CN104101324B - Method for evaluating concrete surface spalling degree - Google Patents

Abstract

The invention discloses a method for evaluating the spalling degree of the concrete surface, which utilizes the mechanical transmission between the parts of the concrete surface spalling degree measuring instrument, passes the probe along the spalled concrete surface, and passes the contour of the surface with the probe The connected shafts and connecting rods are reflected on the record board, and then the quantitative analysis results of the peeling degree of the concrete surface can be obtained by measuring the length of the surface profile and comparing it with the surface profile before peeling off. The method for evaluating the spalling degree of the concrete surface provided by the invention has simple operation steps and can quickly measure the roughness of the tested sample. Compared with the existing methods, the measurement cost is low, the measurement speed is fast, and the test results are easy to observe and have high reliability. .

Description

A method for evaluating spalling degree of concrete surface

technical field

The invention relates to a measuring method for concrete engineering and testing, in particular to a method for evaluating the spalling degree of the concrete surface.

Background technique

Concrete is one of the most important civil engineering materials today. Because of its rich raw materials, low price and simple production process, the consumption is increasing. At the same time, concrete also has the characteristics of high compressive strength, good durability, and a wide range of strength grades. These characteristics make it widely used, not only in various civil engineering, but also as an important material in shipbuilding, machinery industry, ocean development, geothermal engineering, etc. With the continuous development of concrete in the industry, the evaluation results of various performance indicators of concrete need to be more accurate, and the corresponding evaluation methods need to be more scientific.

In my country, in order to prevent the snow on the concrete road surface from affecting the normal operation of road traffic in winter and avoid traffic accidents, deicing salt and deicing fluid are often sprinkled on the road surface to eliminate snowmelt. Therefore, deicing salt and deicing fluid will inevitably come into contact with the concrete pavement, causing denudation and damage to the concrete surface. Therefore, among the various performance indicators of concrete, the degree of surface spalling is an important indicator for examining the quality of concrete.

At present, the method used to evaluate the peeling degree of concrete surface is carried out according to the content of 4.3 single-sided freeze-thaw method (or salt freeze method) in the 4 frost resistance test of GB50082-2009 "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete". Assessed. This method is to put the concrete into a single-sided freeze-thaw test box for repeated freeze-thaw cycles, and finally calculate the mass loss rate of the concrete during the entire freeze-thaw process, that is, the mass of the spalled concrete surface accounts for the mass of the original concrete. The percentage is used to evaluate the degree of spalling of the concrete surface. Due to multiple unstable factors such as different thawing time, different water loss speed, and different air temperature and humidity during the test, this method will cause large deviations in the test results and reduce the accuracy of the test results.

In addition, this method can only evaluate the average degree of peeling of the concrete surface, but in fact, the degree of peeling of the concrete surface is different, and the places with severe peeling will be more likely to be corroded and peeled more seriously under the same test conditions. This method cannot fully and truly evaluate the spalling of each point on the concrete surface, and cannot provide accurate data for the subsequent determination of the actual protective layer thickness of the deteriorated concrete and the weakest point of deterioration, as well as further calculation of the chloride ion penetration depth, which greatly reduces the significance of practical application . The equipment to realize this evaluation method is a single-sided freeze-thaw test chamber, which is bulky, inconvenient to carry, and expensive to manufacture. It requires harsh test conditions, long test time, and complicated operation.

Contents of the invention

Aiming at the technical defects existing in the prior art, the present invention provides a method capable of accurately evaluating the spalling degree of the concrete surface, comprising the following steps:

(1) Put the test piece face up and place it horizontally on the table or the ground;

(2) Select one side of the test surface of the specimen, mark several equal points respectively, use these equal points as vertical feet, make several perpendicular lines of this side, and measure the test surface corresponding to these perpendicular lines Surface contour line length L; Measure the surface contour line length L of the vertical line with a concrete surface peeling degree measuring instrument, and the steps are to make the downward probe of the measuring instrument fully contact with the test piece test surface; slowly move The probe is used to move the probe from the bisection point on the test piece along the vertical line of the point to the opposite side of the side where the bisection point is located; take out the drawing in the record board connected with the probe to obtain the vertical line The corresponding surface contour of the test surface; repeat this step to measure the surface contour of other vertical lines, and finally measure the length L of the surface contour corresponding to each vertical line;

(3) Calculate the length difference R _a between the length L of the surface contour line of each point and the length l of the surface contour line of the test surface before peeling off, _Ra =L1, and use the numerical value of the length difference _Ra to quantitatively evaluate the peeling degree of the test piece test surface , the higher the R _a value, the more serious the exfoliation.

