JP2016041640A - Accelerator for spray material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mortar or concrete system that has excellent adhesion to natural grounds, excavation surfaces, slopes, etc. and can be subjected to finishing adjustment after spraying, and quickly forms a hardened product after the construction. Get the spray material.
A and (A) CaO and Al ₂ O molar ratio of _{3 (CaO / Al 2 O 3} ) is the active ingredient of the glass content of at least 90% of calcium aluminate of 2 to 2.4, as chemical components Fe ₂ O ₃ was contained 1-2.5 wt%, and CaO and Al ₂ O ₃ and Fe ₂ O 100 parts by weight powder of clinker total content is not less than 95 mass% of ₃ as a chemical component, ( B) Rapid setting material for spraying material containing 11-16 parts by mass of alkali metal aluminate, (C) 9-18 parts by mass of alkali metal carbonate and (D) 45-80 parts by mass of gypsum.
[Selection figure] None

Description

  The present invention relates to a spray material made of mortar or concrete.

  For excavation and construction work such as tunnels, underground spaces, and steep slopes, mortar and concrete are sprayed on natural ground and walls for reinforcement. In this case, a quick setting agent such as sodium aluminate or amorphous calcium aluminate is added to the mortar or concrete used for spraying, and the cement is condensed immediately after water injection, and the sprayed material is adhered and fixed. It is carried out. By the way, the sprayed spray material may be left to cure as it is, but depending on the purpose, the surface layer of the sprayed spray material may be leveled and finished. In this case, the sprayed material after spraying needs to keep a state suitable for finishing construction for a certain period of time. A common method for ensuring a state where the spraying material containing the quick setting agent can be applied is to use a setting retarder. (For example, refer to Patent Documents 1 and 2.) However, the use of a setting retarding agent delays the setting reliably, so that even if it is sprayed, it bounces off, and the sprayed sprayed material also drips, peels off or remains deadly deformed. There is a problem of curing. This tendency is more apparent as the spray is sprayed to increase the thickness of the spray. In particular, in the case of an organic acid-based setting retarder, the retarding action increases as the temperature decreases, so that the adhesion is significantly reduced in a low temperature environment. In addition, in order to prevent a rapid increase in strength immediately after spraying, for example, when using a quick setting agent such as calcium chloride or sodium silicate that does not have a rapid setting power, adhesion may not be possible if sprayed immediately after water injection. For this reason, time management from water injection to spraying is difficult, and it is not practical to apply to spraying material on a production scale. In addition, measures to ensure pot life such as increasing the water-cement ratio of mortar and concrete for spraying and keeping the blending ratio of calcium aluminate and sodium aluminate low are insufficient for quick setting and initial strength. Sex is reduced. (For example, refer to Patent Document 3.)

  In this way, with mortar and concrete-based spray materials that use a quick setting agent, it is very difficult to achieve both adhesion and finish construction applicability of the sprayed material after spraying. While maintaining good quick setting immediately after spraying, a rapid increase in strength is temporarily suppressed after about 30 seconds from the time of water injection, and the workable condition such as finishing adjustment is maintained for a certain period of time after spraying. In addition, it must be said that it is impossible to obtain a spray material that hardens quickly and firmly after this workable state.

JP-A-10-78886 JP 2006-151760 A JP 2004-123535 A

  In view of the above circumstances, the present invention can provide sufficient spraying adhesion while preventing the instantaneous setting of the mortar / concrete spray material, and is suitable for construction such as finishing adjustment for the spray material immediately after spraying. Providing a quick-setting material for spraying material that can suppress the strength increase to about a level after about 30 seconds from water injection and can increase the strength until a hardened and hardened state is obtained after the construction. It is possible to perform finishing adjustment after spraying, which has good adhesion that hardly resists rebounding, dripping or peeling, and is hardly affected by temperature. It aims at providing the spraying material which becomes.

