Method for analyzing lightweight cellular concrete and method for evaluating the degree of deterioration of lightweight cellular concrete
The method employs powder X-ray diffraction and pattern fitting to quantify tobermorite and calcium carbonate in ALC, addressing inaccuracies in existing methods by providing a reliable reference for evaluating ALC deterioration.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- K-MUSIPOREX CO LTD
- Filing Date
- 2022-12-12
- Publication Date
- 2026-07-01
Smart Images
Figure 0007883430000001 
Figure 0007883430000002
Abstract
Description
Technical Field
[0001] The present invention relates to a method for analyzing lightweight cellular concrete and a method for evaluating the degree of deterioration of lightweight cellular concrete. Specifically, the present invention relates to a method for analyzing lightweight cellular concrete for calculating the tobermorite content in the initial state, and a method for evaluating the degree of deterioration of lightweight cellular concrete using the same, for lightweight cellular concrete that may be undergoing aging deterioration.
Background Art
[0002] Lightweight cellular concrete (hereinafter also referred to as "ALC"), which is widely used as a building material for walls of buildings and the like due to its light weight and excellent heat insulation, fire resistance, and workability, undergoes aging deterioration such as strength reduction and surface cracking when used continuously for a long time. The main cause of this aging deterioration is known to be the decomposition of tobermorite (5CaO·6SiO2·5H2O), which is the main component, into silica gel (SiO2·nH2O) and calcium carbonate (CaCO3) by reacting with moisture and carbon dioxide in the air (this is generally referred to as the "carbonation" of ALC).
[0003] Here, the progress rate of carbonation of ALC varies greatly depending on the construction environment. Therefore, the degree of deterioration of lightweight cellular concrete, that is, the progress degree of carbonation, cannot be judged simply from the number of years after construction. Therefore, for ALC that may be undergoing aging deterioration, an objective evaluation based on a current situation analysis method that does not rely on the number of construction years is required for the degree of deterioration (progress degree of carbonation) of ALC.
[0004] As a method for evaluating the degree of deterioration (progress degree of carbonation) of ALC, there has already been proposed a method of evaluating the ratio of the calcium oxide equivalent amount of calcium carbonate obtained by quantitative measurement by thermal analysis method to the calcium oxide equivalent amount of the total calcium content obtained by quantitative measurement by chemical analysis for the ALC to be evaluated as the degree of carbonation (see Patent Documents 1 and 2).
[0005] However, the above methods for evaluating the degree of ALC deterioration (degree of carbonation) are all methods for quantifying calcium carbonate, and not methods for directly quantifying the decrease in tobermorite, the main component of ALC. Furthermore, in each of the above evaluation methods, it is not possible to distinguish between calcium carbonate generated by the progression of carbonation and calcium carbonate that was already present in the state before carbonation had progressed (the state at the time of shipment). Therefore, if the state of the ALC at the time of shipment (the initial state of the ALC) is unknown, the accuracy of the diagnosis is likely to decrease. [Prior art documents] [Patent Documents]
[0006] [Patent Document 1] Japanese Patent Publication No. 2000-193658 [Patent Document 2] Japanese Patent Publication No. 2008-175647 [Overview of the project] [Problems that the invention aims to solve]
[0007] To evaluate the degree of ALC degradation (the progression of carbonation) with higher accuracy, it would be desirable to directly quantify the degree of tobermorite reduction in the ALC and use this as an evaluation criterion. However, such an evaluation method has not yet been established.
[0008] The present invention aims to provide a method for evaluating the degree of deterioration (degree of carbonation) of ALC (Autoclaved Lightweight Concrete) with high accuracy, even when the initial state of ALC is unknown, in cases where ALC may be undergoing deterioration over time. [Means for solving the problem]
[0009] As a result of repeated studies to solve the above problems, the inventors of the present invention have come up with a unique process in which diffraction patterns obtained from ALC test samples by powder X-ray diffraction are analyzed by pattern fitting, thereby enabling efficient acquisition of a regression equation showing the correlation between tobermorite content and calcium carbonate content. From this regression equation, the tobermorite content in the initial state can be obtained, and thus the present invention has been completed. Specifically, the present invention provides the following.
