JP6305101B2 - Polysilica iron aqueous solution, cement composition, spraying material, and spraying method - Google Patents

Description

  The present invention mainly relates to a cement material used in the civil engineering and construction fields. In particular, it relates to shotcrete that is constructed during tunnel construction.

Polysilica iron (chemical formula: [SiO ₂ ] _n · [Fe ₂ O ₃ ]) is a flocculant recently developed for water treatment. Aluminum flocculants such as polyaluminum chloride (PAC) and aluminum sulfate used in conventional water treatment applications add flocculants when the water temperature decreases or the amount of organic matter in the water, such as algae, increases. The amount must be increased. However, since aluminum is an amphoteric metal, there is a problem that it becomes soluble aluminum and remains in the treated water. The aluminum-based flocculant has a problem that the amount of the aluminum-based flocculant increases because the cohesiveness decreases at a low water temperature.

  Polysilica iron has been developed to solve these problems. Polysilica iron is produced using ferric chloride or ferric sulfate as an iron source, an alkali metal silicate as a silica source, and sulfuric acid as a pH adjuster (see Patent Documents 1 and 2).

  Since the quick setting agent containing aluminum sulfate has an action of agglomerating mortar and concrete instantaneously, the sprayed concrete for tunnels (refer to Patent Documents 3 and 6), and the sprayed section repair material for concrete structures (Patent Documents 4 and 5). , 7)). However, although aluminum sulfate has a high ability to agglomerate mortar and concrete instantaneously, the strength development from immediately after that is small, and if it is sprayed too thickly, concrete may peel off immediately after spraying. Since aluminum sulfate is water-soluble, the elution amount of aluminum ions and sulfate ions in the wastewater is increased, and there is concern about the impact on the ecosystem, so it was necessary to pay attention to the amount used.

Polysilicato iron as technology applied in spraying material, _{documents SiO} 2 / Fe molar ratio is used polysilica iron 0.2 to 3.0 is disclosed (Patent Document 8). In Patent Document 8, there is an example in which polysilica iron having a maximum Fe concentration of 4.3% is added to the cement up to 15%, and the ratio of Fe to the cement is 0.65% at the maximum. As a ratio of Fe to, the characteristics of less than 1% are shown, and the content of alkali metal is not specified. Patent Document 8 has no description of having an effect of increasing strength at the age of 28 days by adding an alkali metal.

JP 2008-307529 A JP 2009-22925 A JP 2003-55021 A JP 2005-104826 A JP 2006-327865 A JP 2007-55831 A JP 2009-256121 A JP 2012-46383 A

  The present invention provides, for example, polysilica iron that forms a cured product that has excellent agglomeration characteristics and a large strength ratio.

That is, the present invention is a polysilica iron aqueous solution for cement containing 0.3 to 1% alkali metal in an aqueous polysilica iron solution, and the SiO ₂ / Fe molar ratio is 0.2 to 3.0 . a polysilica iron solution is polysilica iron solution for the cement polysilicato iron solution contains 1 to 10 parts in terms of solid content relative to cement 100 parts as Fe, in cement setting accelerators containing said polysilica iron solution A cement composition containing cement and an aqueous solution of polysilica iron for cement, and further containing the admixture, the cement composition containing calcium aluminate and gypsum. And the admixture is a cement composition containing oxycarboxylic acids and / or alkali metal sulfates. The ratio (Cs / Cb) of the compression strength (Cs) of the cured product obtained by adding the silica iron aqueous solution to the age 28 of the cured product and the compression strength (Cb) of the cured product 28 days of the age without adding the polysilica iron aqueous solution is 0. .95 or more of this cement composition, a rapid setting cement composition containing the cement composition, a spraying material containing the cement composition, and a spraying method using the spraying material It is.

  By using the polysilica iron aqueous solution of the present invention, for example, excellent agglomeration characteristics can be obtained, and a cured product having a large strength ratio can be formed.

  Unless otherwise specified, parts and% in the present invention are shown on a mass basis. Hereinafter, the polysilica iron aqueous solution may be collectively referred to as polysilica iron.

  The present invention contains polysilica iron. The polysilica iron of the present invention refers to, for example, an aqueous solution (including unreacted substances generated in the production process) made of polysilica iron alone. The polysilica iron of the present invention may be an aqueous solution containing additives in addition to polysilica iron. For example, polysilica iron aggregates instantaneously when added to a cement composition and rapidly exhibits a hardening promoting effect.

