阅读说明：本技术 一种水泥基材料收缩应力检测装置及其全温度检测方法 (Cement-based material shrinkage stress detection device and full-temperature detection method thereof ) 是由 杨英姿 陈智韬 吕承博 王梦雪 于 2019-12-27 设计创作，主要内容包括：一种水泥基材料收缩应力检测装置及其全温度检测方法。由于混凝土变形产生收缩或膨胀应力检测精度要求高难度大、效率低、准确度差,导致了在施工前快速评定混凝土收缩或膨胀应力的试验装置和方法的匮乏,应用高性能水泥基材料的土木工程建设质量受到严重影响,急需得到快速解决。本发明的检测装置中套管可拆卸连接在模具内,模具的两端分别设置有第一连接件和第二连接件,第二连接件内设有测力传感器,圆盘式柱体的圆盘端与第一连接件可拆卸连接,圆盘式柱体的柱体端穿过套管与测力传感器的探测端相贴紧,圆盘式柱体的柱体端与套管间隙设置,套管和模具间填充有混凝土。本发明的检测方法为基于该检测装置实现。本发明用于水泥基材料收缩应力检测。(A cement-based material shrinkage stress detection device and a full-temperature detection method thereof. The testing device and the method for rapidly evaluating the shrinkage or expansion stress of the concrete before construction are lacked due to high detection precision requirement, high difficulty, low efficiency and poor accuracy of the shrinkage or expansion stress generated by the deformation of the concrete, so that the civil engineering construction quality of the high-performance cement-based material is seriously affected, and the rapid solution is urgently needed. The detection device is characterized in that a sleeve is detachably connected in a mold, a first connecting piece and a second connecting piece are respectively arranged at two ends of the mold, a force measuring sensor is arranged in the second connecting piece, a disc end of a disc type cylinder is detachably connected with the first connecting piece, the cylinder end of the disc type cylinder penetrates through the sleeve to be closely attached to a detection end of the force measuring sensor, the cylinder end of the disc type cylinder is arranged in a gap with the sleeve, and concrete is filled between the sleeve and the mold. The detection method is realized based on the detection device. The invention is used for detecting the shrinkage stress of the cement-based material.)

1. A cement-based material shrinkage stress detection device is characterized in that: comprises a mould (1), a first connecting piece (2), a second connecting piece (3), a disc type cylinder (4), a sleeve (5), a force measuring sensor (6) and two groups of positioning nails (7), wherein the sleeve (5) is detachably connected in the mould (1), the first connecting piece (2) and the second connecting piece (3) are respectively arranged at two ends of the mould (1), the force measuring sensor (6) is arranged in the second connecting piece (3), the disc end of the disc type cylinder (4) is detachably connected with the first connecting piece (2), the cylinder end of the disc type cylinder (4) passes through the sleeve (5) to be closely attached to the detection end of the force measuring sensor (6), the cylinder end of the disc type cylinder (4) is arranged in a clearance with the sleeve (5), concrete (8) is filled between the sleeve (5) and the mould (1), and the two groups of positioning nails (7) are both arranged in the concrete (8), one group of positioning nails (7) in the two groups of positioning nails (7) are inserted into the concrete (8) through the disc type column body (4), and the other group of positioning nails (7) in the two groups of positioning nails (7) are inserted into the concrete (8) through the mould (1).

2. The apparatus for detecting shrinkage stress of cement-based material according to claim 1, wherein: the disc type column body (4) comprises a disc body (4-1) and a steel column (4-2), one end of the steel column (4-2) is fixedly connected to the disc body (4-1), and the steel column (4-2) and the disc body (4-1) are coaxially arranged.

3. The apparatus for detecting shrinkage stress of cement-based material according to claim 1, wherein: the mold (1) comprises an outer cylinder body (1-1) and a bottom plate (1-2), annular bosses (1-3) are respectively machined on the outer walls of two ends of the outer cylinder body (1-1), one of the two annular bosses (1-3) is detachably connected with a first connecting piece (2), the other end of the outer cylinder body (1-1) is provided with the bottom plate (1-2) in a matched mode, the other one of the two annular bosses (1-3) is detachably connected with a second connecting piece (3) through the bottom plate (1-2), the first connecting piece (2) is a first flange, and the second connecting piece (3) is a second flange.

4. The apparatus for detecting shrinkage stress of cement-based material according to claim 3, wherein: the outer cylinder body (1-1) is formed by two semicircular arc pieces in an enclosing mode, and the two semicircular arc pieces are detachably connected.

5. The apparatus for detecting shrinkage stress of cement-based material according to claim 2, wherein: one end of the sleeve (5) is tightly attached to the end face of the disc body (4-1) through the first sealing ring (9), and the other end of the sleeve (5) is tightly attached to the inner wall of the die bottom plate (1-2) through the second sealing ring (10).

6. A cement-based material shrinkage stress detection apparatus as claimed in claim 1, 2, 3, 4 or 5, wherein: a limit ring (12) is sleeved outside the force measuring sensor (6).

7. The apparatus for detecting shrinkage stress of cement-based material according to claim 6, wherein: the force measuring sensor (6) is a disc type pressure sensor.

8. The apparatus for detecting shrinkage stress of cement-based material according to claim 7, wherein: an adjusting screw (13) is arranged on the first connecting piece (2), the adjusting screw (13) is arranged at the central axis of the first connecting piece (2), and a rocker (14) is arranged outside the adjusting screw (13) in a matching manner.

9. The test method using the apparatus for detecting shrinkage stress of cement-based materials according to claim 8, wherein: the test method comprises the following steps:

mounting the mold (1): inserting a steel column (11) into the sleeve (5), holding one end of the steel column (11) and pushing the steel column (11) until the front end of the steel column (11) abuts against the second flange, and stopping pushing;

filling concrete (8) into the mould (1) and inserting and tamping, and taking out the steel column (11) from the sleeve (5) after vibrating and tamping;

a limiting ring (12) is arranged in the second flange, a force measuring sensor (6) is arranged in the limiting ring (12), the force measuring sensor (6) is arranged in the second flange through the limiting ring (12), the central axis of the force measuring sensor (6) is ensured to be coincident with the central axis of the second flange, then the cylinder end of the disc type cylinder (4) is inserted into the sleeve (5) until the cylinder end of the disc type cylinder (4) is attached to the force measuring sensor (6), the pushing is stopped, and then the first flange is arranged on the mold (1);

a group of positioning nails (7) is arranged on the disc type column body (4) to adjust the initial position of the disc type column body (4) in the concrete (8), simultaneously enhance the connection strength of the disc type column body (4) and the concrete (8), and record the initial reading of the force measuring sensor (6);

and recording the readings of the force measuring sensors (6) at different ages, and subtracting the initial readings of the force measuring sensors (6) to obtain the self-contraction stress of the concrete (8) in the normal-temperature or high-temperature environment.

10. The test method of claim 9, wherein: respectively disassembling the first flange and the second flange from the mold (1), sequentially taking out the disc type column body (4), the sleeve (5) and the concrete (8), disassembling the force measuring sensor (6) from the second flange, installing the force measuring sensor at an adjusting screw (13) of the first flange, reinstalling the second flange on one end of the mold (1), reinstalling the disc type column body (4) on the mold (1), ensuring that the column body (4-2) of the disc type column body (4) penetrates through the bottom plate (1-2) and is tightly pressed on the second flange, installing the concrete (8) in the mold (1) and inserting and tamping, and installing the force measuring sensor (6) at the other end of the mold (1) after vibrating and tamping;

placing a mould (1) with a first flange, a second flange, a force measuring sensor (6) and a disc type column body (4) in a low-temperature environment for detection, arranging a group of positioning nails (7) on the disc type column body (4) to adjust the initial position of the disc type column body (4) in concrete (8), enhancing the connection strength of the disc type column body (4) and the concrete (8), and simultaneously recording the initial reading of the force measuring sensor (6);

and recording the readings of the force measuring sensors (6) at different ages, and subtracting the initial readings of the force measuring sensors (6) to obtain the frost heaving stress of the concrete (8) in the negative temperature environment.

Technical Field

The invention belongs to the technical field of civil engineering, and particularly relates to a cement-based material shrinkage stress detection device and a full-temperature detection method thereof.

Background

Cement-based materials undergo volume changes, are autogenous, and are also caused by external factors such as temperature, humidity and load. Volume changes caused by self-drying due to hydration reactions, water evaporation, etc. during the development of concrete strength are called concrete shrinkage. It is a time-dependent deformation property that allows for volume reduction of concrete without being affected by external forces. The volume change is one of important factors influencing the long-term strength and durability of the cement-based material, the self-shrinkage is the reduction of macroscopic volume caused by the reduction of capillary negative pressure and internal relative humidity caused by the hydration reaction of cement under the condition that the concrete is isolated from external moisture, and the generation of shrinkage stress can be considered to be caused by the limitation of volume shrinkage deformation to a certain extent. For practical engineering, when the concrete is subjected to a shrinkage tensile stress greater than the tensile strength at that moment, the concrete will crack. The early shrinkage stress of the high-performance concrete mainly comprises self-shrinkage stress, temperature stress and drying shrinkage stress, wherein the self-shrinkage stress is most remarkable. The high-performance concrete has the obvious characteristics of low water-cement ratio, more cementing materials, addition of a large amount of superfine mineral admixtures and the like, the rapid self-drying effect causes the volume change of the high-performance concrete to be larger than that of common concrete, the early high-performance concrete is restrained by internal restraint and external restraint, the restraint can cause self-contraction stress to be generated in the concrete, and the size of the self-contraction stress is influenced by the mechanical properties of the concrete such as tensile strength besides the relation with the self-contraction stress.