[0010] (1) A method for analyzing lightweight aerated concrete to calculate the tobermorite content in the initial state of lightweight aerated concrete, comprising: a current measurement value measurement procedure to obtain a current measurement value which is a combination of the tobermorite content and calcium carbonate content of a test sample of the lightweight aerated concrete; a post-carbonation-accelerated value measurement procedure in which the test sample is subjected to multiple stages of carbonation-accelerated treatment to obtain a post-carbonation-accelerated value which is a combination of the tobermorite content and calcium carbonate content of the test sample at each stage; and the current measurement value and the multiple carbonation-accelerated value A method for analyzing lightweight cellular concrete, comprising: a regression equation definition procedure for obtaining a regression equation showing the correlation between tobermorite content and calcium carbonate content from comparative values after accelerated carbonation; and an initial state estimation procedure for calculating the tobermorite content in the initial state before the start of carbonation progression of the test sample from the regression equation, wherein in the current measurement value measurement procedure and the comparative value measurement procedure after accelerated carbonation treatment, the tobermorite content of the test sample is obtained by analyzing the diffraction pattern obtained by powder X-ray diffraction using pattern fitting.
[0011] According to the analysis method for lightweight aerated concrete described in (1), even when the initial state of lightweight aerated concrete that may be undergoing deterioration over time is unknown, the tobermorite content in the initial state of the ALC can be obtained with high accuracy. By adopting the "tobermorite content in the initial state" obtained by this method as a reference value, the degree of deterioration (degree of carbonation progression) of the ALC can be evaluated with high accuracy even when the initial state of the ALC is unknown.
[0012] (2) The method for analyzing lightweight aerated concrete as described in (1), wherein in the procedure for measuring the current measured value and the procedure for measuring the comparative value after carbonation acceleration treatment, both the tobermorite content and the calcium carbonate content of the sample to be examined are obtained by analyzing the diffraction pattern obtained by powder X-ray diffraction using pattern fitting.
[0013] According to the analysis method for lightweight aerated concrete in (2), by employing various pattern fitting analysis methods such as the Rietveld analysis method in the analysis method for lightweight aerated concrete in (1), the analysis of tobermorite and calcium carbonate can be performed in parallel within a single process, thus enabling faster analysis.
[0014] (3) The method for analyzing lightweight aerated concrete as described in (1) or (2), wherein the pattern fitting is performed by the Rietveld analysis method.
[0015] According to the analysis method for lightweight aerated concrete in (3), the pattern fitting described above in the analysis method for lightweight aerated concrete in (1) or (2) can be performed by the Rietveld analysis method, for which readily available and general-purpose analysis software and other specific analysis execution means are widely available.
[0016] (4) A method for evaluating the degree of deterioration of lightweight aerated concrete, wherein the ratio of the tobermorite content of the test sample to the tobermorite content in the initial state before the start of carbonation progression of the test sample, obtained by the analytical method for lightweight aerated concrete described in (1) or (2), is Vamo A method for evaluating the degree of deterioration of lightweight aerated concrete, wherein the degree of deterioration of the lightweight aerated concrete is evaluated using the light retention rate as an evaluation criterion.
[0017] According to the method for evaluating the degree of deterioration of lightweight cellular concrete in (4), for various lightweight cellular concretes that may be undergoing aging deterioration at various stages under various different construction environments, even when their initial states are unknown, the degree of deterioration (progress of carbonation) of ALC can be rapidly evaluated with high accuracy. Also, instead of simply using the current tobermorite content rate as the evaluation criterion, the "to Vamo "light residual rate", which is the ratio of the tobermorite content rate of the test sample to the tobermorite content rate in the initial state, enables more accurate and objective evaluation of various lightweight cellular concretes with different initial states.
