JPH0943233A - Method for measuring unit quantity of water of inorganic hydraulic kneaded material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly and accurately measure a unit quantity of water of unsolidified hydraulic inorganic kneaded material by finding a difference between the sample volume of unsolidified inorganic hydraulicity kneaded material and the total volume of concrete and aggregate and making the difference a quantity of water of a sample. SOLUTION: For instance, in the case where a unit quantity of water of concrete is calculated as inorganic hydraulic kneaded material, part of unsolidified concrete is taken out and it is made a concrete sample. Respective masses of the concrete sample in the air and in water are measured and the volume of the concrete sample is found from the difference between both the measured values. In addition, cement density in water is found on the basis of the difference between both the masses, aggregate density by specific gravity and a water absorption method, and the total volume of cement and aggregate is found from the cement density in water, aggregate density, and the ratio of quantities of cement and aggregate at the time of concrete mixing. And the difference between the total volume and the volume of the concrete sample is found and the unit quantity of concrete can be found by making it the water quantity of the concrete sample.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for measuring the unit water content of an inorganic hydraulic kneaded material such as concrete or mortar.

[0002]

2. Description of the Related Art Quality control in a concrete manufacturing factory is extremely rational due to automation of manufacturing, sophistication of equipment, and improvement of accuracy of measuring equipment. However, in the control of concrete mix, the surface water of the aggregate is measured several times a day to set the surface water ratio of the aggregate in concrete production, and the variation of the concrete slump due to the fluctuation of the surface water of the aggregate is adjusted. The current situation is to make fine adjustments by visually observing Charman. For this reason, it cannot be said that the fluctuation of the surface water of the aggregate is sufficiently reflected in the concrete mixing, and the fluctuation of the surface water of the aggregate has a great influence on the unit water amount of the concrete. The unit water content of concrete has an important influence on the strength and durability of concrete after hardening. Therefore, it is necessary to control the quality of concrete by quickly measuring the unit water volume of concrete that has not yet solidified at the time of receiving concrete at the construction site.

However, as a method for measuring the unit water content of concrete that has not solidified yet, a heating and drying method, a method using alcohol and a hydrometer, a method of estimating from the aerial mass of concrete, the mass in water and the density of constituent materials, etc. have been proposed. ing. However, each of them has the following problems, so it is not always appropriate as a method at the construction site. <a> In the heating and drying method, the test time is as long as about 30 minutes, and in order to obtain the result, it is necessary to measure the water content by trial kneading concrete with a different mix as a preliminary experiment. <B> In the method using alcohol and a pycnometer, a part of cement is dissolved in an alcohol-water mixed solution in proportion to the alcohol concentration, and thus there is a problem that the measurement accuracy decreases. <C> In the method of estimating from the aerial mass, the underwater mass and the density of the constituent materials, the volume of the concrete is obtained from the difference between the aerial mass of the concrete and the mass of the underwater, and the cement and aggregate are calculated from the concrete mix and the density of each constituent material. Is a method in which the difference between the total volume and the concrete volume is used as the amount of water, but there is a problem that the amount of water tends to be always underestimated and the measurement accuracy decreases.

[0004]

DISCLOSURE OF THE INVENTION The present invention is a method for rapidly and accurately measuring the unit water content of an inorganic hydraulic kneaded product that has not yet solidified.

[0005]

Means for Solving the Problems The present invention is a method for measuring the unit water content of an inorganic hydraulic kneaded material, in which a part of the inorganic hydraulic kneaded material that is not yet solidified is taken out as a sample, and the mass of the sample in air is measured. Obtain the volume of the sample from the difference in mass in water, the density of the aggregate, the density of the cement measured in water, and the ratio of the amount of cement and the amount of aggregate of the inorganic hydraulic kneading mixture from the cement and bone Obtain the total volume of the material, determine the difference between the volume of the sample and the total volume of the cement and aggregate, and use it as the water content of the sample to determine the unit water content of the inorganic hydraulic kneading mixture that has not yet solidified. Characterized by the unit water content measuring method of the inorganic hydraulic kneaded material, or in the unit water content measuring method of the inorganic hydraulic kneaded material, the inorganic hydraulic kneaded material is characterized in that it is a concrete or mortar, inorganic Hydraulically kneaded single Water amount measuring method, or, in the unit water amount measuring method of the inorganic hydraulic kneaded material, the inorganic hydraulic kneaded material is concrete, take out a part of the concrete not yet solidified as a sample, the mass of the sample in the air After measuring the mass in water and in water, take out the coarse aggregate from the sample, measure the mass of the coarse aggregate in water to obtain the amount of coarse aggregate, and divide the aggregate into coarse aggregate and fine aggregate. The method for measuring the unit water content of an inorganic hydraulically kneaded product is characterized in that

[0006]

Embodiments of the present invention will be described below with reference to the drawings. <A> Measurement principle The method for determining the unit water content of an inorganic hydraulic kneaded material such as fresh concrete and mortar is to take out a part of the inorganic hydraulic kneaded material that has not solidified yet and use it as a sample. The mass measured in 1. and the mass in water, that is, the mass measured in water, are obtained, and the unit amount of water is measured from these masses and the density of the constituent material of the inorganic hydraulic kneaded product. In addition, there are concrete and mortar as the inorganic hydraulic kneaded product, concrete is defined as containing fine aggregate and coarse aggregate as aggregate, and mortar is defined as not containing coarse aggregate. Although concrete will be described in the above, the present invention can be applied to other inorganic hydraulic kneaded products such as mortar.

<B> Density Measurement of Cement Among the densities of the constituent materials, the conventional JIS
Although mineral oil is used in the specific gravity test of the physical test method of R 5201 cement, in concrete, the cement is in contact with water, and in that state the dissolution of the cement component in water and the adsorption of water on the cement particles. It was known that the density of cement changed. The difference is shown in Table 1.

[Table 1]

Therefore, the density of cement in concrete is the density in water. The density of cement in water is determined by measuring the mass in air and the mass in water. For example, for the density measurement of cement, about 1500 g of cement is sampled in a stainless steel container, and the air mass is measured up to 0.1 g. To this, add about equal amount of water and mix evenly. Next, the air bubbles in the cement paste are deaerated with a vacuum pump. Further, the mass of the cement paste in water is measured up to 0.1 g using a solid density measuring device 1 as shown in FIG. The density ρ _C (g / cm ³ ) of cement in water can be calculated from the mass in air × the density in water / (mass in air-mass in water) from the mass in air and the mass in water thus obtained.

In the solid density measuring apparatus 1, an electronic balance 2 is arranged on a pedestal 4, and the weight of the object to be measured is measured by the electronic balance 2. For example, when measuring the weight of the cement paste 8 in water as a measurement object, the cement paste 8 is put in a stainless steel container 7, and the container 7 itself is put in a water tank 5 filled with water 9.
It can be performed by suspending with the suspension rod 3 via the car 6.

It was found that the density of cement in water hardly changed after contact with water, and the density of cement was constant before the setting of concrete, regardless of the time after kneading. This change over time is shown in Table 2.

[Table 2]

<C> Aggregate Density Measurement Since the aggregate is inert to water, the specific gravity and water absorption test method of JIS A 1109 fine aggregate and the specific gravity and water absorption test method of JIS A 1110 coarse aggregate are used. Use the measured density.

<D> Underwater mass measurement of concrete Underwater mass measurement of concrete is carried out by adding water to a concrete sample whose aerial mass is measured in advance and stirring the mixture to completely expel air in the concrete, and then measuring the underwater mass. I do.

The procedure for calculating the unit amount of water will be described below. <a> Taking out concrete samples When calculating the unit water volume of concrete, take out some of the concrete that has not solidified yet and use it as concrete samples. For this concrete sample, the aerial mass (measured value C _ONS (g) in air of the concrete sample) and the mass in water (measured value C in water of the concrete sample C)
_ONW (g)) is measured.

<B> Calculation of Mass of Coarse Aggregate The concrete sample is washed with water to separate the coarse aggregate, and the mass of the coarse aggregate in water (mass measurement value G _W ( g)) is measured. The mass G of the coarse aggregate in the concrete sample is calculated from the measured value G _{W of the} underwater mass and the density ρ _{W of the} water and the density ρ _G of the coarse aggregate which are obtained in advance.
_S (g) is calculated by the equation 1.

(Equation 1)

<C> Calculation of the amount of cement From the water amount W _{C of the} concrete mix, the ratio of the cement amount C _C and the amount of fine aggregate S _C , and the measured air mass C _{ONS of the} concrete sample and the mass G _{S of the} coarse aggregate. The amount of cement C _S in the concrete sample is calculated by Equation 2.

(Equation 2)

<D> Calculation of amount of fine aggregate The estimated value S _S of fine aggregate in the concrete sample is calculated by the equation 3 using the same measurement value as the calculation of the amount of cement.

(Equation 3)

<E> Calculation of water _{content in} sample The measured water content C _{ONW of the} concrete sample and the measured air mass C _ONS of the concrete sample have the relationship of equation (4). The volume V _G , V _S , V _C , and V _W of each material in the equation 4 is given by the density ρ _G ,
Equation 5 is expressed by using ρ _S , ρ _C , and ρ _W. W in Equation 5
_{Since S} is the amount of water in the concrete sample, this formula is developed and the formula for calculating the amount of water is introduced as formula 6. Therefore, the amount W _S of water in the concrete sample can be calculated by the equation 6 using the measured values already obtained.

(Equation 4)

[Formula 5]

[Formula 6]

<F> Calculation of the unit water amount of concrete The unit water amount W of the concrete sample is calculated from the already-measured value by using the formula 7 introduced from the formula 6 of the water amount W _{S in} the sample.

[Formula 7]

[0019]

[Examples] Three types of concrete mixes will be described below.
The method of measuring the unit water content of concrete will be described. <A> Concrete mixing In the concrete mixing, ordinary Portland cement was used as the cement, crushed sand and land sand were mixed as the fine aggregate, hard sandstone crushed stone was used as the coarse aggregate, and a high-performance AE water reducing agent was used as the admixture. Table 3 shows the densities of these cements, fine aggregates, coarse aggregates and water, and Table 4 shows the three types of concrete mixes A, B and C.
Shown in Here, the admixture is treated as equivalent to water.

[Table 3]

[Table 4]

<B> Measurement results of each mix A part of concrete A, which has not yet hardened, was taken out and measured three times. The measurement results are shown in Table 5. For each measurement result, refer to the data in Tables 3 to 4,
The amount of water in the concrete sample is calculated from equation (6). Therefore, first, the mass G _S of the coarse aggregate is obtained from the equation (1). Further, the amount of fine aggregate S _S and the amount of cement C _S in the sample are calculated by the formula (3)
And equation (2). Then, finally, the unit water amount of concrete is obtained from the equation (7), and these calculation results are shown in Table 6.

[Table 5]

[Table 6]

As with the concrete mix A, some of the concrete mixes B and C were taken out and measured three times. The measurement results and calculation results of the concrete mix B are shown in Tables 7 and 8. In addition, Table 9 and Table 10 show the measurement results and calculation results of the concrete mix C. The result of the measurement thus obtained is almost in agreement with the prepared unit water amount, and can be measured accurately and quickly by a simple calculation.

[Table 7]

[Table 8]

[Table 9]

[Table 10]

Although concrete is dealt with as an example, even in the case of mortar, the unit water amount of mortar can be obtained in a similar manner to that of concrete if the calculation is performed excluding the coarse aggregate.

[0023]

According to the present invention, the following effects can be obtained. <A> The device used in the present invention is a versatile scale, is easy to handle, does not require any special technique, can be easily measured by anyone, and can obtain the required accuracy. <B> Since no special procedure such as drying of the sample is required, the measurement is not troublesome. Therefore, the measurement can be performed quickly, and the measurement result can be known at an early stage.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a solid density measuring device.

Claims (3)

[Claims] 1. A method for measuring a unit water content of an inorganic hydraulic kneaded material, wherein a part of the inorganic hydraulic kneaded material which is not yet solidified is taken out as a sample, and a sample is obtained from the difference between the mass of the sample in air and the mass in water. The volume of the sample is obtained, and the total volume of the cement and the aggregate is obtained from the density of the aggregate, the density of the cement measured in water, and the ratio of the amount of the cement and the amount of the aggregate in the inorganic hydraulic kneading mixture, The difference between the volume of the sample and the total volume of the cement and the aggregate is obtained, and the water amount of the sample is used to obtain the unit water amount of the inorganic hydraulic kneaded product that has not solidified yet. Method for measuring unit water content of kneaded material. 2. The unit water content measurement method for an inorganic hydraulic kneaded material according to claim 1, wherein the inorganic hydraulic kneaded material is concrete or mortar, wherein the unit water content of the inorganic hydraulic kneaded material is measured. Method. 3. The unit water content measuring method according to claim 1, wherein the inorganic hydraulic kneaded material is concrete, and a part of the concrete which has not yet solidified is taken out as a sample, After measuring the mass in air and the mass in water, take out the coarse aggregate from the sample, measure the mass of the coarse aggregate in water to obtain the amount of coarse aggregate, and measure the aggregate as coarse aggregate and fine aggregate. A method for measuring the unit water content of an inorganic hydraulically kneaded product, which is characterized by handling the aggregate separately.