JPH10323820A - Compounding ratio determining method for hardened body manufacture using large amount of fine powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compounding ratio determining method by which a water-powder ratio and a cement adding ratio to maximize the compressive strength of a hardened body to be manufactured by using a large amount of a fine powder such as coal ash, can be easily obtained. SOLUTION: This is a method for obtaining a compounding ratio of respective materials in order to manufacture a hardened body comprising a material including cement, a large amount of a fine powder such as coal ash, and water of a water-powder ratio at a degree of an optimum moisture content, and a kneaded article is formed by kneading cement, the fine powder and water, and a water-powder ratio to show a specified flow value is obtained by performing a flow test regarding this kneaded article, and an estimate for the water-powder ratio to maximize the compressive strength of the hardened body is obtained by an operation from the water-powder ratio, and from this estimate for the water-powder ratio, an estimate for the compressive strength of the hardened body is obtained by an operation, and from the estimate for the compressive strength and a required compressive strength for the hardened body, a cement adding ratio is obtained by an operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a cured product using a large amount of fine powder, and more particularly to a method for determining a mixing ratio of each material constituting the cured product.

[0002]

2. Description of the Related Art Coal ash generated by coal-fired power generation is:
Some of them are used for cement raw materials or as admixtures for concrete, but many of them are landfilled, and there is a demand for expanded use from the viewpoint of environmental protection and resource utilization. Similarly, incineration ash such as sludge generated after purifying sewage water is also required to be used for purposes other than landfill disposal.

Therefore, the inventors of the present invention have proposed a method of producing a hardened body using a large amount of fine powder such as coal ash and sludge incineration ash, and application of the hardened body to various structures. did. In other words, the production method of the cured product is as follows: the fine powder such as cement, coal ash or sludge incineration ash, water and the curing accelerator are optimally moisturized. The mixture is kneaded at a water powder ratio close to the water content ratio at which the density can be obtained, and then compacted by applying a vibration having a frequency of about 4000 rpm and an amplitude of about 1.0 mm for about 5 minutes. Here, when fine powder such as cement, coal ash or sludge incineration ash, and a curing accelerator are mixed and kneaded with water having an optimal water content, the kneaded material merely becomes a wet powder state. However, after applying vibration at the above optimal water content,
It changes to a fluid state and can be compacted. Further, it has been found that the above-mentioned optimum water content ratio substantially coincides with the limit water powder ratio at which the kneaded material is fluidized by vibration compaction.

[0004] Regarding concrete, it is well known that the fluidity is increased by vibration, and it is used as a standard for compaction of concrete. However,
The concrete after kneading is in a fluid state even before the vibration, and the vibration only lowers the viscosity of the cement paste to increase the fluidity. On the other hand, in the above-described method for producing a cured body, the wet powdery kneaded material changes into a fluid state by the action of vibration, and the state of the fluid is maintained even after the vibration is stopped. It is completely different from concrete compaction.

[0005] Since the optimum water content in the above-mentioned method for producing a cured product greatly varies depending on the type of fine powder such as coal ash or sludge incineration ash, it is necessary to determine the optimum moisture content by compaction test of soil by compaction for each fine powder. However, in this case, the number of tests may be considerably increased, and there is a problem that it takes time and effort.

The water powder ratio at which the compressive strength of the cured product is maximized (hereinafter referred to as the "optimal water powder ratio") is known to be approximately in the vicinity of the optimum water content ratio. As the water-powder ratio decreases (the water content decreases) in the vicinity of the optimum water content, a higher compressive strength cannot be obtained. Therefore, it is necessary to determine the optimum water-powder ratio for each type of fine powder used.

[0007]

SUMMARY OF THE INVENTION The present invention focuses on the above-mentioned problems of the prior art and attempts to solve them.
An object of the present invention is to provide a method for determining a compounding ratio that can easily determine a water powder ratio and a cement addition ratio that maximize the compressive strength of a cured product produced using a large amount of fine powder.

