JPH07104302B2 - Method for measuring heat of dissolution of cement and cement constituent minerals - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for measuring the heat of dissolution of cement and cement constituent minerals using a hydrogen-type strongly acidic ion exchange resin as a dissolving agent.

[0002]

2. Description of the Related Art Cement is a main raw material powder for building structures and is composed of tricalcium silicate (Ca ₃ S) which is a main constituent mineral.
Abbreviated as iO ₅ and C ₃ S. ), Beta-2 calcium silicate (abbreviated as β-Ca ₂ SiO ₄ , β-C ₂ S),
Tricalcium aluminate (Ca ₃ Al ₂ O ₆ , C ₃ A
Abbreviated. ), 4 calcium ferric aluminate (Ca ₄ F
abbreviated as e ₂ Al ₂ O ₁₀ and C ₄ AF. ), To which gypsum (CaSO ₄ .2H ₂ O) has been added.
The quantitative ratio and fineness of these constituent minerals can be appropriately changed according to the purpose and application of construction, and various chemical substances are added separately to improve workability for the purpose of building a concrete structure. Be used for. The development of mechanical strength of the obtained structure is based on condensation and hardening due to complicated hydration reaction over many years, and there is measurement of hydration rate in hours or months as product quality evaluation. For the evaluation, in addition to physical methods such as measuring the compressive strength of the specimen, the heat of solution is measured using hydrofluoric acid-nitric acid as a solubilizer, and quality control is performed. For the hydration rate measurement in the latter, the hydration rate is calculated by converting the heat of hydration from the difference in the heats of dissolution (former> latter) obtained for unhydrated samples and partially hydrated specimens, and the cement manufacturer, user Widely used in laboratories, test laboratories or on-site.

[0003]

As a method for measuring the heat of dissolution of cement, JIS R52 described in "Method for measuring heat of hydration of cement (method of heat of solution)" is used.
03 is currently the standardized standard method. The calorimeter used here consists of a Dewar bottle, a Beckman thermometer, and a stirrer, and after determining the heat equivalent using zinc oxide (ZnO), the heat of solution of unhydrated cement and hydrated cement was measured. For the dissolution, a chemical dissolving agent of a mixed acid of hydrofluoric acid-nitric acid is used. Due to the use of this harsh dissolving agent, the vitreous portion that is easily corroded by hydrofluoric acid requires a coating treatment such as picein, which results in a decrease in the response and sensitivity of the thermometer (measurement accuracy The sample amount is as large as about 3 grams for improvement). Further, the use of the above-mentioned mixed acid is dangerous and requires careful handling, and the problem of waste acid treatment remains to prevent environmental pollution. Therefore, the present invention, in order to solve the above problems, in operation, there is no danger in handling at all, by using a non-corrosive dissolving agent, irrelevant to the material selection of the measuring instrument, and a small amount of sample An object of the present invention is to provide a novel cement and a method for measuring the heat of solution of a cement-constituting mineral, which can measure the heat of solution with high accuracy.

[0004]

