JPS5838375B2 - Manufacturing method of hardened cement - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention reduces the alkalinity in the cured cement by fixing the lime produced when the cement sets and hardens. This was done to avoid reducing the reinforcing effect.

In other words, cements produce lime when they are hydraulically hardened.

therefore? If fibers that are susceptible to alkalinity, such as glass fibers, are mixed as a reinforcing material, the glass fibers will be eroded over time, reducing the reinforcing effect over time.

In order to improve this problem, attempts have been made to develop and use glass fibers with strong alkali resistance, but this has not yet achieved practicality.

The present invention differs from the direction of conventional improvement research and attempts to improve the above-mentioned drawbacks by fixing fresh lime in cement.

That is, the method is characterized in that crystalline silica having an average diameter of 50 μm or less is mixed with cement, water and fiber reinforcing material are mixed therein, and if necessary, other additives are also mixed and the mixture is allowed to set and harden. do.

The cements targeted by the present invention include all cements that liberate lime during hydraulic hardening and become alkaline, such as boltland cement and blast furnace cement.

Further, crystalline silica having an average particle size exceeding 50 μm is not preferable because it has a low alkali fixing effect.

Further, the use of fine powder of 50 μm or less has the effect of increasing strength.

Note that both silicas may be used in combination.

In principle, there is no need to limit the amount of silica added to the cement, and even a small amount can produce the same effect.

However, the preferred amount varies depending on the amount of fresh lime in the cement, but is preferably 0.2 to 1.2 mol of SiO per 1 mol of fresh lime, and most preferably, with sufficient precision in practice. An amount of 1 molar is used.

Note that if the amount of SIO2 is less than 0.2 mol, sufficient effects cannot be obtained in practice.

On the other hand, if the amount exceeds 1.2 mol, the action of SiO2 becomes like that of an aggregate, which is beyond the scope of the present invention.

If it is against Boltland cement, this is 100
7 to 35 parts by weight is practical.

This is not to say that fibers that are resistant to alkalinity cannot be used as reinforcing materials; for example, any reinforcing material such as asbestos or alkali-resistant glass fibers may be used. A fiber reinforcement material that is weak against lime is used.

Specific examples include glass fibers and synthetic fibers.

The amount of water used only needs to be the amount necessary for setting and hardening the cement, but in reality, the amount of water required for shaping is used, and in this way the amount of water required for setting is kept low. be done.

In the example of Bortland cement, 40 to 150 parts by weight of water are used for every 100 parts by weight of Boltland cement.

It is more preferable to use water within this range because the glass fibers serving as the reinforcing material are less likely to break (during stirring of the slurry).

In addition, as other additives, fillers, pigments, or commonly used cement additives may be added as a general rule.

Further, high temperatures are not required for setting and hardening, and the effect can be produced at temperatures below 100°C or at low temperatures around room temperature.

Another feature of the present invention is that there is no need for autoclaving since high temperatures are not required for curing.

Although effects similar to those of the present invention can be obtained by using amorphous silica, amorphous silica is expensive, difficult to handle, and bulky in itself. In this case, only products with low specific gravity can be obtained, so the strength of the product is low.

As described above, according to the present invention, when a fiber reinforcing material with weak alkali resistance is used, deterioration in strength over time can be improved.

Example A cured cement product was obtained according to the formulation and curing conditions shown in the following table, and the change in strength over time was examined.

The results are shown in the graphs of Figures 1 and 2.

According to the graphs in FIGS. 1 and 2, the bending strength and impact strength of the examples according to the present invention have improved over time.

[Brief explanation of drawings]

FIGS. 1 and 2 are graphs showing the deterioration of bending strength and impact strength over time.

Claims (1)

[Claims] 1 For cements, Si02 is 0.0% per mole of lime that is produced when the cements are hydrated and hardened.
Mix 1 to 1.2 mol of crystalline silica with an average particle size of 50 μ or less, 40 to 150 parts by weight of water and a fibrous reinforcing material to 100 parts by weight of the cement, and add other additives if necessary. A method for producing a hardened cement product characterized by mixing and setting and hardening.