  As a result of investigations to solve the above problems, the present inventor has a specific amount of clinker powder, alkali metal aluminate, alkali metal carbonate and gypsum containing specific calcium aluminate and specific chemical components. As a quick setting material for spraying material, the above problems could be solved as a whole by mixing it with mortar or concrete to complete the present invention.

That is, this invention is the spraying material for spraying materials represented by following (1), and the spraying material represented by (2)-(3). (1) (A) Calcium aluminate with a vitrification ratio of 90% or more having a molar ratio of CaO to Al ₂ O ₃ (CaO / Al ₂ O ₃ ) of ₂ to 2.4 is used as an active ingredient, and Fe is used as a chemical ingredient. the ₂ O ₃ containing 1 to 2.5% by weight and 100 parts by weight powder of clinker total content of CaO and Al ₂ O ₃ and Fe ₂ O ₃ is not less than 95 mass% as chemical components, (B ) Rapid setting material for spraying material containing 11-16 parts by mass of alkali metal aluminate, (C) 9-18 parts by mass of alkali metal carbonate, and (D) 45-80 parts by mass of gypsum. (2) A spraying material containing cement and the quick setting material for spraying material of (1). (3) The spray material according to (2), further comprising a water reducing agent.

  According to the present invention, it has excellent adhesion to natural grounds, excavation surfaces, slopes, etc. without being affected by the temperature, and after spraying it can be applied to finish adjustments etc. Can quickly obtain a mortar or concrete-based spray material that forms a strong cured product.

The clinker powder (A) contained in the quick setting material for spraying material of the present invention is preferably a raw material from which a content of CaO, Al ₂ O ₃ and Fe ₂ O ₃ can be obtained as chemical components by heat treatment or the like. It is obtained by heating the clinker, more preferably quenching after heating, and pulverizing the obtained clinker. Examples of the raw material from which Fe ₂ O ₃ is obtained as a chemical component by heating (hereinafter referred to as Fe ₂ O ₃ source raw material) include Fe ₂ O ₃ itself, Fe ₂ O ₃ hydrate, and iron carbonate. Salts, iron hydroxides, iron nitrates and the like. Examples of the raw material from which CaO (hereinafter referred to as CaO source raw material) is obtained as a chemical component by heating include calcium carbonate, calcium hydroxide, calcium monocarboxylate and the like in addition to CaO. Examples of raw materials from which Al ₂ O ₃ can be obtained by heating (hereinafter referred to as “Al ₂ O ₃ source raw materials”) include, for example, Al ₂ O ₃ itself, aluminum carbonates and hydroxides, bauxite, and the like. And minerals such as boehmite. Similarly, minerals containing any two or more of Fe ₂ O ₃ source, CaO source and Al ₂ O ₃ source may be used as raw materials. The inclusion of impurities in the raw material used is allowed as long as the effect of the present invention is not lost, but the total content of CaO, Al ₂ O ₃ and Fe ₂ O ₃ as chemical components of the clinker obtained by heating the raw material. The amount should occupy 95% by mass or more of the clinker amount. If it is less than 95% by mass, the quick setting property is lowered, and it becomes difficult to obtain a spraying material having good adhesion.

The heating of the raw material may be performed at a temperature at which the mixture of the raw material to be the CaO source and the raw material to be the Al ₂ O ₃ source having a predetermined mixing ratio is melted at least, and the raw material to be the Fe ₂ O ₃ source is considered. The heating temperature may be set without doing so. Specifically, for example, 1500 to 1700 ° C. is a standard, but it is more preferable to determine the details by a preliminary experiment or the like in consideration of the used raw material and the holding time at the heating temperature. It is desirable that the atmosphere during heating is other than a reducing atmosphere because excessive oxygen desorption can be suppressed.

Further, the powder of the clinker (A) has a CaO and Al ₂ molar ratio of _{O 3 (CaO / Al 2 O} 3) is the active ingredient of the glass content of at least 90% of calcium aluminate of 2 to 2.4 To do. By using calcium aluminate having such a vitrification ratio and a molar ratio as an active ingredient, good quick setting can be imparted to the spray material. If the vitrification rate of the calcium aluminate is less than 90%, the quick setting property is insufficient and the adhesion at the time of spraying is liable to decrease, which is not preferable. Further, the CaO and the molar ratio of the content of _{Al 2 O 3 (CaO / Al} 2 O 3) is less than 2 calcium aluminate is not preferable because the adhesion may be lowered quick-setting property is insufficient, by mol Calcium aluminate having a ratio (CaO / Al ₂ O ₃ ) exceeding 2.4 is not preferable because instantaneous setting properties are strong and the spray material may be solidified before adhering to the object.

The clinker contains 1 to 2.5% by mass of Fe ₂ O ₃ as a chemical component. Preferably, Fe ₂ O ₃ as a chemical component is included in an amount of 1.2 to 1.6% by mass. By containing 1 to 2.5% by mass of Fe ₂ O ₃ as a chemical component, it is possible to prevent instantaneous setting, and in particular, it is possible to sufficiently suppress a rapid increase in strength accompanying rapid progress of condensation after about 30 seconds since water injection. . As a result, there is no inadequate construction such as finishing adjustment for spraying material immediately after spraying due to rapid curing as seen with spraying materials using ordinary quick setting agents, and finish adjustment to sprayed spraying material for a while It becomes possible to perform such construction. If the content of Fe ₂ O ₃ as a chemical component is less than 1% by mass, the instantaneous setting property becomes too strong, the clogging occurs in the material passage of the spraying device, or it is almost terminated before reaching the spraying surface. It is not preferable because it lacks adhesion. Moreover, when it exceeds 2.5 mass%, quick setting property will fall and it will become easy to occur dripping and peeling of a spray, and is unpreferable. All Fe ₂ O ₃ as chemical components must be present in the clinker, and the form of presence in the clinker is not particularly limited. On the other hand, it is not contained in the clinker. For example, in the case where a commercial reagent of Fe ₂ O ₃ is mixed with clinker powder of amorphous calcium aluminate, it is expressed when Fe ₂ O ₃ as a chemical component is contained in the clinker. It is not appropriate because it is considerably inferior to the action and effect.

The fineness of the clinker powder is not limited. In order to obtain a rapid hardening and strength development of moderate preferably to 4500cm ² / g~8000cm ² / g in Blaine specific surface area. More preferably, the specific surface area of Blaine is 4500 to 6500 cm ² / g. However, instead of adjusting the fineness by using the clinker alone, the particle size of the quick setting material for spraying material containing the clinker powder can be adjusted. In this case, it is desirable that the specific surface area of Blaine is 4000 to 5500 cm ² / g because optimum reaction activity can be easily obtained to achieve the effects of the present invention.

  Moreover, the quick setting material for spraying material of this invention contains an alkali metal aluminate (B). Containing alkali metal aluminate promotes the setting of mortar and concrete immediately after pouring and improves the adhesion of spray material. As the alkali metal aluminate, any of lithium aluminate, sodium aluminate or potassium aluminate can be used, and two or more kinds may be used in combination. Preferably, sodium aluminate is used. The content of the alkali metal aluminate in the quick setting material for spraying material is preferably 11 to 16 parts by mass with respect to 100 parts by mass of the clinker powder (A). If the amount is less than 11 parts by mass, the adhesiveness is reduced, which is not preferable. If the amount exceeds 16 parts by mass, the medium-to-long-term strength is reduced, which is not preferable.

  Moreover, the quick setting material for spraying material of this invention contains alkali metal carbonate or alkali metal bicarbonate (C). Strength development is promoted and promoted by containing alkali metal carbonate or alkali metal bicarbonate. In particular, it contributes to strength enhancement after finishing construction after spraying, and facilitates the formation of sprayed articles that are unlikely to peel off or deform. As an alkali metal forming carbonate or bicarbonate, either lithium, sodium or potassium can be used, and two or more kinds may be used in combination. Of these, sodium carbonate is preferred because of its particularly good auxiliary promoting action. The content of the alkali metal carbonate or alkali metal bicarbonate in the quick setting material for spraying material is preferably 9 to 18 parts by mass with respect to 100 parts by mass of the clinker powder (A). If it is less than 9 parts by mass, the inclusion effect is hardly obtained, which is not preferable. On the other hand, if it exceeds 18 parts by mass, the rapid coagulation property is lowered, which is not preferable. The combined use of alkali metal carbonate and alkali metal bicarbonate is not disturbed, but the effect of the present invention is not particularly increased by the combined use.

