KR20160096753A - Method and System for spraying shotcrete - Google Patents
Method and System for spraying shotcrete Download PDFInfo
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- KR20160096753A KR20160096753A KR1020150017913A KR20150017913A KR20160096753A KR 20160096753 A KR20160096753 A KR 20160096753A KR 1020150017913 A KR1020150017913 A KR 1020150017913A KR 20150017913 A KR20150017913 A KR 20150017913A KR 20160096753 A KR20160096753 A KR 20160096753A
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- Prior art keywords
- shotcrete
- concrete
- filler
- slurry
- additive
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- 239000011378 shotcrete Substances 0.000 title claims abstract description 79
- 238000000034 method Methods 0.000 title claims abstract description 20
- 238000005507 spraying Methods 0.000 title claims abstract description 15
- 239000000945 filler Substances 0.000 claims abstract description 80
- 239000004567 concrete Substances 0.000 claims abstract description 50
- 239000000654 additive Substances 0.000 claims abstract description 38
- 239000002002 slurry Substances 0.000 claims abstract description 33
- 238000002156 mixing Methods 0.000 claims abstract description 32
- 230000000996 additive effect Effects 0.000 claims abstract description 26
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 20
- 239000000843 powder Substances 0.000 claims abstract description 19
- 238000003756 stirring Methods 0.000 claims abstract description 12
- 238000002347 injection Methods 0.000 claims abstract description 10
- 239000007924 injection Substances 0.000 claims abstract description 10
- 238000005422 blasting Methods 0.000 claims abstract 2
- 239000004568 cement Substances 0.000 claims description 34
- 239000000463 material Substances 0.000 claims description 28
- 239000002893 slag Substances 0.000 claims description 18
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 15
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 12
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 9
- 239000011707 mineral Substances 0.000 claims description 9
- 235000010755 mineral Nutrition 0.000 claims description 9
- 239000011398 Portland cement Substances 0.000 claims description 8
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 claims description 6
- 229910052808 lithium carbonate Inorganic materials 0.000 claims description 6
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims description 6
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 claims description 6
- 229910052939 potassium sulfate Inorganic materials 0.000 claims description 6
- 235000011151 potassium sulphates Nutrition 0.000 claims description 6
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 6
- AEQDJSLRWYMAQI-UHFFFAOYSA-N 2,3,9,10-tetramethoxy-6,8,13,13a-tetrahydro-5H-isoquinolino[2,1-b]isoquinoline Chemical compound C1CN2CC(C(=C(OC)C=C3)OC)=C3CC2C2=C1C=C(OC)C(OC)=C2 AEQDJSLRWYMAQI-UHFFFAOYSA-N 0.000 claims description 5
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 5
- FEWJPZIEWOKRBE-JCYAYHJZSA-N Dextrotartaric acid Chemical compound OC(=O)[C@H](O)[C@@H](O)C(O)=O FEWJPZIEWOKRBE-JCYAYHJZSA-N 0.000 claims description 5
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 5
- FEWJPZIEWOKRBE-UHFFFAOYSA-N Tartaric acid Natural products [H+].[H+].[O-]C(=O)C(O)C(O)C([O-])=O FEWJPZIEWOKRBE-UHFFFAOYSA-N 0.000 claims description 5
- 235000015165 citric acid Nutrition 0.000 claims description 5
- 239000000176 sodium gluconate Substances 0.000 claims description 5
- 229940005574 sodium gluconate Drugs 0.000 claims description 5
- 235000012207 sodium gluconate Nutrition 0.000 claims description 5
- 239000007921 spray Substances 0.000 claims description 5
- 239000011975 tartaric acid Substances 0.000 claims description 5
- 235000002906 tartaric acid Nutrition 0.000 claims description 5
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims description 3
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 3
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 claims description 3
- XFWJKVMFIVXPKK-UHFFFAOYSA-N calcium;oxido(oxo)alumane Chemical compound [Ca+2].[O-][Al]=O.[O-][Al]=O XFWJKVMFIVXPKK-UHFFFAOYSA-N 0.000 claims description 3
- 239000011591 potassium Substances 0.000 claims description 3
- 229910052700 potassium Inorganic materials 0.000 claims description 3
- 229910000027 potassium carbonate Inorganic materials 0.000 claims description 3
