JP2009167042A - Rapid-hardening cement for sea water resistant cement asphalt mortar and sea water resistant cement asphalt mortar using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide rapid-hardening cement for sea water-resistant cement asphalt mortar which exhibits excellent short time strength development and is used for an undersea tunnel or the like and the cement asphalt mortar suitable for filler for the track of the undersea tunnel or the like using the same. <P>SOLUTION: The rapid-hardening cement for the sea water-resistant cement asphalt mortar contains 20-100 pts.mass crystalline calcium aluminate, 10-70 pts.mass gypsum, 5-50 pts.mass granulated blast furnace slug fine powder and 0.5-5 pts.mass lithium salt per 100 pts.mass cement. The sea water-resistant cement asphalt mortar contains the rapid-hardening cement for the sea water-resistant cement asphalt mortar, a setting modifier, fine aggregate, an asphalt emulsion, a polymer-based emulsion, a defoaming agent and water. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rapid hardening cement for cement asphalt mortar, and a cement asphalt mortar using the same, and more particularly, a rapid hardening cement for seawater resistant cement asphalt mortar that can be used as a railroad track filler in a submarine tunnel, and The present invention relates to a seawater resistant cement asphalt mortar using the same.

Railroad tracks include a ballast roadbed track consisting of three elements: rails, sleepers, and ballasts. This ballast roadbed track is used for maintenance work such as ramming after ballast laying, rectification of deviation, and replacement of ballast. Various labor-saving trajectories have been studied in order to deal with problems such as labor shortage, aging of workers, and rising wages.
Typical examples of labor-saving tracks for business lines include slab tracks (tracks filled with a viscoelastic material between the track slab and the base layer) and balance-filled track tracks (ballast gaps of ballast track beds). Orbited).
For the viscoelastic body to be filled, a filler having a performance suitable for each track structure is used. It has been proposed to use a hard cemented bituminous grout material in order to inject the ballast into the ballast within the short closing time of the business line and to quickly develop the strength to withstand the train load (Patent Literature) 1).
However, the hardened material used in this hardened cement bituminous grout material reacts with components in the seawater and becomes overexpanded, which may eventually cause expansion failure. There was a problem to use.
JP 07-069698 A

In order to solve the above problems and improve seawater resistance, a lime-based expansion material is used as a cement-based expansion material for cement asphalt mortar, and a rapid-hardening cement admixture (a mixture of calcium aluminate and anhydrous gypsum). ) Is known for its rapid hardening and seawater-resistant cement asphalt mortar for slab tracks (Patent Document 2), but the improvement in seawater resistance has not been sufficient.
JP 09-86993 A

Furthermore, as for the quick-hardening cement for cement asphalt mortar, Patent Document 3 states that “a low-shrinkage rapid-hardening material for room temperature asphalt pavement characterized by being a mixture of Portland cement, fast-hardening material, blast furnace slag or quartz sand and an expanding material. (Claim 1), "The quick-hardening material is composed of 100 parts by weight of alumina cement, 30 to 100 parts by weight of anhydrous gypsum, and 5 to 50 parts by weight of slaked lime. The low shrinkage hard material for asphalt pavement at room temperature "(Claim 4) is described, but there is no description about containing lithium salt, and the invention described in Patent Document 3 is “Normal temperature asphalt that prevents cracking due to shrinkage in pavement obtained from cement asphalt mixture, and can maintain appropriate rigidity over the long term. “Providing low shrinkage hard materials for pavement” (paragraph [0005]), not for improving seawater resistance, but for use in labor-saving tracks such as undersea tunnels Is not suggested.
JP 2001-278852 A