Effects of the Invention
[0018] According to the present invention, for lightweight cellular concrete that may be undergoing aging deterioration, even when the initial state is unknown, the degree of deterioration (progress of carbonation) of ALC can be rapidly evaluated with high accuracy.
Brief Description of the Drawings
[0019] [Figure 1] It is a working process diagram of the "method for analyzing lightweight cellular concrete" of the present invention. [Figure 2] It is a graph showing the regression equation that can be obtained in the regression equation determination procedure in the "method for analyzing lightweight cellular concrete" of the present invention.
Embodiments for Carrying Out the Invention
[0020] Hereinafter, embodiments of the "method for analyzing lightweight cellular concrete" of the present invention and the "method for evaluating the degree of deterioration of lightweight cellular concrete" performed using the "tobermorite content rate in the initial state before the start of carbonation progress of the test sample" calculated by the analysis method will be described in detail. However, the technical scope of the present invention is not limited to the following embodiments.
[0021] <Method for Analyzing Lightweight Cellular Concrete> The "Analysis Method of Lightweight Cellular Concrete" of the present invention is an analysis method capable of obtaining the tobermorite content rate in the initial state of the lightweight cellular concrete with high accuracy even when the composition of the initial state before the start of carbonation progress is unknown for the lightweight cellular concrete that may be undergoing aging deterioration.
[0022] Moreover, according to the "Analysis Method of Lightweight Cellular Concrete" of the present invention, by using the "tobermorite content rate in the initial state" that can be obtained by the "Analysis Method of Lightweight Cellular Concrete" of the present invention as a reference value, for lightweight cellular concretes placed in various environments where the initial state is unknown and the progress rate of the deterioration degree is different, the deterioration degree of each lightweight cellular concrete can be objectively evaluated with high accuracy.
[0023] As shown in FIG. 1, the "Analysis Method of Lightweight Cellular Concrete" of the present invention is specifically a process of sequentially performing the following procedures to be described in detail, that is, the current measured value measurement procedure st1, the comparison value measurement procedure st2 after carbonation promotion treatment, the regression equation determination procedure st3, and the initial state estimation procedure st4. Moreover, the "Analysis Method of Lightweight Cellular Concrete" of the present invention measures the tober Vamo Quantification of light, etc. in the test sample in the current measured value measurement procedure st1 and the comparison value measurement procedure st2 after carbonation promotion treatment is performed by a method of analyzing the diffraction pattern obtained by powder X-ray diffraction (XRD) by pattern fitting such as the Rietveld analysis method, and this is one of the technical features of the method.
[0024] [[ID=......]] [Current Measured Value Measurement Procedure] The current measured value measurement procedure st1, which is the first procedure in the "Analysis Method of Lightweight Cellular Concrete" of the present invention, is a procedure for obtaining the current measured value, which is a combination of the tobermorite content rate and the calcium carbonate content rate in the current state, for the test sample of the lightweight cellular concrete to be analyzed.
[0025] Here, tobermorite, a crystalline mineral of calcium silicate hydrate, is a major component deeply involved in the overall physical properties of ALC. However, in the conventional ALC deterioration diagnostic methods disclosed in Patent Documents 1 and 2, that is, the conventional diagnostic methods that diagnose the degree of deterioration of ALC based on the carbonation of the test sample, the analysis of the test sample only involves the quantification of calcium carbonate and the quantification of total calcium, and Vamo Direct quantification of tobermorite has not been performed. Furthermore, in the conventional diagnostic methods described above, the quantification of calcium carbonate is performed by thermal analysis using a thermogravimetric-differential thermal analyzer (TG-DTA), and the quantification of total calcium is performed by chemical analysis such as X-ray fluorescence analysis (XRF). However, it was considered impossible to accurately quantify tobermorite in ALC using any of these analytical methods (see paragraphs
[0014] to
[0015] of Patent Document 1).
