding with a spraying machine, it is added alone or mixed with a quick-setting agent, but in this case, it is added to the dry mix and water is added during pumping. In any case, when using this method, the thickening agent must be mixed after the spraying machine installed in a narrow construction site such as a tunnel, and there is a dissolving tank and an addition device for adding the thickening agent. However, there were problems with construction. In addition, when adding a thickening agent to the concrete being pumped after the spraying machine, it is necessary to properly and uniformly mix the thickening agent into the concrete continuously during the spraying process. In order to maintain homogeneous mixing during spraying, an additional amount of silane must be added to the concrete being pumped for safety reasons, which also poses economical problems. The purpose of the present invention is to solve the problems of workability and economy in the thickening agent addition procedure. [Means for solving the problem] The gist of the present invention, which aims to solve the above problem, is to put cement, aggregate, and water into a mixer, mix them, and spray the obtained wet mix. The mixture can be charged into a machine and pumped from the spray machine to a spray nozzle to spray the mix onto a spring or wet surface, or the cement and aggregate can be put into a mixer and then kneaded. , the obtained dry mix is charged into a spray machine, and when the mix is sprayed onto a spring water surface or a wet surface while adding water along the route from the spray machine to the spray nozzle, the mixer is used to knead the mix. Provides a shotcrete construction method for spring water surfaces or wet surfaces, which is characterized by mixing a thickening agent during mixing and kneading, and conveying and charging the mixture with the thickening agent into a spraying machine. It is something to do. According to the method of the present invention, the amount of quick setting agent added can be reduced compared to the case where no thickening agent is used, and even if a small amount of quick setting agent is added, the effect of the thickening agent will not be impaired. do not have. Therefore, it is preferable to include a necessary quick-setting agent. The quick-setting agent may be added before the spray nozzle, but in the case of dry mixes, it may be added at the time of kneading. Furthermore, in order to ensure the required consistency, it is preferable to add a water reducing agent.
The position of adding the water reducing agent is not particularly limited, but it is practical to add the water reducing agent at the same time or after the addition of water in accordance with the usual usage of the water reducing agent. That is, the shotcrete construction method for spring water surfaces or wet surfaces according to the present invention is disclosed in JP-A No. 57-201498.
Unlike the method in the publication, the thickening agent is uniformly mixed in advance into the dry mix or wet mix charged into the spraying machine, and for this reason,
A thickening agent is added in a mixer to obtain these mixes. When a thickening agent is added to wet mixes, the viscosity increases, but on the other hand, there is little change in the flow value over time, and even during the kneading time (for example, after about an hour), material separation and flow do not occur. Because it does not cause any change in gender,
Uniform wet mixes can be made in relatively large quantities, transported to the spraying machine at the spraying site, and used as appropriate for the spraying work, which significantly improves work efficiency. It is possible to economically produce homogeneous materials. In the case of dry mixes, all you need to do is add a thickening agent in a mixer and mix thoroughly.
In this case, more time can be taken for kneading. Figures 1 to 6 schematically show aspects of the method of the present invention. Figures 1 to 3 show how wet mixes are transported and loaded into a spraying machine, and Figures 4 to 6 show how dry mixes are loaded. It shows how it is transported and loaded into a spraying machine. In these figures, 1 is a mixer,
2 is a spray machine, 3 is a spray nozzle, and 4 is a pressure feeding route from the spray machine 2 to the spray nozzle 3. Further, 5 indicates a thickening agent, and 6 indicates an quick setting agent.
C stands for cement, S stands for fine aggregate, G stands for coarse aggregate, and W stands for water. Figure 1 shows that when cement C, fine aggregate S, coarse aggregate G, and water W are put into mixer 1 and mixed, thickening agent 5 is also put into this mixer 1 to make wet mixes. An example is shown in which the material is loaded into the spray machine 2 and fed under pressure to the spray nozzle 3, and at the same time, the quick-setting agent 6 is added in the path 4 before the spray nozzle 3. FIG. 2 shows the same example as in FIG. 1, except that water W is added with a thickening agent 5 and put into the mixer 1. FIG. 3 shows the same example as FIG. 1, except that the fine aggregate S and the thickening agent 5 are mixed in advance and then put into the mixer 1. Figure 4 shows that when cement C, fine aggregate S and coarse aggregate G are put into mixer 1 and then kneaded, thickening agent 5 is also put into this mixer 1 to make dry mix, which is then mixed into a spraying machine. An example is shown in which the water W is added to the water W and the quick-setting agent 6 is also added in the route 4 which is conveyed and loaded into the spray machine 2 and is fed under pressure from the spray machine 2 to the spray nozzle 3. FIG. 5 shows the same example as FIG. 4 except that the fine aggregate S and the thickening agent 5 are mixed in advance and put into the mixer 1. FIG. 6 shows the same example as FIG. 5, except that the quick setting agent 6 and the thickening agent 5 are mixed and then put into the mixer 1 to produce a dry mix. In these examples, it is of course possible to perform spraying with mortar that does not use coarse aggregate G, and the shotcrete construction method according to the present invention includes within its scope the use of mortar that does not contain coarse aggregate. It is something that As the thickening agent used in the present invention, known cellulose ether-based or acrylic-based thickening agents can be used. In other words, any thickening agent (in-water separation prevention agent) that, when added to a concrete mix, dissolves in the water in the mix and increases the viscosity of the water and at the same time reduces the separation of cement and aggregates, can be used in the present invention. can. Cellulose ether-based thickeners are water-soluble cellulose ethers made by introducing various substituents into cellulose, and are divided into many types depending on the type and degree of substitution, but the main component is hydroxypropyl methylcellulose. , hydroxyethylmethylcellulose, hydroxyethylcellulose, etc. are common. These cellulose ether-based thickeners are available on the market, for example under the trade names UWB and UWB-.
M (manufactured by Mitsui Petrochemicals Co., Ltd.), Marine Keep and Marine Keep L (manufactured by Tokuyama Soda Co., Ltd.), Cellcrete H and Cellcrete HB (manufactured by Daicel Chemical Co., Ltd.), Asuka Clean (manufactured by Shin-Etsu Chemical Co., Ltd.), Unishot A10 and Unishot F-350 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), etc., and these can be suitably used in the present invention. Further, acrylic thickening agents are mainly composed of polymers mainly composed of acrylamide, and these are also available on the market. For example, the product names include Sea Better (manufactured by Sankyo Kasei Kogyo Co., Ltd.), Acrys 12A and 12S (manufactured by Nisso Master Builders Co., Ltd.), and these can also be used in the present invention. The amount of these thickeners to be blended is appropriately determined depending on the concrete formulation and type of thickener, but in the case of cellulose ether thickeners, the amount should be 0.1 to 2.0% by weight of cement. Good. 0.1
If less than % by weight is added, the adhesive effect will not be sufficient;
This is because addition of more than 2.0% by weight is undesirable from the viewpoint of workability and excessive delay in curing reaction. Depending on the type of thickening agent, it is desirable to use a water reducing agent from the viewpoint of concrete consistency, and adding a thickening agent may entrain air bubbles into the mix. In such cases, it is desirable to add an appropriate amount of an antifoaming agent such as dibutyl phthalate, water-insoluble alcohols, tributyl phosphate, etc. The cement used in the present invention can be a well-known Portland cement, and the quick-setting agent can be a cement mineral type. There are virtually no restrictions on the type of aggregate, whether it is fine aggregate or coarse aggregate. As the mixer used in the method of the present invention, batch type, continuous type, and other commonly used mixers can be used. As the spraying machine, either a pump-feeding type spraying machine or a pneumatic-feeding type spraying machine can be used in the case of wet mixes, and a pneumatic-feeding type spraying machine can be used in the case of dry mixes. Example Wet mixes were made using a mixer installed outside the tunnel using the concrete mix shown in Table 1 and the method shown in Figure 3, and then transported to a spraying machine that was movably installed near the spraying site inside the tunnel. Approximately 30 to 50 minutes after mixing, it was sprayed onto the inner surface of the tunnel where spring water was occurring. As a result, the shotcrete did not peel or wash away even in areas where spring water was occurring, and a strong concrete layer was formed over the entire surface of the sprayed surface. In addition, although the formulation is the same, dry mixes are made using a mixer installed outside the tunnel using the method shown in Figure 5, and this is transported to a spraying machine that is movably installed near the spraying site inside the tunnel, and then sprayed. Water and quick-setting agent were added along the path from the machine to the spray nozzle and sprayed onto the inner surface of the tunnel where spring water was occurring. In this case as well, the shotcrete did not peel or wash away even in areas where spring water was occurring, and a strong concrete layer was formed over the entire sprayed surface. 【table】

