JPH04164847A - Cement admixture and cement composition - Google Patents

Abstract

PURPOSE:To provide quickly hardening property and resistance to separation of material in water to a cement admixture by adding a calcium aluminosilicate glass, an inorganic sulfate and a cellulose substance to the cement. CONSTITUTION:100 pts.wt. calcium aluminosilicate glass consisting of 60-30wt.% CaO, 20-60wt.% Al2O3 and 5-25wt.% SiO2 and having >=50wt.% vitrification ratio and >=3000cm<2> Blaine's specific surface area is blended with 50-300 pts.wt. inorganic sulfate (e.g. II type anhydrous gypsum) having >=3000cm<2>/g Blaine's specific surface area and 2-30 pts.wt. cellulose substance (e.g. methylcellulose) having >=200 polymerization degree to afford cement admixture. Then 100 pts.wt. cement is blended with 5-30 pts.wt. of the above-mentioned admixture, 1-30 pts.wt. setting controller (e.g. citric agent), a fiber, a polymer emulsion, an AE agent, a water reducing agent, etc., to provide the cement composition.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to cement admixtures, particularly admixtures for special underwater concrete, and cement compositions using the same.

(Prior Art) In recent years, instead of the conventional underwater concrete construction method using ordinary concrete, there has been an increase in construction using new concrete in which the concrete itself has material separation resistance against the washing action of water. This type of concrete is called special underwater concrete, which is defined as ``concrete that has been given underwater separation resistance by adding an admixture for special underwater concrete.'' Construction)”, (Foundation)
Coastal Development Technology Research Center/Fishing Port and Village Construction Technology Research Institute, Published by Sankai Kata, December 1986).

In addition, a special admixture for underwater concrete refers to an admixture that is added to concrete to be placed in water to give it consistency and thereby suppress the separation of cement and aggregate in water. The use of natural or synthetic polymers such as methylcellulose or polyvinyl alcohol (Japanese Unexamined Patent Publication No. 123850/1982)
, use of polyacrylamide (JP-A-59-54656
JP-A-61-111951) and the use of specific acrylic monomers (JP-A-61-111951) have been proposed.

(Problem to be solved by the invention) However, the current special underwater concrete has a problem that its hardening speed is the same as that of conventional concrete or tends to be slower, making it impossible to apply it to emergency construction. there were. In view of the current situation, the present inventors have conducted various studies on cement admixtures that provide rapid hardening and resistance to material separation in water, and have found that a specific cement admixture provides the above-mentioned performance. The present invention has now been completed.

(Means for Solving the Problems) That is, the present invention is a cement admixture characterized by comprising calcium aluminosilicate glass, an inorganic sulfate, and a cellulose material as main components, and further comprising a cement admixture and a cement admixture. This is a cement composition characterized by having as a main component.

The present invention will be explained in detail below.

Calcium aluminosilicate glass (hereinafter referred to as C) according to the present invention
AS glass) has a composition range of Cab:60.
~30% by weight A120ff: 20-60〃SiO□: 5-25〃 is preferable, and more preferably CaO: 55-30% by weight AlzOz: 30-60〃SiO□: 10-20〃. If CaO is less than 30% by weight or AlzOs is more than 60% by weight, the rapid hardening will be poor; conversely, if CaO is more than 60% by weight or Al2O is less than 20% by weight, a large amount of setting modifier must be added. Even if it is used, it will cause instantaneous condensation, which is not preferable from the viewpoint of workability. Furthermore, if 5i02 is less than 5% by weight, long-term strength growth cannot be expected;
Conversely, if it exceeds 25% by weight, the initial strength will be low. In addition, general industrial raw materials include MgO, FezO3, TiOz, K2
Impurities such as O and NazO are naturally included, and since these impurities expand the vitrification region of the CaO-^1□03-3iOz system, their presence in an amount of less than 10% by weight is preferable. There are no problems with rapid hardening, workability, long-term strength growth, etc. - It is preferable to add alkali nitrate (NaNO:+, KNO3, etc.), calcium fluoride (CaFz), borax, etc., which are fluxing agents for glass, because they lower the melting point of the glass.

The glass referred to here is what is commonly referred to in the field of glass, that is, it is "a material that exhibits a glass transition point." Note that it is not necessary that all of the material is glass, and there is no problem as long as the vitrification rate is 50% by weight or more. More preferably 70% by weight
The content is more preferably 80% by weight or more. If it is less than 50% by weight, problems arise in terms of early strength.

In addition, the method for measuring the vitrification rate is that the glass of the present invention is
After heating at 000°C for 12 hours (h), it was slowly cooled at a cooling rate of 5°C/min (m), and the area S0 of the main peak of the crystalline mineral was determined by powder X-ray diffraction method. The vitrification rate χ was determined from the main peak area S of .

χ (weight%) = 100 x (1--)S.

The composition of the above CAS glass is completely different from the composition of granulated blast furnace slag produced as a by-product in metallurgy or metal smelting, and the present invention is not derived from the composition of granulated blast furnace slag. Incidentally, the average chemical composition of granulated blast furnace slag is Cab: 40-43% by weight, MgO: 5-8% by weight, AIZO: 13-15% by weight, and SiO.
□: 31 to 35% by weight.

Furthermore, the CAS glass of the present invention is not derived from alumina cement. That is, the amount of SiO□ in ordinary alumina cement is less than 5% by weight [Jun Kasai, Concrete Engineering, Vol. 22, No. 8, p. 67 (1984)
)), and the vitrification rate does not exceed 25% (
1964, Published by Academic Press, London, Limited, νF, H, F, W, T
The Chemistry of Cement (Th
e Chemistry of Cement), Volume 2, Page 16].

Raw materials for the CAS glass according to the present invention include quicklime (Cab) and slaked lime (Ca(OH)) as CaO raw materials.
), limestone (caco:+), etc. can be used, and as AIZO3 raw materials, alumina, bauxite,
Diaspores, feldspar, clay, etc. can be used, and Si
Silica sand, white clay, diatomaceous earth, etc. can be used as the 0g material. Alternatively, relatively inexpensive blast furnace slag can be
It can also be achieved by supplementing aO quality raw materials and A1□03 quality raw materials.

After blending the above CaO raw materials, Al2O raw materials, and 5102 raw materials in a predetermined ratio, they are melted using a direct current melting furnace or high frequency furnace, and the resulting melt is blown with compressed air or high-pressure water. Manufactured by either jetting or pouring into water. Alternatively, CAS glass can also be produced by melting it in a rotary kiln and rapidly cooling it.

The finer the fineness of the CAS glass, the better the reactivity will be, and in particular, the finer the particle size is, the Blaine specific surface area is 3.000 a.
It is preferably n2/g or more.

The inorganic sulfate according to the present invention refers to an alkali metal or alkaline earth metal sulfate, and preferable examples thereof include anhydrous, hemihydrate, and trihydrate calcium sulfates, and among them, type 1 anhydrous gypsum. Particularly preferred are those that are sparingly soluble or insoluble. The fineness of inorganic sulfate is usually 3,000 an2/g
The above is preferable.

The amount of inorganic sulfate used is 50 to 300 parts by weight, preferably 100 to 200 parts by weight, based on 100 parts by weight of CAS glass. If it is less than 50 parts by weight, the rapid hardening is insufficient, and if it exceeds 300 parts by weight, the dimensional stability of the cement composition may deteriorate.

The cellulose material according to the present invention is cellulose ether, which is obtained by introducing various substituents into cellulose, which is a fiber component of wood and cotton, and specifically, methylcellulose (MC).
, hydroxyethylcellulose (HEC), hydroxyethylmethylcellulose (HEMC), hydroxypropylmethylcellulose (HPMC), and the like are known.

The cellulose material preferably has a degree of polymerization of 200 or more; if the degree of polymerization is less than 200, the thickening effect (viscosity imparting effect) may be insufficient.

Cellulose materials can be easily obtained as commercial products.

The amount of cellulose material used is preferably 2 to 30 parts by weight per 100 parts by weight of CAS glass. Outside this range, the underwater separation resistance or workability of the underwater concrete composition may be impaired.

The cement according to the present invention refers to commonly used ordinary cement.
Various types of Portland cement such as early strength and super early strength, various mixed cements made by mixing these with blast furnace slag, fly ash, or silica, expanded cement made by mixing expansive materials with Portland cement, special cements such as alumina cement, etc. It is.

In the present invention, the amount of the cement admixture to be used is preferably 5 to 30 parts by weight per 100 parts by weight of cement, and if it is outside this range, there is a risk that the object of the present invention may not be achieved.

The aggregate used in the present invention is not particularly limited, and ordinary aggregates such as silica sand, natural sand, gravel, etc. can be used.

Moreover, in the present invention, it is also possible to use various other additives. The various additives mentioned here include, for example, setting modifiers, fibers such as glass fibers, carbon fibers, and steel fibers, polymer emulsions, colorants, AB agents, water reducing agents, AE water reducing agents, fluidizing agents, and rust preventive agents. , water retention agents, waterproofing agents such as calcium chloride and sodium silicate, foaming agents, foaming agents, calcium salts such as calcium hydroxide, antifreeze agents, etc., and one or more of them may be used in the present invention. It is possible to use them together in an amount that does not substantially inhibit the purpose.

As setting regulators, citric acid, tartaric acid, gluconic acid,
Organic acids such as succinic acid and maleic acid and their salts,
Examples include alkali carbonates such as sodium carbonate and potassium carbonate, phosphoric acids and their salts, boric acid, alkali borates, alkali aluminates, silicofluorides, starches, sugars, alcohols, and mixtures thereof.Among them, organic acids Use or preferred.

The amount of setting regulator to be used is determined from the viewpoint of obtaining an appropriate working time.
It is preferably about 1 to 30 parts by weight per 100 parts by weight of CAS glass. A reasonable working time at the construction site is usually 20
~240 minutes.

The mixing device for the cement admixture of the present invention is not particularly limited; Any stirring device can be used. Furthermore, there are no particular restrictions on the method of mixing each material (each material may be mixed at the time of construction, or some or all of the materials may be mixed in advance).

In the present invention, it is further possible to mix water with cement and cement admixtures to prepare underwater concrete, but the amount of water is not particularly specified and can be made in accordance with conventional preparation of concrete. It is possible to determine the

The mixing equipment used to produce underwater concrete is also
In particular, without limitation, it is possible to use the mixing devices described above.

Furthermore, the method for constructing underwater concrete of the present invention includes:
It is possible to use conventional underwater concrete construction methods, such as the tremie method, concrete pump method, and open-bottom container method.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Commercially available special grade reagents CaCO5, A12oz, and Si
n□ was mixed, 300g was placed in a carbon crucible, heated and melted at approximately 000°C in a high frequency furnace, and then quenched in water to synthesize 14 types of glasses A to H shown in Table 1. . In addition, as shown in the remarks column, A, B, HlJSK
Since ,N was not within the vitrification region of the CaO-A1203-3iO□ system, 1% by weight of CaFz was added outside and vitrified by melting and rapidly cooling. Also, L, M.

N is a comparative example other than the present invention. Each of these CAS glasses has a Blaine specific surface area of 4,000 an27g.
It was crushed until it was. The analysis results are also listed in Table 1.

Next, concrete having the composition shown in Table 2 was prepared using the fired products shown in Table 1, the working time and compressive strength were measured, and an underwater drop test was conducted. The materials used and test methods are as follows. The results are shown in Table 3.

(Materials used) Cement Manufactured by Niandes Cement, ordinary Portland cement Inorganic sulfate: ■-type anhydrite, Blaine specific surface area 5,
900 am2/g Set regulator Sodium nigerconate (reagent) Cellulose material: Manufactured by Denki Kagaku Co., Ltd., trade name "Denka Stabilite 1, main component methylcellulose fine aggregate: River sand from Himeyo, Niigata Prefecture, specific gravity, 6, FM
, 62 Coarse aggregate: Crushed stone from Himeyo, Niigata Prefecture, shaft ax 20m
/m, Specific gravity, 6, FM6.7 AH water-reducing material: Manufactured by Denka Brace Co., Ltd., product name: Dalex WRDA J (Test method) ■Working time (H, T,); Time taken for hardening and loss of fluidity. In other words, after mixing all the ingredients in a mixer, place them in a 500cc beaker and let it stand, and the time until it stops flowing even if you lay it down.

■Compressive strength: A cylindrical mold with a diameter of 100n and a height of 200fi is placed in a container to prepare neutral water suitable for mixing, such as drinking water.
Fill with water at a temperature of 20±1℃ and maintain the water depth at 50cm.

A cylindrical 10 m mesh wire mesh with a diameter of 100 n and a height of 300 m is vertically placed on the upper end of the formwork, and set so that the upper end of the wire mesh is in contact with the water surface.

The mixed underwater concrete is gently dropped from the water surface through a wire mesh and filled into the formwork.

The amount of underwater concrete input per formwork is approximately 2
1, and divide into 15 equal amounts. The time required for charging shall be between 30 seconds and 1 minute for each formwork. Adjust so that the water depth does not change before and after injection. After completing the pouring of underwater concrete, the formwork is left in the water for 15 minutes and then taken out into the air. Side 2 of the formwork for the purpose of promoting the replacement of water and concrete within the formwork.
Tap lightly with a mallet 2 to 3 times in each direction. After confirming that no water comes out from the interface between the inner wall of the formwork and the concrete, level the top.

Subsequent curing, capping, and demolding are performed in accordance with JIS A 1132 r "How to make concrete strength test specimens." In this way, the prepared specimen was
After standard curing in water at 3°C, compressive strength was measured using JIS A 1108 r concrete compressive strength test method.

Note that the number of specimens is 3 in each batch, and the average value of 6 specimens in 2 batches is determined.

■ Underwater drop test; 800 cc of water is poured into a 1,000 cc beaker with an outer diameter of 110 B and a height of 150 n. underwater concrete 50
Divide 0g into 10 equal parts and drop them gently from the water surface. The drop is completed between 10 and 20 seconds. After that, let the beaker stand still for 3 minutes, and use a dropper to carefully remove 600 cc of water from the beaker, taking care not to mix the concrete with it. Using this fractionated water, suspended solids and pH were measured.

The pH was measured three times, and the average value was taken as the pH value. Further, the measurement of suspended solids was carried out in accordance with JIS K 0102 "Industrial Wastewater Test Method".

Table 2 Maximum dimensions of coarse aggregate (Tsuru), water-cement ratio and fine aggregate ratio (%) Water, cement, fine aggregate, coarse aggregate, cement admixture and A
E Water reducing agent is in unit amount (kg/l) Example 2 Using the formulation of Experimental No. 1-5 in Table 3, the amount of cement admixture in Table 2 was changed. I did the same. The results are shown in Table 4.

Table 4: Cement admixture (kg/m”), turbidity (ppm) (
Effects of the invention) As explained above, the cement of the present invention)? The R-wood and cement compositions are particularly useful in underwater concrete applications.

Patent applicant Denki Kagaku Kogyo Co., Ltd.

Claims (1)

[Scope of Claims] 1. A cement admixture characterized by containing calcium aluminosilicate glass, inorganic sulfate and cellulose material as main components. 2. A cement composition comprising the cement admixture according to claim 1 and cement as main components.