[0008]

In order to solve the above-mentioned problems, the present invention provides a cured product made of a material containing cement, a large amount of fine powder, and water having a water-powder ratio about the optimum water content. In order to produce, a method of determining the mixing ratio of each material, kneading and mixing cement, fine powder, and water to produce a kneaded material, performing a flow test on the kneaded material, water showing a predetermined flow value The powder ratio is obtained, and from the water powder ratio, an estimated value of the water powder ratio (optimal water powder ratio) at which the compressive strength of the cured body is maximized is calculated, and the estimated value of the water powder ratio is obtained from the calculated value. There is provided a method for determining a mixing ratio, wherein an estimated value of the compressive strength of a hardened body is obtained by calculation, and a cement addition ratio is obtained by calculation from the estimated value of the compressive strength and the required compressive strength of the hardened body.

In the present invention, seawater or fresh water can be used as the water having a water powder ratio of about the optimum water content ratio, and coal ash or sludge incineration ash can be used as the fine powder. . Further, in the present invention, when kneading the cement, fine powder and water to produce a kneaded material, an admixture may be added, and a flow test is performed on the kneaded material thus added with the admixture. A water powder ratio showing a predetermined flow value is determined, and the same procedure as described above can be used to determine the mixing ratio when the admixture is added. Here, a salt (NaCl or the like) can be used as the admixture. For example, when pure water is used as water having a water powder ratio of about the optimum water content, about 3 weight% of water is used. % Salt (such as NaCl) is added. On the other hand, when seawater is used as the water, salt (NaCl or the like) having a similar weight ratio contained in the seawater acts as the admixture. By adding the admixture as described above, the short-term and long-term compressive strength of the cured product is enhanced.

In the present invention, a kneaded material is formed again at the cement addition rate determined by calculation, and a flow test is performed again to obtain a water powder ratio showing a predetermined flow value. The estimated value of the powder ratio may be obtained again by calculation, and this may be used as the correction value of the optimum water powder ratio. If the correction value of the optimum water powder ratio is obtained in this manner, a more optimum compounding ratio can be obtained.

In the present invention, the calculation for obtaining the estimated value of the optimum water powder ratio from the water powder ratio indicating a predetermined flow value is as follows:
If a calculation formula is obtained in advance by a preliminary experiment, the calculation can be performed by this calculation formula. That is, in the preliminary experiment, the flow value is obtained for a plurality of kneaded materials having different water powder ratios prepared at a predetermined cement addition rate for each type of fine powder such as coal ash, and a predetermined flow value is shown from the result. The water-powder ratio is determined, and further, a cured body is prepared from these kneaded materials, and the compression strength is determined by a predetermined material age, for example, a material age such as 3 days, 7 days, 28 days, and the like. The water powder ratio showing the maximum value, that is, the optimum water powder ratio is determined. If the regression equation is determined using the optimum water powder ratio thus determined and the water powder ratio indicating a predetermined flow value as variables, the above-described calculation can be performed using the regression equation.

Further, in the present invention, the calculation for obtaining the estimated value of the compressive strength of the cured product from the estimated value of the water powder ratio can be performed by a calculation formula if a calculation formula is obtained in advance by a preliminary experiment. That is, in the preliminary experiment, the compressive strength was determined by a plurality of materials for a plurality of hardened materials having different water powder ratios prepared at a predetermined cement addition ratio for each type of fine powder such as coal ash, If the regression equation is determined using the compressive strength and the water powder ratio as variables, the above-described calculation can be performed using the regression equation.

Further, in the present invention, the calculation of the cement addition rate from the estimated value of the compressive strength and the required compressive strength can be performed by this formula if the formula is obtained in advance by a preliminary experiment. In other words, in the preliminary experiment, a plurality of hardened bodies with different cement addition rates were created for each type of fine powder such as coal ash, and the compressive strength was determined by several grades. The increase / decrease rate of the compressive strength for every 1% increase / decrease is determined as a constant. Then, if the proportional equation is calculated between the increase / decrease rate of the required compressive strength with respect to the estimated value of the compressive strength and the increase / decrease value of the cement addition rate using the constant, the above-described calculation can be performed by this proportional equation.

