JPH08119700A - Admixture for cement and concrete using the same - Google Patents

Abstract

PURPOSE: To provide an admixture capable of increasing the mechanical strength of concrete, improving the strength of adhesion to metals and preventing the deterioration caused of chemical reaction. CONSTITUTION: This admixture containing acrylic acid and an ester is added to cement together with an aggregate and water and kneaded, then they are solidified. The acrylic acid and the ester are allowed to react with the water and the cement to enhance mutual binding strength among concrete particles and to improve other various physical properties.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an admixture for cement which significantly improves various physical properties of concrete and concrete to which the admixture is added.

[0002]

2. Description of the Related Art Concrete in which aggregate such as gravel or sand and water are added to ordinary Portland cement and kneaded and solidified has the following drawbacks.

(1) It tends to be neutralized by combining with an acid. For this reason, it is likely to become brittle in a relatively short period of time by combining with oxygen in the air.

(2) Alkali resistance is low. Concrete is alkaline, but if a liquid with a stronger alkalinity is applied, the concrete will peel off within a relatively short period of time. In food factories, caustic soda solution and the like are often used as a cleaning agent, but when this solution flows into the floor concrete, the concrete is damaged.

(3) Acid resistance is low. In recent years, the influence of acid rain has become a problem, but conventional concrete may be weakened by acid such as acid rain.

(4) Poor adhesion to metals. When concrete is used as a building material, the goodness of adhesion with metal structural materials such as reinforcing bars and steel frames greatly affects the strength of the building structure, but conventional concrete has good adhesion with metallic structural materials. Is not good, and various strength calculations based on this are common knowledge.

Further, if the metal has a corroded portion, the adhesion of the concrete at that portion is extremely lowered. Therefore, in order to repair the part where the concrete is partially chipped and the rebar is exposed and corroded, the concrete can be easily peeled off even if it is sprayed, so either remove the rust or corrode the part by metal spraying. Need to be coated.

(5) The tensile strength is low. Since the tensile force of concrete is extremely lower than the compressive force, when used as a structural material, it cannot be used alone in a portion where the tensile force acts. For this reason, reinforced concrete and prestressed concrete are required for the tensile force. In addition, since the tensile strength is low, hair cracks are likely to occur due to internal thermal stress caused by repeated thermal stress and vibration load.

(6) High water permeability and air permeability. For this reason, when a certain number of years have passed after placing concrete, water, oxygen in the air, or exhaust gas of automobiles permeates into the concrete to corrode internal reinforcing bars and neutralize the concrete itself. When accelerated, it weakens and cracks frequently, further infiltrating water and air, and rapidly shortening the life of concrete.

Although metal stearate and the like are known as an admixture for imparting waterproofness, a sufficient waterproofing effect has not been obtained.

(7) Poor adhesion to paint. Even if the paint is applied to the surface, the adhesiveness is poor and the paint peels off in a relatively short period of time, and the repainting work must be frequently performed.

It is an object of the present invention to provide an admixture which eliminates all of these drawbacks of conventional concrete.

[0013]

The admixture of the present invention is mainly composed of acrylic acid and ester. This admixture is added together with water and aggregate during concrete kneading. The finished concrete has remarkably higher mechanical strength than conventional ones, and exhibits excellent adhesion to metals and all solids. Therefore, it is possible to use any solid material other than gravel or sand, for example, any solid material such as wood chips, glass pieces, and plastic pieces as the aggregate.

The present invention is applicable to all kinds of hydraulic cements including Portland cement,
Further, it can be applied to other types of cement such as magnesium cement, calcium sulfate cement, phosphate cement, alkali metal cement and ammonium silicate cement.

As the ester used in the admixture of the present invention, various esters such as carboxylic acid ester, sulfonic acid ester and inorganic acid ester can be used.

[0016]

[Function] When acrylic acid and ester are kneaded into cement together with water and aggregate, acrylic acid, ester, water and cement cause a chemical reaction, and at this time, acrylic acid and ester form an acrylic acid ester copolymer, It is presumed that this copolymer acts as a kind of adhesive to increase the bonding strength between the concrete particles and contribute to the densification of the concrete particle voids.

[0017]

EXAMPLES The admixture according to the present invention contains a modified acrylic acid ester copolymer as a main component. The physical properties of this admixture are as shown in FIG. When kneading Portland cement, aggregate and water, the admixture of the present invention is added at the same time. The amount of the admixture added is appropriately adjusted depending on the application of cement, the usage environment, and the like. Cement, water, and admixtures (acrylic acid, ester) chemically react, and concrete with high toughness is completed, as demonstrated by various tests described below.
Although the details of the chemical reaction have not been fully elucidated at this stage, the admixture acts as a kind of adhesive to strongly bond the concrete particles to each other, and the voids between the concrete particles are made fine and dense. It is considered to have a high hardness structure. The same concrete can be obtained by separately kneading the acrylic acid and the ester with the cement, water and the aggregate without combining them.

(Test Results) FIG. 2 shows the results of various physical property tests performed on the concrete containing the admixture of the present invention and the conventional concrete containing no admixture. The test method was performed based on JIS-A-62. It was confirmed that all of the bending strength, compressive strength, and adhesive strength were higher than conventional ones, and that the water absorption rate, water permeability, and length change rate were all lower than conventional ones.

FIG. 3 shows the result of a tensile test conducted on the same sample. Conventional concrete has almost no elongation strain, and fracture occurs when the stress slightly exceeds 50 kgf / cm ² , but the concrete to which the admixture of the present invention is added records an astonishing elongation strain of 100 kgf / cm ² . It was confirmed to withstand the tensile stress exceeding.

[0020]

As described above, the present invention dramatically improves the physical properties of concrete including bending strength by using an admixture of acrylic acid and ester.
With this new concrete, the following new application effects will be realized.

(1) Concrete is prevented from being neutralized due to great alkali resistance, acid resistance, low water permeability, high airtightness, etc., and in combination with an increase in mechanical strength such as bending strength, the average number is several. The life of concrete, which is said to be ten years, can be extended dramatically so that it can reach several hundred years.

(2) Good adhesion to metals can contribute to a dramatic improvement in strength of the concrete structure.

(3) Since it has a high tensile strength, it is possible to use concrete without reinforcing bars in the portion where the structure is subjected to the tensile load. In addition, it is possible to prevent the occurrence of cracks due to thermal strain or vibration load.

(4) Since the adhesiveness to the paint is extremely high, it is not necessary to change the paint by peeling the paint.

(5) In the past, when color pigments were mixed in an amount of 10% or more of the cement weight, the concrete strength decreased. However, by using the admixture of the present invention, the color strength can be maintained while maintaining a predetermined concrete strength. The mixable ratio of pigments can be increased to 10% or more, for example, about 30%, and concrete having a vivid or dense color and sufficient strength can be realized.

Further, although the conventional colored concrete has remarkable surface fading, the concrete to which the admixture of the present invention is added hardly causes the surface fading.

(6) Conventional concrete has a strict aggregate standard depending on the application because its strength greatly changes depending on the type of aggregate used, but the concrete containing the admixture of the present invention is different in the type of aggregate used. The influence on the strength is relatively slight and any solid can be used as an aggregate. This means that the problem of treating industrial waste, which has become a problem in recent years, can be recycled as an aggregate and can be recycled as an aggregate by crushing even concrete that uses this waste as an aggregate. Since it can be reused sufficiently, recycling of resources in the field of building materials can be realized at once.

[Brief description of drawings]

FIG. 1 is a chart showing properties of an admixture of the present invention.

FIG. 2 is a chart showing a comparative performance test of concrete.

FIG. 3 is a chart showing the results of a tensile test of concrete.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location C04B 103: 60 111: 00 (72) Inventor Anichi Kawakami 3-chome, Oyonaka, Kita-ku, Osaka-shi, Osaka 8-2 No. 2 Oyodo Diesel Co., Ltd. (72) Inventor Yoshikazu Fuji 14th floor, Wakasugi Center Building, 2-9-1 Tenma, Kita-ku, Osaka City, Osaka Prefecture

Claims (3)

[Claims] 1. An admixture for cement containing acrylic acid and ester. 2. A concrete obtained by adding acrylic acid and ester together with aggregate and water to cement and kneading and solidifying. 3. The concrete according to claim 2, wherein the aggregate is any solid material other than gravel or sand.