In the above method, the concrete surface spalling degree measuring instrument comprises a cuboid vehicle frame with an open lower end, a T-shaped frame is erected on the frame beam on the upper part of the vehicle frame and is perpendicular to a group of opposite sides of the frame beam, and the lower end of the T-shaped frame extends Into the vehicle frame and connected with the probe frame and the connecting rod through the rotating shaft, the probe is installed vertically downward on the other end of the probe frame, and the recording board is connected to the other end of the connecting rod.

The probe frame is composed of a crossbeam perpendicular to each side of the T-shaped frame and a vertical bar perpendicular to the crossbeam and vertically downward, and the probe is arranged at the lower end of the vertical bar.

In the above method, the surface contour line of the test surface obtained by the concrete surface spalling degree measuring instrument is enlarged several times and printed out, and then the wire rope is taken and allowed to coincide with the surface contour line, and the enlarged several times can be measured. The length of the final surface contour line is divided by the magnification factor to obtain the length L of the original surface contour line.

A counterweight is provided on the beam.

The weight of the counterweight is no more than 10kg.

Wheels are installed at the lower end of the vehicle frame.

The upper surface of the frame beam is provided with sliding grooves matched with the rollers provided on the lower surface of the T-shaped frame.

One end of the connecting rod near the recording board is provided with a recording pen, and the recording board is provided with paper, and the recording pen is a pencil, a ballpoint pen, or a fountain pen.

The method for evaluating the spalling degree of the concrete surface provided by the invention has simple operation steps and can quickly measure the roughness of the tested sample. Compared with the existing methods, the measurement cost is low, the measurement speed is fast, and the test results are easy to observe and have high reliability. . This method directly reflects the roughness of the test surface of the test piece through the mechanical transmission of each part of the concrete surface spalling degree measuring instrument, reduces the error of the intermediate measurement, saves the drying and weighing procedure, reduces the test error, and speeds up the test result. Get speed. The measurement accuracy of the method of the present invention can reach 0.01mm, and can be used for subsequent determination of the concrete surface roughness value, to determine the actual protective layer thickness and the weakest point of deterioration of the concrete after deterioration, and to provide accurate data for further calculation of the penetration depth of chloride ions. It provides a reference for evaluating the failure mechanism and durability of concrete under the synergistic effect of multi-factor corrosion.

Description of drawings

Fig. 1 shows the structural front view of the spalling degree measuring instrument on the concrete surface;

Fig. 2 shows the structural side view of the spalling degree measuring instrument on the concrete surface;

Fig. 3 shows the top view of the structure of the concrete surface spalling degree measuring instrument;

Fig. 4 is a graph showing the relationship between the length difference R _a and the peeling amount measured by the method of the present invention.

detailed description

The method for evaluating the spalling degree of the concrete surface of the present invention utilizes the mechanical transmission between the parts of the concrete surface spalling degree measuring instrument, passes along the concrete surface where the spalling occurs through the probe, and passes the profile of the surface through the rotating shaft connected with the probe and Connecting rods are reflected on the recording board, and then the quantitative analysis results of the peeling degree of the concrete surface can be obtained by measuring the length of the surface profile and comparing it with the surface profile before peeling off.

The content of the present invention will be described in more detail below in conjunction with the accompanying drawings and specific embodiments, and the present invention will be further elaborated, but these embodiments in no way limit the present invention. Any changes made by those skilled in the art to the embodiments of the present invention under the inspiration of this specification shall fall within the scope of the claims of the present invention.

The concrete surface spalling degree measuring instrument mentioned in the present invention comprises a vehicle frame 1, and this vehicle frame 1 is a frame body that is the lower end opening of a cuboid or a cube, and the frame body is composed of a rectangular or square frame beam 2 and a support 3 constitute. The frame beam 2 is composed of 4 metal rods connected end to end in sequence, and the bracket 3 is below the four corners of the frame beam 2 , and the bracket 3 is perpendicular to the plane where the frame beam 2 is located. The lower end of the support 3 is equipped with a wheel 4 . Between the frame beam 2 and the support 3 in the vehicle frame 1 and between the metal rods that constitute the frame beam 2 can be fixed connections or detachable connections. The material of the vehicle frame 1 is not limited to metal, and can also be selected from wood, Synthetic materials, inorganic non-metallic materials, composite materials, etc.

A movable T-shaped frame 5 is placed above one group of parallel metal rods of the frame beam 2, and a sliding groove matched with the rollers on the lower surface of the T-shaped frame 5 is opened on the upper surface of this group of metal rods, and the T-shaped frame The T word horizontal edge of 5 is perpendicular to the metal bar that places it and keeps this vertical state to slide along this metal bar, and the T word vertical edge of T frame 5 then stretches in the vehicle frame 1. The lower end of the T-shaped vertical edge of the T-shaped frame 5 is provided with a probe frame 6 along the sliding direction of the T-shaped frame. 1. The vertical bar 62 parallel to the bracket 3 and extending downwards, so that the probe frame 6 is in an L-shape rotated 90° clockwise. The beam 61 of the probe frame 6 is fixedly provided with a counterweight 7, and the lower end of the vertical bar 62 is provided with a probe 8 for contacting the test surface of the test piece, and the counterweight 7 can ensure that the probe 8 moves along the test surface of the test piece. During the process, it is always in contact with the test surface of the specimen, and the weight of the counterweight can be adjusted within a range of no more than 10kg according to actual needs.

