JP2571186C - - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of providing a concrete layer or a mortar layer by using a kneading / pneumatic pump at a place where construction is difficult, such as a slope in a mountainous area. The present invention relates to a pneumatically fed wet spray mortar for use in air conditioning. 2. Description of the Related Art In order to protect cliffs in mountainous areas and to prevent cliffs from falling, it is preferable to construct reinforced concrete retaining walls on cliffs. However, it was difficult even to secure a place for performing such work. As a method of taking up less space, a method of kneading a cement composition in advance and spraying the cement composition directly on a cliff surface by using air supplied by pressure is employed. As a special slope construction method using this spray construction method, a frame made of iron, wood, resin, cloth or paper is placed in advance on the slope and sprayed with a wet mortar kneaded on the frame. There is a construction method that protects cliffs with a concrete layer having the strength equivalent to reinforced concrete. There are various types of iron frames, including wire meshes, coil frames, punched metal, round bars, square bars, plates, H steel, and the like, used alone or in combination of two or more. In this method, for example, as shown in FIG. 1, a kneading / pneumatic pump called a gun having a hopper, a driving unit, a kneading unit, and a discharge port is installed, and a discharge port of a gun 1 and a nozzle 2 are connected to a hose 3. The worker climbs up the cliff while protecting the body with a rope from the cliff, and sprays concrete or mortar on the cliff surface 4. Reference numeral 5 denotes an aggregate, and a constant amount is sent to a mixer 7 by a belt conveyor while being measured by a measuring device 6. The cement 8 is put into the mixer 7, the aggregate and the cement are mixed, and further put into the hopper of the gun 1 by a belt conveyor. In the gun 1, a certain amount of water is added from the water tank 9, and water is added to the mixture of the aggregate and the cement and kneaded. The kneaded material is discharged by compressed air supplied from the compressor 10 and injected from the nozzle 2 to the cliff surface through the hose 3 for construction. Further, a method of directly charging the raw material to the gun 1 from the belt conveyor without using a mixer is also common. [0004] However, even with the above-mentioned method, the weight of the spraying machine set reaches about 4 tons, and a certain level of flat ground is required to set the spraying machine set. In addition, a hose of at least a length from the bottom of the cliff to the top of the cliff is required. The longer this hose is, the larger the area that can be constructed with one set of spraying machine is increased, which is preferable in terms of workability.If it is difficult to obtain a place to set the spraying machine,
The fact is that you have to work with a long hose even if you try. However, in reality, if the hose is too long, material separation occurs in the hose, and a kneaded material having an abnormally large amount of aggregate is discharged in a certain portion, and a kneaded material having an abnormally large amount of cement component is discharged in a certain portion. A phenomenon such as ejection occurs, and the uniformity of the entire sprayed material is impaired, and the quality, mainly the compressive strength, is significantly reduced. Further, in the cement kneaded material separated from the material as described above, the pulsation of the hose occurs. Using a hose with an inner diameter of 42 to 50 mm and blowing components containing cement and aggregate with high-pressure air, the energy of this pulsation is large,
In some cases, humans are blown away. [0006] When the installation location of the spraying machine is not available, a long hose must be used even if the above-mentioned problem is encountered. Additions have been made to increase the water / cement ratio, increase the amount of fine aggregate, and use fine aggregate having a low specific gravity and obviously reducing the quality of mortar, especially compressive strength. It is generally said that the strength of concrete is proportional to the water / cement ratio, and
% Must be maintained. In addition, the cement: fine aggregate ratio should be suppressed to about 1: 4. However, in order to avoid pulsation due to material separation, the water-cement ratio should be 60%.