  Examples of the method for producing the polysilica iron aqueous solution include a method in which sodium silicate and sulfuric acid are reacted and then ferric chloride is added and reacted. The solid content concentration varies depending on the content ratio of iron and silicon oxide, but is adjusted to 4 to 12%, for example. In addition to sodium silicate, polysilica iron reacted with lithium silicate or potassium silicate can also be used.

When producing an aqueous polysilica iron solution, an additive may be used to adjust the SiO ₂ / Fe molar ratio or the amount of alkali metal. The additive is not particularly limited, but is an additive that promotes the setting action of cement, promotes the development of strength, adjusts the viscosity of the aqueous solution, and improves the stability. Agents and the like. Specifically, those that promote the setting of cement, those that promote strength development, alkali metal sulfates, nitrates, fluorides, alkali metal salts of carboxylic acids and oxycarboxylic acids, and / or alkalis. Examples thereof include earth metal salts, alkaline earth metal nitrates, amines, colloidal silica, and the like. Two or more of these may be used in combination.

  Additives that adjust the viscosity of aqueous solutions and improve stability include cellulose ethers such as methylcellulose and hydroxypropylcellulose, polyalkylene glycols such as polyethylene glycol, acrylamides, alginates, carboxylic acids and oxycarboxylic acids, etc. Is mentioned. Two or more of these may be used in combination.

  The pH of the aqueous solution containing the polysilica iron of the present invention is preferably 1 to 5 in terms of cohesiveness when the polysilica iron of the present invention is an aqueous solution containing 1% polysilica iron. 3 is more preferable. If it is less than 1, strength development may be inhibited, and if it exceeds 5, the stability of the solution may be lowered.

  Although the viscosity of the aqueous solution containing the polysilica iron of this invention is not specifically limited, What is necessary is just 1-30 mPa * S. If the viscosity is too high, the stability may decrease.

The SiO ₂ / Fe molar ratio of the aqueous solution containing the polysilica iron of the present invention is preferably from 0.2 to 3.0, more preferably from 0.25 to 2.0, from the viewpoint of solution stability and coagulation characteristics. If it is less than 0.2, the initial strength development may be reduced, and if it exceeds 3.0, the cohesive force may be reduced.

  The polysilica iron of the present invention contains an alkali metal. For example, an aqueous solution of polysilica iron containing an alkali metal is prepared by mixing an aqueous solution of polysilica iron obtained by reacting sodium silicate with sulfuric acid and then adding ferric chloride and reacting with the alkali metal. Is obtained. The aqueous solution containing the polysilica iron of the present invention preferably contains 0.3 to 1.0% alkali metal, more preferably 0.35 to 0.65%. The alkali metal content is a value converted to an alkali metal element. Alkali metal has an effect of improving the setting acceleration immediately after being added to cement. As an alkali metal, 1 or more types in the group which consists of Li, Na, and K are preferable. If the alkali metal content is less than 0.3%, the effect of improving the setting acceleration may not be observed. If the alkali metal content exceeds 1.0%, long-term strength development may be inhibited and Cs / Cb may be reduced.

  The use amount of the polysilica iron of the present invention is preferably 1 to 10 parts, more preferably 2.5 to 7.5 parts in terms of solid content with respect to 100 parts of cement as Fe. If it is less than 1 part, the setting speed may not be sufficient, and if it exceeds 10 parts, the long-term strength development may be reduced.

The cement according to the present invention includes various portland cements such as ordinary, early strength, ultra-early strength, low heat, and moderate heat, various mixed cements obtained by mixing blast furnace slag, fly ash, or silica with these portland cements, and a brain ratio. Filler cement mixed with limestone powder with a surface area of 2000 cm ² / g or more, blast furnace slow-cooled slag fine powder, etc., and environment-friendly cement (eco-cement) manufactured from municipal waste incineration ash and sewage sludge incineration ash Is mentioned. One or more of these can be used. For example, alumina cement No. 1, alumina cement No. 2, or fondue may be used in combination with these cements.

  The rapid setting cement composition of the present invention may be used as a paste containing no aggregate, or may be used as mortar or concrete containing aggregate.

  In the present invention, an admixture may be further mixed. Examples of the admixture include calcium aluminate and gypsum. You may use calcium aluminate and gypsum together.

