Method for quickly deducing super-early age strength of super-early strength UHPC (Ultra High Performance Concrete)
By detecting the content of C3S and C3A and the heat of hydration in ultra-early strength UHPC, and combining the hydration temperature rise to calculate the compressive strength, the problem of the difficulty in rapidly determining the strength of ultra-early strength UHPC at very early age is solved, and rapid and accurate strength inference is achieved.
Patent Information
- Application Number
- CN202510965792.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-14
- Publication Date
- 2025-10-31
AI Technical Summary
Existing technologies struggle to rapidly and accurately determine the very early-age strength of ultra-early-strength UHPCs, especially within hours, where their strength cannot be effectively inferred.
By detecting the XRD of ordinary Portland cement in ultra-early strength UHPC, the weight percentage of C3S and C3A and the heat of hydration were calculated. Combined with the specific heat capacity and hydration temperature rise, the compressive strength at each time point was estimated.
It enables rapid and accurate inference of the ultra-early age intensity of ultra-early strong UHPCs, is suitable for large-scale application, and is simple to operate and low in cost.
Abstract
Description
Technical Field
[0001] This invention relates to the field of ultra-high performance concrete technology, and particularly to the field of ultra-early strength determination technology for ultra-early strength UHPC, specifically a method for rapidly inferring the ultra-early strength of ultra-early strength UHPC. Background Technology
[0002] Ultra-High Performance Concrete (UHPC) is increasingly widely used in construction engineering due to its superior mechanical properties. With increasingly stringent construction deadlines, there are growing demands for higher strength and earlier strength in UHPC. For example, in a certain project, to quickly open to traffic, a quick-repair expansion joint required the concrete to reach a strength of 40 MPa within 4 hours while maintaining the final performance. UHPC combined with an alkali activator can rapidly improve early strength, but the rapid estimation of ultra-early-age strength remains a challenge.
[0003] Curing test blocks under the same conditions is a common method, but it's impossible to quickly obtain strength data from test blocks within the very early age range. The concrete rebound hammer is a method for rapidly testing concrete strength, but its testing principle has limitations; it can only reflect the hardness of the concrete surface layer (3-5mm), and cannot directly test the true strength of the concrete structure. Furthermore, due to the influence of process and distribution uniformity, the numerical values are highly variable. The microindentation method uses a nanoindenter to measure the indentation depth to estimate the modulus of elasticity, and then calculates the compressive strength. However, this requires specialized equipment, and the indentation size effect is significant, resulting in large dispersion. Currently, there are very few methods in engineering for rapidly determining the strength of ultra-early strength UHPC concrete within the very early age range (within a few hours).
[0004] Therefore, it is desirable to provide a method for rapidly inferring the intensity of ultra-early strong UHPCs at very early ages, which can rapidly infer the intensity of ultra-early strong UHPCs at very early ages with accurate and reliable results. Summary of the Invention
[0005] In order to overcome the shortcomings of the prior art, one object of the present invention is to provide a method for rapidly inferring the intensity of ultra-early-strength UHPC at very early age, which can rapidly infer the intensity of ultra-early-strength UHPC at very early age, and the inference is accurate and reliable, and is suitable for large-scale promotion and application.
[0006] Another objective of this invention is to provide a method for rapidly inferring the intensity of ultra-early strong UHPCs at very early ages. This method is ingeniously designed, has simple steps, is easy to operate, has low operating costs, and is suitable for large-scale application.
[0007] To achieve the above objectives, this invention provides a method for rapidly inferring the intensity of ultra-early-age ultra-early-strength UHPCs, characterized by the following steps:
[0008] (1) Detect the XRD of ordinary Portland cement used in ultra-early strength UHPC and estimate the weight percentage of C3S and C3A in it.
[0009] (2) Calculate the weight percentage W of C3S in ultra-early strength UHPC based on the amount of ordinary Portland cement used in the ultra-early strength UHPC. C3S and the weight percentage of C3A W C3A The heat of hydration of C3S and C3A were measured, and the total heat of hydration H was calculated as follows: H = heat of hydration of C3S after complete hydration + heat of hydration of C3A after complete hydration. The heat of hydration of C3S after complete hydration was calculated as W. C3S *Heat of hydration of C3S, heat of hydration of C3A after complete hydration = W C3A *Heat of hydration of C3A;
[0010] (3) The specific heat capacity C of the ultra-early strength UHPC was determined. The unit of specific heat capacity C is KJ / kg.
[0011] (4) Measure the 3d compressive strength P of non-ultra-early strength UHPC at room temperature to represent the strength of C3S after complete hydration;
[0012] (5) Measure the hydration temperature rise T of the ultra-early-strength UHPC every 1 hour. i Where i is the i-th hour, based on the hydration temperature rise T i Calculate the heat of hydration per unit mass H i =T i *C;
[0013] (6) Calculate the degree of C3S hydration M at each time point. i =H i / H;
[0014] (7) Convert the compressive strength P at each time point proportionally. i =M i *P.
[0015] Preferably, in step (1), the weight percentage of C3S and the weight percentage of C3A are 50% and 5%, respectively.
[0016] Preferably, in step (2), the amount of ordinary Portland cement in the ultra-early strength UHPC is 35%.
[0017] Preferably, in step (2), the heat of hydration of C3S is 500 KJ / kg and the heat of hydration of C3A is 900 KJ / kg.
[0018] Preferably, in step (3), the specific heat capacity C is 1100 J / (kg·K).
[0019] Preferably, in step (4), the compressive strength P is 98 MPa.
[0020] Preferably, in step (5), T1, T2, T3 and T4 are 10°C, 25°C, 40°C and 60°C, respectively.
[0021] The main beneficial effects of this invention are:
[0022] 1. The method for rapidly estimating the early-age strength of ultra-early-strength UHPC according to the present invention includes: (1) detecting the XRD of ordinary Portland cement used in ultra-early-strength UHPC to estimate the weight percentage of C3S and the weight percentage of C3A therein; (2) calculating the weight percentage W of C3S in ultra-early-strength UHPC based on the amount of ordinary Portland cement in ultra-early-strength UHPC. C3S and the weight percentage of C3A W C3A The heat of hydration of C3S and C3A were measured, and the total heat of hydration H was calculated as follows: H = heat of hydration of C3S after complete hydration + heat of hydration of C3A after complete hydration. The heat of hydration of C3S after complete hydration was calculated as W. C3S *Heat of hydration of C3S, heat of hydration of C3A after complete hydration = W C3A *Hydration heat of C3A; (3) Determine the specific heat capacity C of ultra-early strength UHPC, the unit of specific heat capacity C is KJ / kg; (4) Measure the 3-day compressive strength P of non-ultra-early strength UHPC at room temperature, which represents the strength of C3S after complete hydration; (5) Measure the hydration temperature rise T of ultra-early strength UHPC every 1 hour. i Where i is the i-th hour, based on the hydration temperature rise T i Calculate the heat of hydration per unit mass H i =T i *C; (6) Calculate the degree of C3S hydration M at each time point. i =H i / H;(7) Convert the compressive strength P at each time point proportionally. i =M i Therefore, it can quickly infer the intensity of ultra-early strong UHPCs at very early ages, and the inference is accurate and reliable, making it suitable for large-scale application.
[0023] 2. The method for rapidly estimating the early-age strength of ultra-early-strength UHPC according to the present invention includes: (1) detecting the XRD of ordinary Portland cement used in ultra-early-strength UHPC to estimate the weight percentage of C3S and the weight percentage of C3A therein; (2) calculating the weight percentage W of C3S in ultra-early-strength UHPC based on the amount of ordinary Portland cement in ultra-early-strength UHPC. C3S and the weight percentage of C3A W C3AThe heat of hydration of C3S and C3A were measured, and the total heat of hydration H was calculated as follows: H = heat of hydration of C3S after complete hydration + heat of hydration of C3A after complete hydration. The heat of hydration of C3S after complete hydration was calculated as W. C3S *Heat of hydration of C3S, heat of hydration of C3A after complete hydration = W C3A *Hydration heat of C3A; (3) Determine the specific heat capacity C of ultra-early strength UHPC, the unit of specific heat capacity C is KJ / kg; (4) Measure the 3-day compressive strength P of non-ultra-early strength UHPC at room temperature, which represents the strength of C3S after complete hydration; (5) Measure the hydration temperature rise T of ultra-early strength UHPC every 1 hour. i Where i is the i-th hour, based on the hydration temperature rise T i Calculate the heat of hydration per unit mass H i =T i *C; (6) Calculate the degree of C3S hydration M at each time point. i =H i / H;(7) Convert the compressive strength P at each time point proportionally. i =M i Therefore, its design is ingenious, its steps are simple, its operation is convenient, its operating cost is low, and it is suitable for large-scale promotion and application.
[0024] These and other objects, features and advantages of the present invention will be fully apparent from the following detailed description and can be achieved by the means, devices and combinations thereof specifically pointed out in the summary of the invention. Detailed Implementation
[0025] To rapidly infer the strength of ultra-early-strength UHPC at its very early age, the inventors analyzed the magnitude of the heat of hydration of each component within the ultra-early-strength UHPC and their contribution to strength. Based on the fact that the strength of ultra-early-strength UHPC at its very early age is primarily related only to C3S hydration, with only C3S and C3A having a heat of hydration; C4AF has a low heat of hydration and a low contribution to strength; C2S develops strength relatively slowly, generally after 7 days; volcanic ash reactions generally occur after 3 days and are essentially unrelated to the strength at very early age; and the retarding effect of gypsum releases very little heat and can be ignored, this invention was completed.
[0026] This invention provides a method for rapidly inferring the intensity of ultra-early-age ultra-early-strength UHPCs, comprising the following steps:
[0027] (1) Detect the XRD of ordinary Portland cement used in ultra-early strength UHPC and estimate the weight percentage of C3S and C3A in it.
[0028] (2) Calculate the weight percentage W of C3S in ultra-early strength UHPC based on the amount of ordinary Portland cement used in the ultra-early strength UHPC. C3Sand the weight percentage of C3A W C3A The heat of hydration of C3S and C3A were measured, and the total heat of hydration H was calculated as follows: H = heat of hydration of C3S after complete hydration + heat of hydration of C3A after complete hydration. The heat of hydration of C3S after complete hydration was calculated as W. C3S *Heat of hydration of C3S, heat of hydration of C3A after complete hydration = W C3A *Heat of hydration of C3A;
[0029] (3) The specific heat capacity C of the ultra-early strength UHPC was determined. The unit of specific heat capacity C is KJ / kg.
[0030] (4) Measure the 3d compressive strength P of non-ultra-early strength UHPC at room temperature to represent the strength of C3S after complete hydration;
[0031] (5) Measure the hydration temperature rise T of the ultra-early-strength UHPC every 1 hour. i Where i is the i-th hour, based on the hydration temperature rise T i Calculate the heat of hydration per unit mass H i =T i *C;
[0032] (6) Calculate the degree of C3S hydration M at each time point. i =H i / H;
[0033] (7) Convert the compressive strength P at each time point proportionally. i =M i *P.
[0034] In step (1), the weight percentage of C3S and the weight percentage of C3A depend on the specific ordinary Portland cement used. Preferably, in step (1), the weight percentage of C3S and the weight percentage of C3A are 50% and 5%, respectively.
[0035] In step (2), the amount of ordinary Portland cement in the ultra-early strength UHPC can be determined as needed. Preferably, in step (2), the amount of ordinary Portland cement in the ultra-early strength UHPC is 35%.
[0036] In step (2), the heat of hydration of C3S and C3A can be any suitable value. Preferably, in step (2), the heat of hydration of C3S is 500 KJ / kg and the heat of hydration of C3A is 900 KJ / kg.
[0037] In step (3), the specific heat capacity C can be any suitable value. Preferably, in step (3), the specific heat capacity C is 1100 J / (kg·K). The mortar ratio of ultra-early strength UHPC is about 1:1. Compared with ordinary concrete, its water consumption per unit volume is relatively high. Therefore, its specific heat capacity is slightly higher than that of ordinary concrete. The comprehensive calculation shows that its specific heat capacity is 1100 J / (kg·K).
[0038] In step (4), the compressive strength P can be any suitable value, preferably, in step (4), the compressive strength P is 98 MPa.
[0039] In step (5), T1, T2, T3 and T4 can be any suitable hydration temperature rise, preferably, in step (5), T1, T2, T3 and T4 are 10℃, 25℃, 40℃ and 60℃ respectively.
[0040] To provide a clearer understanding of the technical content of this invention, the following embodiments are provided for detailed description. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Unless otherwise stated, the instruments, pharmaceuticals, reagents, etc., used in the following embodiments can all be obtained through conventional commercial means.
[0041] Example 1
[0042] Design requirements: The ultra-early strength UHPC expansion joint should be opened to traffic when its strength reaches 40MPa. Calculate the real-time strength and time.
[0043] 1) According to XRD analysis, the estimated weight percentage of ordinary Portland cement (Southern Cement P.O52.5 type) is 50% C3S, 25% C2S, 5% C3A, 7% C4AF, 4% gypsum, and 9% slag powder.
[0044] 2) The content of ordinary Portland cement in ultra-early strength UHPC is 35%, therefore, the weight percentage of C3S is W. C3S The weight percentage of C3A is 17.5% (W). C3A It is 1.75%; the heat of hydration of C3S upon complete hydration = W C3S *Heat of hydration of C3S = 17.5% * 500 KJ / kg = 87.5 KJ; Heat of hydration of C3A after complete hydration = W C3A *Heat of hydration of C3A = 1.75% * 900 KJ / kg = 15.75 KJ; Heat of hydration after complete hydration = 87.5 KJ + 15.75 KJ = 103.25 KJ.
[0045] 3) The specific heat capacity C of ultra-early strength UHPC is 1100 J / (kg·K);
[0046] 4) The 3-day compressive strength P of non-ultra-early-strength UHPC (ultra-early-strength UHPC is based on non-ultra-early-strength UHPC with the addition of an early-strength activator, without changing other formulation ratios) at room temperature was measured to be 98 MPa, which represents the strength after complete hydration of C3S; the hydration of non-ultra-early-strength UHPC within 3 days is mainly C3S, accounting for 70% of the total hydration process, with C2S as the secondary component, accounting for 14% of the total hydration process. This is because the strength of C2S hydration products is higher than that of C3S (C3S has more plate-like Ca(OH)2).
[0047] 5) The hydration temperature rise of the ultra-early strength UHPC was measured at 1h, 2h, 3h, and 4h, respectively, and was 10℃, 25℃, 40℃, and 60℃ (solid component, approximately under adiabatic conditions); the hydration heat per unit mass was calculated to be 11KJ, 27.5KJ, 44KJ, and 66KJ at 1h, 2h, 3h, and 4h, respectively.
[0048] 6) Compared with the total heat of hydration, the hydration ratios of C3S reached 10.6%, 26.6%, 42.6%, and 63.9%, respectively;
[0049] 7) The strengths, converted proportionally, reached 10.4 MPa, 26.1 MPa, 41.8 MPa, and 62.6 MPa respectively;
[0050] 8) When the hydration temperature rises to 40°C in the third hour, the strength reaches 41.8 MPa, which meets the conditions for opening to traffic.
[0051] This invention describes a method for inferring concrete strength under adiabatic conditions using the heat of hydration. Based on the parallel relationship between concrete hydration and strength development, with strength generally increasing gradually as the heat of hydration increases, the key issue is the relationship between the heat of hydration of different mineral components and strength. X-ray diffraction (XRD) is used to detect different mineral components. Based on the intensity of X-ray diffraction peaks, the weight percentages of each mineral phase can be calculated using a Rietveld full-spectrum analyzer and / or the internal standard method. This allows for relatively accurate calculation of the weight percentages of C3S, C2S, C3A, and C4AF. In ultra-early-age cement, the main contributors to strength are C3S and C3A, with C3A contributing a limited amount. Furthermore, the thermal decomposition of C3A hydration gel intensifies at temperatures above 30°C, leading to a significant decrease in strength.
[0052] This invention provides XRD analysis of ordinary Portland cement used in ultra-early strength UHPC to estimate the weight percentage of C3S and C3A. Based on the amount of ordinary Portland cement in the ultra-early strength UHPC, the weight percentage W of C3S in the ultra-early strength UHPC is calculated.C3S and the weight percentage of C3A W C3A The heat of hydration of C3S and C3A was determined, and the total heat of hydration H was calculated by measuring the hydration temperature rise T of the ultra-early-strength UHPC every 1 hour. i Calculate the heat of hydration per unit mass H2 i via H i Multiplying the ratio of H to the 3-day compressive strength P of non-ultra-early-strength UHPC at room temperature, we obtain the compressive strength P of ultra-early-strength UHPC at various time points during ultra-early-age periods. i .
[0053] In summary, the method for rapidly inferring the intensity of ultra-early strong UHPCs at very early ages according to the present invention can rapidly infer the intensity of ultra-early strong UHPCs at very early ages. The inference is accurate and reliable, the design is ingenious, the steps are simple, the operation is convenient, the operating cost is low, and it is suitable for large-scale promotion and application.
[0054] Therefore, it is evident that the objective of this invention has been fully and effectively achieved. The function and structural principles of this invention have been demonstrated and explained in the embodiments. Any modifications can be made to the implementation methods without departing from these principles. Therefore, this invention includes all modified embodiments based on the spirit and scope of the claims.
Claims
1. A method for rapidly inferring the intensity of ultra-early-strength UHPC at its very early age, characterized in that, Includes the following steps: (1) Detect the XRD of ordinary Portland cement used in ultra-early strength UHPC and estimate the weight percentage of C3S and C3A in it. (2) Calculate the weight percentage W of C3S in ultra-early strength UHPC based on the amount of ordinary Portland cement used in the ultra-early strength UHPC. C3S and the weight percentage of C3A W C3A The heat of hydration of C3S and C3A were measured, and the total heat of hydration H was calculated as follows: H = heat of hydration of C3S after complete hydration + heat of hydration of C3A after complete hydration. The heat of hydration of C3S after complete hydration was calculated as W. C3S *Heat of hydration of C3S, heat of hydration of C3A after complete hydration = W C3A *Heat of hydration of C3A; (3) The specific heat capacity C of the ultra-early strength UHPC was determined. The unit of specific heat capacity C is KJ / kg. (4) Measure the 3d compressive strength P of non-ultra-early strength UHPC at room temperature to represent the strength of C3S after complete hydration; (5) Measure the hydration temperature rise T of the ultra-early-strength UHPC every 1 hour. i Where i is the i-th hour, based on the hydration temperature rise T i Calculate the heat of hydration per unit mass H i =T i *C; (6) Calculate the degree of C3S hydration M at each time point. i =H i / H; (7) Convert the compressive strength P at each time point proportionally. i =M i *P.
2. The method for rapidly inferring the intensity of ultra-early-strength UHPC at very early ages as described in claim 1, characterized in that, In step (1), the weight percentage of C3S and the weight percentage of C3A are 50% and 5%, respectively.
3. The method for rapidly inferring the intensity of ultra-early-strength UHPC at very early ages as described in claim 1, characterized in that, In step (2), the amount of ordinary Portland cement in the ultra-early strength UHPC is 35%.
4. The method for rapidly inferring the intensity of ultra-early-strength UHPC at very early ages as described in claim 1, characterized in that, In step (2), the heat of hydration of C3S is 500 KJ / kg and the heat of hydration of C3A is 900 KJ / kg.
5. The method for rapidly inferring the intensity of ultra-early-strength UHPC at very early ages as described in claim 1, characterized in that, In step (3), the specific heat capacity C is 1100 J / (kg·K).
6. The method for rapidly inferring the intensity of ultra-early-strength UHPC at very early ages as described in claim 1, characterized in that, In step (4), the compressive strength P is 98 MPa.
7. The method for rapidly inferring the intensity of ultra-early-strength UHPC at very early ages as described in claim 1, characterized in that, In step (5), T1, T2, T3 and T4 are 10℃, 25℃, 40℃ and 60℃ respectively.