% Or a spray mortar having a cement: fine aggregate ratio of about 1: 5 to 1: 7. In this way, increasing the amount of water and aggregates naturally lowers the strength.However, since the machine installation location cannot be secured, the part that was worked with a hose that was too long was covered with concrete with insufficient strength. Will be. Generally, the limit of the length of a hose that can be used by using a spray mortar having a cement mixing ratio that provides sufficient strength was about 100 to 120 m. [0008] The present invention is capable of working while preventing material separation and pulsation using a long hose even at a site distant from the spraying machine, and has sufficient strength for concrete and mortar construction. It is an object of the present invention to provide a pneumatic wet blast mortar capable of obtaining a surface. Means for Solving the Problems [0009] The constitution of the present invention is to provide a spray mortar obtained by mixing and kneading cement, aggregate and water,
A spray mortar used for a method of providing a mortar layer on a construction surface by blowing air from a nozzle tip by pneumatic feeding through a hose having a length of 100 m or more, wherein the spray mortar is based on 100 parts by weight of cement and Characterized in that 0.01 to 0.3 parts by weight of a polycarboxylic acid-based cement water-reducing agent component and 2 to 7 parts by weight of ultrafine powder are blended, preferably a polycarboxylic acid-based compound having an oxyethylene group. The oxyethylene group content of the cement water reducing agent component is 50% by weight or more. The cement in the present invention is a hydraulic material such as Portland cement, alumina cement, silica cement, slag cement, fly ash cement, rapid-hardening cement, and expansive cement. Portland cement is generally used. is there. As the aggregate, those commonly referred to as aggregate, such as natural aggregate, crushed aggregate (crushed stone, crushed sand), mining tail, lightweight aggregate and the like can be used. Although fine aggregates such as sand and larger coarse aggregates are used, in the present invention using a pneumatically fed wet spray mortar, the inner diameter of the hose is slightly thinner in a mortar using only fine aggregates, It is about 42 mm in diameter, and it is slightly thick in concrete using fine aggregate and coarse aggregate and about 50 mm. In this case, it is preferable to mix coarse aggregate having a diameter of 15 mm or less. The term “spray mortar” or “mortar” in the present invention is not limited to mortar in a narrow sense using only fine aggregate, but is a broad concept including concrete using slightly smaller coarse aggregate. Further, the term "spraying from the nozzle tip" in the present invention is a concept including spraying from the nozzle tip or the hose itself. The water reducing agent used in the present invention is a polycarboxylic acid cement water reducing agent. That is, it is a copolymer of a polymerizable carboxylic acid such as acrylic acid, methacrylic acid, and maleic anhydride with another monomer copolymerizable therewith, and has many carboxyl groups in the molecule. Maleic acid is preferably used as the polymerizable carboxylic acid. It is used as a free acid or as a salt of a cation such as an alkali metal or an alkaline earth metal. In the present invention, a water reducing agent using ethylene oxide is used as another monomer copolymerizable with the polymerizable carboxylic acid. It is not necessary that all of the other monomers be ethylene oxide, but it is preferable that the oxyethylene group content in the polymer is 50% by weight or more. As such a polymer, commercially available products such as FC-600S manufactured by Nippon Shokubai Chemical Co., Ltd. and Tupole HP8 manufactured by Takemoto Yushi Co., Ltd. can be easily obtained. The polycarboxylic acid-based cement water reducing agent containing an oxyethylene group has a remarkable effect in a small amount, and is a particularly excellent water reducing agent. The amount of use is 0.01 to 0.3 parts by weight as a water reducing agent active ingredient (substantially equivalent to the solid content in the case of using the above-mentioned commercial product) based on 100 parts by weight of cement. The ultrafine powder is a powder having an average particle diameter of 5 μm or less, which is insoluble or hardly soluble in water, and examples thereof include silica fume, fly ash, calcium carbonate, titanium oxide, and aluminum oxide. Silica fume by-produced during alloy production is particularly preferred. The ultrafine