Patent Document 4 states that “a quick-setting cement, water, a setting retarder, an antifoaming agent, and a foaming agent are mixed, and if necessary, one or more asphalt emulsions and polymer emulsions and a short-term strength accelerator. As a fast-hardening cement, 20-60% by weight of clinker containing calcium sulfoaluminate as a main component, 20-70% by weight of Portland cement clinker, type II anhydrous gypsum 0.5 30 wt%, 0.1 to 3.0 wt% of lithium carbonate having a brane value of 5000 cm ² / g, 0.05 to ² wt% of oxycarboxylic acid such as citric acid, It was mixed in during pulverization clinker finely divided balance the Blaine 3000 cm ² / g chemical components of the post-addition and cement in the following coarse powder state SO ₃ / Al ₂ O ₃ molar ratio .4 to 1.0 "(paragraph [0021]) is described, but there is no description about inclusion of granulated blast furnace slag, and it is described in Patent Document 4. The invention is to "obtain a structure that improves deformation capacity and toughness in fast-hardening cement-based injection material and concrete, and prevents the occurrence of cracks and breakage, thereby improving the reliability and longevity of structural members." It is not intended to improve seawater resistance, and is not suggested for use in labor-saving orbits such as undersea tunnels.
JP 11-246252 A

On the other hand, it is also known to mix cement with gypsum and granulated blast furnace slag to obtain a cement excellent in seawater resistance (see Patent Documents 5 and 6), but the seawater resistance described in Patent Documents 5 and 6 Since cement is not quick-hardening and does not sufficiently improve seawater resistance, it has been difficult to use such seawater-resistant cement as cement asphalt mortar for labor-saving orbits such as undersea tunnels.
JP-A-7-242449 JP 2004-137113 A

  The present invention is intended to solve the above-described problems, has excellent strength development in a short time, and can be used even in a submarine tunnel or the like, a rapid hardening cement for seawater-resistant cement asphalt mortar, and a seabed using the same. It is an object of the present invention to provide cement asphalt mortar mortar suitable for fillers for tracks such as tunnels.

  Therefore, the present inventors have made various efforts to solve the above problems, and as a result, have found that a rapid hardening cement asphalt mortar having excellent seawater resistance can be obtained by using a specific quick hardening cement. The present invention has been completed. The present invention is characterized in that the cement contains all the components of crystalline calcium aluminate, gypsum, ground granulated blast furnace slag, and lithium salt to form a quick-hardening cement. As shown in the example, when a hardened cement lacking even one of these components is used, a hardened cement asphalt mortar excellent in seawater resistance cannot be obtained.

In the present invention, the following means are adopted in order to solve the above-mentioned problems.
(1) 20 to 100 parts by mass of crystalline calcium aluminate, 10 to 70 parts by mass of gypsum, 5 to 50 parts by mass of granulated blast furnace slag, and 0.5 to 5 parts by mass of lithium salt with respect to 100 parts by mass of cement A quick-hardening cement for seawater-resistant cement asphalt mortar characterized by containing.
(2) The rapid hardening cement for seawater-resistant cement asphalt mortar according to (1), wherein the cement has a 3CaO · SiO ₂ content of 60% or more.
(3) The rapid hardening cement for seawater-resistant cement asphalt mortar according to (1) or (2), wherein the crystalline calcium aluminate has a CaO / Al ₂ O ₃ molar ratio of 0.75 to 2.0. .
(4) The rapid hardening cement for seawater-resistant cement asphalt mortar according to one of (1) to (3), wherein the gypsum is hemihydrate gypsum.
(5) The rapid hardening cement for seawater-resistant cement asphalt mortar according to one of (1) to (4) above, further comprising a foaming agent.
(6) The quick-hardening cement for seawater-resistant cement asphalt mortar, the coagulation modifier, fine aggregate, asphalt emulsion, polymer emulsion, antifoaming agent, and water according to one of the above (1) to (5) Is a seawater-resistant cement asphalt mortar.
In the present invention, “parts” and “%” are based on mass unless otherwise specified.

  INDUSTRIAL APPLICABILITY The present invention provides a rapid hardening cement asphalt mortar (hereinafter referred to as CA mortar) excellent in seawater resistance by using a specific rapid hardening cement, and is suitable for a filler used in a labor-saving track for business lines of a submarine tunnel. .

Hereinafter, the present invention will be described in detail.
The cement used in the present invention is not particularly limited, and various portland cements such as normal, early strength, super early strength, low heat, and moderate heat, and these portland cements include blast furnace slag, fly ash, silica, etc. Various mixed cements, waste-use cement (eco-cement) manufactured from municipal waste incineration ash, sewage sludge incineration ash, etc., and various fillers mixed with limestone fine powder or ground granulated blast furnace slag, etc. There are cement and the like, and one or more of these can be used.
In the present invention, it is preferable to use cement having a 3CaO · SiO ₂ content of 60% or more and 70% or less from the viewpoint of CA mortar strength development.

The crystalline calcium aluminate used in the present invention is a generic term for compounds mainly composed of CaO and Al ₂ O ₃ , and specific examples thereof include, for example, CaO · 2Al ₂ O ₃ , CaO · Al ₂ O. ₃ , crystalline calcium aluminate represented by 12CaO · 7Al ₂ O ₃ , 11CaO · 7Al ₂ O ₃ · CaF ₂ , 3CaO · 3Al ₂ O ₃ · CaSO _{4 and the} like.
Examples of a method for obtaining crystalline calcium aluminate include a method in which a CaO raw material and an Al ₂ O ₃ raw material are heat-treated with a rotary kiln or an electric furnace.
Examples of the CaO raw material for producing crystalline calcium aluminate include calcium carbonate such as limestone and shells, calcium hydroxide such as slaked lime, and calcium oxide such as quick lime.
As the Al ₂ O ₃ raw material, for example, other industrial products, called bauxite, aluminum residual ash, aluminum powder and the like.

The CaO / Al ₂ O ₃ molar ratio of the crystalline calcium aluminate of the present invention is preferably 0.75 to 2.0, and more preferably 1.0 to 1.5. If the CaO / Al ₂ O ₃ molar ratio is less than 0.75, sufficient strength development may not be obtained. If the CaO / Al ₂ O ₃ molar ratio exceeds 2.0, excellent fluidity and sufficient working time can be obtained. There may not be.
The particle size of the crystalline calcium aluminate is not particularly limited, but it is usually preferably 3,000 to 9,000 cm ² / g, more preferably 4,000 to 8,000 cm ² / g in terms of the specific surface area of the brain (hereinafter referred to as the brain value). preferable. If it is less than 3,000 cm ² / g, strength development may not be sufficient, and if it exceeds 9,000 cm ² / g, it may be difficult to maintain fluidity and secure working time.
The crystallization rate of the crystalline calcium aluminate can be measured by a powder X-ray diffraction method, the crystallization rate is preferably 30 to 90%, and more preferably 40 to 70% from the balance of pot life and rapid hardening.
The crystallization rate can be calculated from the following equation.
Crystallization rate (%) = (peak area / total area) × 100

When producing crystalline calcium aluminate industrially, for example, Li ₂ O, Na ₂ O, K ₂ O, MgO, TiO ₂ , MnO, Fe ₂ O ₃ , SiO ₂ , P ₂ O ₅ , S, and F Impurities may be included.
The presence of these impurities is not particularly problematic as long as the object of the present invention is not substantially impaired, usually in the range where the total amount of impurities is 10% or less.
Further, in the present invention, calcium aluminoferites such as 4CaO · Al ₂ O ₃ · Fe ₂ O ₃ , 6CaO · 2Al ₂ O ₃ · Fe ₂ O ₃ , and 6CaO · Al ₂ O ₃ · 2Fe ₂ O ₃ , 2CaO · Calcium ferrites such as Fe ₂ O ₃ and CaO · Fe ₂ O ₃ , Gelenite 2CaO · Al ₂ O ₃ · SiO ₂ and calcium aluminosilicates such as anorthite CaO · Al ₂ O ₃ · 2SiO ₂ , Melvinite 3CaO · MgO · 2SiO _2, Akerumanaito 2CaO · MgO · 2SiO _2, and Monte calcium magnesium silicate, such as celite CaO · MgO · SiO _2, tri-calcium silicate 3CaO · SiO _2, dicalcium silicate 2CaO · SiO _2, and rankinite night 3CaO · 2SiO _2, Wa Calcium silicate such as lastite CaO ・ SiO ₂ , calcium titanate CaO ・ TiO ₂ , free lime, and leucite (Na ₂ O, K ₂ O) ・ Al ₂ O ₃・ SiO ₂ etc. are crystalline calcium aluminate May contain
The amount of crystalline calcium aluminate used is preferably 20 to 100 parts, more preferably 40 to 80 parts, relative to 100 parts of cement. If it is less than 20 parts, the short-term strength development and seawater resistance may be deteriorated, and if it exceeds 100 parts, the working time may not be secured even if a setting modifier is used.