SUMMARY OF THE INVENTION The present invention is a hydrogen-type strong acid.
Mix the measurement sample with the ion-exchange resin as the dissolving agent.
The heat of fusion generated during the melting process of the sample
Provided is a method for measuring heat of dissolution of cement and cement constituent minerals, which is characterized by being measured by a conduction type calorimeter . The present invention also compares the area of the thermogram of the calorific value generated in the dissolution process of the sample with the measurement sample using the strongly acidic ion exchange resin of hydrogen type as the solubilizing agent, and the area of the thermogram of the reference calorific value. And a method for measuring the heat of solution of cement and cement constituent minerals, characterized by converting the heat of solution of a measurement sample. The measuring method of the present invention is intended for measuring the heat of dissolution of cement and cement constituent minerals in water. Commercially available ordinary Portland cement (abbreviated as OPC) and early strength cement (RHC)
Abbreviated. ), Blast furnace slag cement (abbreviated as BSC), etc., and cement for special purposes and uses, or any cement such as undeveloped cement, which is under development, is subject to measurement. Further, as the cement constituent minerals, various minerals constituting cement such as C ₃ S, C ₂ S, C ₃ A and C ₄ AF are included. The measuring method of the present invention is characterized by using a hydrogen-type strongly acidic ion exchange resin as a solubilizer. Strongly acidic ion exchange resin is a water-insoluble polymer electrolyte, and its hydrogen type has acid activity.
Abbreviated as HR (hydrogen type resin). In the present invention, a commercially available product can be applied as HR, for example, "Diaion" (registered trademark, Mitsubishi Kasei), "Dowex".
[Registered Trademark, Dow Chemicala
l)], "Amber Light" [registered trademark, Rohm & Haas], "Levatit"
(Registered trademark, Mitsui Toatsu Fine) or the like can be used. The HR used is washed beforehand with a sufficient amount of pure water.
Subsequently, this is filtered under reduced pressure to obtain a wet resin, or this is dried at 100 ° C. or lower and used. Suspension water containing an appropriate amount of HR can effectively dissolve a substance that is difficult to dissolve in water at room temperature. The driving force for this dissolution reaction is cation exchange that occurs between the small amount of ions eluted in water and HR, and this ion exchange rate proceeds in seconds, which causes dissolution equilibrium to move to the right. Finally, the poorly soluble substance is completely dissolved. The specific gravity of HR used is slightly higher than that of pure water (about 1.1 on average), and because it consists of spherical particles with a diameter of 1 mm or less, stirring can be performed easily and efficiently, and Since no mineral acid such as hydrofluoric acid-nitric acid used in the measuring method is used, side reactions do not occur at the same time, there is no danger in operation, and HR after use is regenerated with an appropriate concentration of dilute hydrochloric acid. It can be used repeatedly by washing with water, is economical, and has no fear of environmental pollution. As the calorimeter for measuring the heat of dissolution used in the method of the present invention, any commercially available adiabatic or conduction calorimeter can be applied. As the measuring method, there is a method of transferring the amount of heat to an object having a known heat capacity, a method of measuring the temperature rise of the object at that time, a method of comparing with a known amount of heat generated by an electrical or chemical method, and the like. Any of these can be used. In the present invention, a measurement sample is mixed with a solubilizer, and the amount of heat generated in the dissolution process of the sample is measured by a temperature difference detector (or a high-sensitivity thermometer) to draw a thermogram, while being electrically supplied. A method of converting the heat of dissolution of the sample under test by comparing the area of the amount of heat (Joule heat) generated by the standard electric power with the thermogram is preferably used. The mixing ratio of the measurement sample and the solubilizer HR is preferably 15 to 30 times the equivalent amount of HR to the sample. Even if the amount of HR is 15 times or less of the equivalent amount, the sample is of course dissolved, but when the amount of HR is small, the dissolution time gradually increases, which is not preferable for measurement. On the other hand, if the amount of HR used exceeds 30 times the equivalent amount, the solid content increases and the stirring speed cannot be increased, which is not preferable. This measuring method has a large effect on the dissolution time of the stirring speed,
More preferably, 300 rpm or more is necessary. If the dissolution time is long, the change in heat generation becomes gradual and the accuracy of measurement decreases, which is not preferable. Most preferably, it is 400 rpm or more. The amount of the sample used for the measurement is specified as 3.0 g in the method described in JIS, but in the method of the present invention, if the amplification sensitivity of the instrument used is about 50 mV, the sample amount is 200 to 500 mg. The degree is enough. The method for dissolving the sample is to put the precisely weighed unhydrated sample or partially hydrated sample into 15 to 25 ml of pure water in HR dispersed by vigorous stirring. As for the partially hydrated sample, HR may be added to a sample that has been partially hydrated in pure water in advance. Measurement cell is usually 25 ℃
Place in a constant temperature bath maintained at. The temperature of the constant temperature bath is 10
Any temperature from 0 ° C to 60 ° C can be used.
When the temperature is higher than 60 ° C, HR may be deteriorated, which is not preferable. In the above-described measuring method of the present invention, it is preferable to measure the heat of solution for several samples at once in order to improve the measuring efficiency. For example, a reference cell for heat generation by reference power is placed in the center of the measurement device, and several insulated measurement cells are placed around the reference cell (for example, on concentric circles), and the temperature between the reference cell and each measurement cell is set. By using a multipoint measuring device capable of recording the difference, it is possible to efficiently measure the heats of dissolution of several samples at the same time.

[0005]

EXAMPLES The method of measuring the heat of dissolution of the cement and cement constituents of the present invention and the measurement results will be described below. 1. Method of Measuring Heat of Solution FIG. 2 is a schematic diagram showing an example of a device for measuring heat of solution (twin conduction type) using HR suspension water. In FIG. 2, 1 is a measuring cell, and 2 is a reference cell having a standard calorific value, both of which are made of stainless steel. Although FIG. 2 shows the case where there is only one measurement cell 1, several measurement cells can be set around the control cell 2 in order to improve the measurement efficiency. The measurement cell 1 and the control cell 2 are set in a constant temperature bath 3 kept at 25 ° C. The cells 1 and 2 are equipped with stir bars 4 and 5, and temperature difference detectors 6 and 7. Each cell contained 15 ml of pure water, and the measurement cell 1 contained Mitsubishi Kasei's MCIgel wet resin (exchange capacity 2.1 meq / g).
Add 3.0 g, rotate the stirrer 4 at 500 rpm,
Disperse the resin into a uniform suspension. Sample to be measured in the measuring cell 1-RHC (early strong cement) 8 About 200 m
The cylindrical container 9 in which g is precisely weighed and placed is set as shown in the figure. A rubber film 10 is strongly stretched on the bottom of the cylindrical container 9, and the sample 8 is placed on the rubber film 10. When the temperature in the cell 1 reaches equilibrium, the strongly stretched rubber film 10 is attached to the needle 1.
Dissolution begins when sample 8 is dropped into HR suspension water by breaking through at 1. The amount of heat generated at this time is measured by a temperature difference detector (or high-sensitivity thermometer) 6, amplified, and recorded in a thermogram. On the other hand, the amount of heat (Joule heat) generated in the heater 12 by the reference power provided in the control cell 2 is measured by the temperature difference detector 7, amplified and recorded in the thermogram in the same manner. The heat of solution of the sample is converted. 2. Measurement Results of Heat of Solution FIG. 1 is a thermogram showing the measurement results of RHC and its hydrate. This hydrate is a sample having a water / cement ratio of 75 and stirred and hydrated at 25 ° C. for 8 days. Figure 1
The thermogram shows the amount of heat generation (J) with time on the horizontal axis, the solid line (A) is unhydrated RHC, and the solid line (B).
Is the reference power calorific value of the control cell. The broken line (C) is the hydrated RHC, and the broken line (D) is the reference power calorific value. The area of the calorific value of the sample on the thermogram obtained as described above is measured, and compared with the area of the reference calorific value, the heat of solution of the sample is converted. Area measurement is quick and accurate using a computer. RH used here
The results of chemical analysis of commercial OPC (ordinary Portland cement) and BSC (blast furnace slag cement) including C are shown in Table 1. Fig. 3 shows the calorific value measurement results obtained by adding cement powder to the amount of input cement.
It shows in (a).

[0006]

[Table 1]

In FIG. 3 (a), the vertical axis represents the heat generation amount (k
J), the horizontal axis is the amount (g) of the sample used for the measurement. Figure 3
The linear relationship between the amount of generated heat and the amount of cement shown in (a) clearly shows the fact that cement is completely dissolved in HR suspension water, and from the gradients of these, the heats of dissolution of three types of cement are It is calculated. Figure 3 (b) shows about 0.2g of the same RHC sample used for the measurement shown in Figure 3 (a).
The results of measurement of the heat of solution of the hydrated product were hydrated with 15 ml of pure water at 25 ° C. for 3.5 days and 8 days. The vertical axis in FIG. 3 (b) is the same calorific value (kJ) as in FIG. 3 (a), and the horizontal axis is the number of days of hydration (days). Table 2 summarizes the measurement results of the amount of heat of dissolution of cement by HR calculated from the above measurements. This table also shows the results of the constituent minerals of cement and the hydration products of cement,
For some samples, the results of previous researchers using the hydrofluoric acid-nitric acid method are also shown for comparison. Here, Table 2 will be described in a bulleted list including some consideration. 1. Comparing the amounts of heat of dissolution of cement and cement constituent minerals, the value of the hydrofluoric acid-nitric acid method is generally higher than the value of HR and is about 1.3 times. This is presumably due to the concomitant occurrence of chemical side reactions due to severe dissolution by mixed acid, which contributed to the higher value of the heat of solution. 2. There is almost a correlation between the two dissolving agents in the heat of dissolution of cement minerals. That is, the heat of fusion of C ₃ A is the highest, and the heats of C ₃ S and C ₂ S decrease in that order. Also, β
-, And the heat of dissolution of γ-C ₂ S by HR is almost equal to 1.1 kJ in gram units, but γ-in molar units.
C ₂ S slightly exceeds the β-phase and shows a similar relationship to the hydrofluoric acid-nitric acid method. 3. In addition, it is understood that the hydrated constituent compounds of cement are also exothermicly dissolved except for gypsum by treating with HR suspension water.

[0008]

[Table 2]

[0009]

The method for measuring the heat of dissolution of cement, cement hydrate and cement-related compounds using the strong acid ion exchange resin HR of the present invention is found to be superior to the conventional JIS method in the following points and is practically used. Is possible. 1) The resin used as the solubilizer can be recycled and reused without any danger in handling. 2) Since there is no corrosion of the device due to the resin used, there is no need to select the material of the device. 3) The advantage of 2) will enable the manufacture of high-precision, multi-function devices and the like in the future. 4) The waste acid treatment operation is omitted, and there is no concern about environmental pollution. 5) The current device for measurement using hydrofluoric acid-nitric acid can be applied.

[Brief description of drawings]

1 is a thermogram of RHC and its hydrate.

FIG. 2 is a schematic diagram showing an example of a melting heat measuring device of the present invention.

FIG. 3A is a graph of measurement results of calorific value with respect to sample amount. (B) Change in heat of solution with OPC hydration days
The graph showing.

[Explanation of symbols]

 1 Measurement Cell 2 Control Cell 3 Constant Temperature Bath 4, 5 Stirrer 6, 7 Temperature Difference Detector 8 Sample 9 Cylindrical Container 10 Rubber Membrane 11 Needle 12 Standard Power Heater

Claims (2)

[Claims] 1. A hydrogen-type strongly acidic ion exchange resin as a solubilizer
Then, the measurement sample is mixed with the lysing agent,
Measure the generated heat of dissolution with an adiabatic or conduction calorimeter
A method for measuring heat of dissolution of cement and cement constituent minerals, which is characterized by: 2. The area of the thermogram of the calorific value generated during the dissolution process of the sample is compared with the area of the thermogram of the reference calorific value by mixing the measurement sample with the hydrogen-type strongly acidic ion exchange resin as the solubilizing agent. And a method for measuring heat of dissolution of cement and cement constituent minerals, which comprises converting the heat of dissolution of a measurement sample by means of the above.