  Moreover, the quick setting material for spraying material of this invention contains gypsum (D). The inclusion of gypsum increases the medium- to long-term strength of the spray material, making it easy to achieve strong and stable natural ground reinforcement, slope reinforcement, underground space structure reinforcement, and the like. As gypsum, calcium sulfate or the like can be used in addition to anhydrous, semi-water, and dihydrate gypsum, and two or more kinds may be used in combination. Preferably, anhydrous gypsum is used because a more stable strength development effect can be obtained. As for content in the quick setting material for spray materials of plaster, 45-80 mass parts is preferable with respect to 100 mass parts of clinker powder (A) content. If the amount is less than 45 parts by mass, the elongation of the long-term strength becomes poor, which is not preferable. If the amount exceeds 80 parts by mass, the rapid coagulation property decreases, which is not preferable.

  Moreover, the quick setting material for spraying material of this invention may contain components other than said (A)-(D), unless the effect of this invention is lost.

  Moreover, the spraying material of this invention contains a cement and the said quick setting material for spraying materials. More specifically, it is preferable to contain 5 to 15 parts by mass of the quick setting material for spraying material with respect to 100 parts by mass of cement. Moreover, it is desirable from the point of intensity | strength expression and the spraying construction property that the amount of water injection shall be 38-62% by water cement ratio. As for the water injection, for example, it is desirable to add the quick setting material for the spraying material after adding water to the cement in advance to form an aqueous slurry.

  The cement used for the spray material of the present invention is not particularly limited as long as it is a hydraulic cement. Examples thereof include mixed cement mixed with powder, silica fume and the like.

  The spray material of the present invention can contain other admixtures that can be used for mortar and concrete and fine aggregates such as sand, as long as the effects of the present invention are not lost. As such an admixture, for example, use of water reducing agents is desirable. The flowability immediately after water injection is improved without increasing the water ratio that leads to a decrease in strength and durability by using water reducing agents, and spraying using a spraying device can be performed smoothly. As the water reducing agent, in addition to the water reducing agent, any of what is called a high performance water reducing agent, an AE water reducing agent, a high performance AE water reducing agent, a dispersing agent or a fluidizing agent may be used, and the active ingredient is not particularly limited. The amount of the water reducing agent is preferably 0.05 to 5 parts by mass in terms of solid content with respect to 100 parts by mass of cement.

  Further, as a miscible agent other than the water reducing agents, a setting retarder may be blended and used for the purpose of adjusting the setting time. Any setting retarder can be used as long as it can be used for mortar and concrete. Preferably, those having little influence on strength development, for example, citric acid and tartaric acid can be used. The amount of the organic setting retarder to be blended is preferably 0.01 to 3 parts by mass in terms of solid content with respect to 100 parts by mass of cement. Furthermore, an initial setting modifier may be used in combination with the setting retarder to efficiently adjust the setting time. Examples of the initial setting modifier include alkali metal hydroxides, slaked lime, alum and the like, and the amount thereof depends on the amount of the retarder, but is generally about 0. 05-20 mass parts is preferable.

  The spray construction method of the spray material of this invention is not specifically limited. The mixture may be sprayed with a sprayer after mixing with cement, the above admixture for spraying, and other admixtures or fine aggregates as necessary, and sprayed with a sprayer, or consists of an aqueous slurry such as cement excluding rapid setting components Base mortar or base concrete may be prepared in advance, and the spraying admixture may be added to the base mortar or base concrete immediately before spraying using a spraying device. Also, the method for the finishing adjustment of the spray material sprayed on the wall surface or the like is not particularly limited. For example, finishing adjustment can be performed by dredging work or the like.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to the described examples.

