JP6032489B2 - Concrete dry unit volume mass acceleration test method - Google Patents

Description

  The present invention relates to JASS 5N T-602 “Method for accelerating dry unit volume mass of concrete”.

Concrete or steel shields are installed in facilities that generate radiation, such as nuclear power plants, accelerator facilities, and neutron generation facilities, and are designed to protect the human body from radiation and prevent interference of radiation with measurement equipment. The radiation shielding performance of the radiation shielding concrete is measured by JASS 5N T-602 “Drying unit volume mass acceleration test method of concrete” (hereinafter referred to as “test method”). The outline of the test method is as follows.
(1) A cylindrical specimen having a diameter of 15 cm and a height of 30 cm is prepared and cured according to JIS A 1132 (how to make a specimen for concrete strength test).
(2) A specimen that has passed the age of 28 days is immersed in water, and the mass of the specimen in water is measured.
(3) A specimen is taken out of water and cured in a drier kept at 100 to 110 ° C.
(4) The mass of the dried specimen is measured. The measurement of the specimen mass is repeated until the drying time in the dryer is 3 days or more and the mass change is less than 0.5 g (identification of the convergence time of the dry state of the specimen).
(5) The dry unit volume mass is calculated by the following formula (I).
Dry unit volume mass = (mass of dry state of specimen) / (mass before drying) − (mass in water)
... (I)

  The greater the dry unit volume mass of the concrete determined by the test method, the higher the radiation shielding ability of the concrete. A weight grout mortar material having a large dry unit volume mass containing a binder and a heavy aggregate having a specific gravity of 4.0 or more and a maximum particle diameter of 5 mm and a ratio of the particle diameter of 5 to 2.5 mm of 20 to 40% (For example, refer to Patent Document 1).

JP 2002-97053 A

  When an operator who carries out the test method takes out the specimen from the dryer and measures the mass of the specimen, there is a disadvantage that the specimen absorbs water or a piece is peeled off from the specimen. The burden on the operator who takes out the specimen from the drier kept in the chamber is large.

Recently, there has been a demand for a test method that does not cause the above-mentioned inconveniences, but has not been found.
The problem to be solved by the present invention is to provide a test method in which the burden on the operator is small and the above-mentioned disadvantage does not occur.

The test method of the present invention includes a step in which the mass of the moisture absorbent placed in the dryer is measured.
The mass of the hygroscopic agent is measured two or more days after measuring for 3 days or more, and after the change of the mass of the hygroscopic agent becomes less than 0.5 g, the dry unit volume mass of the concrete is measured. .
A preferred hygroscopic agent is silica gel.

  Since the identification of the convergence time of the dry state of the specimen measured by the test method of the present invention is made by measuring the mass of a small amount of desiccant, the test method of the present invention has a small burden on the operator. Furthermore, since the specimen used in the test method of the present invention is not taken out from the dryer, there is no inconvenience that the specimen absorbs water or the pieces are peeled off from the specimen.

Identification of the convergence time of the dry state of the specimen in the test method of the present invention is performed by changing the mass of the moisture absorbent placed in the dryer where the specimen is dried.
Since the hygroscopic agent absorbs moisture generated from the specimen, the mass of the hygroscopic agent increases with time.
When the increase in the mass of the hygroscopic agent is less than 0.5 g after 3 days or more, it is identified as the convergence time of the dry state of the specimen, and the dry unit volume mass is calculated by the above formula (I).

  The hygroscopic agent adsorbs moisture and is not limited to a specific compound. Specific examples of the hygroscopic agent are silica gel, calcium chloride, sodium hydroxide, concentrated sulfuric acid, magnesium perchlorate, and phosphorus pentoxide. A preferred hygroscopic agent is silica gel.

  The mass of the hygroscopic agent is measured by a mass measuring device installed inside or outside the dryer. When the moisture absorbent is carried out of the dryer, it is preferably placed in a desiccator to prevent moisture absorption.

  Since the test method of the present invention does not require removal of the specimen from the dryer, the burden on the operator is small, and the test specimen absorbs water, or an excellent method that does not cause inconvenience that the fragments are peeled off from the specimen. It is.

Claims (3)

  A drying unit volume mass acceleration test method for concrete, comprising a step of measuring a mass of a hygroscopic agent placed in a dryer.   The process in which the mass of the hygroscopic agent is measured for 3 days or more is repeated twice or more, and after the change in the mass of the hygroscopic agent becomes less than 0.5 g, the dry unit volume mass of the concrete is measured. The dry unit volume mass acceleration | stimulation test method of the concrete described in Claim 1.   The dry unit volume mass accelerated test method for concrete according to claim 1 or 2, wherein the hygroscopic agent is silica gel.