JPH0585797A - Hydraulic composition - Google Patents

Abstract

PURPOSE:To improve the brittleness of a high strength concrete by suppressing the generation of microcracks by relaxing concentration of stress on the boudarys between water hardened powders of cement particles, etc., and fine powders, while securing a high strength of the water hardened composition. CONSTITUTION:Cement 1, silica fumes 2 and water are charged in a mixer and a polymer of superfine particles 3 is added at the same time as the deposition of the first water. They are kneaded and then a high performance water decreasing agent 4 and the remaining water are added to mix and later the agitation is interrupted. The reason that the agitation is interrupted like this after the high performance water decreasing agent 4 is added, is because the cement particles 1, the silica fumes 2 and the polymers 3 filling the spaces between those are settled and there surfaces are perfectly coated with the high performance water decreasing agent 4. Then, an aggregate is added and they are kneaded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic composition capable of improving brittleness in high-strength concrete in which strength is pursued and preventing brittle fracture.

[0002]

2. Description of the Related Art Considering that cement mortar and cement concrete are two-phase materials composed of cement paste and aggregate, the following methods have been used to obtain high strength, high durability and high dimensional stability. Three items are listed as typical ones. (1) Strength improvement of cement paste (2) Strength improvement of aggregate (3) Improvement of adhesion strength between cement paste and aggregate Then, when considering strength improvement of cement paste,
The following Feret equation is useful. σ = f · {Vc / (Vw + Va)} where σ: strength of cement paste f: constant Vc: amount of cement Vw: amount of water Va: amount of air Therefore, in order to increase strength, there is a large amount of cement and voids are generated. It is considered that an essential condition is that the amount of water and the amount of air that cause the above are small. As a method for improving the strength of cement paste, the use of a high-performance water reducing agent and ultrafine powder (hereinafter referred to as fine powder) is the most common method today.

In order to further increase the strength of a hydraulic mixture such as cement mortar and cement concrete, the strength of the cement paste is increased by dispersing and reducing water, and the difference in Young's modulus between the cement paste and the aggregate is reduced. Therefore, it is important to avoid stress concentration at the interface and increase the adhesive force (PCAICIN, La.
technologie des betons a tres haute resistance en
Amerique du Nord, Materiaux et Construction magazine,
1987, No. 20, pp. 180-189).

[0004]

However, in order to improve the strength of the hydraulic compound as described above, if the water-cement ratio is kept low and the porosity is kept as small as possible, on the other hand, the hydraulic mixture is The object becomes brittle and may cause brittle fracture. That is, in order to improve the strength of cement paste, a high-performance water reducing agent and fine powder are used to reduce the water-cement ratio and the porosity. Stress concentration is likely to occur, and such a state will eventually appear as brittleness of the hydraulic compound.

The present invention was devised in view of the above-mentioned conventional problems, and an object of the present invention is to improve the strength of a hydraulic compound while at the same time providing a fine powder with hydraulic powder such as cement particles. It is an object of the present invention to provide a hydraulic mixture that can alleviate stress concentration at the interface with the powder to suppress the generation of microcracks and improve the brittleness of high-strength concrete.

[0006]

The hydraulic compound according to the present invention is a hydraulic powder such as cement, a fine powder, an aggregate,
A water-reducing agent, and a hydraulic composition produced by kneading water, characterized in that an ultrafine particle polymer filled in a gap formed between the hydraulic powder and the fine powder is added. To do.

The particle size distribution of the ultrafine particle polymer is 0.01 to 0.1 μ, and the average particle size is 0.02 μ.
It is characterized by a degree.

Further, the above ultrafine particle polymer is added to the hydraulic powder in an amount of 3 to 20% by weight.

As the hydraulic powder to be used, general ordinary Portland cement and the like can be mentioned.

The high-performance water-reducing agent significantly improves the dispersibility of cement and exerts a great water-reducing effect, which makes it possible to reduce the water-cement ratio, thereby enabling the cement paste to have high strength. .. This high-performance water reducing agent is roughly classified into naphthalene type, melamine type, and polycarboxylic acid type, and among them, it is preferable to use naphthalene type having a small amount of entrained air.

The fine powder contributes to the hydration reaction by the pozzolanic reaction and latent hydraulicity, and examples thereof include silica fume, fly ash, limestone powder, and blast furnace slag fine powder, but silica fume with high activity is used. Preferably. Silica fume is a by-product in manufacturing silicon, ferrosilicon, etc., and has a SiO ₂ content of about 90%.
And ultrafine particles having an average particle size of about 0.2 μm. Silica fume is a very fine amorphous silica,
The pozzolanic reaction can be expected as in fly ash.
In the case of silica fume, compared to fly ash,
Due to its high silica content and high fineness, it binds to calcium hydroxide from the initial stage of hydration to form a C-S-H gel. There is also a report that it is possible to produce concrete with a compressive strength of 700 kgf / cm ² or more by mixing silica fume with 25% or more of the unit cement amount (ACI Commit)
tee 226: Silica Fume in Concrete, ACIMaterials Jou
rnal magazine, Volume 84, No.2, pp.158-166, American Concrete I
nstitute, March-April 1987 issue). However, since silica fume is an ultrafine powder, it is necessary to use it together with a high-performance water reducing agent in order to improve the workability of concrete and ensure the dispersibility of silica fume.

Next, if the strength of the aggregate is smaller than the strength of the cement paste, the aggregate will be broken by compressive loading, and the concrete will be broken. On the other hand, as the aggregate strength increases, the concrete strength increases, but when the aggregate strength is larger than the cement paste, it is also reported that the compressive strength rather decreases because stress concentration acts at the interface. Yoshio Kosaka, Yasuo Tanigawa, Materials, 1975, 24, 368). Good quality aggregate strength is about 1500 to 2000 kgf / cm ² . Specifically, as the aggregate, it is preferable to use high-strength aggregate such as granite, basalt, and diabase. The most important factor in selecting an aggregate is the particle size of the aggregate. Depending on the type of hydraulic compound,
The particle size must be selected appropriately. The standard is shown below. Paste hydraulic compound: 0-0.1 mm diameter Mortar hydraulic compound: 0.1-2.0 m
m diameter Concrete hydraulic mix: 2.0-10 mm
The diameter is preferably 4 to 8 mm, and in high-strength concrete, the water cement ratio is usually 25.
%, The amount of water with respect to the weight of cement is generally extremely small, so it is important to consider the sealing cure to prevent the evaporation of water in the initial curing.

The ultrafine particle polymer particularly added in the present invention has a particle size distribution of 0.01 to 0.1 μm.
It is preferable that the average particle diameter is about 0.02 μ. Such a polymer is preferable because it is about 1/10 of that of the above-mentioned silica fume, and the gap formed between the silica fume and the cement particles can be filled with this polymer. As this ultrafine particle polymer, those used in paints and the like can be used. Furthermore, ultrafine polymer is
It is desirable to add 3 to 20% by weight, preferably 5 to 10% by weight.

[0014]

The hydraulic compound of the present invention is used to produce a hydraulic compound by kneading hydraulic powder such as cement, fine powder, aggregate, water reducing agent, and water. By adding an ultrafine particle polymer that fills the gap created between the ultrafine powder and the ultrafine powder, this ultrafine particle polymer creates a gap between the fine powder and the hydraulic powder. Function to fill. Although this polymer does not undergo a hydration reaction itself, it fills the voids and exerts a function such as a cushioning material, relaxing the stress concentration at the interface between these hydraulic powder and fine powder. To prevent the occurrence of microcracks without sacrificing high strength. Therefore, the brittleness of a high-strength hydraulic compound can be improved and its brittle fracture can be prevented.

[0015]

EXAMPLES The hydraulic compound according to the present invention will be described in detail below. The present invention can be basically applied to any kneading method adopted when producing cement mortar or cement concrete. For example, hydraulic powder such as cement, fine powder, aggregate, water-reducing agent, and water are simultaneously charged into a mixer, and ultrafine polymer is added at the same time as this water is charged. The kneading procedure described below is one example.

Example 1 As shown in FIG. 1 (A), first, a hydraulic powder such as cement and a fine powder such as silica fume are put into a mixer, and each cement particle 1 has a particle diameter of several tens of several. In order to coat one-hundredth to one-hundredth of the silica fume 2, the maximum amount of water for suppressing the hydration reaction of the cement and the minimum amount of water required for coating the silica fume 2 on the cement particles 1 are obtained. Water (H ₂ O) was added, and at the same time as this first addition of water, the ultrafine particle polymer 3
Is added. At this time, the total amount of the ultrafine particle polymer 3 added was 3 to 2 with respect to the cement weight.
It is 0%, preferably 5 to 10%. The ultrafine particle polymer 3 has an average particle size of about 0.02μ, which is about 1/10 of that of the silica fume 2 so that the gap generated between the silica fume 2 and the cement particle 1 can be filled with the ultrafine particle polymer 0. It is preferable that the particle size distribution is 01 to 0.1 μ. And these are kneaded. The ultrafine particle polymer 3 itself does not undergo a hydration reaction, but when filled in the gap, it exerts a function such as a cushioning material and contributes to alleviation of stress concentration at the interface between the cement particles 1 and the silica fume 2. However, the occurrence of microcracks is prevented without impairing the securing of high strength. It should be noted that dividing the water in this way and first adding the minimum amount of water does not cause the hydration reaction completely, and has the reaction of the silica fume 2 and the adhesive force with the aggregate to be added later. This is because it causes only a hydration reaction.

After the above coating step is completed, the high-performance water reducing agent 4 and the remaining water are added and kneaded as shown in FIG. 1 (B), and then the stirring is interrupted. After adding the high-performance water-reducing agent 4 in this manner, the stirring is stopped so that the cement particles 1 and the silica fume 2 and the ultrafine particle polymer 3 filling the gaps between them are settled down, and their surfaces are completely high-performance. This is for coating with the water reducing agent 4. After that, the aggregate is added and kneaded.

Example 2 This example takes into consideration the dry mix of cement, fine powder and powdery high-performance water reducing agent, and the procedure is as follows.

First, a predetermined amount of 1/2 to 1/3 of the aggregate is first put into a mixer, and a dry mix of cement, fine powder and powdery high performance water reducing agent is added and kneaded.

Next, a predetermined amount of water of 4/10 to 5/10 is charged, and in the same manner as described above, the entire amount of the ultrafine particle polymer is added and kneaded at the same time when the first water is charged.
Then, the stirring is stopped.

Next, the remaining water is added and kneaded, and finally the remaining aggregate is added and kneaded. If a fiber-reinforced material such as steel fiber is to be mixed in, add it at this point.

[0022]

In summary, according to the present invention, in producing a hydraulic compound by kneading hydraulic powder such as cement, fine powder, aggregate, water reducing agent, and water, hydraulic powder By adding the ultrafine particle polymer filled in the gap formed between the body and the ultrafine powder, the ultrafine particle polymer forms a gap between the fine powder and the hydraulic powder. To fill in. By filling the voids with this polymer, it functions as a cushioning material, contributes to the relaxation of stress concentration at the interface between these hydraulic powder and fine powder, and does not impair the securing of high strength. , To prevent the generation of microcracks. Therefore, the brittleness of a high-strength hydraulic compound can be improved and its brittle fracture can be prevented.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an example of a production process of a hydraulic compound according to the present invention.

[Explanation of symbols]

 1 Cement particles 2 Silica fume 3 Ultrafine polymer 4 High performance water reducing agent

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location C04B 16:04) 2102-4G (72) Inventor Yoshimasa Hayashi, Kiyoshi-shi, Tokyo 4-640 Obayashi Technical Research Institute Co., Ltd.

Claims (3)

[Claims] 1. A hydraulic powder produced by kneading hydraulic powder such as cement, ultrafine powder, aggregate, water-reducing agent, and water, and the above hydraulic powder and ultrafine powder. A hydraulic compound characterized in that an ultrafine particle polymer filled in a gap formed between the fine powder and the fine powder is added. 2. The particle size distribution of the ultrafine particle polymer is:
The hydraulic composition according to claim 1, wherein the hydraulic composition has an average particle size of 0.01 to 0.1 µ and an average particle diameter of about 0.02 µ. 3. The hydraulic composition according to claim 1 or 2, wherein the ultrafine particle polymer is added in an amount of 3 to 20% by weight based on the hydraulic powder.