The T word vertical limit lower end of T-shaped frame 5 is connected with a connecting rod 9, and the other end of connecting rod 9 is connected with recording board 10. The beam 61 of the connecting rod 9 and the probe frame 6 is connected to the lower end of the T-shaped vertical side of the T-shaped frame 5 through the same rotating shaft 11, so that the probe 8 passes through the probe frame 6, the rotating shaft 11 and the connecting rod along the movement track of the test piece test surface. The rod 9 is reflected on the drawing of the recording board 10, and the trajectory of the probe 8 along the test surface of the test piece is the surface profile of the test surface after peeling, and then compared with the surface profile before peeling, we can get The peeling degree of the test surface of the specimen.

When in use, put a concrete cube specimen with a bottom surface of 10cm×10cm (the concrete cube specimen can be put into the standard test mold according to the concrete forming steps to get the concrete cube specimen) with the measuring surface facing up, and place it flat on the horizontal storage table Or on the ground; select one side of the measurement surface of the specimen as the starting side of the measurement, mark 5 equal points according to the length, and use these 5 equal points as vertical feet to make 5 lines of this starting side vertical line; the concrete surface peeling degree measuring instrument is placed on the top of the test piece, the test piece is placed in the vehicle frame of the concrete surface peeling degree measuring instrument, the beam 61 of the probe frame 6 is kept coincident with one of the vertical lines, and the probe is allowed to The needle 8 is in full contact with the test surface of the test piece; the T-shaped frame 5 is slowly moved to slide along the frame beam 2 of the vehicle frame 1, so that the probe 8 moves from the bisection point on the test piece along the vertical line of this point to the starting edge. until the opposite side; take out the drawing in the recording board, and obtain the surface contour line of the test surface of the test piece corresponding to the perpendicular line. The surface contour line obtained by the concrete surface spalling degree measuring instrument is magnified 5 times and printed out, then take the wire rope and let the wire rope coincide with the surface contour line, then the length of the enlarged surface contour line can be measured, and then divided by 5 The length L of the contour line of the surface before being enlarged is obtained. Calculate the length difference R _a between the length L of the surface contour line and the length l of the surface contour line of the test piece before peeling off, that is, _Ra = Ll. According to the same operation, calculate the length difference R _a between the surface contour line of the test surface corresponding to the five perpendicular lines and the surface contour line of the specimen before peeling off, and obtain the average value of five R _a .

If you want to make the measurement results more accurate, you can increase the number of equally divided points, so as to obtain more drawings that record the surface contour lines of the test surface of the test piece, and obtain more surface contour line length differences R _a .

Measure the length difference R _a of ordinary concrete, fly ash concrete and limestone powder concrete after 14 times of salt freezing, 28 times and 42 times with a concrete surface spalling degree measuring instrument, and it is recommended by the International Structural Materials Laboratory and RILEM The CIF method (RILEM TC176) was used to measure and calculate the corresponding spalling value of concrete. The measurement results are shown in Table 1.

Table 1 The length difference R _a of the surface contour lines of various concrete after salt freezing and the corresponding spalling amount

Taking the R _a value as the abscissa and the spalling amount as the ordinate, the relationship between the R _a value and the spalling amount of the three concretes subjected to salt freezing for 14, 28 and 42 times is shown in Figure 4. As can be seen from Fig. 4, the linear correlation of _Ra and the peeling amount is very good, and the _Ra value calculated by the method of the present invention is in a one-to-one correspondence with the peeling amount measured by RILEM TC176, and linearity can be obtained. The equation y=556.2x+138.8, the fitting degree R is 0.979, which shows that the linear correlation between R _a and the peeling amount is very good. Also can find out from Fig. 4, the _Ra value measured with the method of the present invention is not limited to the kind of concrete, that is to say the _Ra value of any kind of concrete and the spalling amount relation are all applicable to this linear equation, therefore, can The _Ra value of concrete is measured on-the-spot by concrete surface spalling degree measuring instrument and the method of the present invention, then substituting in above-mentioned linear equation, has just obtained the spalling degree (being spalling amount) of measured concrete, has saved traditional method needing After the process of filtering, drying, and weighing, it saves manpower, material resources, and financial resources, and the measurement speed is fast and more efficient.

It can be seen that the method of the present invention has simple operation steps, is easy to operate, and can quickly measure the roughness of the tested sample. Compared with the existing methods, the measurement cost is low, the measurement speed is fast, and the test results are easy to observe and reliable. high. This method directly reflects the roughness of the test surface of the test piece through the mechanical transmission of each part of the concrete surface spalling degree measuring instrument, reduces the error of the intermediate measurement, saves the drying and weighing procedure, reduces the test error, and speeds up the test result. Get speed. The concrete surface spalling degree measuring instrument has a simple structure and can be assembled immediately. Compared with the single-sided freeze-thaw test chamber, it is light in size and easy to carry. The measurement accuracy of the method of the present invention can reach 0.01mm, and can be used for subsequent determination of the concrete surface roughness value, to determine the actual protective layer thickness and the weakest point of deterioration of the concrete after deterioration, and to provide accurate data for further calculation of the penetration depth of chloride ions. It provides a reference for evaluating the failure mechanism and durability of concrete under the synergistic effect of multi-factor corrosion.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, these improvements and Retouching should also be regarded as the protection scope of the present invention.

Claims (14)

1. a kind of concrete surface of evaluating peels off the method for degree it is characterised in that comprising the following steps:

(1) test specimen test is faced up, be placed horizontally on desktop or ground；

(2) choose a line of test specimen test surfaces, mark several Along ents respectively, with these Along ents as intersection point, make Some vertical lines of this edge, measure these vertical lines corresponding test surfaces surface profile line length l；Peeled off with concrete surface Degree measuring instrument measures surface profile line length l of described vertical line, and its step is to make downward probe and the examination of described measuring instrument Part test surfaces are fully contacted；Slowly move described probe, make Along ent from test specimen for the probe move to decile along this vertical line Till the opposite side on point place side；Take out the drawing in the data board being connected with probe, that is, obtain this vertical line corresponding test surfaces table Facial contour line；Repeat the surface profile line of the other bar vertical line of this step measurement, finally measure each vertical line corresponding surface profile line Length l；

(3) the length difference r of test surfaces surface profile line length l before calculating each point surface profile line length l and do not peel off_a, r_a= L-l, using length difference r_aNumerical value quantitative assessment test specimen test surfaces peeling degree, r_aNumerical value is higher, peels off degree more serious.

2. according to claim 1 method it is characterised in that described concrete surface peel off degree measuring instrument include lower end open Mouthful cuboid vehicle frame, have a t type frame to be located on the Vierendeel girder on vehicle frame top and one group of opposite side perpendicular to Vierendeel girder, t type frame Lower end stretch in vehicle frame and probe holder and connecting rod be connected with by rotating shaft, described probe is arranged on the another of probe holder straight down End, described data board is connected to the connecting rod other end.

3. according to claim 2 method it is characterised in that described probe holder is by the crossbeam all vertical with each side of t type frame And montant composition with beam vertical and straight down, described probe is located at the lower end of montant.

4. according to claim 3 method it is characterised in that described concrete surface peel off degree measuring instrument gained survey Examination face surface profile line, amplifies several times and prints, and then line taking rope allow cotton rope to be overlapped with described surface profile line just may be used Measure the length of the surface profile line after amplifying several times, then length l just obtaining original surface outline line divided by multiplication factor.

5. according to claim 3 or 4 methods describeds it is characterised in that described crossbeam is provided with balancing weight.

6. according to claim 5 method it is characterised in that the weight of described balancing weight is less than 10kg.

7. according to the arbitrary methods described of claim 2-4 it is characterised in that described vehicle frame lower end is provided with wheel.

8. according to claim 5 method it is characterised in that described vehicle frame lower end is provided with wheel.

9. according to the arbitrary methods described of claim 2-4 it is characterised in that described Vierendeel girder upper surface is provided with and described t type frame The sliding tray that the roller that lower surface sets matches.

10. according to claim 7 method it is characterised in that described Vierendeel girder upper surface is provided with and described t type frame lower surface If the sliding tray that matches of roller.

11. according to claim 8 method it is characterised in that described Vierendeel girder upper surface is provided with and described t type frame lower surface If the sliding tray that matches of roller.

12. according to the arbitrary methods described of claim 2-4 it is characterised in that described connecting rod is provided with note near one end of data board Record pen, described data board is provided with paper, and described recording pen is pencil, ball pen, pen.

13. according to claim 10 method it is characterised in that described connecting rod is provided with recording pen near one end of data board, Described data board is provided with paper, and described recording pen is pencil, ball pen, pen.

14. according to claim 11 methods described it is characterised in that described connecting rod is provided with recording pen near one end of data board, Described data board is provided with paper, and described recording pen is pencil, ball pen, pen.