Method for estimating cement milk replacement rate and soil cement strength

Abstract

To provide a cement milk substitution ratio estimation method allowing a cement milk substitution ratio to be estimated without securely setting a curing period.SOLUTION: A cement milk substitution ratio estimation method includes steps of: drying an unconsolidated sample of soil cement formed by mixing cement milk and soil at a site; measuring a content of a specific element in the unconsolidated sample using a fluorescent X-ray analyzer after the dried unconsolidated sample is crushed; calculating a mass ratio of soil and cement in the soil cement using the content of the specific element in the unconsolidated sample, a content of a specific element of the soil at the site, and a content of a specific element in cement used for the cement milk; and calculating a ratio of the cement milk of the soil cement from the calculated mass ratio, a water content ratio and density of the soil at the site, a density of the cement, and a mass ratio of water and cement of the cement milk.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method for estimating a cement milk replacement rate and a method for estimating soil cement strength. [Background technology]

[0002] In underground structures constructed using soil cement, such as piles formed by the precast pile embedding method, there is a need for a method to estimate the amount of cement in the soil cement and the proportion of cement milk in the soil cement for construction management and strength confirmation.

[0003] For example, the following Patent Document 1 describes a method of taking an unconsolidated sample from the soil cement in a pile hole base protection section and estimating the amount of cement from the temperature change of this unconsolidated sample. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-220092 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the method for estimating the amount of cement in the above-mentioned Patent Document 1, in order to create a graph showing the relationship between time and temperature, it is necessary to cure the unconsolidated sample for a certain period of time. Therefore, it takes time to estimate the amount of cement. In addition, in order to accurately measure the temperature, it is necessary to cure the unconsolidated sample in an insulated container, which is time-consuming to manage.

[0006] Taking into consideration the above facts, the present invention aims to estimate the proportion of cement milk in soil cement, i.e., the cement milk replacement rate, without ensuring a curing period. [Means for solving the problem]

[0007] The method for estimating the cement milk replacement rate of claim 1 includes the steps of drying an unconsolidated sample of soil cement formed by mixing cement milk and on-site generated soil, crushing the dried unconsolidated sample, and measuring the content of a predetermined element in the unconsolidated sample using a fluorescent X-ray analyzer, and In Predetermined element of Content, on-site generated soil The above Predetermined element of The content and cement used in the cement milk The above Predetermined element of calculating a mass ratio of soil to cement in the soil cement using the content; and calculating a mass ratio of the cement milk in the soil cement from the calculated mass ratio, the water content and density of the site generated soil, the density of the cement, and the mass ratio of water to cement in the cement milk. volume and calculating the ratio.

[0008] Soil cement is made by mixing cement milk (a mixture of cement and water) with soil generated at the site, and it is difficult to grasp the mixture ratio of these two. Therefore, it is difficult to grasp the percentage of cement milk contained in soil cement.

[0009] Here, cement and on-site generated soil each contain various elements. If it is possible to focus on a specific element (predetermined element, such as calcium) among these various elements and grasp the content of the specified element in the soil cement and the on-site generated soil, it is possible to calculate the percentage of cement milk contained in the soil cement.

[0010] Therefore, in the method for estimating the cement milk replacement rate of claim 1, the content of a specific element in an unconsolidated sample of soil cement is measured using an X-ray fluorescence analyzer. At this time, the unconsolidated sample is dried and pulverized, so that the cement component and the on-site generated soil component are mixed uniformly, and the content of the specific element can be measured with high accuracy.

[0011] Then, the mass ratio of soil to cement in the soil cement is calculated using the measured content of specific elements in the unconsolidated sample, the content of specific elements in the soil generated at the site, and the content of specific elements in the cement used in the cement milk.

[0012] Furthermore, the proportion of cement milk in the soil cement is calculated from the calculated mass ratio, the water content and density of the on-site generated soil, the density of the cement, and the mass ratio of water to cement in the cement milk.

[0013] In this way, the cement milk replacement rate estimation method of this embodiment makes it possible to estimate the proportion of cement milk in the soil cement, i.e., the cement milk replacement rate, without ensuring a curing period. The method for estimating the cement milk replacement rate of claim 2 comprises the steps of drying an unconsolidated sample of soil cement formed by mixing cement milk and soil generated at a site, crushing the dried unconsolidated sample and measuring the concentration of a predetermined element in the unconsolidated sample using an X-ray fluorescence analyzer, calculating a mass ratio of soil to cement in the soil cement using the concentration of the predetermined element in the unconsolidated sample, the concentration of the predetermined element in the soil generated at a site and the concentration of the predetermined element in the cement used in the cement milk, and calculating the volume fraction of the cement milk in the soil cement from the calculated mass ratio, the water content and density of the soil generated at a site, the density of the cement and the mass ratio of water to cement in the cement milk. The method for estimating a cement milk replacement rate of claim 3 is the method for estimating a cement milk replacement rate of claim 2, in which the concentration of a specified element in the unconsolidated sample is Ca(sc), the concentration of the specified element in the on-site generated soil is Ca(s), the concentration of the specified element in the cement used in the cement milk is Ca(c), and the mass ratio is α, and the following formula (A) holds. α=[Ca(c)-Ca(sc)] / [Ca(sc)-Ca(s)] ···(A) The method for estimating a cement milk replacement rate of claim 4 is the method for estimating a cement milk replacement rate of claim 2 or 3, in which the water content of the on-site generated soil is ωs, the density of the on-site generated soil is ρs, the density of the cement is ρc, the mass ratio of water to cement in the cement milk is R, and the volume fraction of the cement milk in the soil cement is Vh, and the following equation (B) holds. Vh=1 / [1+α·{(1 / ρs)+ωs} / {(1 / ρc)+R}]···(B) The method for estimating a cement milk replacement ratio according to claim 5 is the method for estimating a cement milk replacement ratio according to claim 2, further comprising the steps of: defining a concentration of a predetermined element in the unconsolidated sample as Ca(sc); defining a concentration of the predetermined element in the on-site generated soil as Ca(s); defining a concentration of the predetermined element in the cement used in the cement milk as Ca(c); defining the mass ratio as α; defining a water content of the on-site generated soil as ωs; The density of the on-site soil is ρs, the density of the cement is ρc, the mass ratio of water to cement in the cement milk is R, and the volume fraction of the cement milk in the soil cement is Vh, the following equations (A) and (B) hold. α=[Ca(c)-Ca(sc)] / [Ca(sc)-Ca(s)] ···(A) Vh=1 / [1+α·{(1 / ρs)+ωs} / {(1 / ρc)+R}]···(B)

[0014] Claim 6 The method for estimating the cement milk replacement rate of claim 1 Any one of ~5 In the method for estimating the cement milk replacement rate described in the above, the content of a predetermined element in the on-site generated soil is measured by crushing the dried on-site generated soil and using an X-ray fluorescence analyzer.

[0015] Claim 6 In the method for estimating the cement milk replacement rate, the content of a specific element in the on-site generated soil is dried and crushed, and measured using a fluorescent X-ray analyzer. This provides a higher accuracy in the content of a specific element in the on-site generated soil compared to the case where the content of a specific element in the on-site generated soil is based on previous data.

[0016] Claim 7 The method for estimating the cement milk replacement rate of claim 1 Any one of ~6In the method for estimating a cement milk replacement rate described above, the soil cement forms a base protection portion of the pile hole.

[0017] Claim 7 The method for estimating the cement milk replacement rate can estimate the cement milk replacement rate in the soil cement forming the base protection part of the pile hole. This makes it possible to grasp the mixing condition of the cement milk and the soil in the base protection part and estimate the strength of the base protection part.

[0018] Claim 8 The method for estimating the strength of soil cement comprises correlation data between the proportion of cement milk in soil cement and compressive strength, and the method according to claims 1 to 5. 7 The compressive strength of the soil cement is estimated using the ratio of cement milk in the soil cement calculated by the method for estimating the cement milk replacement rate described in any one of the above.

[0019] Claim 8 In the soil cement strength estimation method, the compressive strength of soil cement is estimated from correlation data between the cement milk ratio in soil cement and the compressive strength. This makes it possible to estimate the strength of soil cement without ensuring a curing period until the soil cement hardens. Effect of the Invention

[0020] According to the present invention, the cement milk replacement rate can be estimated without ensuring a curing period. [Brief description of the drawings]

[0021] [Figure 1] (A) is an elevational section showing the state of forming a pile hole for burying a precast pile to which the cement milk replacement rate estimation method and soil cement strength estimation method of the present invention are applied, (B) is an elevational section showing the state of forming a foot protection portion in the pile hole, (C) is an elevational section showing the state of pulling up the drilling rod from the pile hole, and (D) is an elevational section showing the state of inserting a precast pile into the pile hole. [Diagram 2]FIG. 1 is a conceptual diagram showing the components of soil cement. [Diagram 3] 1 is a graph showing correlation data between the cement milk replacement rate of soil cement and compressive strength. [Figure 4] FIG. 1 is a conceptual diagram showing the components of soil cement in a dry state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, a method for estimating a cement milk replacement rate and a method for estimating soil cement strength according to an embodiment of the present invention will be described with reference to the drawings. Components indicated by the same reference numerals in each drawing are the same components. However, unless otherwise specified in the specification, each component is not limited to one, and may be present in multiple numbers.

[0023] In addition, the description of the same configuration and reference numerals in each drawing may be omitted. Note that the present invention is not limited to the following embodiment, and may be modified as appropriate within the scope of the object of the present invention, such as omitting configurations or replacing them with different configurations.

[0024] <Pile construction method> The method for estimating the cement milk replacement rate and the method for estimating the strength of soil cement according to the embodiment of the present invention are used, for example, for the soil cement forming the base of a pile. Therefore, prior to the explanation of these methods, an outline of a construction method for a pile using the soil cement for which the cement milk replacement rate and strength are to be estimated will be given.

[0025] 1(A) to 1(D) show an example of a method for embedding a precast pile 10 in ground G by an embedding method. The precast pile 10 shown in Fig. 1(D) is a concrete pile that is cast in advance in a factory or the like and then transported to a construction site.

[0026] In order to bury the precast pile 10 in the ground G, first, as shown in Fig. 1 (A), the ground G is excavated while injecting drilling fluid using a drilling rod 20 to form a pile hole GH. In this embodiment, in order to make the precast pile 10 a tip-support pile, the tip of the pile hole GH is made to reach the supporting layer GA.

[0027] Next, as shown in FIG. 1(B), cement milk is injected from the drilling rod 20 to the tip (bottom) of the pile hole GH. By stirring this cement milk, it is mixed with the soil in the ground G to form the soil cement 12 that forms the foot protection part.

[0028] Cement milk is formed by mixing cement and water, or by mixing cement, water and various additives. Soil cement is a mixture of cement milk and soil. In this specification, the mixture of minerals, organic matter, gas, liquid, and living organisms that form the "ground G" is referred to as "soil."

[0029] At the tip of the pile hole GH, it is preferable to form a root-stabilizing bulb 12A, which is a portion where the diameter of the pile hole GH is expanded and filled with soil cement 12. When forming the root-stabilizing bulb 12A, the drilling head of the drilling rod 20 has a known structure that can be expanded in diameter. Then, the drilling head is expanded in diameter at a predetermined depth to form the root-stabilizing bulb 12A.

[0030] Next, as shown in Fig. 1(C), while the drilling rod 20 is being withdrawn, cement milk is injected and stirred above the soil cement 12. This forms soil cement 14 as a fixing liquid around the pile. The soil cement 14 may be formed using lean cement milk that has a smaller amount of cement per unit volume compared to the soil cement 12.

[0031] Next, as shown in FIG. 1(D), the prefabricated pile 10 is inserted into the pile hole GH. At this time, the tip of the prefabricated pile 10 is depressed into the root-hardening bulb 12A at the tip of the pile hole GH. As a result, the prefabricated pile 10 is buried in the ground G.

[0032] <Pile strength estimation method> The soil cement strength estimation method according to the embodiment of the present invention is a method for estimating the strength of soil cement 12, which is, for example, the base reinforcement portion of a precast pile 10, after it has hardened.

[0033] The reason for estimating the strength of the soil cement 12 after solidification is that the bearing capacity of the precast pile 10 is affected by the strength of the soil cement 12. Specifically, the soil cement 12 integrates the tip portion of the precast pile 10 with the bearing layer GA, and resists the pressing force acting on the precast pile 10. For this reason, when evaluating the bearing capacity of the precast pile 10, it is preferable to estimate the strength of the soil cement 12 in addition to the strength of the precast pile 10 itself.

[0034] Furthermore, "estimating" the strength of the soil cement 12 after it has solidified means evaluating the strength of the soil cement 12 before it has solidified. In this case, compared to "measuring" the strength of the soil cement 12 after it has solidified, there is no need to secure a curing period until the soil cement 12 has solidified. This makes it possible to shorten the construction period.

[0035] In this embodiment, the soil cement for estimating the strength does not have to be that used for permanent piles, and may be soil cement with approximately the same composition as that used for permanent piles.

[0036] In this case, a temporary pile hole is drilled on the same site as the site where the precast pile 10 as the permanent pile will be installed, and cement milk is injected and stirred. This makes it possible to form soil cement with approximately the same composition as the soil cement 12 used for the permanent pile. "Approximately the same" means, for example, that the mixture ratio of cement and soil is approximately the same.

[0037] In addition, the soil cement for which strength is estimated in this embodiment does not necessarily have to be used in the base of the pile, and may be used in parts other than the base of the pile. Furthermore, the soil cement may be used in an earth retaining wall or a ground improvement body. In the following explanation, a method for estimating the strength of soil cement in general, including the soil cement 12 used in permanent piles, will be explained.

[0038] (Outline of soil-cement strength estimation method) The strength of soil cement can be estimated from the correlation data between the cement milk replacement rate Vh and compressive strength if the ratio of the volume of cement milk to the unit volume of soil cement, i.e., the cement milk replacement rate Vh, is known. 2 ]) can be obtained as known information, for example, as shown in Fig. 3. The example shown in Fig. 3 shows a case where the water-cement ratio of the cement milk is 60%.

[0039] In Fig. 3, the measured values ​​of the unconfined compressive strength of a number of samples having various cement milk replacement rates Vh are plotted. In addition, Fig. 3 shows an approximation line C1 that approximates these plotted points with a linear curve. The unconfined compressive strength corresponding to the cement milk replacement rate Vh of the sample is derived in one-to-one correspondence from the approximation line C1.

[0040] (Cement milk replacement rate) As shown in Figure 2, the cement milk that forms soil cement is formed by mixing, for example, C [g] cement and C·R [g] water. R is the water-cement ratio (mass ratio) in the cement milk, and is a known value that can be set arbitrarily.

[0041] In addition, the on-site generated soil, which is the soil that is mixed with the cement milk, contains S [g] soil particles (in a dry state) and S ωs [g] water. ωs is the water content (mass ratio) of the on-site generated soil, and is a value that can be measured by a preliminary survey, which will be described later.

[0042] The density of cement is ρc [g / cm 3 ], soil particle density ρs [g / cm 3 ], then the volume of cement C[g] is (C / ρc)[cm 3 ] and the volume of a soil particle of S [g] is (S / ρs) [cm 3 Furthermore, if the density of water is 1, the volume of water (C R) [g] is (C R) [cm 3 ] and the volume of water (S ωs) [g] is (S ωs) [cm 3 ].

[0043] That is, the volume of cement milk Vcm [cm 3 ] is expressed by the following equation (1-1).

[0044] Vcm = C [(1 / ρc) + R] (1-1)

[0045] In addition, the volume of the soil generated on site Vsl [cm 3 ] is expressed by the following equation (1-2).

[0046] Vsl=S·[(1 / ρs)+ωs]···(1-2)

[0047] Furthermore, the ratio of the volume of cement milk to a unit volume of soil cement, i.e., the "cement milk replacement rate" Vh, is expressed by the following equation (1-3).

[0048] Vh = Vcm / (Vcm + Vsl) (1-3)

[0049] As mentioned above, the strength of soil cement can be estimated from the correlation data between the cement milk replacement rate Vh and compressive strength if the cement milk replacement rate Vh is known. However, since it is difficult to grasp the mixture ratio of cement milk and on-site generated soil in soil cement, it is difficult to grasp the cement content C [g] in soil cement. Therefore, it is also difficult to grasp the cement milk replacement rate.

