JPS5840484B2 - Manufacturing method of cement products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a hardened cement product, and is aimed at improving the strength of a cement product in the so-called dry method, in which cement products are produced using as little mixing water as possible. Ta.

Conventionally, in the production of cement-based building materials such as cement tiles and floating slate, the basic mix has been to use cement with river sand or sea sand as an aggregate.

However, because the particles of river sand and sea sand are relatively rounded, when the resulting product is subjected to bending, impact, or other forces, the adhesion between the cement and the sand surface is not necessarily strong, resulting in a high-strength product. In order to obtain a product, it is necessary to increase the wall thickness of the product or add expensive reinforcing fibers, so depending on the application, it is uneconomical and has no practical value.

Despite these drawbacks, river sand and sea sand are still used because their particles are rounded and easy to knead. Moreover, it was possible to knead uniformly with a small amount of kneading water, resulting in quick development of strength and less local unevenness in strength.

In addition to the above-mentioned aggregates, there is also crushed stone, which has a higher product strength than river sand or sea sand.

The reason is that the particles are rounded. However, on the other hand, the kneading properties were poor, and in particular, when the amount of kneading water was reduced, uniform kneading could not be achieved.

In order to improve this problem, kneading water is used for kneading, but in this case, voids are created in the product due to the excess water added, and the strength tends to be lower than that of river sand, etc. was recognized.

Therefore, it has hardly been put into practical use.

In order to obtain a cement product by using crushed stone as aggregate and using as little mixing water as possible, the present invention involves adding water to crushed stone, and gradually adding cement and other additives as necessary. It is characterized by being added and kneaded all at once.

In this case, each is preferably added while stirring.

The amount of water added to the crushed stone in advance is the amount of cement added later)
It is preferably 35 to 45 parts per 100 parts by weight (hereinafter referred to as "parts").

If it is less than this, there will be a shortage of water for cement irrigation, and if it is too much, there will be many voids due to excess water, and sufficient strength will not be obtained.

As described above, the amount of water added to the crushed stone in advance is actually the amount necessary and sufficient to wet the surface of the crushed stone, and when water is added, the entire surface of the crushed stone becomes wet.

When cement is added to this, the water on the surface of the crushed stone turns the cement into a paste, covering the surface of the crushed stone.

In this case, the kneading may be carried out to the same extent as when using ordinary river sand or sea sand.

Specifically, 100 to 3 parts of crushed stone to 100 parts of cement.
50 parts are used.

As for other additives, those commonly used are also applicable.

According to the present invention, the bending strength of the product is improved by 50 to 70% when crushed stone is used, compared to when river sand is used, when comparing the same amounts of cement and aggregate.

Even when compared with the conventional method using crushed stone, an improvement in strength of 20 to 30% is observed when the same amount of kneading water is used.

Furthermore, when cement and crushed stone are mixed in advance and a small amount of kneading water is added to obtain a product, the development of strength is slow and the strength of the product varies widely, but this can be greatly improved.

To give a concrete explanation using rough numerical values, if the mixing ratio of crushed stone to cement is 1:3 by weight, and the amount of mixed water is 35 parts of water to 100 parts of cement, the conventional kneading method , after one week of natural curing, bending strength 68ky/crd,
79kg/cra in 3 weeks, 85kf/era in 4 weeks
However, when the method of the present invention was applied to the same formulation, the strength increased from 85 to 9/cr after one week.
? 1. 94kg/crA after 3 weeks, 98k after 4 weeks
g/cr? 1 intensity development is observed.

In addition, in the case of the present invention, since the amount of mixed water is small, no wastewater is generated during shaping, so there is also the secondary effect that no expense is required for wastewater treatment.

Example 1 Put 30kg of crushed stone that has passed through a 2.5-meter mesh into a mixer, add 3.5kg of water to it, and add 10kg of Portland cement while stirring until the surface of the crushed stone is well wet.
was added and kneaded for 3 minutes, and 5 kg of flat plates with a thickness of 15 mm were prepared.
/cr? Manufactured under a pressure of 1.

This thing has a bending strength of 85 kg/c after the first week of natural curing.
yrfl was 94 kg/cra- at the 3rd week and 98 ky/- at the 4th week.

Example 2 40kg of crushed stone that had passed through the mesh for 2.5 minutes was placed in a mixer, 9kg of water was added, and while stirring, when the surface of the crushed stone was well wet, 20kg of Portland cement was added, and the mixture was stirred and kneaded for 3 minutes to form a plate with a thickness of 15mm. A flat plate was made by applying a pressure of 5 kg/-.

The S bending strength of this item increased to 118 after the first week of natural curing.9/
cra, 128kg/crd in 3rd week, 1 in 4th week
It was 36 kg/cn yen.

Comparative Example 1 30 kg of river sand passed through mesh for 2.5 minutes and 1 kg of Portland cement were mixed in advance, put into a mixer, added 3.5 kg of water, kneaded for 10 minutes, and made 5 kg of flat plates with a thickness of 15 mm. /cii pressure was applied.

This thing has a bending strength of 60 kg/c after the first week of natural curing.
J, 65 kg/era in 3rd week, 70 in 4th week
kg/-.

Comparative Example 2 40 kg of crushed stone passed through a mesh for 2.5 hours and 20 kg of Portland cement were mixed in advance, and this was placed in a mixer, and 9 kg of water was added and kneaded for 3 minutes.

Next, a flat plate with a thickness of 151 m was made by applying a pressure of 5 kg/-.

This item's bending strength is 68kg/crfl in the first week of natural curing, 79kg/crfl in the third week, and 85k in the fourth week.
g/-.

Claims (1)

[Claims] 1. In the case of manufacturing a cement product by kneading, shaping, and curing cement, aggregate, water, and other additives added as necessary, crushed stone is used as the aggregate, and A method for producing a cement product, which is characterized in that crushed stone is mixed with water in advance, and then cement and other additives are added and kneaded. 2. In the invention described in claim 1, the ratio of use of cement, aggregate and water is 100 to 350 parts by weight of aggregate and 35 to 45 parts by weight of water to 100 parts by weight of cement. A manufacturing method for cement products characterized by: