An on-site testing method for the strength of a repair mortar for concrete structures

Abstract

The present invention discloses an on-site testing method for the strength of concrete structure repair mortar, comprising: preparing N concrete specimens with a thickness of H and preparing repair mortar; performing roughness treatment on the concrete specimens to simulate on-site working conditions; using the repair mortar to prepare a thickness of H on the N concrete specimens. x Different experimental repair layers are used to obtain N repair specimens; the laboratory comprehensive strength f of the N repair specimens is obtained by testing. x , draw the relationship curve H x ‑f x ; Measure and obtain the effective thickness T of the on-site repair area e , from the relationship curve H x ‑f x Obtain the corresponding laboratory comprehensive intensity f e ; Use repair mortar to repair the repair area, use rebound hammer to measure the actual comprehensive strength F of the on-site repair layer, according to the formula p = F / f e Calculate the scale effect parameter p; according to the formula F a =f N ×p to calculate the repair mortar strength F a The method of the present invention can effectively improve the accuracy of measuring the actual strength of repaired deteriorated concrete and has a wide range of applications.

Description

Technical Field

[0001] The present invention relates to the technical field of geotechnical material testing, and in particular to an on-site testing method for the strength of concrete structure repair mortar. Background Art

[0002] Modern buildings often involve large-volume concrete construction, such as high-rise building foundations, large equipment foundations, water conservancy dams, tunnel foundations, etc. Due to the characteristics of the concrete material itself, concrete in actual service continues to deteriorate under external corrosion and load changes, thereby damaging the engineering structure and shortening its service life. In order to ensure that the relevant concrete buildings and structures can perform their established functions and meet the corresponding service requirements, it is necessary to repair the damaged parts in a timely manner. Generally, the method of injecting repair mortar is used for repair, and the strength of the mortar repair area needs to be tested to determine whether it has been effectively modified. In the prior art, the rebound method is usually used to measure the strength of the mortar repair area after repair. However, since the mortar repair layer and the internal concrete structure layer have relatively obvious differences, there is a large error in directly using a rebound tester (rebound method) to measure the strength of the mortar repair area at the repair site, which cannot accurately reflect the strength of the mortar repair area. Summary of the Invention

[0003] In view of this, the present invention provides a method for detecting the strength of mortar for repairing concrete structures, so as to solve the problem of how to improve the accuracy of measuring the actual strength of concrete after repair of deterioration.

[0004] To achieve the above objectives, the present invention provides the following technical solutions:

[0005] A method for detecting the strength of concrete structure repair mortar, comprising:

[0006] S1. Prepare N concrete specimens of thickness H according to the concrete structure to be repaired on site and prepare repair mortar; where N is an integer greater than 8;

[0007] S2. collecting the basic morphology of the failure surface of the concrete structure to be repaired, and performing corresponding roughness treatment on the concrete specimen to simulate the on-site working conditions;

[0008] S3, using the repair mortar to prepare experimental repair layers of different thicknesses on N concrete specimens to obtain N repair specimens; the thickness of the experimental repair layer H x =(0%~100%)H, and H1=0%H,H N =100%H;

[0009] S4. Test and obtain the laboratory comprehensive strength f of N repaired specimens x , draw the thickness H of the experimental repair layer xCompared with the laboratory comprehensive strength f x The relationship curve H x -f x ; where x = 1, 2, ..., N-1, N;

[0010] S5. Measure and obtain the effective thickness T of the repair area of the concrete structure to be repaired on site e , from the relationship curve H x -f x Get the effective thickness T e Corresponding laboratory comprehensive strength f e ;

[0011] S6. Repair the repair area with the repair mortar and use a rebound hammer to measure the actual comprehensive strength F of the on-site repair layer. According to the formula p=F / f e Calculate and obtain the scale effect parameter p;

[0012] S7, according to formula F a =f N ×p calculates the on-site repair mortar strength F a .

[0013] Specifically, in step S1, the size of the concrete specimen is 10 cm×10 cm×10 cm, that is, H=10 cm.

[0014] Specifically, in step S2, a 3D scanning instrument is used to scan and collect the basic morphology of the failure surface of the concrete structure to be repaired, and then the concrete specimen is subjected to corresponding roughness processing using 3D printing technology to simulate on-site working conditions.

[0015] More specifically, the information on the basic morphology of the failure surface includes the moisture content, temperature and aggregate exposure conditions of the concrete structure to be repaired on site.