Any of the commercially available powder reagents CaCO ₃ , Al ₂ O ₃ and Fe ₂ O ₃ are used as raw materials, and at least the contents (mass%) of CaO, Al ₂ O ₃ and Fe ₂ O ₃ as chemical components are shown in Table 1. The resulting clinker was mixed, and dry-mixed for about 10 minutes with a Henschel mixer. This raw material mixture is heated in the atmosphere at 1600 ° C. (± 50 ° C.) for 60 minutes using an electric furnace, and the heated material is taken out of the furnace immediately after the heating time has elapsed, and is rapidly cooled by blowing compressed nitrogen gas for cooling. I got a clinker.

The quenched clinker was pulverized with a ball mill and adjusted to a powder having a brain specific surface area of 5000 cm ² / g using a classifier. Using a powder X-ray diffractometer for this powder, the mass of each mineral contained in the calcium aluminate with a mass of M1 is quantified by an internal standard method, etc., and the total mass (M2) of the contained mineral phase that can be quantified is calculated. Was regarded as a pure glass phase, and the vitrification rate was calculated by the following formula. Vitrification rate (%) = (1-M2 / M1) × 100

Further, the contents (mass%) of Fe ₂ O ₃ , CaO, and Al ₂ O ₃ as chemical components in the quenched clinker were quantified by chemical analysis. In the powder X-ray diffraction method, clear diffraction peaks of the iron compound and metallic iron were not detected from any of the rapidly cooled powders, and it was confirmed that they did not exist in such a state. The quantitative results obtained by chemical analysis of the quenched clinker are summarized in Table 1. The vitrification rate of calcium aluminate is also shown. In Table 1, for comparison, some rapidly-cooled powders not containing iron were prepared by adding a commercially available crystalline Fe ₂ O ₃ powder and listed.

  Mix the quick-cooled powder of Table 1, sodium aluminate (commercially available reagent), sodium bicarbonate or sodium carbonate (all commercially available reagents), and type II anhydrous gypsum (commercially available) with a Henschel mixer so that the formulation shown in Table 2 is obtained. Then, a quick setting material for spray material was produced.

450 g of ordinary Portland cement (commercially available product), 1350 g of JIS standard sand and 270 g of water were put together in a Hobart mixer, kneaded for about 3 minutes, and left in a room at 20 ° C. for 30 minutes. The mortar slurry after the elapse of the standing time was re-kneaded for 1 minute, and 27 g of the quick setting agent for spray material shown in Table 2 was added and kneaded for 5 seconds. The kneaded product is immediately filled into a bottomed cylindrical container having an inner diameter of 10 cm and a height of 10 cm, and 30 seconds and 60 seconds from when the spraying agent for the spraying agent is wetted (when the spraying agent for spraying agent is added to the mortar slurry). , 180 seconds, 5 minutes, 10 minutes, and 30 minutes elapsed time, the Procter penetration resistance value of the filled mortar was measured. The measurement method of the penetration resistance value of the proctor was performed using a proctor needle having a cross-sectional area of 0.125 cm ² in accordance with the Japan Society of Civil Engineers concrete standard specification “Quality standards for quick setting for shotcrete”. When the penetration resistance value is approximately 28 N / mm ² , it is considered that the setting time has ended, and those that have finished within 30 minutes of water contact are evaluated as having a good fast setting and within 30 minutes of water contact. Those that could not be terminated were evaluated as “bad”. The measured values and evaluation results are shown in Table 3.