Examples of the gypsum used in the present invention include anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum. Furthermore, natural gypsum, chemical gypsum such as phosphate byproduct gypsum, drainage gypsum, and hydrofluoric acid byproduct gypsum, or these And gypsum obtained by heat-treating. Among these, hemihydrate gypsum is preferable in terms of high strength development for a short time.
The particle size of gypsum is not particularly limited, but it is usually in the range of 3,000 to 9,000 cm ² / g as a Blaine specific surface area value, and more preferably about 4,000 to 8,000 cm ² / g. If it is less than 3,000 cm ² / g, strength development may not be sufficient, and if it exceeds 9,000 cm ² / g, excellent fluidity may not be obtained.
The amount of gypsum used is preferably 10 to 70 parts, more preferably 30 to 50 parts, per 100 parts of cement. If it is less than 10 parts, strength development and seawater resistance may be deteriorated, and if it exceeds 70 parts, the amount of expansion becomes too large, which may cause expansion and destruction.

The ground granulated blast furnace slag used in the present invention is an industrial by-product generated from the steel industry, and is also established by JIS.
The particle size of the ground granulated blast furnace slag of the present invention is not particularly limited, but a grain having a specific surface area of 4000 to 8000 cm ² / g as defined by JIS can be used. If it is less than 4000 cm ² / g, strength development may not be sufficient, and if it exceeds 8000 cm ² / g, excellent fluidity may not be obtained.
The amount of ground granulated blast furnace slag powder is preferably 5 to 50 parts, more preferably 10 to 30 parts, per 100 parts of cement. If it is less than 5 parts, the seawater resistance may deteriorate, and if it exceeds 50 parts, excellent fluidity may not be obtained.

The lithium salt used in the present invention includes lithium carbonate, lithium bicarbonate, lithium hydroxide, lithium silicate, lithium citrate, lithium phosphate, lithium nitrate, lithium nitrite, etc., one or more of these Can be used. Of these, lithium carbonate is most preferred from the standpoint of short-term strength development.
The amount of lithium salt used is preferably 0.5 to 5 parts, more preferably 1 to 3 parts, relative to 100 parts of cement.
If it is less than 0.5 part, the short-term strength development and seawater resistance may be deteriorated, and if it exceeds 5 parts, the working time may not be secured even if a setting modifier is used.

Examples of the foaming agent of the present invention include aluminum powder, magnesium powder, zinc powder, and carbon materials, as well as peroxidation materials such as perborate, percarbonate, persulfate, and permanganate. . In the present invention, it is preferable to use a peroxide substance because it has a large effect of suppressing the settlement and contraction of the CA mortar in a state where the CA mortar is not yet solidified.
The amount of foaming agent used varies depending on the type, but in the case of a peroxide material, it is preferably 0.05 to 1 part and more preferably 0.1 to 0.5 part with respect to 100 parts of cement. If the amount is less than 0.05 part, the effect of suppressing settlement and contraction in a state where the CA mortar is not yet solidified may not be obtained. If the amount exceeds 1 part, expansion due to foaming may be excessive, and strength development may be reduced.

The setting modifier of the present invention is not particularly limited, and specific examples thereof include, for example, oxycarboxylic acids such as citric acid, tartaric acid, malic acid, gluconic acid, and succinic acid, or sodium, potassium thereof. , Organic acids such as calcium, magnesium, ammonium, and aluminum salts, alkali carbonates such as lithium carbonate, sodium carbonate, potassium carbonate, ammonium carbonate, lithium bicarbonate, sodium bicarbonate, potassium bicarbonate, and ammonium bicarbonate In the present invention, the combined use of organic acids and alkali carbonates is preferable from the viewpoint of satisfying both sufficient working time and short-time strength development.
The mixing ratio of the organic acid and the alkali carbonate is preferably 15 to 50:85 to 50 (mass ratio) in a total of 100 parts by mass of the organic acid and the alkali carbonate from the viewpoint of fluidity and short-term strength development. 20-40: 80-60 (mass ratio) is more preferable.
Although the usage-amount of a setting regulator is not specifically limited, Usually, 0.1-10 parts are preferable with respect to 100 parts of cement, and 0.5-5 parts are more preferable. If it is less than 0.1 part, it may be difficult to secure the working time, and if it exceeds 10 parts, the setting delay effect may be too great, and the strength development property for a short time may deteriorate.

For the fine aggregate of the present invention, natural sand or quartz sand can be used.
The amount of fine aggregate used is preferably 50 to 300 parts, more preferably 100 to 200 parts, per 100 parts of cement. If the amount is less than 50 parts, the volume change of the CA mortar is large and cracks may occur. If the amount exceeds 300 parts, fine aggregates may settle or strength development may be reduced.

In the present invention, the asphalt emulsion is used for the purpose of imparting viscoelasticity to the CA mortar and withstanding the vibration of the train load.
The asphalt emulsion of the present invention is a colloidal liquid obtained by dispersing asphalt fine particles mainly composed of bituminous substances obtained as a natural or petroleum distillation residue in water. Products, for example, straight asphalt with a penetration of about 40/60 to 200/500 as a main material, a surfactant and a polyvalent metal salt are added thereto, and further, an emulsification aid, a dispersant, And a protective colloid or the like used as appropriate and emulsified in water.
In the present invention, it is also possible to use a bituminous material obtained by emulsifying a modified bituminous material by adding and mixing rubber or a synthetic polymer.
The bitumen content in the asphalt emulsion is preferably 40 to 70%, more preferably 55 to 65%. If it is less than 40%, the effect of imparting viscoelasticity to CA mortar may not be obtained, and if it exceeds 70%, the development of strength may be reduced.
The amount of the asphalt emulsion used can be appropriately selected depending on the intended use, but is usually preferably 10 to 300 parts with respect to 100 parts of cement. If it is less than 10 parts, the effect of imparting viscoelasticity may not be obtained, and if it exceeds 300 parts, the development of strength may be reduced.

As the polymer emulsion of the present invention, rubber latex such as styrene-butadiene-rubber (SBR), synthetic polymer emulsion, synthetic resin emulsion, and water-soluble polymer can be used. The SBR rubber latex having excellent mixing properties with the seawater resistant CA mortar quick-hardening cement and asphalt emulsion is preferred.
The amount of the polymer emulsion used can be appropriately selected depending on the intended use, but is usually preferably 5 to 100 parts with respect to 100 parts of cement. If it is less than 5 parts, the effect of imparting brittleness or weather resistance may not be obtained, and if it exceeds 100 parts, the development of strength may be reduced.

Examples of the antifoaming agent of the present invention include, in addition to silicone antifoaming agents, alcohol-based antifoaming agents, fatty acid-based antifoaming agents, fatty acid ester-based antifoaming agents, amine-based antifoaming agents, amide-based antifoaming agents, Ether type antifoaming agents and metal soaps can be used. These antifoaming agents are used when kneading the seawater resistant CA mortar quick-setting cement, foaming agent, setting agent, fine aggregate, asphalt emulsion, polymer emulsion, antifoaming agent and water. There is an effect of reducing the inclusion of unnecessary embracing bubbles.
Although the usage-amount of an antifoamer is not specifically limited, 0.05-10 parts is preferable with respect to 100 parts of cement. If it is less than 0.05 parts, the effect of reducing the inclusion of bubbles may not be obtained, and if it exceeds 10 parts, the effect of reducing the inclusion of bubbles will not be improved, and conversely, the strength development of CA mortar May be adversely affected.

  The amount of water used in the CA mortar is preferably 5 to 200 parts, more preferably 20 to 100 parts, per 100 parts of cement. If it is less than 5 parts, the flowability of the CA mortar may be poor, and if it exceeds 200 parts, the fine aggregate may settle or strength development may be reduced.

In the present invention, in order to further improve the strength development property for a short time, it is possible to add a sulfate of a metal other than calcium and an alkali carbonate other than lithium to the rapid-hardening cement for seawater-resistant CA mortar.
The sulfate of a metal other than calcium is a generic term for sulfates of alkali metals, alkaline earth metals other than calcium, aluminum, or double salts thereof. Among these, sodium, potassium, lithium, magnesium, and aluminum sulfates are preferable from the viewpoint of strength development for a short time, and among them, sulfates containing potassium are most preferable. Specific examples thereof include potassium sulfate and alums.
Examples of the alkali carbonate other than lithium include sodium carbonate, potassium carbonate, and sodium bicarbonate, and one or more of these can be used. Among these, potassium carbonate is most preferable from the viewpoint of strength development for a short time.
The amount of sulfates of metals other than calcium and alkali carbonates other than lithium is preferably 0.5 to 20 parts, more preferably 1 to 10 parts, relative to 100 parts of cement. If it is less than 0.5 part, the strength development in a short time may not be improved, and if it exceeds 20 parts, it may be difficult to secure the working time even if a setting modifier is used.

The method of preparing the CA mortar is not particularly limited. For example, first, water, a setting modifier, and an antifoaming agent are mixed, and then an asphalt emulsion and a polymer emulsion are added thereto. A quick-hardening cement for basic CA mortar is prepared by adding sand and foaming agent and mixing with a mixer.
The prepared CA mortar is pumped by a pump and is usually injected by pouring into a ballast.
In the CA mortar of the present invention, a commercially available water reducing agent can be used as necessary.

  Rapid hardening cement was prepared by mixing 20 parts of ground granulated blast furnace slag, 2 parts of lithium salt, 0.2 part of foaming agent, and crystalline calcium aluminate and gypsum shown in Table 1 with 100 parts of cement. Next, with respect to 100 parts of cement in the rapid-hardening cement, 2 parts of a setting modifier, 180 parts of fine aggregate, 200 parts of asphalt emulsion, 40 parts of polymer emulsion, 1 part of antifoaming agent, and 70 parts of water When mixed with hard cement, the fluidity, pot life, initial expansion rate, compressive strength, and compressive strength after artificial seawater curing were measured at a temperature of 20 ° C. The results are also shown in Table 1.

<Materials used>
Cement: Early strong Portland cement, 66% 3CaO · SiO ₂ content, crystalline calcium aluminate manufactured by Denki Kagaku Kogyo Co., Ltd .: CaO / Al ₂ O ₃ molar ratio 1.0, loss on ignition 1.5%, main component CaO · Al ₂ O ₃ , Brain value 5,000cm ² / g, Crystallization rate 55%
Gypsum: hemihydrate gypsum, brain value 6,000 cm ² / g, commercial blast furnace granulated slag fine powder: Blaine specific surface area 4000 cm ² / g, commercial product lithium salt: lithium carbonate, commercial product foaming agent: sodium percarbonate, reagent 1 Grade coagulation modifier: mass ratio of citric acid and potassium carbonate 1: 3, reagent grade 1 fine aggregate: silica sand No. 8, asphalt emulsion manufactured by Tohoku Seizuna Co., Ltd .: B emulsion, main component asphalt, bitumen content 60%, Toa Highway emulsion manufactured by Road Industry Co., Ltd .: SBR latex, Defoamer manufactured by Toa Road Industry Co., Ltd .: Silicone antifoaming agent, commercial product