[0016] Specifically, in step S3, the value of N is 11, and the thicknesses of the experimental repair layers corresponding to the 11 repair specimens are set as follows: H1 = 0% H, H2 = 10% H, H3 = 20% H, H4 = 30% H, H5 = 40% H, H6 = 50% H, H7 = 60% H, H8 = 70% H, H9 = 80% H, H 10 =90%H,H 11 =100%H.

[0017] Specifically, in step S4, the test to obtain the laboratory comprehensive strength of the repair specimen specifically includes: placing the repair specimen on a pressure testing machine with the concrete layer at the bottom and the experimental repair layer at the top, loading at a predetermined loading rate until the repair specimen is destroyed, and recording the laboratory comprehensive strength of the repair specimen.

[0018] Specifically, in step S5, the effective thickness T of the repair area of the concrete structure to be repaired on site is obtained by measuring e ,include:

[0019] Arrange i measurement areas in the repair area of the concrete structure to be repaired on site, where i is not less than 30;

[0020] Use the laser rangefinder to measure the repair thickness T1, T2, ..., T corresponding to the i measurement area i ;

[0021] According to the formula Calculate the effective thickness T of the repair area e .

[0022] More specifically, among the i measurement areas, the distance between any one of the measurement areas and the edge of the repair area is not less than 0.1m, and the area of any one of the measurement areas is not greater than 0.9m. 2 The distance between any two adjacent measurement areas shall not exceed 1.5m.

[0023] The embodiment of the present invention provides a method for detecting the strength of repair mortar for concrete structures. The method uses a repair mortar thickness-laboratory comprehensive strength relationship curve drawn in an indoor experiment as a reference, and then uses the scale effect to calculate the repair mortar strength based on the actual comprehensive strength on site obtained by rebound hammer measurement, thereby effectively improving the accuracy of measuring the actual strength of concrete after deterioration repair. The method has a wide range of applications and is not only applicable to concrete under normal working conditions, but also to concrete with obvious differences in surface and internal quality or internal defects, as well as to concrete with loose or flaking surfaces caused by frost damage, chemical erosion, high temperature, etc. In addition, the experimental equipment and measuring equipment used in the method are relatively common, easy to operate, and inexpensive, which is conducive to large-scale promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 3 is a graph showing the relationship between the thickness of the repair mortar and the laboratory comprehensive strength in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] To make the objectives, technical solutions, and advantages of the present invention more apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. Examples of these preferred embodiments are illustrated in the accompanying drawings. The embodiments of the present invention shown in and described with reference to the accompanying drawings are merely exemplary, and the present invention is not limited to these embodiments.

[0026] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, the accompanying drawings only show structures and / or processing steps closely related to the solutions according to the present invention, while other details that are not closely related to the present invention are omitted.

[0027] An embodiment of the present invention provides a method for detecting the strength of concrete structure repair mortar, the method comprising the following steps:

[0028] Step S11: According to the concrete structure to be repaired on site, prepare N concrete specimens with a thickness of H and prepare repair mortar; wherein N is an integer greater than 8.

[0029] As a preferred solution, in this embodiment, 11 concrete specimens (i.e., N is 11) with a concrete strength of C40 were prepared based on the concrete structure to be repaired on-site. These specimens were 10 cm × 10 cm × 10 cm (i.e., a thickness H of 10 cm) and the concrete mix proportions are shown in Table 1. Before filling, a layer of lubricating oil was evenly applied to the inner wall of the mold. After completion, concrete was prepared and placed in the oiled mold. After the concrete specimens were formed, they were demolded and cured for later use.

[0030] Table 1: Concrete mix proportions

[0031]

[0032] The repair mortar in this embodiment is epoxy mortar, and the epoxy mortar mix ratio is shown in Table 2.

[0033] Table 2 Epoxy mortar mix ratio

[0034]

[0035] Step S2: collecting the basic morphology of the failure surface of the concrete structure to be repaired, and performing corresponding roughness treatment on the concrete specimen to simulate the on-site working conditions.

[0036] Specifically, in this embodiment, a 3D scanner is used to capture the basic morphology of the failure surface of the concrete structure to be repaired. 3D printing technology is then used to roughen the concrete specimens to simulate on-site working conditions. More specifically, the basic morphology of the failure surface includes the moisture content, temperature, and aggregate exposure of the concrete structure at the site.

[0037] Step S3: Using the repair mortar, prepare experimental repair layers with different thicknesses on N concrete specimens to obtain N repair specimens; the thickness of the experimental repair layer H is x =(0%~100%)H, and H1=0%H,H N =100%H.

[0038] As a preferred solution, in this embodiment, the repair mortar is used to prepare experimental repair layers of different thicknesses on 11 concrete specimens to obtain 11 repair specimens. The thicknesses of the experimental repair layers corresponding to the 11 repair specimens are set as follows: H1 = 0% H, H2 = 10% H, H3 = 20% H, H4 = 30% H, H5 = 40% H, H6 = 50% H, H7 = 60% H, H8 = 70% H, H9 = 80% H, H 10 =90%H,H 11 =100% H. That is, H1=0cm, H2=1cm, H3=2cm, H4=3cm, H5=4cm, H6=5cm, H7=6cm, H8=7cm, H9=8cm, H 10 =9cm, H 11 =10cm.

[0039] Step S4: Test and obtain the laboratory comprehensive strength f of N repaired specimens x , draw the thickness H of the experimental repair layer x Compared with the laboratory comprehensive strength f x The relationship curve H x -f x ; where x = 1, 2,…, N-1, N.

[0040] Specifically, in this embodiment, after the 11 repair specimens obtained in step S3 are subjected to standard curing, their compressive strength is tested using a pressure testing machine. Specifically, the repair specimens are placed on the pressure testing machine with the concrete layer at the bottom and the experimental repair layer at the top. Loading is performed at a predetermined loading rate (the loading rate in this embodiment is 0.65 MPa / s) until the repair specimens are destroyed, and the laboratory comprehensive strength of the repair specimens is recorded. Each repair specimen is tested to obtain a laboratory comprehensive strength parameter, from which the thickness H of the experimental repair layer is fitted. x Compared with the laboratory comprehensive strength f x The relationship curve H x -f x . Figure 1 3 is a graph showing the relationship between the thickness of the repair mortar and the laboratory comprehensive strength in this embodiment.

[0041] Step S5: Measure and obtain the effective thickness T of the repair area of the concrete structure to be repaired on site. e , from the relationship curve H x -f x Get the effective thickness T e Corresponding laboratory comprehensive strength f e .

[0042] As a preferred solution, in this embodiment, the effective thickness T of the repair area of the concrete structure to be repaired is measured and obtained. e The step includes the following sub-steps:

[0043] Step S51: Arrange i measurement areas in the repair area of the concrete structure to be repaired on site, where i is an integer not less than 30.

[0044] Among the i measurement areas, the distance between any measurement area and the edge of the repair area is not less than 0.1m, and the area of any measurement area is not greater than 0.9m 2 The distance between any two adjacent measurement areas shall not exceed 1.5m.

[0045] Step S52: After the measurement area is arranged, the laser rangefinder is used to measure the repair thickness T1, T2, ..., T corresponding to the i measurement areas. i .

[0046] Step S53: According to the formula Calculate the effective thickness T of the repair area e .

[0047] In this embodiment, the effective thickness T of the on-site repair area measured according to the above method is e is 5.0 cm, as established in step S4. Figure 1 The relationship curve H x -f x Obtain the corresponding laboratory comprehensive intensity f e It is 56.2MPa.

[0048] Step S6: Use the repair mortar to repair the repair area, and use a rebound hammer to measure the actual comprehensive strength F of the on-site repair layer. According to the formula p = F / f e Calculate and obtain the scaling effect parameter p.

[0049] The actual comprehensive strength F of the on-site repair layer can be measured by using a rebound hammer, which can be carried out by referring to existing technologies. In this embodiment, the actual comprehensive strength F measured is 68 MPa, so according to the formula p = F / f e The calculated scaling effect parameter p=1.21.

[0050] It should be noted that in step S6, in the on-site repair area, including the bottom concrete layer and the surface mortar repair layer, the actual comprehensive strength F of the on-site repair layer measured by the rebound hammer cannot accurately reflect the strength of the mortar repair layer. Therefore, the technical solution of the present invention modifies the scale effect parameter p obtained by calculation to improve the accuracy of the measurement results.

[0051] Step S7: According to formula F a=f N ×p calculates the on-site repair mortar strength F a .

