JPS6319464B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an admixture for use in hard-mixed concrete for vibratory pressure forming, which improves the surface appearance and freeze-thaw resistance of concrete products such as concrete blocks, and improves workability. Here, hard-mixed concrete refers to concrete containing 90 to 110 kg of water in 1 m ³ of concrete. Advances in concrete technology have made it possible to pressurize hard-mixed or super-hard-mixed concrete while performing external vibration compaction using machines, immediately demold it, and obtain concrete products by steam curing. I'm getting used to it. However, concrete products that can be immediately demolded (immediately demolded) require careful attention to the management of materials and manufacturing conditions. Variations in quality such as compressive strength are likely to occur. Therefore, there is a need for an admixture with which products with excellent properties can be easily obtained. For example, when foaming anionic surfactants and nonionic surfactants such as alkylbenzene sulfonates are added to soft concrete, air is entrained and the workability of the concrete is improved.
Additionally, foaming anionic surfactants often have improved freeze-thaw resistance. However, simply adding a foaming surfactant to hard-mixed concrete under vibration has the disadvantage that workability and freeze-thaw resistance cannot be satisfied. Furthermore, it has been found that there is a tendency for the compressive strength to decrease and the dimensional stability to deteriorate. Therefore, for hard-mixed concrete and super-hard-mixed concrete, mixing only a foaming surfactant cannot entrain air which is excellent in improving freeze-thaw resistance. The purpose of the present invention is to improve the formability and dimensional stability of hard mixed concrete and super hard mixed concrete, and to obtain concrete that has excellent freeze-thaw resistance, as well as excellent compressive strength and surface appearance. The objective is to provide an admixture. The present inventors have conducted intensive research on improving the above-mentioned qualities of hard-mixed concrete and super-hard-mixed concrete. To mix air bubbles into concrete, there are two methods: adding a foaming surfactant to the concrete mixing water, and foaming the foaming surfactant with an appropriate foaming machine to add the necessary amount when mixing the concrete. There is a method of mixing foam, and the most commonly applicable method is to add a foaming surfactant to the mixing water and mix the necessary amount of foam with it during mixing of concrete. ,This method is simple and easy to adopt. However, as mentioned above, it was found that it was difficult to impart moldability, surface aesthetics, and dimensional retention just by adding a foaming surfactant, so we investigated ways to improve these physical properties. Therefore, in order to increase the inclusion of air bubbles without reducing the compressive strength and to improve the surface appearance, it is necessary to improve the dispersion and filling of the cement milk and mortar, and to improve the freeze-thaw resistance. It is necessary to maintain effective fine entrained air bubbles stably even under mechanical vibration and pressurized conditions, and we have discovered that sorbitol exhibits excellent effects for this purpose. In addition, dextrin is a substance that achieves the objectives of good shape retention during formwork removal work immediately after molding and dimensional stability of molded products during and after steam curing, but does not impair the workability of concrete. We discovered that it is a substance that can be effective without any problems. Therefore, by making various combinations of these substances, adding them when mixing concrete with cemented carbide, and performing pressure forming under mechanical vibration, we were able to successfully obtain concrete products of extremely desirable quality. We have now completed the present invention. That is, the present invention provides alkylbenzene sulfonates, alkyl sulfates, alkyl polyoxyethylene glycol sulfates, alkylphenol polyoxyethylene glycol sulfates, alkanesulfonates, α-olefin sulfonates, rosinates, and rosin derivatives. One or more foaming anionic surfactants selected from salts, alkyl sulfosuccinates, or one selected from polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, and alkylolamides.
Species or two or more foaming nonionic surfactants 10
~90% by weight and sorbitol or dextrin
The invention relates to a hard mixing concrete admixture for vibratory pressure molding containing a mixture of 90 to 10% by weight. The sorbitol used in the present invention has the effect of increasing friction-reducing properties and water-reducing properties under pressure. This strengthens the interlocking between the aggregate and the coarse aggregate and improves the filling properties. Moreover, it is effective in making cement milk and mortar appear on the surface more easily, stabilizing entrained air bubbles in the cement milk portion, and finishing the surface neatly and uniformly. In addition, dextrin has an appropriate dispersibility for cement particles, and has the property of imparting pseudo-plasticity or plasticity to the concentrated suspension system of fine particles in water, which is a characteristic of this type of polymeric substance, so that it can be used to form concrete. This can have extremely favorable effects on properties and dimensional stability. Therefore, even if anionic or nonionic surfactants are mixed alone, some effects can be achieved, but by blending the above-mentioned substances in specific proportions, instant deblocking products can be obtained. It turns out that the required quality can be sufficiently provided,
This made the invention a success. As the anionic or nonionic surfactant that is the first component of the present invention, those generally used as air entraining agents or foaming agents can be used, but examples of the anionic surfactant include alkylbenzene sulfonates, Alkyl sulfate, alkyl polyoxyethylene glycol sulfate, alkyl phenol polyoxyethylene glycol sulfate,
Examples of the nonionic surfactants include alkanesulfonates, α-olefin sulfonates, rosinates, salts of rosin derivatives, alkylsulfosuccinates, and nonionic surfactants such as polyoxyethylene alkyl ethers and polyoxyethylene alkyl phenyl ethers. , alkylolamides, and the like. Particularly typical general formulas are shown below. (R ₁ = C ₁₀ to C ₁₄ alkyl group, M = alkali metal, ammonium or alkanolamine) R ₂ OSO ₃ M (R ₂ = C ₈ to C ₁₈ saturated or unsaturated hydrocarbon group, M
= Same as above) R ₃ O (CH ₂ CH ₂ O) _o SO ₃ M (R ₃ = C ₁₀ to C ₁₈ saturated or unsaturated hydrocarbon group,
M = same as above) (R ₄ = C ₈ -C ₁₂ alkyl group, M = same as above) R ₅ -CH ₂ SO ₃ M (R ₅ = C ₇ - C ₂₃ alkyl group, M = same as above) R ₆ -CH=CH (CH _{2 ) oSO3M} (R ₆ = C ₄ to C ₂₂ alkyl group, n = 1 to 2, M =
(same as above) (R ₇ = C ₆ to C ₁₂ alkyl group, M = same as above) R ₈ O (CH ₂ CH ₂ O) _o H (R ₈ = C ₁₀ to _{C 18} saturated or unsaturated hydrocarbon group,
n=5-50) ( _R9 = _C6 - _C12 alkyl group, m=5-50) Also, the second component of the present invention is sorbitol or dextrin. Further, when it is made into an aqueous solution, a small amount of urea or an inorganic salt effective in reducing viscosity can be added as a viscosity reducing agent. Hereinafter, the present invention will be explained in further detail with reference to Examples. Example 1 Concrete was prepared under the following mixing conditions. still,
The weight of the materials used is per cubic meter (Kg). Ordinary Bolt Land Cement (Chichibu Cement)
270Kg, Kneading water 95Kg, River sand 998Kg, Natural river gravel 998
Kg, W/C=35%, S/A=50%, table in kneading water-
Add 0.108Kg (0.54Kg of 20% liquid) of the admixture shown in 1.
Knead for 3 minutes using a forced stirring mixer. On the other hand, the mix of plain concrete without any admixtures is as follows. (Chichibu cement) 270Kg, kneaded water
100Kg, river sand 1017Kg, natural river gravel 1018Kg, W/C
= 37%, S/a = 50%. Cement specific gravity 3.17 Sand (from Kinokawa) specific gravity 2.56 Sand water absorption rate
2.0% Coarse aggregate (from Hidaka River) Specific gravity 2.56 Gravel water absorption rate
1.1% Coarse aggregate maximum dimension 20mm Gravel moisture content
1.1% This was processed at 3900~4000R.PM (65~
67Hz), amplitude 1.3-1.5mm, vibration acceleration
Filling was carried out at 10.2 to 12.G for 3 seconds, and pressure molding was carried out for 5 seconds at a press pressure of 1.0 Kg/cm ² . The amount of concrete to be filled is approximately 45.5 kg per one block. Immediately after demolding, the mold is removed, the dimensions are measured on the surface and the back, and steam curing is performed. Steam curing conditions are as follows:
Preliminary time is 2 hours, the temperature is raised from 20°C to 60°C in 2 hours, maintained at 60°C for 1 hour, and then allowed to cool naturally.
After steam curing, the expansion and contraction of the dimensions of the surface part (30cm x 45cm) and the retaining part were measured, and the dimensional retention was determined from the percentage of expansion and contraction relative to the original dimensions. We also looked at the surface aesthetics from the surface finish and smoothness. Concrete specimens measuring 10 cm x 10 cm x 40 cm were cut using a diamond cutter to measure freeze-thaw resistance, degree of air bubbles, and compressive strength. Compressive strength was measured using a conventional method on a 10 x 10 x 20 cm square column that had undergone standard curing in water for 28 days. The degree of air bubble inclusion was measured with the naked eye using a microscope on a surface polished smooth with an abrasive.
Measure the number, diameter, etc. of bubbles existing in cm = 25 cm ² ,
It was measured as the number of bubbles per 1 cm ³ . The results are shown in Table-2. As is clear from Table 2, the present invention was found to be more effective than the control plain concrete and conventional foaming agents.

【table】

【table】

【table】

[Table] Example 2 Concrete mixing conditions, materials, and block forming conditions were the same as in Example 1. Concrete mix: 240kg of normal boltland cement, 116g of mixing water
Kg, river sand 1011 Kg, and river gravel 1004 Kg per cubic meter, respectively, S/A = 51%, water-cement ratio 0.483. The compressive strength test piece is 10 cm in diameter and 20 cm in height.
The cylindrical core was removed and cured in air for 14 days without steam curing. Dimensional retention, surface aesthetics, freeze-thaw resistance, etc.
Regarding the test piece that was air cured for 14 days,
It was carried out according to Example 1. The results are shown in Table-3.

【table】

Claims (1)

[Claims] 1 Alkylbenzene sulfonate, alkyl sulfate, alkyl polyoxyethylene glycol sulfate, alkyl phenol polyoxyethylene glycol sulfate, alkanesulfonate, α-olefin sulfonate, rosinate, salt of rosin derivative, alkyl sulfosuccinate One or more foaming anionic surfactants selected from acid salts, or one or more foaming agents selected from polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, and alkylolamides. 10 to 90% by weight of a nonionic surfactant;
Hard mix concrete admixture for vibratory pressing containing a mixture with 90-10% by weight of sorbitol or dextrin.