The flow test in the present invention is carried out according to JIS R 5201
It can be performed by the test equipment and test method specified in -1992. In the present invention, in the step of obtaining a water powder ratio indicating a predetermined flow value, the predetermined flow value is, when a flow test is performed on a plurality of kneaded materials created by changing the water powder ratio, the flow value and Any value within a range in which a certain proportional relationship with the water-powder ratio is observed may be used, and more preferably the lower limit value in the range. That is, using a fine powder of different types of coal ash and the like, mixing the fine powder, cement and water, preparing a kneaded material with a plurality of water powder ratios, and conducting a preliminary experiment for obtaining a flow value. When the flow value is in the range of approximately 130 to 170, a proportional relationship is observed between the flow value and the water powder ratio. 1
It is preferably set to 40. The predetermined flow value can be appropriately changed by a preliminary experiment for obtaining the relationship between the flow value and the water powder ratio.

In the present invention, in the step of obtaining a water powder ratio showing a predetermined flow value, a kneaded product having a predetermined water powder ratio is first prepared, and a flow test is performed on the kneaded material. It can be obtained by increasing or decreasing the water powder ratio as appropriate according to the flow value and repeating the flow test until the flow value reaches the vicinity of the predetermined value. Here, when the predetermined flow value cannot be obtained, the water powder ratio indicating the flow value before and after this predetermined value may be obtained, and the water powder ratio may be obtained by proportional distribution.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments will be described below with reference to the accompanying drawings, but the present invention is not limited to these embodiments. FIG. 1 is a list showing the quality of the coal ash used in the present embodiment.
FIG. 3 is a graph showing the relationship between the water powder ratio and the compressive strength, and FIG. 3 is a graph showing the relationship between the water powder ratio and the flow value;
FIG. 4 is a graph showing the relationship between the water powder ratio at which the flow value becomes 140 and the optimum water powder ratio. FIGS. 5 (a) to 5 (d) show the relationship between the powder water ratio and the compressive strength for each material. It is a graph shown for each order,
FIGS. 6A to 6D are graphs showing the relationship between the cement addition ratio and the compressive strength for each material age. In this embodiment, the weight of cement is "C", the weight of coal ash is "F",
Further, the weight of water is simply indicated by “W”.

In the method for determining the mixing ratio of the present invention, cement and coal ash are mixed in a predetermined ratio, for example, cement: coal ash =
Mix at a weight ratio of 15:85, knead water and powder (cement and coal ash) to make a kneaded material with a plurality of water powder ratios, and for a plurality of kneaded materials having different water powder ratios A flow test is performed to determine a water powder ratio showing a predetermined flow value. Then, this water powder ratio is substituted into a first equation (a relational expression between the optimum water powder ratio and a water powder ratio indicating a predetermined flow value) determined in advance, and the optimum water powder ratio, An estimated value of the water powder ratio at which the compressive strength of the cured product is maximized is determined. Further, the estimated value of the optimum water-powder ratio is substituted into a second equation (the relational expression between the optimum water-powder ratio and the compressive strength) obtained in advance, and the compression of the cured product at the optimum water-powder ratio is performed. Find an estimate of the intensity. The estimated value of the compressive strength obtained in this way and the required compressive strength of the hardened body (target compressive strength) are converted into a third equation (the relational equation between the compressive strength and the cement addition rate) obtained in advance. Substituting to obtain an estimated value of the cement addition rate that can obtain the required compressive strength. As described above, the cement addition ratio and the water powder ratio are obtained, and the compounding ratio of the material for producing the cured product is determined. Next, the first to third equations used in the method for determining the blending ratio of the present embodiment will be described.