[0026] In contrast to such conventional methods, the current measurement procedure st1 in the "Method for Analyzing Lightweight Aerated Concrete" of the present invention includes at least, Vamo Regarding the quantitative determination of luminescence, the method used is "analyzing the diffraction pattern obtained by powder X-ray diffraction (XRD) using pattern fitting such as Rietveld analysis," which determines the amount of luminescence in ALC. Vamo The method was designed to directly quantify the crystalline content. It is known that various pattern fitting methods, such as the Rietveld analysis method, which is originally a technique for refining crystal structures, can calculate the content ratio of each crystalline mineral when multiple crystalline phases are present, because the scale factor of each crystalline phase is refined during the analysis process. Such analytical methods have already been used in other fields, such as the cement industry, as a method for quantifying crystalline minerals (see Japanese Patent Publication No. 2007-76931). However, applying various pattern fitting methods, such as the Rietveld analysis method, to a process for estimating the initial state of lightweight aerated concrete products that may be undergoing deterioration over time is an unprecedented attempt.
[0027] Furthermore, according to the above-mentioned "method for analyzing diffraction patterns obtained by powder X-ray diffraction (XRD) by pattern fitting (hereinafter also referred to as "the analysis method of the present invention")," which combines powder X-ray diffraction (XRD) and pattern fitting such as Rietveld analysis, Vamo In addition to quantifying lyte, the quantification of calcium carbonate can also be performed in parallel within the same process. Therefore, in both the current measurement procedure st1 and the comparative measurement procedure st2 after carbonation acceleration treatment, the analysis of the tobermorite content and calcium carbonate content of the test sample can be performed using the "analysis method of the present invention" described above, thereby enabling both procedures (st1, st2) to be performed extremely efficiently.
[0028] For pattern fitting to analyze the diffraction pattern of powder X-ray diffraction (XRD), the Rietveld analysis method is preferred, but it is not limited to this method, and other methods such as profile fitting and WPPD can be used as alternatives.
[0029] The method of analyzing diffraction patterns obtained by powder X-ray diffraction (XRD) using pattern fitting specifically involves the crystalline mineral (T) to be quantified. Vamo By importing the "crystal structure model data" of lyte (calcium carbonate) from the ICSD database (https: / / icsd.products.fiz-karlsruhe.de / en / ), etc., and then analyzing the test sample using software for Rietveld analysis (for example, "RigakuPDXL2.1 (Rigaku Corporation)"), the typographical features of the test sample can be determined. VamoThis method allows for the quantitative determination of lyte and calcium carbonate. While the "method of analyzing diffraction patterns obtained by powder X-ray diffraction (XRD) using pattern fitting" allows for the calculation of amorphous components by adding internal standard substances, the present invention also allows for the highly accurate quantification of the content of the crystalline mineral to be analyzed by calculating the amorphous mass by adding one or more, preferably two or more, internal standard substances. Furthermore, tobermorite can be directly quantified using this analytical method, and calcium carbonate can be quantified using calcium carbonate... cormorant It is possible to quantify the mineral content by considering the combined value of its crystalline components: calcite, vaterite, and aragonite.
[0030] [Procedure for measuring comparative values after carbonation acceleration treatment] The second step in the "Analysis Method for Lightweight Aerated Concrete," which is the procedure for measuring comparative values after carbonation acceleration treatment (st2), is a procedure in which multiple stages of carbonation acceleration treatment are applied to the ACL test sample, and then comparative values after carbonation acceleration treatment are obtained, which are combinations of tobermorite content and calcium carbonate content of the test sample at each stage where the degree of carbonation progression differs.
[0031] The carbonation acceleration treatment is performed by holding the ALC test sample in a test environment for a predetermined time (number of days) under environmental conditions such as temperature, relative humidity, and carbon dioxide concentration, which are adjusted to predetermined values so that carbonation proceeds in a shorter time than in the actual construction environment. A specific example of environmental conditions is a temperature of 20°C, relative humidity of 90%, and carbon dioxide concentration of 3% by volume. Furthermore, holding the sample under these environmental conditions for periods of 10, 20, and 100 days can be given as examples of treatment times in the specific treatment.