<Measurement method>
Fluidity: According to JSCE, J10 funnel flow value usable time: When J10 funnel flow value exceeds 12 seconds, and sufficient pouring is not possible Initial expansion rate: 250 ml of CA mortar is sampled into a 300 ml graduated cylinder, dip Using a gauge, measure the depth from the top of the graduated cylinder to the surface of the CA mortar, measure it in the same way after 24 hours of age, and calculate the expansion rate using the following formula:-in the table is the contraction side, + is the expansion Side (expansion coefficient calculation formula)
Expansion rate (%) = 0.000314 x (depth immediately after collection-depth after 24 hours) x (graduated cylinder diameter) 2
Compressive strength: CA mortar is packed in a mold to create a specimen of φ5 × 5cm, and the compressive strength at 1 hour, 7 days, 28 days, and 6 months is measured according to JIS R 5201. Compressive strength after artificial seawater curing: CA mortar was packed in a mold to make a specimen of φ5 × 5cm, immersed in artificial seawater of JIS A 6205 after 3 hours of age, 28 days old, and 6 months old Measure compressive strength according to JIS R 5201

From Table 1, the CA mortar of the example containing 20 to 100 parts of crystalline calcium aluminate with respect to 100 parts of cement has sufficient short-time strength development, excellent fluidity, and sufficient working time. It can be seen that it has a suitable expansion amount and is excellent in seawater resistance (Experiment No.1-2 to No.1-6). In order to further improve the short-term strength development and seawater resistance, the crystalline calcium aluminate is preferably 40 to 80 parts with respect to 100 parts of cement (Experiment No. 1-3 to No. 3). 1-5). In contrast, the comparative CA mortar containing no crystalline calcium aluminate is not only poor in strength development for a short time as compared with the CA mortar of the example containing crystalline calcium aluminate. Looking at the compressive strength after 6 months, there was no difference in the case of air-dried curing, but it was extremely low in the case of artificial seawater curing and poor in seawater resistance (Experiment No. 1-1) ).
Further, the CA mortar of the example containing 10 to 70 parts of gypsum with respect to 100 parts of cement has sufficient strength development, excellent fluidity, can secure sufficient working time, and has an appropriate expansion amount. It can be seen that it has excellent seawater resistance (Experiment No. 1-9 to No. 1-12). In order to further improve seawater resistance, it is preferable that the gypsum be 30 to 50 parts with respect to 100 parts of cement (Experiment No. 1-10, No. 1-11). On the other hand, the CA mortar of the comparative example not containing gypsum has poor strength expression compared to the CA mortar of the example containing gypsum, in particular, the compressive strength after artificial seawater curing is extremely low, It was inferior in seawater resistance (Experiment No. 1-8).

  To 100 parts of cement, 60 parts of crystalline calcium aluminate, 40 parts of gypsum, 2 parts of lithium salt, 0.2 part of foaming agent, and ground granulated blast furnace slag as shown in Table 2 were mixed to prepare a rapid hardening cement. Except that, the same procedure as in Example 1 was performed. The results are also shown in Table 2.

  From Table 2, the CA mortar of the example containing 5 to 50 parts of granulated blast furnace slag powder with respect to 100 parts of cement has sufficient strength development, excellent fluidity, and sufficient working time. It can be ensured, has an appropriate amount of expansion, and is excellent in seawater resistance (Experiment No.2-2 to No.2-5, No.1-4). In order to further improve the seawater resistance, it is preferable that the granulated blast furnace slag powder is 10 to 30 parts per 100 parts of cement (Experiment No. 2-3, No. 1-4, No. .2-4). In contrast, the comparative CA mortar containing no ground granulated blast furnace slag has lower strength development than the CA mortar of the example containing ground granulated blast furnace slag, especially artificial seawater. The compressive strength after curing was extremely low and the seawater resistance was poor (Experiment No. 2-1). The CA mortar of this comparative example corresponds to the CA mortar described in Patent Document 4.

  To 100 parts of cement, 60 parts of crystalline calcium aluminate, 40 parts of gypsum, 20 parts of ground granulated blast furnace slag, 0.2 part of foaming agent, and lithium salt shown in Table 3 were mixed to prepare a quick hardening cement. Except that, the same procedure as in Example 1 was performed. The results are also shown in Table 3.

  From Table 3, the CA mortar of the example containing 0.5 to 5 parts of lithium salt with respect to 100 parts of cement has sufficient strength development, excellent fluidity, and sufficient working time can be secured. It can be seen that it has a large expansion amount and is excellent in seawater resistance (Experiment No. 3-2 to No. 3-5, No. 1-4). In order to further improve short-term strength development and seawater resistance, the lithium salt is preferably 1 to 3 parts per 100 parts of cement (Experiment No.3-3, No.1-4). , No.3-4). On the other hand, the CA mortar of the comparative example containing no lithium salt is compared with the CA mortar of the example containing the lithium salt. Although there was no difference, the artificial seawater curing was extremely low and inferior in seawater resistance (Experiment No. 3-1). The CA mortar of this comparative example corresponds to the CA mortar described in Patent Document 3.

  To 100 parts of cement, 60 parts of crystalline calcium aluminate, 40 parts of gypsum, 20 parts of ground granulated blast furnace slag, 2 parts of lithium salt, and a foaming agent shown in Table 4 were mixed to prepare a rapid hardening cement. Except that, the same procedure as in Example 1 was performed. The results are also shown in Table 4.

  From Table 4, it can be seen that by mixing the foaming agent, the initial expansion rate of the CA mortar is increased, and the effect of suppressing the settlement and contraction of the CA mortar in a state where the CA mortar is not yet solidified is obtained.

  As shown in the above examples, in the present invention, a rapid-hardening cement containing all components of crystalline calcium aluminate, gypsum, granulated blast furnace slag, and lithium salt is used as the cement. As a result, a quick-hardening cement asphalt mortar with excellent seawater resistance was obtained.If a quick-hardening cement lacking one of these components was used, a quick-hardening cement asphalt mortar with excellent seawater resistance was obtained. I couldn't.

  When the rapid-hardening cement of the present invention is used for CA mortar, CA mortar having excellent effects such as excellent strength development for a short time, small decrease in strength even when exposed to seawater, and excellent seawater resistance is obtained. Among labor-saving orbits, it is particularly suitable for fillers used in submarine tunnels.

Claims (6)

  Contains 100 to 100 parts by weight of crystalline calcium aluminate, 10 to 70 parts by weight of gypsum, 5 to 50 parts by weight of granulated blast furnace slag, and 0.5 to 5 parts by weight of lithium salt with respect to 100 parts by weight of cement A quick-hardening cement for seawater-resistant cement asphalt mortar. The quick-hardening cement for seawater-resistant cement asphalt mortar according to claim 1, wherein the cement has a 3CaO · SiO ₂ content of 60% or more. The rapid hardening cement for seawater resistant cement asphalt mortar according to claim 1 or 2, wherein the crystalline calcium aluminate has a CaO / Al ₂ O ₃ molar ratio of 0.75 to 2.0.   The quick-setting cement for seawater-resistant cement asphalt mortar according to one of claims 1 to 3, wherein the gypsum is hemihydrate gypsum.   The rapid-hardening cement for seawater-resistant cement asphalt mortar according to one of claims 1 to 4, further comprising a foaming agent.   The rapid hardening cement for seawater-resistant cement asphalt mortar according to claim 1, a setting modifier, fine aggregate, asphalt emulsion, polymer emulsion, antifoaming agent, and water Seawater resistant cement asphalt mortar.