- 239000011734 sodium Substances 0.000 claims description 3
- 229910052708 sodium Inorganic materials 0.000 claims description 3
- 235000015424 sodium Nutrition 0.000 claims description 3
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 3
- 235000011152 sodium sulphate Nutrition 0.000 claims description 3
- 238000007865 diluting Methods 0.000 claims 1
- 239000012530 fluid Substances 0.000 claims 1
- 239000007788 liquid Substances 0.000 description 12
- 239000004570 mortar (masonry) Substances 0.000 description 11
- 238000009412 basement excavation Methods 0.000 description 8
- 239000000203 mixture Substances 0.000 description 7
- 239000002994 raw material Substances 0.000 description 7
- 239000000428 dust Substances 0.000 description 6
- 238000002474 experimental method Methods 0.000 description 6
- 230000008901 benefit Effects 0.000 description 5
- 230000036571 hydration Effects 0.000 description 5
- 238000006703 hydration reaction Methods 0.000 description 5
- 239000012615 aggregate Substances 0.000 description 4
- 238000010348 incorporation Methods 0.000 description 4
- 238000010276 construction Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 239000012764 mineral filler Substances 0.000 description 3
- 239000011435 rock Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 238000003823 mortar mixing Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- -1 However Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 239000011400 blast furnace cement Substances 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 229910001653 ettringite Inorganic materials 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000000116 mitigating effect Effects 0.000 description 1
- 239000010893 paper waste Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 230000005641 tunneling Effects 0.000 description 1
- 230000003313 weakening effect Effects 0.000 description 1
- 239000000080 wetting agent Substances 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B22/00—Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators, shrinkage compensating agents
- C04B22/02—Elements
- C04B22/04—Metals, e.g. aluminium used as blowing agent
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/14—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing calcium sulfate cements
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/10—Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Structural Engineering (AREA)
- Mining & Mineral Resources (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
The present invention relates to a shotcrete jetting method and a jetting system.
A method of spraying shotcrete according to the present invention is a method of spraying a shotcrete mixed with concrete, a filler, and an additive onto a blasting surface using an injection system,
The injection system includes a spraying body formed in a hollow shape and connected to a concrete supply line at a rear end thereof and having a nozzle portion at its tip, a stirring tank for mixing a filler, an additive and water to form a slurry, A connecting line connected to the chamber immediately after the nozzle portion of the jetting member and an injecting device provided in the connecting line for feeding the slurry to the jetting body through the connecting line,
The filler is in powder form and is characterized by slurry mixed with water and mixed with concrete to form shotcrete just before the concrete is sprayed on the wave front.
Description
TECHNICAL FIELD The present invention relates to a shotcrete spraying method for spraying a shotcrete as a support material, and a shotcrete spraying system used therefor.
Shotcrete is a mixture of concrete and additives. It is sprayed on the excavation surface by using compressed air immediately after excavation of the rock mass, so that the ground is closely contacted to suppress the loosening of the ground and to smooth the unevenness of the surface.
When the shotcrete is injected onto the excavation surface, it is possible to prevent cracks from expanding to the ground by the stress concentration due to the excavation and to prevent the weathering of the excavation surface, thereby stabilizing the excavation. As a result, shotcrete plays an important role as a tunnel support material for the NATM (New Australian Tunneling Method) method used in domestic tunnel construction.
The shotcrete increases the shear resistance of the excavated surface so that the rock mass on the surface of the excavation surface is prevented from falling down due to gravity action and the resistance against flexural compression or axial force is increased to generate internal pressure in the surrounding ground, It has an effect of preventing weakening. Especially, it is very effective in mitigating the stress concentration in the soft rock and the soil and forming the ground arch which forms the ground arch near the wall of the tunnel by giving the shear resistance to cracks and cracks around the tunnel.
From the viewpoint of material, shotcrete is a mixture of concrete and paper-based material. Powdered paper-based materials and liquid-based paper-based materials are mainly used as the paper materials.
Powder type filler is widely used as a shotcrete filler because of its high strength and high toughness. However, when a powdery filler is used, too much dust is generated at the work site and the working conditions are remarkably lowered. In addition, the powdery filler is mixed with the concrete just before the concrete is sprayed, and it is pointed out that the mixing ratio of the powder and the concrete is extremely low. In particular, concrete is injected at a constant rate and amount, and the supply of the powder is supplied with a period of time, just like a pulsating phenomenon. Therefore, when the concrete is continuously laminated, the amount of the powder mixture differs greatly depending on the layer. In other words, in the shotcrete layer, areas including quick-setting and areas not included are alternately displayed. As a result, the shotcrete does not settle on the excavation surface in the area where the filler is not included, and is easily dropped off, thereby increasing the rebound ratio.
Although the liquid phase type filler has a great advantage in that it has excellent mixing ratio with concrete and does not cause dust problems, the strength of the shotcrete is lower than that of the powder type filler and the drawability thereof is lower than that of the powder type filler .
It is an object of the present invention to provide a shotcrete jetting method and a shotcrete jetting system using a slurry-type water-dispersible material so as to satisfy not only the dust generation but also the strength and toughness of the shotcrete .
According to an aspect of the present invention, there is provided a shotcrete spraying system comprising: a spray body formed in a hollow shape and connected to a concrete supply line at a rear end thereof and having a nozzle at a tip thereof; A connecting line connected to the stirring tank and a chamber immediately below the nozzle portion of the jetting body and an injecting device provided on the connecting line for feeding the slurry to the jetting body through the connecting line, .
In addition, in the shotcrete spraying method using the injection system, the powdery filler, the additive and the water are mixed in advance in the mixing tank to form a slurry state, and then the slurry-type filler is fed to the jetting body, The concrete and the slurry type filler are mixed to form the shotcrete.
In one embodiment of the present invention, the powder-type filler may be a mineral-based powder filler including C 12 A 7 , CSA and calcium aluminate.
Further, in one embodiment of the present invention, the additive preferably comprises sodium gluconate, citric acid and tartaric acid.
The additive may be a carbonate-based additive such as lithium carbonate, sodium carbonate, potassium carbonate, or a sulfate-based additive such as sodium sulfate, potassium sulfate, sodium aluminosulfate, potassium aluminosulfate and aluminum sulfate, have. Particularly, it is more preferable to include sodium carbonate, potassium sulfate, and lithium carbonate as additives.
In an embodiment of the present invention, the amount of the filler and the additive is in the range of 3 to 10 parts by weight based on 100 parts by weight of the concrete, and the additive is mixed in the range of 0.1 to 1 part by weight with respect to 100 parts by weight of the filler .
Also, in one embodiment of the present invention, the concrete usually includes mixed cement in which Portland cement and slag cement are mixed, and the slag cement is preferably blended in a range of 10 to 50 wt% in the total cement.
In the shotcrete spraying method according to the present invention, the following effects can be obtained by using the slurry-type filler.
First, the strength of shotcrete increases. As described in the prior art, the compressive strength of the powdery filler is much larger than that of the liquid filler when compared with the currently used powdery filler and the liquid filler. In the present invention, the powdery filler is a raw material and the compressive strength is increased although the filler is in the form of a slurry.