<< First Equation (Relationship Equation between Optimal Water Powder Ratio and Water Powder Ratio Showing a Predetermined Flow Value) >> As shown in FIG.
As a result of performing a flow test on the five types of coal ashes A to O by the method specified in JIS R 5201-1992, the graph of FIG. 3 was obtained. That is, powder materials (cement, coal ash) are weighed so that the cement addition rate (C / (C + F) × 100) of coal ash A to O becomes 15%, and these powder materials are put into a mixer. Then, the mixture is kneaded for a predetermined time, water is added thereto at a predetermined water powder ratio (W / (C + F) × 100), and the mixture is further kneaded for a predetermined time. The kneaded material is divided into two layers in a flow cone, packed 15 times each with a push rod, and the flow cone is placed on a table and slowly pulled up. Thereafter, the table was moved up and down 15 times in 15 seconds, the maximum diameter and the diameter in the direction perpendicular to the maximum diameter were measured, and the average value was used as the flow value. Such a flow test is performed for each coal ash at a water powder ratio of 3 to 5 types,
The results are shown in the graph of FIG. The kneaded material used in FIG. 3 was prepared with a water-powder ratio that exhibited sufficient fluidity only by stirring and kneading, and was not subjected to vibration compaction at all. As shown in FIG. 3, although the relationship between the water powder ratio and the flow value differs depending on the type of coal ash, a predetermined range for each coal ash, that is, a flow value in a range of approximately 130 to 170, is used. Proportional relationship (linear graph)
It was found to be. As a result, the water powder ratio becomes as small as possible, and the water powder ratio and the flow value tend to show a proportional relationship. The ratio was determined from FIG. Also, a plurality of coal ashes A to F were added under the condition that a cement addition rate was 15%, a plurality of water powder ratios near an optimum water content ratio, and a salt as a hardening accelerator was added by 3% by weight to water. A cured product was prepared and the compressive strength of each 28-day age was determined, and the results are shown in FIG. From FIG. 2, it can be seen that the smaller the water powder ratio, the higher the strength is not necessarily obtained. Ratio). FIG. 4 shows the relationship between the optimum water powder ratio obtained from FIG. 2 and the water powder ratio at a flow value of 140. As shown in FIG. 4, a very good correlation was found between the two values for the different coal ashes A to F, and the following regression equation, that is, the first equation was obtained.

<< First formula >> (Optimal water powder ratio%) = 0.789 × (water powder ratio% at a flow value of 140 mm) +3.05 Therefore, a flow test is performed for each type of coal ash to be used, and By obtaining the water powder ratio at a value of 140 mm and substituting this water powder ratio into the first equation, it is possible to obtain an estimated value of the optimum water powder ratio with high accuracy.

<< Second Equation (Relationship Equation between Optimum Water Powder Ratio and Compressive Strength) >> FIGS. 5 (a) to 5 (d) show the results of the coal ashes A to F prepared at a cement addition rate of 15%. Powder water ratio ((C
+ F) / W) and compressive strength (kgf / cm ² )
Shown every 7, 28, and 91 days. 5 (a) to 5 (d), there is a slight variation depending on the type of coal ash,
The powder water ratio and the compressive strength showed a very good proportional relationship (correlation) in all the ages, and the following regression equation, that is, the second equation was obtained for each ages. << Second formula >> Material age 3 days (compressive strength (kgf / cm ² )) = 100 × 23.5 / (water powder ratio (%)) − 43.2 Material age 7 days (compressive strength (kgf / cm ² )) = 100 × 57.2 / (water powder ratio (%)) - 119 material age 28 days (compressive strength ^{(kgf / cm 2)) =} 100 × 105 / ( water powder ratio (%)) - 167 material age 91 days (Compressive strength (kgf / cm ² )) = 100 × 103 / (water powder ratio (%)) − 67.6 Therefore, the optimal water powder ratio derived from the first equation is
By substituting into the water powder ratio of the second equation in each material age, an estimated value of the compressive strength at the optimum water powder ratio can be obtained with high accuracy.

<< Third Equation (Relationship Equation Between Compressive Strength and Cement Addition Rate) >> In FIGS. 6 (a) to 6 (d), the water powder ratio is set to each optimum water powder ratio, and coal ash is set. Using B, C, D, F, the cement addition rate (C / (C + F) × 100 (%)) was 10, 15, 20
%, And a curing accelerator is added under the condition that a curing accelerator is added at a weight ratio of 3% with respect to each water.
Calculating the compressive strength on days 7, 7, 28 and 91,
Each was graphed. In FIGS. 6 (a) to 6 (d), although there is a variation depending on the type of coal ash, the compressive strength tends to increase at a predetermined slope if the cement addition rate is increased in each age, Addition rate 15%
Before and after, the slope of the graph was different. Therefore, for each material age, the compressive strength at each cement addition rate (10, 15, 20%) is weighted and averaged, and the weighted average value is used to calculate the section of the cement addition rate of 10 to 15%,
%, The increase rate (%) of the compressive strength was calculated. Then, the increase rate of the compressive strength in the above two sections was divided by the increase amount of the cement addition rate to obtain a compressive strength increase rate (%) per 1% of the cement addition rate shown in Table 1 below.

[0022]

[Table 1]

In Table 1, α is a cement addition ratio of 15 to
The increase rate (%) of the compressive strength per 1% of the cement addition rate in the section of 20% is shown, and β is the cement addition rate of 10 to 10.
The increase rate of the compressive strength per 1% of the cement addition rate in the section of 15% is shown.

The estimated value of the compressive strength derived from the above first and second equations is calculated at a cement addition rate of 15%. Therefore, when increasing or decreasing the compressive strength of the hardened body from the estimated value, it is necessary to correct the cement addition rate by increasing or decreasing the cement addition rate.
Can be calculated by the following third equation using the compressive strength increase rate of << Third Formula >><When the estimated compressive strength is lower than the target compressive strength> α × (cement addition rate (%) − 15) = (target compressive strength) / (estimated compressive strength) × 100−100 <estimated compressive strength Is higher than the target compressive strength> β × (15-cement addition rate (%)) = 100-(target compressive strength)
/ (Estimated compressive strength) × 100 Therefore, by substituting the target compressive strength and the estimated compressive strength into the third equation, a correction value of the cement addition rate can be obtained.

Next, the method for determining the compounding ratio of the present invention will be described in more detail. In the method of determining the mixing ratio of the present invention,
First, a flow test is performed. That is, powder materials (cement, coal ash) weighed so that the cement addition ratio becomes 15% are put into a mixer and kneaded for a predetermined time, and then water weighed so that a water powder ratio becomes 35%. Put into a mixer and mix for a predetermined time. Using the kneaded material thus prepared, a flow test similar to the above is performed to determine a flow value. The water powder ratio is changed according to the flow value as shown in Table 2, and the flow test is repeated with the flow value 140 interposed therebetween until two or three values higher and lower than this value are obtained.

[0026]

[Table 2]

Next, a water powder ratio that gives a flow value of 140 mm is calculated from the values sandwiching the flow value 140 by equal distribution. Then, the estimated value of the optimum water powder ratio is obtained by substituting the water powder ratio into the first equation. Next, the estimated value of the optimum water-powder ratio is substituted into the second equation to obtain an estimated value of the compressive strength at a predetermined material age. Further, the estimated value of the compressive strength is compared with the target compressive strength, and the two compressive strengths are substituted into the third equation to obtain a correction value of the cement addition rate. Here, since the optimal water powder ratio may vary depending on the cement addition rate, a kneaded material is prepared in the same manner as described above with the corrected cement addition rate, and the kneaded material is subjected to the flow test again in the same manner as described above, and the A correction value of the optimum water powder ratio is obtained from one equation. As described above, by obtaining the cement addition rate and the correction value of the optimum water powder ratio, the mixing ratio of cement, coal ash, and water that maximizes the compressive strength is obtained.

<< Calculation Example 1 >> As a result of a flow test, a water powder ratio at a flow value of 140 mm is 42.1%, and a target compressive strength of 28 days old is 150 kgf / cm ² . The optimum water powder ratio is determined by substituting the water powder ratio of 42.1% into the first equation. Optimal water powder ratio = 0.789 x (water powder ratio% at a flow value of 140 mm) + 3.05 = 0.789 x 42.1 + 3.05 = 36.3 (%) Substituting the optimum water powder ratio 36.3% into the second equation Obtain an estimate of compressive strength. Material age compressive strength of 28 = 100 × 105 / (water powder ratio (%)) - 167 = 100 × 105 / 36.3-167 = 122 estimate of compressive strength (kgf / cm ²⁾ material age 28 days 122kgf / Cm ² and the target compressive strength of 150 kgf / cm ² are substituted into the third equation to determine the correction value of the cement addition rate. In this case, since the estimated compression strength is lower than the target compression strength, the following equation is used. α × (cement addition rate (%) − 15) = (target compression strength) / (estimated compression strength) × 100−100 cement addition rate (%) = 15 + ｛(target compression strength) / (estimated compression strength) × 100 −100｝ / α = 15 + {150/122 x 100-100｝ / 7.38 = 18.1 (%) A kneaded product is prepared with a cement addition rate of 18.1 (%), and a flow test is performed again to determine the optimum water from the first equation. Find the correction value of the powder ratio.

[0029]

According to the present invention, a kneaded material is produced by kneading cement, fine powder such as coal ash, and water, and a flow test is performed on the kneaded material to determine a water-powder ratio showing a predetermined flow value. From the water powder ratio, an estimated value of the water powder ratio at which the compressive strength of the cured product is maximized is obtained by calculation, and an estimated value of the compressed strength of the cured product is calculated from the estimated value of the water powder ratio. The cement addition rate is obtained by calculation from the estimated value of the compressive strength and the required compressive strength of the hardened body. Therefore, in order to obtain the water powder ratio and the cement addition ratio, a complicated flow test such as a soil compaction test as in the related art is performed, and a flow test is simply performed on the resulting kneaded material to obtain a predetermined flow value. By calculating the water powder ratio, the water powder ratio and the cement addition ratio that maximize the compressive strength of the cured product can be easily obtained by calculation, and the mixing ratio can be determined.

[Brief description of the drawings]

FIG. 1 is a list showing the quality of coal ash used in this example.

FIG. 2 is a graph showing a relationship between a water powder ratio and compressive strength.

FIG. 3 is a graph showing a relationship between a water powder ratio and a flow value.

FIG. 4 is a graph showing a relationship between a water powder ratio that gives a flow value of 140 and an optimum water powder ratio.

FIGS. 5A to 5D are graphs showing the relationship between the powder water ratio and the compressive strength for each material age.

6 (a) to 6 (d) are graphs showing the relationship between the cement replacement ratio and the compressive strength for each material age.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Mamoru Sakamoto 2-5-8 Kitaaoyama, Minato-ku, Tokyo

Claims (2)

[Claims] 1. A method for determining a compounding ratio of each material in order to produce a hardened body comprising a material containing cement, a large amount of fine powder, and water having a water powder ratio of about an optimum water content ratio. Kneading cement, fine powder and water to produce a kneaded material,
A flow test is performed on the kneaded material to obtain a water powder ratio indicating a predetermined flow value.From the water powder ratio, an estimated value of a water powder ratio at which the compressive strength of the cured product is maximized is calculated, An estimated value of the compressive strength of the hardened body is obtained by calculation from the estimated value of the water powder ratio, and a cement addition rate is obtained by calculation from the estimated value of the compressive strength and the required compressive strength of the hardened body. How to determine the mixing ratio. 2. A kneaded product is formed by adding an admixture to the cement, the fine powder, and the water, and a flow test is performed on the kneaded product to obtain a water-powder ratio showing a predetermined flow value. The method according to claim 1, wherein: