JPH01242445A - Hydraulic cement composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to cement for civil engineering and construction. In more detail, it is a cement that has good workability and strength development, and has excellent durability such as carbonation, drying shrinkage, and chemical resistance. It can be used as paste, mortar or concrete.

[Conventional Art] Portland cement is usually manufactured by adding clinker and a required amount of gypsum and pulverizing it. In this case, the powder is pulverized using a tube mill, a vertical roller mill, etc., and the main constituent particle size thereof is a continuous particle size composition consisting of a group of intermediate particles of about 10 to 30 μm. In the case of mixed cement, for example, blast furnace slag is pulverized separately from Tallinn slag, and then the two are mixed. The particle size structure of the former and the latter is similar. When cement with such a relatively narrow particle size structure and close to continuous particle size is used in the production of paste, mortar, or concrete, the amount of water required to achieve the desired workability increases, resulting in a decrease in strength and intermediate particle size. There were problems such as an increase in sexualization rate and a decrease in chemical resistance.

On the other hand, as a method for reducing the amount of water, it is necessary to add a water reducer, but this method is affected by the particle size composition of the cement, so it is necessary to add a large amount of water reducer in order to secure the desired fluidity. As a result, there were problems such as delayed setting of cement and increased manufacturing costs.

[Objective of the Invention] The object of the present invention is to define the essential particle groups of 10 μm or less, 20 to 45 μm, and 63 to 150 μm among the constituent particle sizes of cement, and to improve workability and strength by limiting the amount of the particle groups. Our goal is to provide cement with excellent strength and durability.

[Means and details for solving the problem] Cement with a relatively narrow particle size range and continuous particle size, or cement with discontinuous particle size consisting of two types of grain groups, has poor particle filling properties and has many voids between particles. Become. For this reason, when producing paste, mortar, or concrete, the amount of water required to obtain a predetermined fluidity is large, which adversely affects various physical properties.

On the other hand, since physical properties vary depending on the grain size of cement, it is not possible to obtain optimal physical properties simply by adjusting the grain size structure of cement to discontinuous grain sizes using three types of grain groups. That is, it is important to optimally select the particle size and amount of the grain groups that make up the cement.

As a result of examining the appropriate particle size composition from the viewpoints of workability, strength development, and durability, we found that the appropriate values for the particle size and amount of the essential grain groups of cement are 10 to 35% by weight of 10μ or less, 20 to 4% by weight.
10 to 40% by weight of 5 μm, 40 to 40% of 63 to 150 μm
80% by weight, and other unavoidable grain groups (i.e., more than 10 μm and less than 20 μm, more than 45 μm and 63 μm)
It has been found that the maximum amount of carbon dioxide is 25% by weight or less.

The details of the present invention will be described below.

The present invention limits the particle size composition of hydraulic cement. Hydraulic cement includes Portland cement and mixed materials, and its constituent components include various boltland cement clinkers, gypsum, and mixed materials such as blast furnace slag, fly ash, limestone powder, silica sand, and other pozzolanic substances. be.

As Boltland cement clinker, medium heat, early strength, super early strength, low heat, sulfate resistant, verite type, white clinker, etc. can be used alone or in a mixture of two or more types depending on the purpose of use. It is also effective to change the type of clinker depending on the grain group. For example, to impart normal hardening or early strength, an early-strength or ultra-early-strength Portland cement clinker is usually used in the fine grain group or the fine powder and intermediate grain group to impart slow hardening and low heat properties. It is preferable to use a low heat, sulfuric acid resistant, or verite Portland cement clinker. However, 63-150
From the viewpoint of stability, it is necessary to use a clinker for use in the coarse grain group having free lime (f-CaO) i of 1.5% or less.

Although the cement of the present invention contains gypsum, the form and amount of gypsum added are not limited, but preferably 2
$03 in cement with water or anhydrous gypsum is 1.0-3.
It is desirable to add it to 0%. Mixing materials include blast furnace slag 50% by weight or less, fly ash 25% by weight or less, limestone powder 10% by weight or less, and silica powder 10% by weight.
Below, other natural pozzolanic substances can be added under conditions of 10% by weight or less. It is a preferred embodiment that these mixed materials are also used depending on the grain group amount depending on the purpose of use, such as strength development, heat of hydration, chemical resistance, etc.

Regarding the size and amount of grain groups, 10 μm or less is 10
~35% by weight, 20~45μ and 10~40% by weight, 6
It is preferable that the particle diameter of 3 to 150 μm is 40 to 80% by weight, and the amount of other grains unavoidably mixed during production is 25% by weight or less. If it falls outside this range, the filling properties of the particles cannot be improved to the extent expected, and the effects of reducing water content, improving strength development, heat of hydration, neutralization rate, drying shrinkage, etc. will be undesirable.

This grain group is obtained by crushing clinker, gypsum, various admixtures alone or in a mixture to a predetermined particle size, or by classifying some of them, or by classifying a part of them. Any particle group according to the present invention can be used, such as a particle group (fine powder, coarse powder) or a particle group collected by a dust collector or the like.

The cement of the present invention is produced by mixing water to form a paste or slurry, mortar containing coarse aggregate, coarse aggregate, and concrete mixed with ordinary concrete admixtures. - Can be used in the production of membrane structures or secondary products. In this case, the paste, mortar or concrete can be applied not only by the usual pouring method but also by vibration molding, pressure molding, extrusion molding, centrifugal molding, ``rolling molding'', etc.

In order to accelerate hardening of the cement of the present invention, high temperature curing such as steam curing or autoclave curing may be performed.

Next, examples of the present invention will be shown.

Example 1 Table 1 shows the key density of the powder when the cement of the present invention and the comparative cement were tapped 1000 times with a powder tapping device. By the way, the test cement is ordinary Portland cement clinker with gypsum and S in the cement.
03 to 2.1%, crushed to 300/im or less or 45 μm or less, and 10 μm or less, 10 to 20 t1m, 20 to 45 μm using a mesh sieve or Virco type classification filter.
m.

Grain groups on the 45 to 63μ side and 63 to 150μ side were sampled, and the proportions of each grain group were changed and mixed again for testing.

As can be seen from the table, the cements of samples Nα1 to 5 of the present invention were 1
The key density of the powder after tapping 00'O times is large. That is, it is confirmed that the weight per unit volume is large and the filling property is excellent.

Example 2 Regarding samples Nα3.11 and 12 used in Example 1,
Either alone or after dissolving the water reducing agent (main ingredient sodium naphthalene sulfonate formalin condensate) in kneading water and kneading, paste specimens (dimensions 2 x 2 x 2 cm) were prepared, and the compressive strength after curing in water at 20°C was measured. An example of the results is shown in Table 2.

Table 2 *: As can be seen from the stratified sample table, the cement of the present invention has excellent fluidity, which makes it possible to reduce the amount of mixed water and develops hypertonicity, whereas the comparative cement has a higher amount of mixed water. Decreasing this is not preferable because fluidity decreases and strength development deteriorates.

Example 3 Sample Nα3.11.12 of Example 1 (without blast furnace slag added in Table 3) and cement of grain groups of 10 μm or less and 20 to 45 μm were mixed with blast furnace slag of the same grain group. After pre-curing cement mortar in water at 20'C, 20'C-R. H.

It was cured for 35 weeks in a 50% constant temperature and humidity chamber, and the depth of carbonation was measured. The mortar composition is cement: Toyoura standard sand: water =
1:2:0.65, and the specimen dimensions were 4 x 4 x 16 cm. The results are shown in Table 3.

Table 3 *: By adding the comparative sample blast furnace slab, the carbonation depth generally increases, but it is understood that the cement of the present invention has a smaller carbonation depth than the comparative cement, which is preferable. .

[Effects of the Invention] Normally, in order to ensure workability, cement is constructed by adding approximately twice the amount of water required for hydration of the cement. However, if more water than necessary is added, the structure or product becomes porous after curing, and there are also problems in durability. The present invention aims to improve the solidity of structures and products after hardening, and to find an appropriate particle size distribution for hydraulic cement by taking into consideration physical properties such as workability, strength development, low heat resistance, and durability. Furthermore, by selecting various materials to use, it became possible to improve and expand the performance.

Therefore, by appropriately selecting the materials used, the hydraulic cement composition of the present invention can be used not only for general civil engineering and construction work, but also for work that requires high density or for manufacturing secondary products. It has the following effects.

Claims (3)

[Claims] (1) The essential grain group of hydraulic cement is 10μm or less 10~
35% by weight, 20-45 μm 10-40% by weight, 63-45% by weight
150 μm 40 to 80% by weight, and the amount of unavoidable other grains is 25% by weight or less. (2) The cement composition according to claim (1), which comprises Portland cement clinker and gypsum. (3) The cement composition according to claim (1), comprising 50% by weight or less of blast furnace slag, the balance being Portland cement clinker and gypsum.