The calcium aluminate of the present invention is a calcium aluminate obtained by heat-treating a mixture of a CaO raw material or an Al ₂ O ₃ raw material, such as baking in a kiln or melting in an electric furnace, Examples of other components include calcium aluminate in which alkali metal salts such as sodium, potassium, and lithium are partly dissolved, calcium aluminate containing SiO ₂ , calcium aluminate containing SO _3, and the like. Among these, amorphous calcium aluminate is preferable from the viewpoint of reaction activity.

The particle size of the calcium aluminate is preferably 3000 cm ² / g or more in terms of a brain value. If it is less than 3000 cm ² / g, the rapid setting force may decrease. The brane value is measured using a brane air permeation device specified in JIS R 5201.

  The amount of calcium aluminate used is preferably 1 to 15 parts, more preferably 2 to 10 parts, relative to 100 parts of cement. If it is less than 1 part, the initial strength enhancement effect may not be obtained, and if it exceeds 15 parts, long-term strength development may be reduced.

  The gypsum of this invention can improve initial strength and long-term strength by using together with calcium aluminate. Examples of gypsum include anhydrous gypsum, half-water gypsum, and two-water gypsum. Gypsum produced as a by-product in the factory or gypsum produced in nature may be used. Among these, anhydrous gypsum is preferable in terms of strength development.

The gypsum particle size is preferably 3000 cm ² / g or more in terms of a brain value. If it is less than 3000 cm ² / g, the effect of improving the strength development may not be obtained.

The amount of gypsum used is preferably 1 to 15 parts, more preferably 2 to 10 parts, relative to 100 parts of cement.
If it is less than 1 part, the initial strength enhancement effect may not be obtained, and if it exceeds 15 parts, cracks may occur due to expansion.

  The present invention may further contain oxycarboxylic acids and / or alkali metal sulfates as admixtures.

  The oxycarboxylic acids of the present invention are used, for example, in order to improve the initial strength of several hours level of a hardened cement in a system in which calcium aluminate is present.

Examples of oxycarboxylic acids include oxycarboxylic acids such as citric acid, malic acid, gluconic acid, tartaric acid, sodium salts and potassium salts thereof. The mixture which combined these, 1 type, or 2 or more types and these, carbonate, nitrate, hydroxide, and silicate is also mentioned.
Of these, the use of oxycarboxylic acids alone is preferred.

The amount of oxycarboxylic acids used is preferably 0.02 to 3 parts, more preferably 0.1 to 2 parts, relative to 100 parts of cement. If it is less than 0.02 part, it may be difficult to adjust fluidity, and if it exceeds 3 parts, the initial strength development may be inhibited.

  The alkali metal sulfate of the present invention is used, for example, to improve strength development up to the age of 3 days.

  Examples of the alkali metal sulfate include lithium sulfate, sodium sulfate, and potassium sulfate. Among these, sodium sulfate is preferable in that the effect of improving strength development is large.

  The amount of alkali metal sulfate used is preferably 0.3 to 5 parts, more preferably 0.5 to 3 parts, relative to 100 parts of cement. If it is less than 0.3 part, the effect of enhancing the strength may not be obtained, and if it exceeds 5 parts, the initial strength development may be inhibited.

  The mixing order of the admixture is not particularly limited. The admixture may be premixed with polysilica iron or cement, or may be mixed separately with polysilica iron or cement.

In the cement composition of the present invention, the amount of cement used is preferably 300 to 500 kg / m ³ , and the water cement ratio is preferably 40 to 65%.

  The rapid setting cement composition of the present invention is a ratio of the compressive strength (Cs) of the hardened material obtained at the age of 28 days to the compressive strength (Cb) of the hardened material at the age of 28 days without adding polysilica iron (Cs / Cb) is preferably 0.95 or more, and more preferably 0.98 or more.

  The reason why the strength ratio is large is that, when polysilica iron is added, ultrafine silica is produced, and the ultrafine silica fills the voids of the hardened body, so that the hardened body becomes dense and contributes to improvement of strength expression. It is considered a thing. This effect is considered to be a finding that cannot be seen when the amount of polysilica iron used is small.

  The rapid setting cement composition of the present invention can be used for various applications. In particular, it can be used as a spray material because of its excellent quick setting properties.

  The spraying method of the spray material using the quick setting cement composition of the present invention is not particularly limited, but the cement mortar or concrete mixed with water and pumped is pumped, and the spray material is placed in front of the nozzle. Examples include a wet spraying method in which the polysilica iron of the invention is joined and sprayed, and a dry spraying method in which cement mortar and concrete are conveyed with compressed air in a dry state and the polysilica iron of the present invention is joined and sprayed before the nozzle. .

  In the present invention, cement, water reducing agent, AE water reducing agent, high performance water reducing agent, high performance AE water reducing agent, cellulose ethers, polyethylene oxides, polysaccharides, etc., within a range that does not hinder the performance of the construction and cured body. Thickeners, defoamers, rust inhibitors, antifreeze agents, shrinkage reducers, cement retarders, cement accelerators, polymer flocculants, short fibers, anions such as bentonite and hydrotalcite It is possible to add various additives such as exchangers, polymer emulsions, γ-type dicalcium silicate, calcium aluminate and the like. Apart from those previously mixed with cement, it is possible to use hydrated inorganic powders such as blast furnace slag, silica fume and fly ash in combination.

"Experiment 1"

  To 100 parts of cement, 300 parts of sand and 63 parts of water were added and mortar was mixed. A setting accelerator was added to 100 parts of cement in the kneaded mortar so that the amount of Fe shown in Table 1 (amount converted to solid content as Fe) was added, and kneaded with a mortar mixer for 10 seconds. Thereafter, the reduction rate (stiffness state), setting speed, and compressive strength were measured. The results are shown in Table 1.

(Materials used)
Cement: Ordinary Portland cement, commercially available sand: Himekawa water crushed sand, Itoigawa City, Niigata Prefecture, density 2.62 g / cm ³
Setting accelerator (1): polysilica iron aqueous solution, SiO ₂ / Fe molar ratio 0.2, Na content 0.31%, pH 1.5, viscosity 1.9 mPa · S
Setting accelerator (2): polysilica iron aqueous solution, SiO ₂ / Fe molar ratio 0.25, Na content 0.34%, pH 2.2, viscosity 1.6 mPa · S
Setting accelerator (3): polysilica iron aqueous solution, SiO ₂ / Fe molar ratio 0.5, Na content 0.38%, pH 2.4, viscosity 2.8 mPa · S
Setting accelerator (4): polysilica iron aqueous solution, SiO ₂ / Fe molar ratio 1.0, Na content 0.42%, pH 2.5, viscosity 4.3 mPa · S
Setting accelerator (5): polysilica iron aqueous solution, SiO ₂ / Fe molar ratio 2.0, Na content 0.62%, pH 3.3, viscosity 7.2 mPa · S
Setting accelerator (6): polysilica iron aqueous solution, SiO ₂ / Fe molar ratio 3.0, Na content 0.98%, pH 4.4, viscosity 8.2 mPa · S
Setting accelerator (A): aluminum sulfate aqueous solution, 8.1% contained as _AL 2 _{O 3,} commercially available setting accelerator (B): Calcium aluminate quick-setting admixture commercially setting accelerator (C): Calcium Saruho Aluminum Nate-based quick set

(Measuring method)

Reduction rate (stiffness state): The flow rate specified in JIS R 5201 of the mortar kneaded before adding the setting accelerator was evaluated by the reduction rate of the flow value of the mortar after adding the setting accelerator. . It can be evaluated that the larger the reduction rate, the greater the aggregation effect (stronger stiffness state).
Flow reduction rate (%) = (1− (mortar flow after addition of setting accelerator) / (flow before adding setting accelerator)) × 100

Setting speed: Evaluated by a Procter penetration resistance test according to ASTM C403. And initial set time indicating a 3.5 N / mm ² or more, and a termination time indicating the 28N / mm ² or more.
Compressive strength: measured in accordance with JIS R 5201. Measurement age is 1 hour, 28 days.
Cs / Cb (compressive strength ratio): The compressive strength at the age of 28 days was measured, and the compressive strength ratio was determined by the following formula.
Compressive strength ratio = Cs (compressed strength of mortar cured product with added polysilica iron) / Cb (compressed strength of mortar cured product without added polysilica iron)

The following tendencies are seen from Table 1. In the present invention, by using polysilica iron, excellent agglomeration characteristics can be obtained, and a cured product having a large strength ratio can be formed. In particular, when the SiO ₂ / Fe molar ratio of polysilica iron is 0.2 to 3.0, the polysilica iron contains 1 to 10 parts in terms of solid content with respect to 100 parts of cement as the effect of the present invention. Is big. When setting accelerators (A) to (C) other than polysilica iron are used, the strength ratio is small and the effects of the present invention cannot be obtained.

"Experimental example 2"
It was carried out in the same manner as in Experimental Example 1 except that the setting accelerator shown in Table 2 was added so that Fe was 5 parts in terms of solid content with respect to 100 parts of cement. The results are shown in Table 2.

(Materials used)
Setting accelerator (7): polysilica iron aqueous solution, SiO ₂ / Fe molar ratio 1.0, Li content 0.45%, pH 3.1, viscosity 3.9 mPa · S
Setting accelerator (8): polysilica iron aqueous solution, SiO ₂ / Fe molar ratio 1.0, K content 0.43%, pH 3.2, viscosity 3.8 mPa · S
Setting accelerator (9): polysilica iron aqueous solution, SiO ₂ / Fe molar ratio 1.0, Na content 0.02%, pH 1.7, viscosity 5.1 mPa · S
Setting accelerator (10): polysilica iron aqueous solution, SiO ₂ / Fe molar ratio 1.0, Na content 0.30%, pH 2.1, viscosity 4.7 mPa · S
Setting accelerator (11): polysilica iron aqueous solution, SiO ₂ / Fe molar ratio 1.0, Na content 0.35%, pH 2.4, viscosity 4.5 mPa · S
Setting accelerator (12): polysilica iron aqueous solution, SiO ₂ / Fe molar ratio 1.0, Na content 0.65%, pH 2.5, viscosity 4.2 mPa · S
Setting accelerator (13): polysilica iron aqueous solution, SiO ₂ / Fe molar ratio 1.0, Na content 1.00%, pH 3.6, viscosity 3.9 mPa · S
Setting accelerator (14): polysilica iron aqueous solution, SiO ₂ / Fe molar ratio 1.0, Na content 1.1%, pH 3.7, viscosity 3.8 mPa · S

  Table 2 shows the following trends. When the polysilica iron of the present invention contains 0.3 to 1.0% of an alkali metal, excellent aggregation characteristics can be obtained, and a cured product having a large strength ratio can be formed. If the alkali metal content is less than 0.3%, the aggregation characteristics cannot be obtained, the strength ratio is small, and the effect of the present invention cannot be obtained. If the alkali metal exceeds 1.0%, the strength ratio is small and the effect of the present invention cannot be obtained.

"Experiment 3"

  A setting accelerator (2) in which Fe is 2.5 parts in terms of solid content, calcium aluminate, gypsum, alkali metal sulfate, and oxycarboxylic acids in amounts shown in Table 3 were added to 100 parts of cement. Except for this, the same procedure as in Experimental Example 1 was performed. The results are shown in Table 3.

(Materials used)
Calcium aluminate: amorphous C ₁₂ A ₇ , Blaine specific surface area 5800 cm ² / g
Gypsum: Natural anhydrous gypsum, commercial product, Blaine specific surface area 5800 cm ² / g
Alkali metal sulfate: anhydrous sodium sulfate, commercially available oxycarboxylic acids: citric acid, commercially available

  Table 3 shows the following trends. The present invention can improve strength by containing calcium aluminate or gypsum. The present invention can improve strength, particularly initial strength, by containing oxycarboxylic acids and alkali metal sulfates.

"Experimental example 4"

The unit quantity of each material, cement 360 kg / ^{m 3,} fine aggregates 1,021kg / ^{m 3,} coarse aggregate 691kg / ^{m 3,} the water 216 kg / ^{m 3,} spray pressure 0.4MPa the shotcrete, It pumped with the concrete pumping machine "MKW-25SMT" on the conditions of spraying speed 10m < ³ > / h. Together with compressed air using a liquid pump, a setting accelerator is added at a position 0.6 m behind the nozzle tip so that the amount of Fe shown in Table 4 (the amount converted to solid content as Fe) is 100 parts of cement. Mixed and mixed with concrete. Quick setting spray concrete obtained by mixing was sprayed from the tip of the nozzle. About this quick setting shotcrete, dust concentration and concrete compressive strength were measured. The results are shown in Table 4.

