JPS60218100A - Method of kneading cement - 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 (a) 0 Technical Field of the Invention The present invention relates to a cement kneading method suitable for use in coagulating a radioactive waste aqueous solution such as a tritium aqueous solution with cement.

(b), Background of the Technology When treating radioactive waste aqueous solutions such as tritium aqueous solutions, usually cement is kneaded using the aqueous solution, and the kneaded cement is put into a container such as a drum pipe.
It is stored in that state by solidifying it.

Originally, when mixing cement with water, the theoretical hydration amount of water required for the hydration reaction between cement and water is about 30% of the cement weight, but in order to ensure the workability of cement after mixing. In normal cases, the weight ratio is 50~
About 60% water is used.

(C), Prior art and problems However, when cement is kneaded with water exceeding the theoretical hydration amount,
There was a disadvantage that air was drawn in during water mixing, increasing the voids in the cement after solidification, and reducing the strength of the cement as a whole. In addition, since the water mixing itself is carried out using water containing radioactive waste, if cement adhering to the mixer is cleaned and removed after work, the removed material will also contain radioactive materials, creating secondary waste. become.

(d) 6 Purpose of the Invention In order to eliminate the above-mentioned drawbacks, the present invention is capable of sufficiently reacting and solidifying cement with water at a theoretical hydration level, and producing a dense cement hardened product without the generation of voids due to crosstalk. Our first objective is to provide a cement mixing method that can obtain A second object of the present invention is to provide a method for mixing cement, which has high performance and can significantly reduce the generation of secondary waste due to cleaning of the mixer.

(e) 0 Structure of the invention That is, the present invention performs dry kneading of cement and aggregate in a sub-zero atmosphere, and at that time, adds finely divided ice into the cement and performs dry kneading, The cement that has been dry-wired is similarly put into a formwork in a sub-zero atmosphere, compressed and formed, and then heated to melt the ice mixed into the cement. It is constructed in such a way that it reacts with cement to solidify it.

(f) 0 Examples of the invention Examples of the present invention will be specifically described below.

To mix cement, first add aggregate such as sand to the dry cement and perform dry mixing. The purpose of this dry mixing is to mix cement and aggregate evenly, and during this dry mixing, ice in the form of fine particles is simultaneously added to the cement and mixed.

This operation is carried out in sub-zero conditions, so that the ice mixed with the cement is mixed as a solid with the cement and other aggregates. The grain size of the ice is preferably similar to that of cement, and to produce ice with this grain size, ultrasonic vibrations are applied to liquid water to atomize it, and the atomized water is instantly cooled. Manufactured by

In this way, once the dry kneading of the fine particulate ice, cement, and aggregate at sub-zero temperatures is completed, the dry-kneaded cement is similarly poured into the formwork in a sub-zero atmosphere, and
Compression forming. Next, when the compressed cement is forcibly or naturally heated, the ice in the compressed cement melts and becomes water, causing a hydration reaction with the surrounding concrete and solidifying and hardening. Since the ice in the concrete is thoroughly and uniformly mixed with the concrete by dry mixing, the concrete will sufficiently cause a hydration reaction and harden with water in the theoretical hydration amount.

In addition, when a tritium aqueous solution is used as water to coagulate with concrete, the aqueous solution is made into fine particle ice and mixed with cement in the same manner as described above, and the dry-mixed cement is placed in a nuclear waste container such as a drum pipe. The cement is placed in a container, tamped and sealed, and then heated to melt the ice, causing the cement and tritium solution to react, solidifying the cement, and sealing the tritium solution in the cement in the container. .

(g) 0 Effects of the Invention As explained above, according to the present invention, cement and aggregate are mixed in air in a sub-zero atmosphere, and at that time, micronized ice is poured into the cement. The dry-mixed cement was similarly put into a formwork for a nuclear waste container in a sub-zero atmosphere, compressed and formed, and then heated and mixed into the cement. By melting the ice, the melted ice reacts with the surrounding cement to solidify the cement, so that the cement can be sufficiently reacted and solidified with water of about the theoretical hydration amount. In addition, since there is no mixing of cement with water, air does not get mixed into the cement, and therefore, a dense hardened cement product can be obtained without the generation of voids, greatly increasing the strength of the cement after hardening. It becomes possible to increase the

In addition, since cement is solidified with water at a theoretical hydration level, there is less evaporation of excess water that occurs when cement is solidified with water at a logical hydration level or higher, and radioactive waste such as tritium aqueous solutions can be disposed of as water. Even when cement is used, there is less leaching of waste due to evaporation of excess water after solidification of cement, resulting in high safety. Furthermore, since there is no mixing with water, cement is less likely to adhere to the mixer, and therefore, it is possible to significantly reduce the generation of secondary cable waste due to cleaning of the mixer.

Furthermore, in order to ensure the toughness of the cement after solidification, it is naturally possible to mix a high-performance fiber material such as steel fiber as an aggregate during dry kneading.

It should be noted that the present invention is not limited to the treatment of nuclear waste such as tritium aqueous solution, but can of course be applied to all cases where it is necessary to solidify and coagulate cement with an amount of water approximately equal to the logical hydration amount. .

Applicant: Mitsui Construction Co., Ltd. Agent Patent Attorney Phase 1) Shinji

Claims (2)

[Claims] (1) Dry kneading of cement and aggregate is carried out in a sub-zero atmosphere. At that time, micronized ice is added to the cement and the dry kneading is carried out. After the dry mixing is completed, the cement is similarly mixed. The cement is put into a formwork in a sub-zero atmosphere and compressed, and then heated to melt the ice mixed into the cement, causing the melted ice to react with the surrounding cement and solidifying the cement. A method for kneading cement composed of (2) The cement crosstalk method according to claim 1, wherein the ice is produced from an aqueous radioactive waste solution.