Second, the rebound ratio of shotcrete is significantly lower than that of liquid type filler. That is, since the powdery type water-dispersible material is superior in the tackability as compared with the liquid type water-dispersible material, the shotcrete is sprayed on the blade surface, In the present invention, since the powdery filler is used as a raw material, the advantages thereof are maintained.
Third, the use of a slurry-type filler improves the mixing ratio with concrete. The powder type filler has a disadvantage in that the mixing ratio with the concrete is low as described above. However, since the slurry type filler has a good mixing ratio with concrete, the quality of the shotcrete discharged from the spray device is advantageously kept constant. Moreover, since the powdery filler is supplied while pulsating, the powder can not be supplied in a certain ratio and amount, and the amount varies depending on the amount supplied. As a result, the quality of the shotcrete is not stable due to excessive mixing of the water-swellable material with the concrete over time or too little mixing with the concrete. However, when the slurry-type dispenser is used as in the present invention, the quality of the shotcrete can be stably maintained because the dispenser can be supplied at a constant rate and amount through the pump.
Fourth, since the slurry-type dispenser is supplied by mixing the powder-type dispenser with water in the stirring tank, it is advantageous in that it is free from the generation of dust in the workplace which is pointed out as a weak point of the powder-type dispenser. As the working conditions are improved, the shotcrete can be installed more effectively.
1 is a schematic view of a shotcrete jetting system according to an embodiment of the present invention.
The table in FIG. 2 is a table showing the composition of ordinary portland cement and blast furnace slag cement as raw materials of shotcrete.
The table in FIG. 3 shows the composition of the shotcrete sample for the experiment of the present invention.
The graphs of FIGS. 4 and 5 show the agglomeration times of the respective fillers according to the BFS mixing amount.
6 to 8 are the results obtained by measuring the strength of one day using each of the paper materials, FIG. 6 is a liquid-phase paper-based material, FIG. 7 is a cement mineral system, and FIG. 8 is a slurry- Strength).
Hereinafter, a shotcrete jetting system and a shotcrete jetting method using the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
1 is a schematic view of a shotcrete jetting system according to an embodiment of the present invention.
Referring to FIG. 1, a
The
The connecting
The
The most important technical feature in the shotcrete jetting system having the above-described constitution is that the powdery filler is mixed with water to form a slurry, and then the slurry filler is mixed with the concrete. More fundamentally, the present invention is important in that the powdery filler is mixed with concrete in the form of a slurry. For this purpose, the
When the powdery filler is formed into a slurry form, various advantages arise.
First, the strength of shotcrete increases. As described in the prior art, the compressive strength of the powdery filler is much larger than that of the liquid filler when compared with the currently used powdery filler and the liquid filler. In the present invention, the powdery filler is a raw material and the compressive strength is increased although the filler is in the form of a slurry.
Second, the rebound ratio of shotcrete is significantly lower than that of liquid type filler. That is, since the powdery type water-dispersible material is superior in the tackability as compared with the liquid type water-dispersible material, the shotcrete is sprayed on the blade surface, In the present invention, since the powdery filler is used as a raw material, the advantages thereof are maintained.
Third, the use of a slurry-type filler improves the mixing ratio with concrete. The powder type filler has a disadvantage in that the mixing ratio with the concrete is low as described above. However, since the slurry type filler has a good mixing ratio with concrete, the quality of the shotcrete discharged from the spray device is advantageously kept constant. Moreover, since the powdery filler is supplied while pulsating, the powder can not be supplied in a certain ratio and amount, and the amount varies depending on the amount supplied. As a result, the quality of the shotcrete is not stable due to excessive mixing of the water-swellable material with the concrete over time or too little mixing with the concrete. However, when the slurry-type dispenser is used as in the present invention, the quality of the shotcrete can be stably maintained because the dispenser can be supplied at a constant rate and amount through the pump.
Fourth, since the slurry-type dispenser is supplied by mixing the powder-type dispenser with water in the stirring tank, it is advantageous in that it is free from the generation of dust in the workplace which is pointed out as a weak point of the powder-type dispenser. As the working conditions are improved, the shotcrete can be installed more effectively.
That is, in the present invention, only the merits of the powdery filler and the liquid filler are retained, and the strength, mixing ratio, and uniform quality of the shotcrete can be maintained as they are.
Hereinafter, the material and properties of the shotcrete used in the present invention will be described.
In the present invention, shotcrete is formed by mixing concrete and a slurry-type filler. Concrete is manufactured by mixing cement, aggregate, and water. Cement can usually be used as portland cement. However, the present invention is characterized in that a part of portland cement is replaced with slag cement. Slag cement is an economical material with excellent chemical resistance including salt resistance, high long-term strength. However, since slag cement has low initial hydration rate, initial strength is lower than ordinary portland cement. Therefore, there is a limit to the use of shotcrete materials that require rapidity. However, in one embodiment of the present invention, the slag cement is blended in the range of 10 to 50 wt% in the whole cement. In the present invention, the weak point of the slag cement is compensated by using the powdery filler and the additive in the form of a slurry. As will be explained below, the initial strength of the shotcrete is guaranteed above the current construction standard, even though slag cement is used. Moreover, the slag cement has a stronger point than the portland cement at long-term compressive strength. When the weakness against the initial compressive strength is compensated as in the present invention, excellent quality as shotcrete can be assured.
The slurry-type filler is formed by mixing a powdery filler and an additive in water, and the combined amount of the powdery filler and the additive is mixed in a range of 3 to 10 parts by weight based on 100 parts by weight of the cement. The additives are mixed in the range of 0.1 to 1 part by weight based on 100 parts by weight of the powdery filler.
The powdery filler is a mineral filler based on amorphous C 12 A 7 (12CaO · 7Al 2 O 3 ), calcium sulfoaluminate (CSA) and calcium aluminate. And the additives include sodium gluconate, citric acid and tartaric acid. The above three additives act to prevent hydration in the agitating tank and to increase the strength of the shotcrete before the powdered filler is mixed with the concrete. That is, the main reason that the conventional powder-type water-dispersible powder is not mixed with water to form a slurry is that the powder-type water-dispersible powder does not react smoothly with the water, However, additives such as sodium gluconate, citric acid, and tartaric acid can alleviate the level of water solubility to some extent and mix with concrete and then hydrate rapidly. In addition, one embodiment of the present invention further includes a carbonate-based and sulfate-based additive. That is, lithium carbonate, sodium carbonate, and potassium carbonate are used as the carbonate additive, and sodium sulfate, potassium sulfate, sodium aluminosulfate, potassium aluminosulfate, and aluminum sulfate are used as the sulfate based additives. It is found that these mainly improve the strength of shotcrete and control the solidification speed of the powdery filler.
It has been found through repeated experiments of the present inventors that the most effective combination of additives for strength and saturation of shotcrete is to mix sodium carbonate, potassium sulfate and lithium carbonate together with sodium gluconate, citric acid and tartaric acid as described above. When 6 additives are mixed, it is confirmed that the slurry - type filler does not solidify before mixing with concrete, and that after forming shotcrete by mixing with concrete, the quickness and initial strength are guaranteed.
Hereinafter, results of a shotcrete test using a slurry type filler (including additives) in concrete (OPC and slag cement) according to the present invention will be described.
1. Performance Evaluation of Each Waste Paper by Slag Mixing Ratio
In order to evaluate the performance of the slurry cement binder used for increasing the flame resistance of shotcrete, we have conducted experiments on the liquid alkali-free system, the powder mineral system and the slurry-type water-dispersible material newly developed in the present invention . Shotcrete mortar was prepared according to the mixing ratio of slag. The properties of the mortar were investigated experimentally.
2. Experimental material
The cement used in this experiment was one kind of ordinary Portland cement (hereinafter referred to as OPC) having a specific surface area of 3,400 cm 2 / g of H Company. The blast furnace slag fine powder was a 1-type slag fine powder having a specific surface area of 4,300 cm 2 / g ) Were used. The chemical composition of OPC and BFS is shown in the table of FIG. Fine aggregate for shotcrete mortar was used for ISO standard for strength measurement. In this experiment, the recommended amount of 10% and 7% were applied to the alkali-free system of domestic S company, the cement mineral system of domestic U company, and the newly developed slurry C 12 A 7 system, respectively. Was applied at 7%.
3. Shotcrete mortar mixing condition
The mortar was prepared as shown in Table 3 with a water-binding ratio of 0.485 and a binding material: fine aggregate ratio of 1: 3 in the shotcrete mortar. In the early stage, BFS was replaced with 0 ~ 30% of OPC in units of 10% to evaluate the performance of each paper. However, the performance of the new slurry type paper filler was superior to that of BFS, 80% OPC was replaced with BFS. Mortar mixing and quick-setting mixing were carried out in accordance with KS F 2782.
4. Experimental Method
(1) Setting time
The settling time of shotcrete mortar was measured in accordance with KS F 2763, and the initial and final times were determined as the time when the penetration resistance values were 3.5 MPa and 28 MPa, respectively.
(2) Compressive strength
Shotcrete mortar was molded into a 50
5. Results and discussion
(1) Setting time
The graphs of FIG. 4 (crispness) and FIG. 5 (closing) show the setting time of the respective fillers according to the BFS content. The alkali-free system and the cement mineral system were similar, but the alkali-free system was much slower than the cement mineral system. As the BFS content increased, the freshness and the finishing time increased. However, the slurry type C 12 A 7 solidifying agent, which was a new filler, showed a decrease in condensation time as the BFS content increased. Respectively. This is probably due to the activation of Ettringite of C 12 A 7 as the free-CaO content derived from BFS increases. For each of the filler materials, the BFS content rate was within 30 minutes, within 5 minutes of the KS standard, and within 15 minutes.
(2) Compressive strength
According to Korea Highway Corporation's specifications, the daily strength of shotcrete is required to be over 9.8MPa and the strength of shotcrete over 19.6MPa. In addition, KS F 2782 is applied to mortar as a quick-setting standard and requires more than 9MPa strength per day and 75% strength ratio on 28 days. Thus, the strength of each paper by one day was measured, and the results are shown in the graphs of FIGS. 6 to 8. FIG. The cement mineral system and the new slurry-type quick-setting admixture met all of these criteria, but the alkali-free admixture did not satisfy the one-day strength standard regardless of the BFS incorporation rate. All of the cement mineral fillers were able to secure more than the reference strength, and the compressive strength of 1 day was decreased with the mixing ratio. In particular, when 20% of BFS was incorporated, the strength was lowered to the level of barely satisfying the daily compressive strength standard. For the newly developed slurry type filler, the reduction of the compressive strength per day by the incorporation rate of BFS was very small as compared with the case of using other fillers. The initial strength was very good and the BFS content was 70% The results are as follows.
Compared with the results of the strength of the cement mineral system, which is known as C 12 A 7 , the main raw material is considered to be a strength-dependent expression based solely on the hydration of C 12 A 7 and other cured admixtures of the new slurry-type filler And the strength of the conventional slag cement is considerably different from that of the conventional cement. Therefore, the strength development characteristics of the BFS mixed cement using the new slurry-type filler are not limited to that of C 12 A 7 , but also the interaction between the additive for slurrying the filler powder and the BFS, It is considered that hydration of hard raw material is accompanied by hydration of BFS itself, which is consistent with the result that the setting time of the mortar of the new slurry wetting agent decreases as the BFS incorporation ratio increases. Generally, in the mortar test, as the BFS incorporation rate increases, the strength decreases not only in the 1-day compressive strength but also in the 28-day compressive strength (see the graph in FIG. 8) Strength was equal to or higher than that of mortar with only OPC up to the mixing ratio ~ 60%.
Based on the above-mentioned experimental results, it was confirmed that the shotcrete according to the present invention is excellent in the setting time and compressive strength as compared with the liquid type filler and the mineral filler.
Particularly, by using the slurry-type water-dispersible material, the dust is not generated when the shotcrete is poured, and therefore, the working condition is improved, so that it can provide a very advantageous advantage in practical application of the field construction.
100 ... shotcrete injection system
10 ...
30 ...
Claims (13)
The jetting system includes a jetting body formed in a hollow shape and connected to a concrete supply line at a rear end thereof and having a nozzle portion at its tip, a stirring tank for mixing the diluting material, the additive and the water to form a slurry, The other end of the tank is connected to a chamber immediately after the nozzle portion of the jetting body, and an injecting device provided on the connecting line for feeding the slurry to the jetting body through the connecting line,
Wherein the filler is mixed with water to form a shotcrete immediately before the concrete is sprayed onto the surface of the concrete in the form of a slurry mixed with water to form a shotcrete.
Wherein the filler is a mineral powder filler including C 12 A 7 , CSA and calcium aluminate.
Wherein the additive comprises sodium gluconate, citric acid and tartaric acid.
Wherein the additive comprises a carbonate-based or sulfate-based additive.
Wherein the carbonate-based additive is at least one of lithium carbonate, sodium carbonate, and potassium carbonate.
Wherein the sulfate-based additive is at least one of sodium sulfate, potassium sulfate, sodium aluminosulfate, potassium aluminosulfate, and aluminum sulfate.
Wherein the additive comprises sodium carbonate, potassium sulfate, lithium carbonate.
Wherein the sum of the amount of the filler and the additive is in the range of 3 to 10 parts by weight based on 100 parts by weight of the concrete.
Wherein the additive is mixed in a range of 0.1 to 1 part by weight with respect to 100 parts by weight of the filler.
Wherein the pressurized fluid is high-pressure compressed air.
Wherein the concrete comprises slag cement.
Wherein the cement contained in the concrete usually includes Portland cement and slag cement, and the slag cement is blended in a total amount of 10 to 50 wt% in the total cement.
A spray body formed in a hollow shape and connected to a concrete supply line at a rear end thereof and having a nozzle portion at a tip end thereof;
An agitating tank for mixing a filler, an additive and water to form a slurry;
A connecting line connected to the stirring tank and a chamber immediately below the nozzle portion of the jetting body; And
And an injection device provided in the supply line for feeding the slurry to the spray through the connection line,
Wherein the quick-setting material is mixed with water to form a shotcrete immediately before the concrete is sprayed onto the surface of the concrete in a slurry state mixed with water.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2019085424A1 (en) * | 2017-10-30 | 2019-05-09 | 中国矿业大学 | Smart grouting system and grouting method for geologically complex regions |
| CN111039585A (en) * | 2019-12-31 | 2020-04-21 | 山东永正水泥有限公司 | Composite mineral powder, preparation method and application |
| CN111441772A (en) * | 2020-03-26 | 2020-07-24 | 河北大白阳金矿有限公司 | Striping and roof cutting stoping method for pre-control roof-pillar method |
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2015
- 2015-02-05 KR KR1020150017913A patent/KR20160096753A/en active Search and Examination
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2019085424A1 (en) * | 2017-10-30 | 2019-05-09 | 中国矿业大学 | Smart grouting system and grouting method for geologically complex regions |
| CN111039585A (en) * | 2019-12-31 | 2020-04-21 | 山东永正水泥有限公司 | Composite mineral powder, preparation method and application |
| CN111441772A (en) * | 2020-03-26 | 2020-07-24 | 河北大白阳金矿有限公司 | Striping and roof cutting stoping method for pre-control roof-pillar method |
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