(Materials used)
Coarse aggregate: Himekawa Sakegawa gravel, Itoigawa City, Niigata Prefecture, surface dry condition, specific gravity 2.66, maximum dimension 13mm
Fine aggregate: Himekawa Sakegawa gravel, Itoigawa city, Niigata prefecture, surface dry condition, specific gravity 2.62
Cement: Ordinary Portland cement, commercial product

(Measuring method)

Dust concentration: Rapid setting spray concrete was sprayed to the simulated tunnel at a pumping speed of 10 m ³ / h for 10 minutes. The amount of dust was measured with a dust meter (Shibata Chemical Co., Ltd., measuring range 0.01 to 100 mg / m ³ , P-5L type) at a fixed position of 5 m from the spraying place.

Concrete compressive strength: Age 1 hour, 1 day compressive strength, the pin installed in the pullout formwork of width 25cm x length 25cm is covered with the quick setting sprayed concrete from the surface of the pullout formwork, The pin was pulled out from the back side, the pulling strength at that time was determined, and the compressive strength was calculated from the formula of (compressive strength) = (pullout strength) × 4 / (test specimen contact area). The compressive strength at the age of 28 days was obtained by spraying quick setting sprayed concrete on a mold of width 50 cm x length 50 cm x thickness 20 cm, and a specimen 5 cm in diameter x 10 cm in length taken with a core drill one day later. The compressive strength was determined by measuring with a 20-ton pressure machine. Curing up to the measurement was water curing at 20 ° C.

  Table 4 shows the following trends. In the present invention, by using polysilica iron, it is possible to form a cured body having a large initial strength and long-term strength and a large strength ratio. In particular, when the polysilica iron is contained in an amount of 1 to 10 parts in terms of solid content with respect to 100 parts of cement as Fe, the effect of the present invention is great.

“Experimental Example 5”
A setting accelerator is mixed with 100 parts of cement so that the amount of Fe shown in Table 5 (amount converted to solid content as Fe) is obtained, and 10 parts of calcium aluminate and 10 parts of gypsum with respect to 100 parts of cement. The sample was sprayed in the same manner as in Experimental Example 4 except that 1 part of alkali metal sulfate and 0.3 part of oxycarboxylic acids were added. The results are shown in Table 5.

  From Table 5, the following tendencies are observed. In the present invention, by using polysilica iron, it is possible to form a cured product having a small dust concentration, a large initial strength and a long-term strength, and a large strength ratio. The present invention can improve strength, particularly initial strength, by containing an admixture.

  By using the polysilica iron of the present invention, excellent setting characteristics can be obtained, spraying work with good thickness can be performed, and construction speed can be shortened. By using the polysilica iron of the present invention, a low dust environment can be realized, excellent in initial and long-term strength development, and high-quality spraying can be performed in consideration of a work environment that could not be achieved conventionally. Since the polysilica iron of the present invention does not contain aluminum ions or sulfate ions, there is no elution of aluminum ions or sulfate ions, and environmentally friendly spraying can be realized. From the above, it can be used in a wide range of fields such as repairing concrete structures, spraying slopes, and tunnels.

Claims (12)

A polysilica iron aqueous solution for cement containing 0.3 to 1% of an alkali metal in the polysilica iron aqueous solution. Cement polysilica iron solution according to claim 1, wherein SiO ₂ / Fe molar ratio is 0.2 to 3.0. Cement polysilica iron aqueous solution according one of claims 1 to 2 polysilicato iron solution contains 1 to 10 parts in terms of solid content relative to cement 100 parts as Fe. The setting accelerator for cement containing the polysilica iron aqueous solution for cement of any one of Claims 1-3. A cement composition comprising cement and the aqueous polysilica iron solution for cement according to claim 1. Furthermore, the cement composition of Claim 5 containing an admixture. The cement composition according to claim 6, wherein the admixture contains calcium aluminate and gypsum. Furthermore, the cement composition according to claim 7, wherein the admixture contains oxycarboxylic acids and / or alkali metal sulfates. The ratio (Cs / Cb) of the compression strength (Cs) of the cured product obtained by adding the polysilica iron aqueous solution to the age 28 days of the cured product and the compression strength (Cb) of the cured product 28 days old of the polysilica iron aqueous solution is 0. The cement composition according to any one of claims 5 to 8, wherein the cement composition exhibits .95 or more. A rapid setting cement composition containing the cement composition according to claim 5. A spraying material containing the cement composition according to claim 5. A spraying method using the spraying material according to claim 11.