[Brief explanation of the drawing]

1 to 6 are process diagrams showing the material mixing procedure of the method of the present invention.
Figures 6 to 6 show examples of loading dry mixes into a spraying machine. 1... Mixer, 2... Spraying machine, 3... Spraying nozzle, 4... Material pressure feeding route from the spraying machine to the spraying nozzle, 5... Thickening agent, 6... Rapid setting agent,
C...Cement, S...Fine aggregate, G...Coarse aggregate,
W...Water.

Claims (1)

[Claims] 1. Cement, aggregate, and water are put into a mixer and mixed, the resulting wet mix is charged into a spraying machine, and the mix is force-fed from the spraying machine to a spraying nozzle. When spraying the mix onto spring water surfaces or wet surfaces, mix the mixer with a thickening agent and a water-reducing agent, and load the resulting wet mix into the spray machine. A shotcrete construction method for a spring or wet surface characterized by adding an quick-setting agent to the wet mix in the route from the spraying machine to the spraying nozzle before the spraying nozzle. 2. Put the cement and aggregate into a mixer and knead it, then charge the resulting dry mix into a spraying machine, and add water along the route from the spraying machine to the spray nozzle while spraying the mix on the surface of spring water or in a wet area. When spraying on a surface, a thickening agent must be added during mixing in the mixer, and an accelerating agent must be added during mixing in the mixer or during the route from the spraying machine to the spray nozzle. A shotcrete construction method for spring or wet surfaces characterized by: