JPWO2013077378A1 - Rapid hardening cement - Google Patents

Abstract

Provided is a quick setting cement with a long setting time. (A) a cement, (B) a rapid hardening material containing calcium aluminate and anhydrous gypsum, and (C) a rapid hardening cement containing a setting modifier, wherein (A) hemihydrate gypsum is contained in 100 parts by mass of cement. A rapid-hardening cement containing 1.4 to 2.7 parts by mass and 2.0 to 5.4 parts by mass of dihydrate gypsum.

Description

  The present invention relates to a rapid setting cement.

  The quick-hardening cement is made by adding a quick-hardening material such as calcium aluminate to the cement, and is characterized in that it can exhibit high strength in a very short time compared to ordinary Portland cement. For this reason, rapid-hardening cement has been put to practical use as paste, mortar, and concrete, for example, as a repair material, a spraying material for tunnels, and an early mold release material for concrete secondary products.

Examples of rapid-hardening cement include spraying materials composed of a quick setting aid in which alkanolamine is added to calcium aluminate, calcium sulfoaluminate, or calcium aluminosilicate (Japanese Patent No. 3412795), 3CaO · 3Al ₂ O ₃ · Super hard kneaded concrete containing CaF ₂ and inorganic sulfate (JP-A-2-180740), clinker containing 3CaO · SiO ₂ solid solution and 11CaO · 7Al ₂ O ₃ · CaF ₂ , anhydrous gypsum, calcium aluminosilicate Super hard cement composition containing glass or the like (JP 2007-320833 A), rapid hardening clinker composition in which Fe ₂ O ₃ and CaF ₂ are added to C12A7 (12CaO · 7Al ₂ O ₃ ) system -268037 discloses), Clean mainly composed of 12CaO · 7Al ₂ O ₃ The chromatography material, rapid hardening clinker composition with the addition of Fe ₂ O ₃ and CaF ₂ (JP-A-6-115986 JP), and the like.

Japanese Patent No. 3412795 JP-A-2-180740 JP 2007-320833 A Japanese Patent Laid-Open No. 9-268037 JP-A-6-115986

  The quick setting cement is kneaded with water using an aggregate or the like and placed. For this reason, it is necessary to maintain fluidity for a certain time required for kneading and placing. In this regard, the conventional rapid hardening cement has a problem that the setting and hardening time is short, and the casting time, particularly, the casting time at a low temperature of about 0 to 10 ° C. cannot be secured sufficiently. As described in Patent Document 3, a method for securing fluidity by adding a coagulation regulator such as an oxycarboxylic acid such as citric acid or a salt thereof is also known, but there is still room for improvement. is there. Therefore, an object of the present invention is to provide a quick-hardening cement in which a long setting and hardening time is secured.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the hydration state of gypsum significantly affects the setting and hardening time. In addition, a predetermined amount of hemihydrate gypsum (CaSO ₄ · 1 / 2H ₂ O) and dihydrate gypsum (CaSO ₄ · 2H ₂ O) is contained in the rapid-hardening cement to ensure sufficient setting and hardening time. Found that it is possible to do. Since hemihydrate gypsum usually pseudo-conges, it was surprising that such a result was obtained because it was regarded as a component that should not be added to cement.

  The present invention completed on the basis of the above knowledge is, in one aspect, (A) a cement, (B) a rapid hardening material containing calcium aluminate and anhydrous gypsum, and (C) a rapid hardening cement containing a setting modifier. (A) A rapid-hardening cement containing 1.4 to 2.7 parts by mass of hemihydrate gypsum and 2.0 to 5.4 parts by mass of dihydrate gypsum in 100 parts by mass of cement.

  In one embodiment of the quick-hardening cement according to the present invention, the mass ratio of hemihydrate gypsum to dihydrate gypsum is hemihydrate gypsum / dihydrate gypsum = 0.2 to 1.0.

  In another embodiment of the quick-hardening cement according to the present invention, the mass ratio of hemihydrate gypsum to dihydrate gypsum is hemihydrate gypsum / dihydrate gypsum = 0.4 to 0.6.

  In another embodiment of the quick-hardening cement according to the present invention, (A) the cement has a weight loss of 0.25% by mass or less after drying at 90 ° C. for 20 hours.

  In still another embodiment of the rapid setting cement according to the present invention, the content of (A) cement in the rapid setting cement is 70 to 95% by mass, and calcium aluminate and anhydrous gypsum are (A) cement 100. It is 5-40 mass parts in total with respect to a mass part, and (C) setting controller is 0.01-5 mass% with respect to the total mass of (A) cement, calcium aluminate, and anhydrous gypsum.

  In another aspect, the present invention is a cement paste, cement mortar, or cement concrete using the quick-hardening cement according to the present invention.

  In one embodiment of the cement paste, cement mortar or cement concrete according to the present invention, the gelation time at 5 ° C. is 60 minutes or more.

  In one embodiment of the cement paste, cement mortar or cement concrete according to the present invention, the curing time at 5 ° C. is 60 minutes or more.

  In yet another aspect, the present invention is a cured product of the cement paste, cement mortar, or cement concrete according to the present invention.

  In still another aspect, the present invention is a method for using a cement paste, cement mortar, or cement concrete, which includes placing the cement paste, cement mortar, or cement concrete according to the present invention in a temperature environment of 1 to 10 ° C. .

  Since the rapid hardening cement according to the present invention has a long setting and hardening time, a sufficient working time can be secured at the time of placing.

It is a schematic diagram of the gelation time and the hardening time about a rapid hardening cement with a normal setting and hardening rate. It is a schematic diagram of gelation time and hardening time about a rapid hardening cement with an abnormal setting hardening rate. It is a figure which shows the result of the elution test done in the Example.

<Cement>
The quick-hardening cement according to the present invention contains cement as a base component. There are no particular restrictions on the cement, but ordinary cement, early-strength cement, ultra-early-strength cement, moderately hot cement, sulfate-resistant cement, low-heat cement, oil well cement and other Portland cement, and blast furnace cement, fly ash cement, and silica Any of mixed cement such as cement and eco-cement can be used. The cement content in the quick-setting cement is not particularly limited, but can be typically 70 to 95% by mass, and more typically 75 to 90% by mass.

In the present invention, the minerals contained in the _{cement, Alite (3CaO · SiO 2)} , Belite (2CaO · SiO 2), 3CaO · Al 2 O 3, 4CaO · Al 2 O 3 · Fe 2 O 3, hemihydrate gypsum _{(CaSO 4 · 1 / 2H 2} O), gypsum _{(CaSO 4 · 2H 2 O)} , CaCO 3 , and the like. The content of these minerals in the cement is not particularly limited, but if the total amount of substances present in the cement is 100 parts by mass, typically 30 to 70 parts by mass of Alite (3CaO · SiO ₂ ), Belite (2CaO · SiO ₂₎ 20 to 60 parts by mass, 3CaO · Al ₂ O ₃ is 3 to 20 parts by _{mass, 4CaO · Al 2 O 3 ·} Fe 2 O 3 is 3 to 20 parts by weight, gypsum hemihydrate (CaSO ₄ · 1 / 2H ₂ O) is 1.4 to 2.7 parts by mass, dihydrate gypsum (CaSO ₄ · 2H ₂ O) is 2.0 to 5.4 parts by mass, and CaCO ₃ is 0 to 7 parts by mass. There, more typically Alite (3CaO · SiO ₂₎ 40 to 65 parts by weight, Belite (2CaO · SiO ₂₎ 10 to 30 parts by mass, 3CaO · Al ₂ O ₃ is 5 to 10 parts by mass, 4CaO · _{al 2 O 3 · Fe 2 O} 3 is 5 to 15 parts by weight, hemihydrate Plaster _{(CaSO 4 · 1 / 2H 2} O) is 1.4 to 2.4 parts by weight, gypsum (CaSO ₄ · 2H ₂ O) is from 2.0 to 4.7 parts by weight, CaCO ₃ is 0 to 6 Part by mass.

Generally, an appropriate amount of dihydric gypsum is added to the cement during the pulverization process during cement production in order to prevent rapid setting due to a rapid hydration reaction such as 3CaO · Al ₂ O _{3 and} to secure a stable setting time. The On the other hand, hemihydrate gypsum was not actively added because it promotes false setting of cement. One feature of the present invention is that the setting and hardening time is delayed by containing a predetermined amount of hemihydrate gypsum and dihydrate gypsum in the cement in the rapid-hardening cement.

The reason why the setting and hardening time is delayed by containing a predetermined amount of hemihydrate gypsum and dihydrate gypsum in the cement is not necessarily clear, and it is not intended that the present invention be limited by theory. It is considered that dehydration of CaSO ₄ · 2H ₂ O to CaSO ₄ · 1 / 2H ₂ O proceeds, and as a result, a long setting time of the hardened cement is secured.

  Since dihydrate gypsum causes problems such as abnormal setting when too small, and expansion when too large, it is desirable to add dihydrate gypsum so as to be contained in the cement within the above-mentioned range. If hemihydrate gypsum is too small, the effect of delaying the setting and hardening time cannot be sufficiently obtained, and if too much, false setting tends to be promoted. Therefore, it is desirable to add it so as to be contained in the cement within the above-mentioned range.

  If the mass ratio of hemihydrate gypsum to dihydrate gypsum becomes too large, false setting tends to be promoted. On the other hand, when the ratio becomes too small, the setting and hardening time tends to be shortened. Therefore, it is preferable that hemihydrate gypsum / dihydrate gypsum = 0.2 to 1.0, and hemihydrate gypsum / dihydrate gypsum. = 0.3 to 0.95 is more preferable, and it is even more preferable that hemihydrate gypsum / dihydrate gypsum = 0.4 to 0.6.

  As a method of securing a predetermined amount of hemihydrate gypsum and dihydrate gypsum in cement, a method of adding a predetermined amount of hemihydrate gypsum and dihydrate gypsum in a cement clinker, gypsum, etc. in a cement manufacturing process, There are a method in which gypsum is added in the pulverizing and mixing step to raise the pulverization temperature to produce hemihydrate gypsum, and a method in which the gypsum is dried in the subsequent step of the pulverizing and mixing step to obtain hemihydrate gypsum. In general, in the drying process, when there is sufficient free water on the surface of the object to be dried, the object surface becomes equal, and the drying rate is constant regardless of the moisture content of the object, and the drying is further promoted. And a reduced rate drying rate area where free water replenishment from the inside of the object cannot keep up with the evaporation rate, but in the constant rate drying rate range, the moisture content after drying is in the process of decreasing, so the reduced rate drying rate It is preferable to dry to the area. As a method of drying to the reduced rate drying speed range, there are a method of drying the cement with an air dryer, a method of increasing the pulverization temperature at the time of adding dihydrate gypsum in the pulverization process at the time of cement production, and the like.

  Examples of the method of adding a predetermined amount include a method in which a preliminarily obtained hemihydrate gypsum and dihydrate gypsum are quantitatively supplied to a cement grinding mill or the like together with a cement clinker or the like. In this case, in order to secure the amount of hemihydrate gypsum and dihydrate gypsum to be produced, a method of controlling the temperature of the cement grinding mill to, for example, 120 ° C. or less is necessary. As a method of adding dihydrate gypsum in the pulverization and mixing and classifying step to raise the pulverization temperature and generate semi-hydrate gypsum, the temperature of the cement pulverization mill is operated at, for example, over 110 ° C. In order to control the ratio of water gypsum, it is effective to perform temperature control not exceeding 120 ° C. by water spray or the like. As a method for drying in the subsequent step of the pulverization and mixing step to obtain hemihydrate gypsum, a method of drying cement at 100 to 80 ° C., more preferably 95 to 85 ° C. is effective. Examples of the drying method include a method of drying cement with an air dryer.

As an index indicating gypsum in cement, SO ₃ is used, and SO ₃ is about 0.1 to 0.2% by mass in the clinker in the form of Na ₂ SO ₄ or the like as a circulating material when producing the cement clinker. In addition to this, it is composed of dihydrate gypsum and hemihydrate gypsum. SO ₃ in the cement, JIS R5210 SO ₃ ≦ 3.5% by weight in Portland cement, SO ₃ ≦ 4.0% by weight in JIS R5211 Blast furnace cement, SO ₃ ≦ 3.0% by weight in JIS R5212 silica cement, JIS In R5213 fly ash cement, SO ₃ ≦ 3.0% by mass, and in JIS R5214 ecocement, SO ₃ ≦ 4.5% by mass. Most of the SO _{3 in} the cement is dihydrate added during clinker grinding. It is based on gypsum and hemihydrate gypsum. Hemihydrate gypsum and dihydrate gypsum in cement are quantitatively measured by the X-ray diffraction Rietveld method.

<Rapid hardwood>
(1) Calcium aluminate Calcium aluminate is a component generally used as a rapid hardening material, and is indispensable for exhibiting rapid hardening. Usually, it is a mineral obtained by synthesizing a CaO raw material, an Al ₂ O ₃ raw material, and optionally an SiO ₂ raw material at 1,200 to 1,700 ° C. in an electric furnace or kiln and quenching. Exemplary compositions, CaO 35 to 50 wt%, Al ₂ O ₃ is 40 to 55 wt%, SiO ₂ is 1 to 15 mass%. Exemplary _{chemicals, 3CaO · Al 2 O 3,} 12CaO · 7Al 2 O 3, 11CaO · 7Al 2 O 3 · CaF 2, CaO · Al 2 O 3, 2CaO · Al 2 O 3 · SiO 2, CaO _{· Al 2 O 3 · 2SiO 2} , 3CaO · 3Al 2 O 3 · CaF 2, 3CaO · 2Na 2 O · 5Al 2 O 3 and the like, preferably 12CaO · 7Al ₂ O _3.

  If the content of calcium aluminate is too high, there is abnormal expansion after curing, while if it is too low, the strength will be insufficient for a short time. % Is more preferable.

  Calcium aluminate can be in any form of crystalline or glassy, but glassy obtained by quenching the melt with an electric furnace or the like is preferable. When the glassy quality is 60% by mass or more, excellent strength development is achieved in a short time.

The fineness of calcium aluminate is preferably 3,000 to 9,000 cm ² / g in terms of Blaine value.

(2) Anhydrous gypsum Anhydrous gypsum is also an important component as a rapid hardening material and, together with the hydration of calcium aluminate, acts to form the rapid hardening hydrate Ettringite, which is essential for the rapid hardening cement according to the present invention. It is. If the content of anhydrous gypsum is too high, abnormal expansion after curing will occur, while if it is too low, the rapid hardening performance will be insufficient. Therefore, the content is preferably 2 to 30% by mass in the rapid hardening cement, and 5 to 20% by mass. % Is more preferable.

The fineness of anhydrous gypsum is preferably 3,000 to 9,000 cm ² / g in terms of Blaine value.

  Calcium aluminate and anhydrous gypsum are added in a total amount of 5 to 40 parts by weight, more preferably 5 to 30 parts by weight, in total with respect to 100 parts by weight of cement. If the total of calcium aluminate and anhydrous gypsum is less than 5 parts by mass, it is difficult to show rapid hardening performance in which the strength for 3 hours in mortar and concrete is 20 MPa or more, and even if the amount added exceeds 40 parts by mass The rapid hardening performance, which is 3 hours strength, does not increase and tends to cause abnormal expansion after curing.

<Setting agent>
In the present invention, it is essential to add a coagulation adjusting agent such as carbonate and oxycarboxylic acid. Examples of the carbonate include potassium carbonate, sodium carbonate, lithium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate and the like. Examples of oxycarboxylic acids include oxycarboxylic acids such as citric acid, tartaric acid, gluconic acid, malic acid, acetic acid, adipic acid, and succinic acid, and salts thereof. Examples of the oxycarboxylate include sodium, potassium, calcium, magnesium, ammonium, and aluminum salts of the above acids, and examples include sodium citrate and sodium gluconate. The setting modifier can be used alone or in combination of two or more.

  The amount of setting modifier added is preferably 0.01 to 5% by mass, more preferably 0.05 to 2% by mass, based on the total mass of cement and rapid hardening material (calcium aluminate + anhydrous gypsum). To do. If the setting modifier is less than 0.01% by mass, sufficient gelation time cannot be secured. Even if the addition amount exceeds 5% by mass, the gelation time may be shortened. It is difficult to stably ensure a time, for example, a gelation time of 60 minutes or more.

<Other cement admixtures>
In the quick-hardening cement according to the present invention, various conventional cement admixtures can be appropriately added. For example, a water reducing agent, aggregate, etc. can be added. It is also effective to add an appropriate amount of a substance such as a pozzolanic material such as silica fume, 3CaO.3Al ₂ O ₃ .CaSO ₄ or the like in order to impart denseness and expandability.

<Characteristics of rapid hardening cement according to the present invention>
(1. Loss on drying)
In one embodiment of the quick-hardening cement according to the present invention, the raw material cement used has a weight loss after drying at 90 ° C. for 20 hours of 0.25% by mass or less, preferably 0.2% by mass or less, More preferably, it is 0.1 mass% or less. Thus, by reducing the loss on drying at 90 ° C., the gelation time at 5 ° C. can be lengthened, preferably 60 minutes or longer, and the curing time at 5 ° C. can be lengthened, preferably 60 minutes or longer. can do.

(2. Gelation time and curing time)
In the present invention, gelation time is defined as one of the indexes for evaluating the setting and hardening characteristics of rapid-hardening cement. The gelation time is determined by measuring the relationship between the time after pouring water mixing and the temperature rise for 200 g of rapid hardening cement paste (fast hardening cement 156 g + 44 g of water) at a specific ambient temperature. This is the time required for the temperature to rise. In the present invention, the setting time is defined as one of the indexes for evaluating the setting and setting time of the rapid hardening cement. The setting time is a time required for the temperature of the kneaded cement paste to rise by 5 ° C. due to the heat generated by hardening, after measuring the relationship between the time after water pouring and the temperature rise for 200 g of the rapid hardening cement paste.

  Rapid hardening cement paste loses its fluidity with increasing temperature due to gelation and hardening. As an index for losing fluidity, it is effective to use an index that the residence time in the funnel becomes long. FIGS. 1-1 and 1-2 show the setting and hardening time from the viewpoint of ease of understanding. The gelation time and the setting time for the insufficiently setting rapid setting cement and the setting cement having a sufficiently long setting time are shown schematically together with an increase in temperature and a decrease in fluidity. It is hardened through gelation, and dripping time measured by J-Roth non-shrink mortar quality control test method (Japan Highway Public Corporation Standard JHS 312), KC-57 J-Roth (Highway Public Corporation type) is drastically increased and fluidity is increased. I can understand the phenomenon of losing.

Along with gelation, the viscosity of the rapid hardening cement paste increases, and when it hardens, the rapid hardening paste hardens, and the strength rapidly increases. After about 3 hours, the strength of the hardened mortar / concrete is increased. It exceeds 20 Mpa and is used for civil engineering structures. Specifically, the viscosity is about 800 cps immediately after kneading of the rapid hardening cement paste, but with the gelation, the viscosity of the rapid hardening cement paste exceeds 10,000 cps, kneading with a mixer, injection of the rapid hardening paste, It is difficult to secure operations such as placing and compacting. The measurement method of the viscosity of the quick-hardening cement paste after kneading is the J-rote non-shrink mortar quality control test method (Japan Highway Public Corporation Standard JHS 312), and the funnel is KC-57 J ), A mortar flow shown in JIS R5210, a rotational viscosity measurement method according to JIS Z8803 “Liquid Viscosity-Measurement Method”, and the like. Generally, a rapid hardening cement paste hardens after the curing time has elapsed, and records about 1 [N / mm ² ] according to the Procter penetration resistance test method (JIS A 6204 Annex I).

  If the gelation time and setting time are too short, construct a structure with cement concrete, etc. with the addition of aggregate (sand, gravel, etc.) to rapid hardening cement paste, or repair work with cement mortar with addition of sand, etc. It becomes impossible to ensure the work time generally performed. It is desirable that the gelation time and the curing time at 5 ° C. be sufficiently long in order to practically perform mass placement with mortar, concrete, etc. using a concrete pump or the like at a construction site in the cold season.

  In one embodiment of the rapid hardening cement paste, cement mortar or cement concrete according to the present invention, the gelation time at 5 ° C. is 60 minutes or longer, preferably 70 minutes or longer, for example 60-80 minutes. be able to.

  In one embodiment of the rapid hardening cement paste, cement mortar or cement concrete according to the present invention, the curing time at 5 ° C. is 60 minutes or more, preferably 70 minutes or more, for example, 60 to 80 minutes. Can do.

<Manufacturing method>
The quick-hardening cement according to the present invention can be manufactured by mixing the above-mentioned cement, quick-hardening material, setting modifier, and the like. Then, by adding water to the rapid-hardening cement and kneading the raw materials with a general mixer, preferably a forced kneading mixer, a quick-hardening cement paste can be produced. When the amount of water added is too large, material separation occurs. On the other hand, when the amount is too small, fluidity cannot be obtained. Therefore, the amount is preferably 10 to 50 parts by mass with respect to 100 parts by mass of the rapid-hardening cement. It is more preferable to set it as -45 mass parts, and it can typically be 20-40 mass parts.

  The quick-hardening cement paste according to the present invention has high workability and workability because the setting and hardening time is long. For this reason, for example, a grader, a bulldozer, a finisher or the like can be used to spread and further high strength can be obtained at an early stage by compacting and rolling with a hammer, a tire roller, a vibration roller, or the like. The rapid-hardening cement paste according to the present invention is particularly excellent in workability and workability in a low-temperature environment, and can be suitably used for placing in a temperature environment at 1 to 10 ° C., for example.

  The hardened cement paste according to the present invention is a hardened mortar or concrete, for example, in tunnels such as roads, railways, water conduits, etc. It can be used sometimes.

  Examples of the present invention will be described below, but these are for illustrative purposes and are not intended to limit the present invention.

  Powdered ordinary Portland cement (Nos. 1 to 4) having the respective compositions shown in Table 1 was prepared. The amount of substance in the cement is a value obtained by chemical composition analysis by Rietveld method. Specifically, the amount of each chemical component was determined from the diffraction intensity by powder X-ray diffraction using “SIROQUANT Version 2.5” (manufactured by Sietronics). Table 2 also shows the results of chemical analysis according to JIS R5202.

<Loss on drying at various temperatures>
About each said cement, loss on drying was measured. Geotechnical Society standards (draft draft) “JGS0121: 0000 Soil moisture content test method” is a method for measuring the loss on drying at 110 ° C., and the constant temperature drying furnace is a circulating fan type that forcibly circulates the air in the furnace with an electric fan. Therefore, the loss on drying at 50 ° C., 90 ° C., 105 ° C., and 140 ° C. was measured by the drying furnace. Since the time until reaching a constant mass is generally described to be about 18 to 24 hours, drying was performed in 20 hours. The results are shown in Table 3. From Table 3, it can be seen that the loss on drying especially at 50 ° C. and 90 ° C. is smaller in the inventive examples than in the comparative examples, and the loss on drying at 90 ° C. is 0.25% by mass or less.

<Density and Blaine specific surface area>
In accordance with JIS R5201 (cement physical test method), the density and brane specific surface area of each cement were measured. The results are shown in Table 4.

<Ion analysis by dissolution test>
Further, the following elution test was performed on the cement, and ion analysis was performed at 5 ° C. 25 g of cement and 25 mL of pure were put into a beaker, stirred with a stirrer for a predetermined time, and separated into a solid phase portion and a liquid phase portion by suction filtration. Various ions contained in the liquid phase are quantified by flame atomic absorption spectrometry (Ca, Na, K, JIS K0102 “Factory wastewater test method”) and ion chromatographic analysis (SO ₄ ^2- , JIS K0102 “Factory wastewater test method”). did. The results are shown in Table 5 and FIG.

The following raw materials (A) to (E) are mixed with each of the above-mentioned cements in each part by mass shown in Table 6 to produce a quick-hardening cement, and then, the parts by mass of water shown in Table 6 are added. Kneading was carried out to produce pastes of the quick-hardening cements of the inventive examples and comparative examples.
(A) Calcium aluminate _{(12CaO · 7Al 2 O 3)} : 2000kVA by quenching the melt of 1600 ° C. by an electric furnace, a 12CaO · 7Al ₂ O ₃ was vitrified by step blow off, degree of fineness 4,500 [ cm ₂ / g] (brane value), manufactured by Denki Kagaku Kogyo Co., Ltd., Aomi factory, glass quality: 95% by mass, glass quality is measured by X-ray diffraction Rietveld method, “SIROQUANT Version2.5” (Sietronics Co., Ltd.) was used to quantify the diffraction intensity by powder X-ray diffraction.
(B) Anhydrous gypsum: Electrochemical Industry Co., Ltd. Aomi factory manufactured to a fineness of 4,500 cm ² / g (Brain value) (C) Water reducing agent (Cell Flow 110P): “Cell Flow 110P” (Daiichi Kogyo Seiyaku) )
(D) Potassium carbonate: Asahi Glass Co., Ltd. manufactured product (E) Purified citric acid: Fuso Chemical Industry Co., Ltd. manufactured product (F) Water: Industrial water

  About the obtained quick-hardening cement paste, the hardening characteristic (Table 7) was measured. The experimental conditions are shown below.

<Curing characteristics>
With respect to 200 g of the quick-hardening cement paste, the relationship between the time after water pouring and the temperature rise was measured. The time when the temperature of the kneaded cement paste was raised by 2 ° C. was defined as the gel time, and the time when the temperature was raised by 5 ° C. was defined as the setting time. After the gelation time has elapsed, the viscosity of the paste increases, and the paste exhibits a stiff state. After the curing time has elapsed, the paste hardens and is approximately 1 N / mm ^{2 according} to the Procter penetration resistance test method (JIS A 6204 Annex I). Was recorded.
In addition, when both the gelation time and the setting time of the rapid hardening cement paste were secured for 60 minutes or more, it was determined as “normal”, and when either one was less than 60 minutes, it was determined as “abnormal”.

  From Table 7, in the rapid-hardening cement (No. 1, 2) according to the present invention, as the temperature rise is suppressed and the curing temperature decreases to 30 ° C., 20 ° C., 5 ° C., the gelation time is in the range of 50 minutes, It increased to 60 minutes and 70 minutes, and more than 50 minutes were secured. On the other hand, in the quick-hardening cement (No. 3, No. 4) according to the comparative example, the gelation time is in the range from 40 minutes to 20 minutes as the curing temperature decreases to 30 ° C., 20 ° C., and 5 ° C. Especially at 5 ° C., it is remarkably short as less than 30 minutes. Also, the curing time is significantly shorter than that of the inventive examples.

<Discussion>
The amount of each chemical component in the cement shown in Table 1 according to the Rietveld method is 60 to 50% by mass of Alite (3CaO · SiO ₂ ) and Belite (2CaO · SiO ₂ ) in any of the hardened cements according to any test number. ₂ ) is 20 to 10% by mass, 3CaO · Al ₂ O ₃ is 10 to 5% by mass, and 4CaO · Al ₂ O ₃ · Fe ₂ O ₃ is 15 to 5% by mass, which is significant in the present invention and the comparative example. There is no difference. On the other hand, when dihydrate gypsum and hemihydrate gypsum that affect the initial setting and hardening are compared, in the invention examples, the amount of hemihydrate gypsum is 1.4 to 2.2% by mass, and dihydrate gypsum is 2.4%. While it is as low as ˜2.8% by mass, in the comparative example, the amount of hemihydrate gypsum is as low as 0.8 to 1.3% by mass and the amount of dihydrate gypsum is as large as 3.3 to 3.7% by mass.

  From this, it can be seen that the gelation time, setting time, and loss on drying have a significant effect on the mixing conditions of hemihydrate gypsum and dihydrate gypsum in the rapid-hardening cement, and the mixing conditions specified in the present invention. It can be understood that it is advantageous.

Further, from Table 5 showing the results of the ion analysis by the dissolution test and FIG. 2, in the comparative example, the amount of Ca and SO ₄ ^{2- in} 1 to 5 minutes in the initial stage of dissolution is low, and Ca and SO ₄ ^2- Dissolution is suppressed. On the other hand, in the present invention, high Ca and SO ₄ amount of ² at 1-5 minute elution early stages, Ca and SO ₄ dissolved in ^2-fast. The dissolution of Ca and SO ₄ ^2- correlates with the amount of hemihydrate gypsum. That is, in the quick-hardening cement paste of the present invention, the amount of hemihydrate gypsum is as large as 1.4 to 2.2% by mass, so the amount of Ca and SO ₄ ²⁻ is high in 1 to 5 minutes in the initial stage of elution. . Therefore, Ca and SO ₄ ^{2-dissolution} is promoted, usually 3CaO · Al ₂ O ₃ the cement contained _{in, 4CaO · Al 2 O 3 ·} Fe 2 O 3 and gypsum, and hemihydrate gypsum It is considered that the hydration of the rapid hardening admixture is suppressed by accelerating the hydration of the mixture, thereby suppressing the hydration of the rapid-hardening admixture.

Claims (10)

  (A) a cement, (B) a rapid hardening material containing calcium aluminate and anhydrous gypsum, and (C) a rapid hardening cement containing a setting modifier, wherein (A) hemihydrate gypsum is contained in 100 parts by mass of cement. A rapid-hardening cement containing 1.4 to 2.7 parts by mass and 2.0 to 5.4 parts by mass of dihydrate gypsum.   The rapid-hardening cement according to claim 1, wherein the mass ratio of hemihydrate gypsum and dihydrate gypsum is hemihydrate gypsum / dihydrate gypsum = 0.2 to 1.0.   The rapid-hardening cement according to claim 1, wherein the mass ratio of hemihydrate gypsum and dihydrate gypsum is hemihydrate gypsum / dihydrate gypsum = 0.4 to 0.6.   The rapid-hardening cement according to any one of claims 1 to 3, wherein (A) the cement has a weight loss of 0.25 mass% or less after drying at 90 ° C for 20 hours.   The content of (A) cement in the quick-hardening cement is 70 to 95% by mass, and calcium aluminate and anhydrous gypsum are 5 to 40 parts by mass in total with respect to 100 parts by mass of (A) cement (C The setting agent is 0.01-5% by mass with respect to the total mass of (A) cement, calcium aluminate, and anhydrous gypsum.   Cement paste, cement mortar, or cement concrete using the rapid hardening cement according to any one of claims 1 to 5.   The cement paste, cement mortar or cement concrete according to claim 6, wherein the gelation time at 5 ° C is 60 minutes or more.   Cement paste, cement mortar or cement concrete according to claim 6 or 7, wherein the curing time at 5 ° C is 60 minutes or more.   Hardened | cured material of the cement paste, cement mortar, or cement concrete as described in any one of Claims 6-8.   A method for using a cement paste, cement mortar or cement concrete, comprising placing the cement paste, cement mortar or cement concrete according to any one of claims 6 to 8 in a temperature environment of 1 to 10 ° C.

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