[0050] Here, both the cement and the on-site generated soil contain calcium. If the calcium content of the soil cement and the on-site generated soil can be ascertained, the cement milk replacement rate Vh of the soil cement can be calculated by the method shown below. Note that calcium is an example of a specified element in the present invention. The "specified element" used in the present invention may be any element that is contained in cement, such as calcium.

[0051] (Calcium concentration of cement, density and water-cement ratio of cement milk) The calcium concentration Ca(c) [ppm] of the cement used in soil cement is known. For example, as shown in Figure 4, the calcium content Cca in cement C [g] is expressed by the following formula (2). The calcium concentration of cement may be measured using an X-ray fluorescence analyzer.

[0052] Cca = C·Ca(c) ···(2)

[0053] Also, the density of cement ρc [g / cm 3 ] is also known information. Furthermore, the water-cement ratio R in the cement milk is a known value that can be arbitrarily set as described above. Cement and water are mixed to obtain a predetermined water-cement ratio, but it is preferable to check the water-cement ratio R of the cement milk to be injected into the pile hole GH shown in FIG. 1, for example, when the cement milk is produced at the plant.

[0054] (Preliminary survey - sample collection) In order to estimate the strength of soil cement, a preliminary investigation is carried out. As an example of the preliminary investigation, first, a sample of on-site generated soil is collected from the ground (for example, ground G shown in FIG. 1). It is preferable to collect the sample in conjunction with a boring test for a ground investigation. This sample is, for example, the on-site generated soil (hereinafter sometimes referred to as the "soil sample") that forms the bearing layer GA shown in FIG. 1.

[0055] (Preliminary survey - measurement of soil generated on site) Next, the mass of the collected soil sample is measured, then it is dried and pulverized. Any equipment such as a heat-drying moisture meter or a microwave oven can be used to dry the soil sample. A mill or the like can be used to pulverize the soil sample. The mass and volume of the dried soil sample are then measured.

[0056] This gives the density of the soil particles (dry state) ρs [cm 3 ] and the water content of the soil sample before drying, ωs. As shown in Figure 2, the soil sample contains soil particles (in a dry state), S[g], and water, S ωs[g].

[0057] (Preliminary survey - Measurement of calcium content in on-site soil) Next, the calcium concentration in the dried and crushed soil sample (soil particles) is measured using an X-ray fluorescence analyzer. As shown in Figure 4, when the calcium concentration in the soil particles (in a dry state) is measured as Ca(s) [ppm], the calcium content Sca in the soil particles (in a dry state) of S [g] is expressed by the following formula (3).

[0058] Sca = S·Ca(s) ··· (3)

[0059] (Measurement of calcium content in soil cement) Next, for example, the cement milk and the on-site generated soil are mixed inside the pile hole GH shown in Figure 1 to form soil cement. Then, the unconsolidated soil cement is collected as an unconsolidated sample.

[0060] Next, the collected unconsolidated samples are dried and pulverized. As with soil samples, any equipment can be used to dry unconsolidated samples, such as a heat-drying moisture meter or a microwave oven. A mill or the like can be used to pulverize unconsolidated samples. The time required for drying, pulverization, and calcium measurement using a microwave oven or the like is approximately 1 hour (of which drying using a heat-drying moisture meter takes approximately 30 minutes and drying using a microwave oven takes approximately 15 minutes), which is sufficiently short compared to the time required for testing and curing the specimens for uniaxial compression tests (approximately 3 to 7 days).

[0061] Next, the calcium concentration in the dried and crushed unconsolidated sample (i.e., dry soil cement) is measured using an X-ray fluorescence analyzer. Since the unconsolidated sample is dried and crushed, the cement component and the on-site generated soil component are mixed uniformly, allowing the calcium content to be measured with high accuracy.

[0062] As shown in Figure 4, when the calcium concentration of soil cement (dry state) is measured as Ca(sc) [ppm], the calcium content Cca+Sca in this soil cement (dry state) is expressed by the following equation (4).

[0063] Cca+Sca=(C+S)·Ca(sc)···(4)

[0064] (Mass ratio of cement to soil particles (dry state) in soil cement) As shown in FIG. 4, if the mass ratio C:S of cement to soil particles (in a dry state) in soil cement is 1:α, then this coefficient α (hereinafter referred to as the mass ratio α) is expressed by the following equation (5-1).

[0065] α = S / C (5-1)

[0066] In addition, the calcium concentration Ca(sc) in soil cement is expressed by the following equation (5-2) from equations (2), (3), and (4).

[0067] Ca(sc)=[C·Ca(c)+S·Ca(s)] / (C+S) ···(5-2)

[0068] Using these Ca(c), Ca(s), and Ca(sc), the mass ratio α is calculated as shown in the following equation (5).

[0069] α=[Ca(c)-Ca(sc)] / [Ca(sc)-Ca(s)] ···(5)

[0070] (Cement milk replacement rate in soil cement) Volume of cement milk in soil cement Vcm [cm 3 ] and the volume of the soil generated on site Vsl [cm 3 ] is expressed by the following equation (1-4) based on the above equations (1-1) and (1-2).

[0071] Vcm:Vsl=1:(S / C)·[(1 / ρs)+ωs] / [(1 / ρc)+R] (1-4)

[0072] Using equation (5-1), equation (1-4) can be expressed as the following equation (1-5).

[0073] Vcm:Vsl=1:α·[(1 / ρs)+ωs] / [(1 / ρc)+R] (1-5)

[0074] Here, if the coefficient X = α · [(1 / ρs) + ωs] / [(1 / ρc) + R], equation (1-5) can be expressed as the following equation (1-6).

[0075] Vcm:Vsl=1:X (1-6)

[0076] From equations (1-3) and (1-6), the cement milk replacement ratio Vh is expressed by the following equation (1). That is, the cement milk replacement ratio Vh is calculated or measured in the above process using the mass ratio α of cement to soil particles (in a dry state) in the soil cement, the density ρs [cm 3 ], the moisture content of the soil sample before drying ωs, and the cement density ρc [g / cm 3 ] and the coefficient X derived from the water-cement ratio R of the cement milk, are expressed by the following equation (1).

[0077] Vh = 1 / (1 + X) (1)

[0078] (Estimation of soil-cement strength) Next, the soil cement strength (unconfined compressive strength) is estimated from the correlation data between the cement milk replacement rate Vh and compressive strength shown in Figure 3. Specifically, the unconfined compressive strength value corresponding to the calculated cement milk replacement rate Vh on the approximation line C1 is estimated as the soil cement strength. This allows the unconfined compressive strength of the soil cement sample to be estimated when it is solidified.

[0079] (Action and Effects) In this way, according to the soil cement strength estimation method and cement milk replacement rate estimation method of this embodiment, it is possible to estimate the strength without ensuring the curing period until the soil cement hardens.

[0080] If the estimated strength is less than the design strength, the strength of the soil cement can be increased to the design strength by injecting additional cement milk before the soil cement in the pile hole GH hardens.

[0081] In addition, if the soil cement whose strength has been estimated is the soil cement used to form temporary piles, the strength of the soil cement in the permanent piles can be increased to the design strength by using a rich cement milk mixture to inject into the permanent piles.

[0082] In addition, the amount of cement milk injected into the foot protection section can be reduced compared to the case where the strength of the foot protection section is ensured by sufficiently increasing the injection rate of cement milk (amount of cement milk injected / for example, amount of excavation of the foot protection section), while omitting the compressive strength test. This allows for reduction in material costs.

[0083] In the above embodiment, the cement milk replacement rate is estimated, and then the soil cement strength is estimated using the estimated value, but the embodiment of the present invention is not limited to this. For example, after estimating the cement milk replacement rate, it is not necessary to estimate the soil cement strength.

[0084] For example, the soil cement 12 forming the foot protection section shown in Fig. 1 is applied by injecting cement milk at a predetermined volume ratio to the volume of the foot protection section. Then, unconsolidated soil cement is collected as an unconsolidated sample, and the cement milk replacement rate is estimated according to the above process. This makes it possible to confirm whether the cement milk has been injected at the predetermined volume ratio into the foot protection section.

[0085] Furthermore, according to the above method, the cement milk replacement rate can be estimated on-site, in a short time, and in a simple manner with high accuracy.

[0086] In contrast, a conventional method for estimating the mix proportion of concrete is, for example, to heat the concrete to 110°C, 600°C, 1000°C, etc., and determine the various moisture contents. This type of drying takes time and requires large-scale equipment. In addition, it is not easy to transport the equipment to the site.

[0087] Another example of a conventional method for estimating the mix ratio of concrete is to analyze the calcium oxide in the solution obtained by dissolving and filtering concrete in acid, and then calculate the amount of cement from the residue to determine the amount of aggregate. This type of chemical analysis requires specialized knowledge, so there are limited personnel who can perform the work. In addition, calcium components in shells and other materials may dissolve in the acid, resulting in an overestimation of the amount of cement, making it difficult to use this method on sea sand, etc. [Explanation of symbols]

[0088] 12 Soil Cement

Claims

1. Drying an unconsolidated sample of soil cement formed by mixing the cement milk with the on-site generated soil; A step of crushing the dried unconsolidated sample and measuring the content of a predetermined element in the unconsolidated sample using an X-ray fluorescence analyzer; Calculating the mass ratio of soil to cement in the soil cement using the content of a predetermined element in the unconsolidated sample, the content of the predetermined element in the on-site generated soil, and the content of the predetermined element in the cement used in the cement milk; A step of calculating the volume ratio of the cement milk in the soil cement from the calculated mass ratio, the water content and density of the site generated soil, the density of the cement, and the mass ratio of water to cement in the cement milk; A method for estimating cement milk replacement rate comprising:

2. Drying an unconsolidated sample of soil cement formed by mixing the cement milk with the on-site generated soil; pulverizing the dried unconsolidated sample and measuring the concentration of a predetermined element in the unconsolidated sample using an X-ray fluorescence analyzer; Calculating the mass ratio of soil to cement in the soil cement using the concentration of a predetermined element in the unconsolidated sample, the concentration of the predetermined element in the on-site generated soil, and the concentration of the predetermined element in the cement used in the cement milk; A step of calculating the volume ratio of the cement milk in the soil cement from the calculated mass ratio, the water content and density of the site generated soil, the density of the cement, and the mass ratio of water to cement in the cement milk; A method for estimating cement milk replacement rate comprising:

3. The concentration of a predetermined element in the unconsolidated sample is Ca(sc), The concentration of the specified element in the on-site generated soil is Ca(s), The concentration of the predetermined element in the cement used in the cement milk is Ca(c), The mass ratio is α, The following formula (A) holds: The method for estimating cement milk replacement rate according to claim 2. α=[Ca(c)-Ca(sc)] / [Ca(sc)-Ca(s)]...(A)

4. The water content of the on-site generated soil is ωs, The density of the site generated soil is ρs, The density of the cement is ρc, The mass ratio of water to cement in the cement milk is R; The volume ratio of the cement milk in the soil cement is Vh, The following formula (B) holds true: The method for estimating cement milk replacement rate according to claim 2 or 3. Vh=1 / [1+α・{(1 / ρs)+ωs} / {(1 / ρc)+R}]...(B)

5. The concentration of a predetermined element in the unconsolidated sample is Ca(sc), The concentration of the specified element in the on-site generated soil is Ca(s), The concentration of the predetermined element in the cement used in the cement milk is Ca(c), The mass ratio is α, The water content of the on-site generated soil is ωs, The density of the site generated soil is ρs, The density of the cement is ρc, The mass ratio of water to cement in the cement milk is R; The volume ratio of the cement milk in the soil cement is Vh, The following formulas (A) and (B) hold: The method for estimating cement milk replacement rate according to claim 2. α=[Ca(c)-Ca(sc)] / [Ca(sc)-Ca(s)]...(A) Vh=1 / [1+α・{(1 / ρs)+ωs} / {(1 / ρc)+R}]...(B)

6. The method for estimating a cement milk replacement rate according to any one of claims 1 to 5, wherein the content of the predetermined element in the on-site generated soil is measured by crushing the dried on-site generated soil and using a fluorescent X-ray analyzer.

7. The method for estimating a cement milk replacement rate according to any one of claims 1 to 6, wherein the soil cement forms a base fixing portion of a pile hole.

8. A method for estimating the compressive strength of soil cement using correlation data between the proportion of cement milk in soil cement and compressive strength and the proportion of cement milk in soil cement calculated by the method for estimating the cement milk replacement rate according to any one of claims 1 to 7. A method for estimating the compressive strength of soil cement.

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