[0052] Among them, f N The thickness of the experimental repair layer is H N =100%H corresponding to the laboratory comprehensive strength. N =f 11 =79.2MPa, the repair mortar strength F obtained by calculation a It is 95.832MPa.

[0053] In summary, the method for detecting the strength of the repair mortar provided in the embodiment of the present invention is based on the repair mortar thickness-laboratory comprehensive strength relationship curve drawn in the indoor experiment as a reference, and then according to the actual comprehensive strength on site obtained by the rebound hammer measurement, the scale effect is adopted to calculate the strength of the repair mortar, which effectively improves the accuracy of the actual strength measurement of the concrete after deterioration repair; moreover, the method has a wide range of applications, not only applicable to concrete under normal working conditions, but also applicable to concrete with obvious differences in surface and internal quality or internal defects, as well as to concrete with loose surface and peeling caused by frost damage, chemical erosion, high temperature, etc.

[0054] The above is only a specific implementation method of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A method for on-site testing of the strength of concrete structure repair mortar, characterized in that: include: S1. Prepare N concrete specimens with a thickness of H and prepare repair mortar according to the concrete structure to be repaired on site; Wherein N is an integer greater than 8; S2. collecting the basic morphology of the failure surface of the concrete structure to be repaired, and performing corresponding roughness treatment on the concrete specimen to simulate the on-site working conditions; S3, using the repair mortar to prepare experimental repair layers of different thicknesses on N concrete specimens to obtain N repair specimens; the thickness of the experimental repair layer H x =(0%~100%)H, and H1=0%H,H N =100%H; S4. Test and obtain the laboratory comprehensive strength f of N repaired specimens x , draw the thickness H of the experimental repair layer x Compared with the laboratory comprehensive strength f x The relationship curve H x -f x ; where x = 1, 2, ..., N-1, N; S5. Measure and obtain the effective thickness T of the repair area of the concrete structure to be repaired on site e , from the relationship curve H x -f x Get the effective thickness T e Corresponding laboratory comprehensive strength f e ; S6. Repair the repair area with the repair mortar and use a rebound hammer to measure the actual comprehensive strength F of the on-site repair layer. According to the formula p=F / f e Calculate and obtain the scale effect parameter p; S7, according to formula F a =f N ×p calculates the on-site repair mortar strength F a .

2. The detection method according to claim 1, wherein In step S1 , the size of the concrete specimen is 10 cm×10 cm×10 cm, that is, H=10 cm.

3. The detection method according to claim 1, wherein In step S2, a 3D scanning instrument is used to scan and collect the basic morphology of the failure surface of the concrete structure to be repaired, and then the concrete specimen is subjected to corresponding roughness processing using 3D printing technology to simulate the on-site working conditions.

4. The detection method according to claim 3, characterized in that The information on the basic form of the failure surface includes the moisture content, temperature and aggregate exposure conditions of the concrete structure to be repaired on site.

5. The detection method according to claim 1, wherein In step S3, the value of N is 11, and the thicknesses of the experimental repair layers corresponding to the 11 repair specimens are set as follows: H1 = 0% H, H2 = 10% H, H3 = 20% H, H4 = 30% H, H5 = 40% H, H6 = 50% H, H7 = 60% H, H8 = 70% H, H9 = 80% H, H 10 =90%H,H 11 =100%H.

6. The detection method according to claim 1, characterized in that In step S4, the test to obtain the laboratory comprehensive strength of the repair specimen specifically includes: placing the repair specimen on a pressure testing machine with the concrete layer at the bottom and the experimental repair layer at the top, loading at a predetermined loading rate until the repair specimen is destroyed, and recording the laboratory comprehensive strength of the repair specimen.

7. The detection method according to claim 1, characterized in that In step S5, the effective thickness T of the repair area of the concrete structure to be repaired is obtained by measuring e ,include: Arrange i measurement areas in the repair area of the concrete structure to be repaired on site, where i is not less than 30; Use the laser rangefinder to measure the repair thickness T1, T2, ..., T corresponding to the i measurement area i ; According to the formula Calculate the effective thickness T of the repair area e .

8. The detection method according to claim 7, characterized in that Among the i measurement areas, the distance between any measurement area and the edge of the repair area is not less than 0.1m, and the area of any measurement area is not greater than 0.9m. 2 The distance between any two adjacent measurement areas shall not exceed 1.5m.

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