Manufacturing method for resin concrete deterioration model, deterioration prediction method for resin concrete, and resin concrete deterioration model

Abstract

Provided are a method for manufacturing a resin concrete deterioration model, a method for predicting resin concrete deterioration, and a resin concrete deterioration model. The method for manufacturing a resin concrete deterioration model comprises adding water to a resin concrete precursor and kneading the same, the resin concrete precursor including a thermosetting resin, calcium carbonate, and an aggregate. A resin concrete deterioration model 1 includes a thermosetting resin, calcium carbonate, an aggregate, and water.

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a resin concrete deterioration model, a method for predicting deterioration of resin concrete, and a resin concrete deterioration model. [Background technology]

[0002] Resin concrete is concrete made by firmly solidifying aggregate, calcium carbonate, etc., using a thermosetting resin (resin) as a binder. Unsaturated polyester resin, which is inexpensive and allows for freely adjustable hardening time, is often used as the binder resin. Because resin is used as a binder, resin concrete is superior in strength, formability, etc., compared to conventional concrete. For this reason, resin concrete is widely used as a material for forming structures such as manholes, sewer pipes, and boxes for information equipment. For example, there are more than 100,000 communication manholes made of resin concrete in Japan.

[0003] Non-Patent Document 1 describes resin concrete and its characteristics. Non-Patent Document 1 describes that resin concrete is concrete made by firmly solidifying crushed stone, sand, and calcium carbonate using thermosetting resin (resin) as a binder without using any cement or water. It also describes that unsaturated polyester resin, whose hardening time can be freely adjusted, is usually used as the binder resin for resin concrete, and that epoxy resin is also used depending on the application. It also describes that resin concrete hardens quickly and can obtain a predetermined strength in a short period of time, has high strength and excellent adhesiveness, is a dense material, has excellent watertightness and insulation, and has excellent acid resistance. It also describes that resin concrete has about 3 to 5 times higher strength than general cement concrete because it uses thermosetting resin as a binder.

[0004] Non-Patent Document 2 describes the results of a study on the deterioration of resin concrete. It describes that there is no need to consider corrosion of reinforcing bars, and that when unsaturated polyester resin is used in resin concrete, it was previously assumed that the resin may be hydrolyzed and cause a decrease in strength. The new results of the study also describe that apart from the decrease in strength due to hydrolysis, the cause of deterioration of resin concrete is likely to be a decrease in strength due to water content, and that there is a strong negative linear correlation between water content and bending strength. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Characteristics of resin concrete, Sunrec Co., Ltd., [Retrieved May 24, 2021], Internet<https: / / www.sunrec.co.jp / about_concrete / > [Non-Patent Document 2] Takashi Miwa, Kazue Takahashi, Hiroyuki Takahashi, Takashi Sawada, "Study on the mechanism of strength reduction and strength estimation of unsaturated polyester resin concrete buried underground", Materials and Environment, Vol. 69, No. 6. pp. 161-167 (2020) Summary of the Invention [Problem to be solved by the invention]

[0006] When the strength of a resin concrete structure decreases over time (hereinafter simply referred to as aging deterioration), there is concern about the impact on its bearing capacity or strength (hereinafter simply referred to as strength). For existing structures, samples (specimens) of the resin concrete part can be taken from the structure, and bending tests and compression tests (hereinafter simply referred to as strength evaluation) can be performed according to JIS A 1181:2005, for example, to grasp the current strength. By performing such evaluation, it is possible to accurately grasp the strength and deterioration state of the resin concrete structure. However, in order to perform an accurate strength evaluation, it is necessary to take a specimen of a specified shape and a specified amount from the structure. Therefore, there are cases where the structure is small and not suitable for taking specimens, or where taking specimens reduces the strength of the structure, and therefore taking specimens is not suitable from the viewpoint of safety, etc. In addition, for structures that are planned to be built using resin concrete in the future, it is desirable to design them assuming a decrease in strength in advance, and there are also cases where it is desired to grasp the strength after aging deterioration in advance.

[0007] In this way, even if it is not possible to collect specimens from existing structures or it is not suitable to do so, if the deterioration characteristics of resin concrete over time can be understood by other means, it can be used to evaluate the safety of existing structures. Also, if the deterioration characteristics of resin concrete over time can be understood in advance, structures to be constructed can be designed with the deterioration of strength in mind in advance.

[0008] However, there is no established method for manufacturing aged resin concrete or a model to replace aged resin concrete. Therefore, there is a need for a method for grasping the mechanical strength of resin concrete after aged deterioration, that is, a method for predicting deterioration of resin concrete, a resin concrete deterioration model (specimen), and a manufacturing method for a resin concrete deterioration model.

[0009] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a method for manufacturing a resin concrete deterioration model, a method for predicting deterioration of resin concrete, and a resin concrete deterioration model. [Means for solving the problem]

[0010] In order to achieve the above object, the present invention provides a method for manufacturing a resin concrete deterioration model, comprising the steps of: Water is added to a precursor of resin concrete containing a thermosetting resin, calcium carbonate, and aggregate, and the mixture is kneaded.

[0011] The manufacturing method of the resin concrete deterioration model according to the present invention further includes: a mixing step of mixing the thermosetting resin, the calcium carbonate, and the aggregate to prepare the precursor; and a kneading step of adding water to the precursor and kneading the precursor.

[0012] The manufacturing method of the resin concrete deterioration model according to the present invention further includes: When producing a deteriorated model simulating a material that is older, the amount of water added may be increased.

[0013] In order to achieve the above object, the method for predicting deterioration of resin concrete according to the present invention comprises: A model manufacturing process for manufacturing a resin concrete deterioration model including a thermosetting resin, calcium carbonate, and aggregate; A strength evaluation step of acquiring the strength of the resin concrete deterioration model; A data accumulation process of producing two or more resin concrete deterioration models with different amounts of water added in the model production process and performing the strength evaluation process to obtain the strength value corresponding to the amount of water added; and acquiring a correlation equation of the intensity with respect to the amount of addition based on the two or more acquired intensities and the amounts of addition corresponding to the two or more intensities.

[0014] The method for predicting deterioration of resin concrete according to the present invention further includes: Based on the correlation equation, a resin concrete deterioration model that has deteriorated to a target strength may be produced.

[0015] The method for predicting deterioration of resin concrete according to the present invention further includes: determining a target amount of water to be added corresponding to the target strength based on the correlation equation; The resin concrete deterioration model may be manufactured by adding the target amount of water to a precursor of resin concrete containing the thermosetting resin, the calcium carbonate, and the aggregate.

[0016] The method for predicting deterioration of resin concrete according to the present invention further includes: The strength may be bending strength.

[0017] In order to achieve the above object, the resin concrete deterioration model according to the present invention comprises: A thermosetting resin; Calcium carbonate, Aggregate; and water. Effect of the Invention

[0018] It is possible to provide a method for manufacturing a resin concrete deterioration model, a method for predicting deterioration of resin concrete, and a resin concrete deterioration model. [Brief description of the drawings]

[0019] [Figure 1] 1 is a graph showing the strain-bending stress of resin concrete at each age. [Diagram 2] FIG. 13 is a diagram showing the shape of a resin concrete deterioration model. [Diagram 3] This is a graph in which the strain-bending stress graph of the 2% hydrated sample is superimposed on the graph in Figure 1. [Figure 4] 1 is a graph showing the correlation between the amount of water added and bending strength. [Diagram 5] 1 is a flow chart for producing a resin concrete deterioration model for predicting deterioration of resin concrete. [Figure 6]FIG. 13 is a diagram showing another shape of the resin concrete deterioration model. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Prior to describing the embodiments of the present invention, the deterioration of resin concrete over time will be described. FIG. 1 shows the results of a bending strength test of specimens taken from resin concrete of each age. FIG. 1 shows a graph of the relationship between strain and bending stress obtained based on the "bending strength test" described in Section 8.3 of JIS A 1181:2005. In FIG. 1, a specimen taken from resin concrete aged 0 years is described as a "0-year sample", and specimens taken from resin concrete aged 15 years and 25 years are described as a "15-year sample" and a "25-year sample", respectively. From FIG. 1, it can be seen that the strength of a specimen of resin concrete with a large age (hereinafter, sometimes simply referred to as a specimen) has decreased after a certain number of years from manufacture, that is, it has deteriorated over time.

[0021] The behavior of each specimen at the time of fracture differs depending on the age of the material. In Figure 1, the 0-year-old specimen fractures after elastic deformation. In contrast, the 15-year-old and 25-year-old specimens, whose strength has decreased with age, have a small fracture stress and a large strain at fracture. In other words, resin concrete that is young and has not deteriorated with age exhibits elastic fracture behavior. In contrast, resin concrete that is older and whose strength has decreased due to deterioration with age exhibits elastoplastic fracture behavior.

[0022] If it becomes possible to provide a resin concrete deterioration model that can replace the above-mentioned aged resin concrete and reproduce its characteristic mechanical strength and fracture characteristics, it can be used to evaluate the safety of existing structures even when it is not possible to collect specimens from existing structures (e.g., manholes, sewer pipes, boxes for information equipment, etc.) or when it is not suitable to collect specimens. Furthermore, if such a resin concrete deterioration model can be provided, it is possible to grasp the characteristics of the aged deterioration of resin concrete in advance and to design structures to be constructed assuming a decrease in strength in advance. In other words, if it becomes possible to provide a resin concrete deterioration model that can simulate or reproduce the mechanical strength of resin concrete according to the material age and replace the mechanical evaluation of resin concrete that has actually deteriorated over time, it will facilitate the safety evaluation of existing structures and enable the design of structures to be constructed assuming a decrease in strength.

[0023] Hereinafter, with reference to the drawings, a manufacturing method of a resin concrete deterioration model, a method for predicting deterioration of resin concrete, and a resin concrete deterioration model according to an embodiment of the present invention will be described.

[0024] FIG. 2 shows a resin concrete deterioration model 1 (hereinafter referred to as deterioration model 1) according to this embodiment. The deterioration model 1 is a model (for example, a test piece or specimen) that simulates the mechanical strength of resin concrete of a specified age. The deterioration model 1 contains at least a thermosetting resin, calcium carbonate, and aggregate, and further contains water according to the age to be simulated. The deterioration model 1 is manufactured by adding water to a resin concrete precursor that contains a thermosetting resin, calcium carbonate, and aggregate, and kneading it. Note that the deterioration model 1 with an age of 0 years does not contain water.

[0025] A manufacturing method of the deteriorated model 1 (an example of a model manufacturing process) will be described in detail. In manufacturing the deteriorated model 1, a mixing process is first performed to prepare a precursor of resin concrete. In the mixing process, a thermosetting resin, calcium carbonate powder, and aggregate are mixed to prepare the precursor. That is, the precursor is a mixture of a thermosetting resin, calcium carbonate, and aggregate. The aggregate is sand or gravel. Examples of thermosetting resins are unsaturated polyester resin, phenolic resin, and epoxy resin.

[0026] An example of a precursor formulation is shown in Table 1 below. The precursor formulation shown in FIG. 1 is the same as the formulation of the resin concrete of each age shown in FIG.

[0027] [Table 1]

[0028] The recipe shown in Table 1 shows a case where the thermosetting resin is an unsaturated polyester resin. The unsaturated polyester resin shown in Table 1 is a resin before heat curing, and is a liquid resin. Although the items are not listed separately in Table 1, the unsaturated polyester resin shown in Table 1 is mixed with a specified amount of a curing agent. The curing agent is, for example, a crosslinkable monomer. Table 1 shows a case where gravel and sand are used as aggregates.

[0029] Next, a kneading process is carried out in which water is added to the precursor and kneaded. The kneaded product obtained in the kneading process (hereinafter simply referred to as the kneaded product) is poured into a mold or the like and hardened to obtain a deterioration model 1 of any shape. This makes it possible to manufacture a deterioration model 1 that reproduces the characteristic mechanical strength and fracture characteristics of resin concrete that has deteriorated over time.

[0030] In the kneading process, water may be added to the precursor before kneading, but it is preferable to knead the precursor while gradually adding water to it. This allows the water to be evenly distributed throughout the precursor. Specifically, the water is evenly distributed between the thermosetting resin and the aggregate (at the boundary). By dispersing the water evenly throughout the precursor, it is possible to manufacture a deterioration model 1 that can appropriately reproduce the characteristic mechanical strength and fracture characteristics of resin concrete. That is, in the deterioration model 1, water exists between the thermosetting resin and the aggregate. Since the structure of such deterioration model 1 is similar to the structure of resin concrete that has deteriorated over time, the deterioration model 1 can reproduce the characteristic mechanical strength and fracture characteristics of resin concrete that has deteriorated over time.

[0031] When manufacturing a deteriorated model 1 simulating an aged resin concrete, it is advisable to increase the amount of water added (weight of water added, hereinafter sometimes referred to as the amount of added water). In other words, when manufacturing a deteriorated model 1 simulating an aged resin concrete, it is advisable to increase the amount of added water compared to when manufacturing a deteriorated model 1 simulating a young resin concrete. One example of the amount of added water is a weight that is 5% or less of the weight of the precursor (5 parts by weight or less per 100 parts by weight of the precursor, the same applies below). In many cases, a deteriorated model aged 50 years or less can be manufactured with an amount of added water that is greater than 0% and is 3% or less.

[0032] When the deterioration model 1 is to be a specimen of a prescribed shape (for example, "specimen for bending strength, water absorption and chemical resistance test" in section 7.2 of JIS A 1181:2005), the kneaded product is poured into a prescribed mold capable of molding into a shape that meets the relevant standard. The mold may be, for example, one capable of molding into a rectangular parallelepiped of 60 x 60 x 250 mm. The kneaded product is then cured at room temperature until it can be demolded. The mold frame is then removed and the molded product is taken out of the mold. The molded product is again cured at room temperature until it has completely hardened. This allows the deterioration model 1 of the prescribed shape to be manufactured.

[0033] In the present embodiment, a case will be described below in which the deterioration model 1 (see FIG. 2) is molded into a rectangular parallelepiped specimen of 60×60×250 mm.

[0034] Fig. 3 shows a graph of strain vs. bending stress for degradation model 1 (hereinafter referred to as the 2% hydrated sample) in which the amount of water added was 2% (2 parts by weight relative to 100 parts by weight of precursor) in the formulation shown in Table 1. In Fig. 3, the graph of the 2% hydrated sample is shown superimposed on the graph shown in Fig. 1. Note that the strain vs. bending stress graph for the 2% hydrated sample was obtained based on the "bending strength test" described in Section 8.3 of JIS A 1181:2005, just like the samples at each material age.

[0035] As shown in Figure 3, the 2% hydration sample, like the 15-year and 25-year-old samples, exhibits elastoplastic fracture behavior, closely simulating the deterioration state of resin concrete over time. The bending stress at break, i.e., bending strength, of the 2% hydration sample shown in Figure 3 (deterioration model 1 with 2% water content) is 6.5 MPa. The bending strength of a 0-year-old sample, which corresponds to deterioration model 1 with 0 (zero)% water content, is 25 MPa.

[0036] As described above, by increasing the amount of water added to the deterioration model 1, it is possible to simulate a resin concrete of a large material age. Therefore, when it is desired to manufacture a deterioration model 1 that has deteriorated to a desired strength, the deterioration model 1 may be manufactured by adding water corresponding to the desired strength.

[0037] When it is desired to manufacture a deteriorated model 1 that has deteriorated to a desired strength, as an example, first, two or more deteriorated models 1 with different amounts of added water are manufactured. Then, the strengths of these two or more deteriorated models 1 with different amounts of added water are obtained (an example of a strength evaluation process), and strength values ​​corresponding to each amount of added water are obtained (an example of a data accumulation process). Then, based on the two or more obtained strength values ​​and the amounts of added water corresponding to the two or more strength values, a correlation equation of strength (for example, bending strength) versus amount of added water is obtained (correlation equation acquisition process).

[0038] Then, based on this correlation equation, a deteriorated model 1 deteriorated to a target strength is manufactured.

[0039] An example of the correlation equation is shown in Fig. 4. The correlation equation shown in Fig. 4 is a correlation equation based on a plot of two points: the bending strength (6.5 MPa) and amount of added water (2%) at break of the 2% hydrated sample (deterioration model 1 with 2% added water) shown in Fig. 3, and the bending strength (25 MPa) and amount of added water (0%) of a 0-year-old sample corresponding to deterioration model 1 with 0 (zero)% added water. In Fig. 4, when the amount of added water is x and the bending strength is y, the correlation equation is expressed by the following equation (1): y=-9.25x+25 (1) The following is an example.

[0040] A specific example of manufacturing a deteriorated model 1 deteriorated to a target strength based on the above correlation equation will be described with reference to the flow chart of Fig. 5. First, the bending strength of the deteriorated model 1 to be manufactured is determined (step S1). For example, the bending strength of the deteriorated model 1 to be manufactured is determined to be 20 MPa.

[0041] Next, a target amount of water to be added (one example of a target amount to be added) is determined based on the correlation equation (step S2). Specifically, the bending strength of the deterioration model 1 to be manufactured determined in step S1 is substituted into the correlation equation to determine the amount of water to be added to manufacture the deterioration model 1 with that bending strength. For example, if the bending strength of the deterioration model 1 to be manufactured is 20 MPa, substituting this for y in the above formula (1) results in a value of x of approximately 0.54. In other words, it can be predicted that the amount of water to be added to manufacture the deterioration model 1 with a bending strength of 20 MPa will be approximately 0.54%.

[0042] Then, the deteriorated model 1 is manufactured with the amount of water added determined in step S2. For example, by manufacturing the deteriorated model 1 with an amount of water added of about 0.54%, it is possible to manufacture the deteriorated model 1 with a bending strength of 20 MPa.

[0043] The deterioration model 1 produced in this manner is an imitation of resin concrete that has deteriorated to a specified degree (at a specified material age). In other words, various evaluations performed using the deterioration model 1 are evaluations that predict the deterioration of resin concrete (one example of a method for predicting deterioration of resin concrete). For example, by using the deterioration model 1 that mimics a state that has been deteriorated to a specified degree, it is possible to realize a safety evaluation of an existing structure or a design that assumes (predicts) a decrease in strength of a structure to be constructed.

[0044] In this manner, a method for manufacturing a resin concrete deterioration model, a method for predicting deterioration of resin concrete, and a resin concrete deterioration model can be provided.

[0045] [Another embodiment] (1) In the above embodiment, bending strength has been described as an example of the strength (mechanical strength) of the deterioration model 1. However, as the strength of the deterioration model 1, other (mechanical) strengths such as compressive strength and tensile strength may be adopted in addition to bending strength. In this case, these other strengths may be obtained by measurement or the like as the strength of the deterioration model 1 in the strength evaluation process. The compressive strength and tensile strength may be obtained based on the descriptions in JIS A 1181:2005, Sections 8.1 and 2 (compressive strength test) and Section 8.4 (tensile strength test), similar to the bending strength.

[0046] (2) In the above embodiment, the correlation equation is obtained based on the plot of two points. However, the method of obtaining the correlation equation is not limited to the case where the correlation equation is obtained based on the plot of two points. For example, the correlation equation may be obtained based on the plot of three or more points. In this case, an approximation equation obtained based on the least squares method or the like may be used as the correlation equation. The correlation equation is not limited to a linear equation, and may include a quadratic or higher degree polynomial or an exponential function.

[0047] (3) In the above embodiment, the deterioration model 1 (see FIG. 2) as the specimen is a rectangular parallelepiped of 60×60×250 mm. However, the deterioration model 1 as the specimen is not limited to this shape. For example, as shown in FIG. 6, a resin concrete deterioration model 1A (hereinafter, referred to as deterioration model 1A) that imitates the shape of a real structure may be used. Then, the deterioration model 1A that imitates the shape of a real structure may be used to predict and evaluate the deterioration of various resin concretes. FIG. 6 shows an example in which the deterioration model 1A imitates the shape or structure of a manhole. The deterioration model 1A may imitate a sewer pipe, a box for information equipment, or other structures other than a manhole.

[0048] In addition, the configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, provided no contradiction arises. Furthermore, the embodiments disclosed in this specification are illustrative, and the embodiments of the present invention are not limited thereto, and can be appropriately modified within the scope that does not deviate from the purpose of the present invention. [Industrial Applicability]

[0049] The present invention can be applied to a method for manufacturing a resin concrete deterioration model, a method for predicting deterioration of resin concrete, and a resin concrete deterioration model. [Explanation of symbols]

[0050] 1. Deterioration model (resin concrete deterioration model) 1A Deterioration model (resin concrete deterioration model)

Claims

1. A manufacturing method for a resin concrete deterioration model that reproduces the bending strength of resin concrete that has deteriorated over time, by adding water to a resin concrete precursor containing a thermosetting resin, calcium carbonate, and aggregate, and kneading the precursor.

2. a mixing step of mixing the thermosetting resin, the calcium carbonate, and the aggregate to prepare the precursor; The method for producing a resin concrete deteriorated model according to claim 1 , further comprising: a kneading step of adding water to the precursor and kneading the precursor.

3. 3. The method for producing a deteriorated model of resin concrete according to claim 1 or 2, wherein the amount of water added is increased when producing a deteriorated model simulating a case where the material is older.

4. A model manufacturing process for manufacturing two or more test specimens containing a thermosetting resin, calcium carbonate, aggregate, and water of 0% or more, and having different amounts of water added, as a resin concrete deterioration model that reproduces the bending strength of resin concrete deteriorated over time; A strength evaluation step of acquiring a bending strength of the resin concrete deterioration model; a data accumulation step of acquiring the bending strength value corresponding to the addition amount by executing the strength evaluation step; and acquiring a correlation equation of the bending strength against the amount of addition based on the two or more acquired bending strengths and the amounts of addition corresponding to the two or more bending strengths.

5. 5. The method for predicting deterioration of resin concrete according to claim 4, further comprising the step of producing a deterioration model of said resin concrete having a target bending strength based on said correlation equation.

6. determining a target amount of water to be added corresponding to the target bending strength based on the correlation equation; The method for predicting deterioration of resin concrete according to claim 5, further comprising adding the target amount of water to a precursor of resin concrete containing the thermosetting resin, the calcium carbonate, and the aggregate to produce the resin concrete deterioration model.

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