[0032] After performing the carbonation acceleration treatment described above, the comparative values after carbonation acceleration treatment, which are combinations of tobermorite content and calcium carbonate content, are measured for the test samples after the treatment. Specifically, as an example, the comparative values after carbonation acceleration treatment are measured for each test sample after 10 days, 20 days, and 100 days under the above conditions. The carbonation acceleration treatment is performed under at least two stages, preferably three stages, and more preferably five stages with different treatment times, in order to obtain multiple (preferably three or more, more preferably five or more) comparative values after carbonation acceleration treatment.
[0033] The measurement of the comparative value after carbonation acceleration treatment in procedure st2, as described above, should be performed in the same way as in procedure st1 for measuring the actual measured value: "a method of analyzing the diffraction pattern obtained by powder X-ray diffraction (XRD) by pattern fitting such as Rietveld analysis."
[0034] [Procedure for defining the regression equation] The third step in the "Analysis Method for Lightweight Aerated Concrete," which is the regression equation specification procedure st3, is a procedure to obtain a regression equation showing the correlation between tobermorite content and calcium carbonate content from the current measured values obtained in the current measured values procedure st1 (combinations of tobermorite content and calcium carbonate content of the test sample) and multiple comparative values after carbonation acceleration treatment obtained in the comparative values after carbonation acceleration treatment procedure st2 (combinations of tobermorite content and calcium carbonate content of the test sample after carbonation acceleration treatment).
[0035] Figure 2 is an example of a graph showing a regression equation that can be obtained in regression equation specification procedure st3. The graph in Figure 2 plots each combination of tobermorite content and calcium carbonate content of the test samples obtained in current measurement procedure st1 and comparative measurement procedure st2 after carbonation acceleration treatment on a coordinate system with the calcium carbonate content of each test sample on the x-axis and the tobermorite content of each test sample on the y-axis. In regression equation specification procedure st3, a regression equation showing the correlation between tobermorite content and calcium carbonate content is set from such plots using various regression analysis methods such as the least squares method. Note that in ALC with a typical composition, the amount of increase in calcium carbonate after the start of carbonation is usually Vamo Since it is proportional to the decrease in light, it can be predicted in advance that the regression equation will be linear.
[0036] [Initial state estimation procedure] The fourth step in the "Analysis Method for Lightweight Aerated Concrete," which is the initial state estimation step st4, is performed by using the regression equation obtained in the regression equation specification step st3 to determine the tobermorite content in the initial state of the ACL sample before the start of carbonation progression (hereinafter referred to as "tobermorite"). Vamo This is the procedure for calculating an estimated value of the initial light content (also known as the "light initial content").
[0037] to Vamo The estimated initial light content can be approximated by using the value of y when x=0 in the regression equation obtained in the regression equation definition procedure st3. For example, the value of y in the y-intercept of the regression equation (linear equation) in the graph of Figure 2 can be used as the initial light content. Vamo This can be used as an estimate of the initial content of lyte. Furthermore, if data on the calcium carbonate content in the initial state (hereinafter also referred to as "Ca-0") can be obtained for the test sample, the value of y when x = (Ca-0) can be used. Vamo By using this as an estimate of the initial light content, we can achieve a higher accuracy in "light VamoIt is possible to estimate the "initial content of light". However, in commonly available ALC, the calcium carbonate content (Ca-0) in the initial state before carbonation has progressed is generally known to be within the range of 5% or less, so in the regression equation such as in Figure 2, the value of y when x=0 is... Vamo Even when using an estimated value for the initial lite content, it is possible to evaluate the degree of deterioration of lightweight aerated concrete with sufficient accuracy for practical purposes.