powder fills the gaps between the cement particles and densifies the cement coagulate, increasing its strength. When used in combination with the high-performance cement water reducing agent of the present invention, sufficient strength can be exhibited even when the water / cement ratio is large, and the length of the hose can be further extended. The used amount is 2 to 7 parts by weight based on 100 parts by weight of cement. If the amount exceeds 10 parts by weight, the workability decreases, and if the amount is less than 2 parts by weight, the effect is insufficient. It is easy to handle the ultrafine powder by using a slurry or paste of 20 to 50% by weight in advance. [0016] The spraying machine used in the present invention is not particularly limited, and a commercially available machine can be used. That is, a hopper into which a mixture of cement and aggregate can be added, a stirrer and a stirring space for adding and mixing water or ordinary water mixed with a water reducing agent and an admixture such as an ultrafine powder slurry to the charged mixture, and stirring. And a discharge port for pressure-feeding the obtained spray mortar together with the compressed air sent from the compressor. The present invention makes it possible to use a long hose for pumping a slurry when placing a concrete layer or mortar layer on a slope in a mountainous area where it is difficult to install an air pump. It is. In a long hose, the pulsation of the hose causes a danger to human life due to separation of the cement slurry, adhesion to the hose, and the like. The present invention prevents the pulsation of long hoses that could not be used conventionally, or even if used, had reduced the strength of mortar or concrete sprayed by changing the material mixing ratio while maintaining sufficient strength. It is made usable. That is, among the high-performance cement water reducing agents, the polycarboxylic acid-based cement water reducing agent containing an oxyethylene group was found to be particularly effective and completed. Polycarboxylic acid-based cement water reducing agent having an oxyethylene group has no significant difference from other polycarboxylic acid-based cement water reducing agents by looking only at its water-reducing performance, but as in the present invention. When using for wet spraying with a long hose,
It has a specific effect of preventing material separation in the hose. By using ultra-fine powder in combination with the high-performance water reducing agent of the present invention, spraying with a longer hose becomes possible without lowering the strength, and the water / cement ratio and the cement: aggregate ratio are properly maintained. On the other hand, it has become possible to cast high-strength mortar or concrete by a wet spray mortar construction method using a long hose as long as 250 m. Example 1 and Comparative Example 1 Ordinary Portland cement (specific gravity 3.15), fine aggregate (water sand from Teraizumi, Nagai-shi, Yamagata prefecture, specific gravity 2.58) and water / water using tap water were used. A spray mortar having a cement ratio of 56% and a cement: fine aggregate ratio of 1: 4 was prepared, which is a conventionally used spray mortar, which is referred to as Comparative Example 1. A polycarboxylic acid-based tap water was used. Using kneading water mixed with a cement water reducing agent (FC-600S, manufactured by Nippon Shokubai Kagaku Co., Ltd.), in the same manner as in Comparative Example 1 except that the amount of kneading water was increased or decreased so that the same fluidity as in Comparative Example 1 was obtained. A spraying mortar of Experiment No. 8 was prepared from Experiment No. 1 to Experiment No. 8. A kneading and spraying machine (gun 1), Sanwa S4C-1T (pneumatic feeding type), capacity 1
Using a compressor of 7.0m ³ / min, an electric weighing machine and a belt conveyor of 7m,
These were driven by a 10 KVA generator. Using a hose with an inner diameter of 42 mm with a nozzle at the tip, place a formwork with a width of 300 mm, a height of 300 mm, and a length of 1000 mm on a blue sheet, and apply mortar of various formulations until the formwork is full from the nozzle tip of the gun. Sprayed, cured on site. Two types of hoses having a length of 100 m and 160 m were used. After three days of spraying, four cylindrical cores having a diameter of 100 mm are cut vertically (about 300 mm in length) from the surface at equal intervals around the longitudinal center line of the surface of the sprayed body, and the next day, Both ends were cut to obtain a specimen having a length of 200 mm and a diameter of 100 mm, and the compressive strength of this specimen was measured. The strength after one week is on-site curing, 4
The strength after one week is the compressive strength of a specimen having a length of 200 mm and a diameter of 100 mm obtained by the above method, immersed in water and then cured in water. [Table 1] The separation resistance in Table 1 and Tables 2 and 3 described below was determined based on the following criteria by spraying mortar discharged from a nozzle and visually observing the uniform state. ◎: Extremely uniform state ：: Uniform state Δ: State where some separation was observed X: State where separation was performed to the point where work was impossible The workability was determined according to the following criteria. ：: There is no pulsation of the hose at all, and the work can be performed with confidence. ：: Slight pulsation is felt, but there is no problem in work. Δ: There is pulsation, but work is possible. ×: There is pulsation to the extent that work is impossible. Comparative Example 2 Work 500 (a copolymer of maleic acid and an unsaturated hydrocarbon having 5 carbon atoms) manufactured by Nippon Zeon Co., Ltd. was used as a polycarboxylic acid-based high-performance water reducing agent in an amount of 0 parts by weight with respect to 00 parts by weight of cement. A test was conducted in the same manner as in Example 1 except that .20 parts by weight was blended. The results are shown in Table 2 together with Comparative Example 1 and Experiment No. 5 of Example 1. [Table 2] Example 2 Spraying and testing were carried out in the same manner as in Example 1 except that a 20% slurry of silica fume was used as the ultrafine powder, and this slurry was blended at a ratio shown in Table 3 with respect to 100 parts by weight of cement. Table 3 shows the results. [Table 3] Example 3 Using the same equipment as in Example 1 except that the length of the hose was changed to 220 m, spraying mortar having the composition of Experiment No. 5 of Comparative Example 1 and Example 1 was sprayed. The test was performed in the same manner as in Example 1. In the case of Comparative Example 1, the separation and pulsation of the material were remarkably impossible. In the case of the experiment No. 5 in Example 1, the material separation was small, and pulsation was felt but the work was not affected. When the compressive strength of the sprayed mortar was measured in the same manner as in Example 1, the compressive strength after 4 weeks was 336 kgf / cm ² . According to the present invention in which a polycarboxylic acid cement water reducing agent having an oxyethylene group is added to a pneumatically fed wet spray mortar, the uniformity of the spray mortar can be maintained even after passing through a long hose. At the same time, high-strength mortar can be safely sprayed even in places with poor scaffolding. Further, by using the ultrafine powder together with the cement water reducing agent of the present invention, a mortar or concrete spray layer having higher strength can be obtained.

[Brief description of the drawings]     FIG.   FIG. 1 is an explanatory view showing a working state using a wet spray mortar.     [Explanation of symbols]   1 Gun   2 nozzles   3 hose   4 Cliff surface   5 Aggregate   6 measuring instrument   7 mixer   8 cement   9 Aquarium   10 Compressor

Claims (1)

[Claim 1] A mortar obtained by mixing and kneading cement, aggregate and water is blown from the nozzle tip by air pressure feeding through a hose having a length of 100 m or more, and mortar is applied to a construction surface. A spray mortar used in a method of forming a layer, wherein the spray mortar is mixed with 0.01 to 0.3 parts by weight of a polycarboxylic acid-based cement water reducing agent component having an oxyethylene group per 100 parts by weight of cement. Pneumatic wet blasting mortar. 2. The pneumatically fed wet spray mortar according to claim 1, wherein the polycarboxylic acid-based cement water reducing agent component having an oxyethylene group has an oxyethylene group content of 50% by weight or more. 3. A spray mortar obtained by mixing and kneading cement, aggregate and water, is pneumatically fed through a hose having a length of 100 m or more and sprayed from a nozzle tip, and is used in a method of providing a mortar layer on a construction surface. Spray mortar, wherein the spray mortar is 100 to 100 parts by weight of cement, a polycarboxylic acid-based cement water reducing agent component having an oxyethylene group, 0.01 to 0.3 parts by weight, and 2 to 7 parts by weight of ultrafine powder. Pneumatically fed wet spray mortar characterized by being compounded.