  Further, 400 g of ordinary Portland cement (commercially available product) and 200 g of water were put into a bottomed cylindrical container having an internal volume of 500 cc, kneaded with a hand mixer for 1 minute, and allowed to stand in a room at a temperature of 10 ° C. or 20 ° C. for 30 minutes. The mixture was remixed for about 1 minute after the standing time had elapsed, 48 g of the spraying quick-setting agent shown in Table 2 was added, and the mixture was further kneaded for several seconds to prepare a cement paste. The cement paste after preparation is immediately filled into a spraying machine (commercial spraying mortar gun), and is a concrete flat surface 2m long x 2m wide x 10cm thick placed vertically on the ground at a location 150cm away at the same temperature. It was sprayed so that it was almost vertical angle. This was left as it was for 24 hours at the same temperature as the above-mentioned standing. As a result of observing the condition of spraying after one day after spraying, the cement paste that was sprayed did not sag or adhered without peeling or peeling off. It was judged that the adhesiveness was “bad” including those that could hardly adhere to those other than this. The results are shown in Table 4.

In addition, 400 g of ordinary Portland cement (commercially available product), 987 g of fine aggregate (specific gravity 2.62, coarse particle ratio 2.37), coarse aggregate (specific gravity 2.64, crushed stone having a maximum particle size of 15 mm) 688 g and water 200 g The mixture was kneaded for about 3 minutes with a Hobart mixer, placed in a bottomed cylindrical container with an internal volume of 500 cc, kneaded for 1 minute with a hand mixer, and allowed to stand in a room at a temperature of 10 ° C. or 20 ° C. for 30 minutes. The mixture was remixed for about 1 minute after the standing time had elapsed, 25 g of the spray setting agent shown in Table 2 was added and kneaded for 5 seconds to produce spray concrete. Immediately after the production, the concrete for spraying was naturally dropped from a position 1 m high from the floor. Observe the state after dropping with the naked eye, the coarse aggregate in the concrete does not fly out and scatter, and the fallen fallen objects hardly spread on the floor surface, and the rebound prevention of the concrete for spraying is `` good '' Judgment was made and it was judged that the rebound prevention was “bad” for those other than this. The results are shown in Table 5.

Furthermore, 450 g of ordinary Portland cement (commercial product), 1350 g of JIS standard sand, and 225 g of water were put together into a Hobart mixer, kneaded for about 3 minutes, and allowed to stand indoors at 20 ° C. for 30 minutes. The mortar slurry after the elapse of the standing time was re-kneaded for 1 minute, and 40.5 g of the quick setting agent for spray material shown in Table 2 was added and kneaded for 5 seconds. This kneaded material was immediately filled into a molding mold with an inner size of 40 × 40 × 160 mm, and left standing in the room at the same temperature for a predetermined time. After standing, the mold was removed to obtain a specimen comprising a molded product having a material age of 1, 7 and 28 days. The compressive strength of the specimen was measured using an Amsler type compressive strength tester. The results are shown in Table 6.

  From the above results, the quick setting material for spraying material of the present invention does not instantly set, but has sufficient spraying adhesion, and if it is within about 10 minutes from the water injection even after spraying, the uncured state of mid-condensation is Since it is maintained, construction such as finishing adjustment can be performed on the sprayed product, and it can be seen that both the progress of setting and the increase in strength development after that are good. On the other hand, the spraying material outside the present invention is in a state in which the adhesion is inferior, or even if it can be adhered, the adhered matter has been terminated in a very short time and is not suitable for construction such as finishing adjustment. I understand.

Claims (3)

(A) Calcium aluminate with a vitrification ratio of 90% or more having a molar ratio of CaO to Al ₂ O ₃ (CaO / Al ₂ O ₃ ) of ₂ to 2.4 is used as an active ingredient, and Fe ₂ O ₃ as a chemical ingredient. 100 parts by mass of clinker powder, wherein the total content of CaO, Al ₂ O ₃ and Fe ₂ O ₃ as chemical components is 95% by mass or more, (B) alkali metal A quick setting material for spraying material containing 11 to 16 parts by mass of aluminate, (C) 9 to 18 parts by mass of alkali metal carbonate, and (D) 45 to 80 parts by mass of gypsum. A spraying material comprising cement and the quick setting material for spraying material according to claim 1. Furthermore, the spraying material of Claim 2 containing water reducing agents.