[0038] <Method for evaluating the degree of deterioration of lightweight aerated concrete> The "Method for Evaluating the Deterioration Degree of Lightweight Aerated Concrete" of the present invention provides for lightweight aerated concrete that may be undergoing deterioration over time, and the above-mentioned "Method for Analyzing Lightweight Aerated Concrete" can be obtained by the "Method for Analyzing Lightweight Aerated Concrete" of the present invention. Vamo This evaluation method uses the "initial light content" as a reference value, allowing for a highly accurate and objective assessment of the degree of deterioration of lightweight aerated concrete, even when the initial state is unknown.
[0039] The present invention's "Method for Evaluating the Deterioration Degree of Lightweight Aerated Concrete" includes, as a specific procedure, the "T" obtained in the initial state estimation procedure st4 of the "Method for Analyzing Lightweight Aerated Concrete" for the ALC test sample to be evaluated. Vamo The "initial tobermorite content" is compared with the "current tobermorite content" obtained when performing the current measurement procedure st1 using the same analysis method, and the ratio of the latter to the former is "tobermorite content". Vamo This evaluation method calculates the "light retention rate" and uses this as an evaluation criterion to assess the degree of deterioration of lightweight aerated concrete.
[0040] As an example of an embodiment of the "Method for Evaluating the Deterioration Degree of Lightweight Aerated Concrete," the "T" obtained in the initial state estimation procedure st4 of the "Method for Analyzing Lightweight Aerated Concrete" is Vamo The above "initial light content" was calculated using the "initial light content" as the standard value. Vamo When the "light remaining rate" is 80% or higher, it is considered "healthy"; when it is between 60% and 80%, it is considered "caution"; and when it is less than 60%, it is considered "healthy". EssentialOne possible embodiment is one that can be evaluated as "repair work." [Explanation of Symbols]
[0041] st1 Current Measurement Procedure st2 Procedure for measuring comparative values after carbonation acceleration treatment st3 Regression Equation Definition Procedure st4 Initial state estimation procedure
Claims
1. A method for analyzing lightweight cellular concrete to calculate the tobermorite content in its initial state, A procedure for measuring current measured values to obtain the combination of tobermorite content and calcium carbonate content of the test sample of the aforementioned lightweight aerated concrete, A procedure for measuring comparative values after carbonation enhancement treatment, comprising subjecting the test sample to multiple stages of carbonation enhancement treatment and obtaining comparative values after carbonation enhancement treatment, which are combinations of tobermorite content and calcium carbonate content of the test sample at each stage, A regression equation definition procedure for obtaining a regression equation showing the correlation between tobermorite content and calcium carbonate content from the aforementioned current measured values and multiple comparative values after the carbonation-promoting treatment, The procedure includes an initial state estimation procedure for calculating the tobermorite content in the initial state before the start of carbonation of the test sample from the regression equation, In the above-mentioned procedure for measuring current measured values and the procedure for measuring comparative values after carbonation-promoting treatment, the tobermorite content of the test sample is obtained by analyzing the diffraction pattern obtained by powder X-ray diffraction using pattern fitting. Analytical methods for lightweight aerated concrete.
2. The method for analyzing lightweight cellular concrete according to claim 1, wherein in the procedure for measuring the current measured value and the procedure for measuring the comparative value after carbonation acceleration treatment, both the tobermorite content and the calcium carbonate content of the sample to be examined are obtained by analyzing the diffraction pattern obtained by powder X-ray diffraction using pattern fitting.
3. The aforementioned pattern fitting is performed using the Rietveld analysis method. The method for analyzing lightweight aerated concrete according to claim 1 or 2.
4. A method for evaluating the degree of deterioration of lightweight aerated concrete, The degree of deterioration of the lightweight aerated concrete is evaluated using the tobermorite retention rate, which is the ratio of the tobermorite content of the test sample to the tobermorite content in the initial state before the start of carbonation progression of the test sample, obtained by the analytical method for lightweight aerated concrete according to claim 1 or 2, as an evaluation criterion. A method for evaluating the degree of deterioration of lightweight aerated concrete.