The existing self-contraction stress experimental evaluation method comprises a single-axis constraint test, a circular ring method and the like, and as for the constraint form, the axial constraint test can be divided into two forms, namely end constraint and continuous constraint inside a steel bar. The steel bar internal constraint shrinkage experiment is used for simulating the limitation of the steel bars on the concrete shrinkage, and belongs to incomplete constraint. When the length of the test piece is far greater than the size of the cross section, only axial shrinkage can be considered approximately, if the test piece is limited, tensile stress which is uniformly distributed, namely shrinkage stress, is generated in the cross section, the test piece is slender, axial restraint is easy to realize, cracks are fully developed, and the experiment effect is good. One of the concrete shrinkage stress measuring instruments is that a concrete sample is pulled back to the initial position of the concrete sample by a tension system based on slender shrinkage, and the tensile stress of the system is the shrinkage stress of the concrete at the moment, so that the test device is complex and has high precision requirement. The axial constraint shrinkage experiment adopted in teaching is to compare a concrete sample embedded in a steel bar in molding with a free shrinkage experiment with the same size, and attach a strain gauge on the steel bar to monitor constraint deformation, so that constraint stress can be indirectly measured.

At present, more and more high-performance concrete and ultrahigh-performance cement-based materials are applied to practical engineering, the water-cement ratio of the materials is low, the using amount of a cementing material is large, the self-shrinkage amount of the materials is 2-4 times that of common concrete, the risk of cracking caused by shrinkage deformation is greatly increased, and in order to quickly and simply determine the crack resistance of the materials, the self-shrinkage stress testing device and the method need to be accurately, reliably and quickly obtained. The shrinkage (frost heaving) stress of the cement-based material under the high-temperature, normal-temperature or negative-temperature environment is difficult to realize quantitative detection. In a word, the concrete volume deformation detection precision requirement is high, the self-contraction stress detection difficulty is high, the efficiency is low, and the accuracy is poor, so that the test device and the method for quickly evaluating the concrete contraction stress before construction are lacked, the civil engineering construction quality of the high-performance cement-based material is seriously influenced, and the problem of quick solution is urgently needed.

The invention content is as follows:

aiming at the problems, the invention discloses a cement-based material shrinkage stress detection device and a full temperature detection method thereof.

The technical scheme adopted by the invention is as follows:

the utility model provides a cement-based material shrinkage stress detection device, includes mould, first connecting piece, second connecting piece, disc type cylinder, sleeve pipe, force cell sensor and two sets of location nail, the connection can be dismantled in the mould to the sleeve pipe, the both ends of mould are provided with first connecting piece and second connecting piece respectively, be provided with force cell sensor in the second connecting piece, the disc end and the first connecting piece of disc type cylinder can be dismantled and be connected, the cylinder end of disc type cylinder passes the sleeve pipe and pastes closely with force cell sensor's probe end, the cylinder end and the sleeve pipe clearance of disc type cylinder set up, it has the concrete to fill between sleeve pipe and the mould, two sets of location nail all set up in the concrete, a set of location nail in two sets of location nail inserts in the concrete through the disc type cylinder, another set of location nail in two sets of location nail inserts in.

As a preferable scheme: the disc type cylinder body comprises a disc body and a steel column, one end of the steel column is fixedly connected to the disc body, and the steel column and the disc body are coaxially arranged.

As a preferable scheme: the mould includes outer barrel and bottom plate, processes respectively on the outer wall at outer barrel both ends annular boss, one in two annular bosses annular boss can be dismantled with first connecting piece and be connected, and the cooperation of the other end department of outer barrel is provided with the bottom plate, another in two annular bosses annular boss passes through the bottom plate and can dismantle with the second connecting piece and be connected, and first connecting piece is first flange, and the second connecting piece is the second flange.

As a preferable scheme: the outer cylinder body is formed by two semicircular arc pieces in an enclosing mode, and the two semicircular arc pieces are detachably connected.

As a preferable scheme: one end of the sleeve is tightly attached to the end face of the disc body through the first sealing ring, and the other end of the sleeve is tightly attached to the inner wall of the die bottom plate through the second sealing ring.

As a preferable scheme: the force cell is sleeved with a limit ring.

As a preferable scheme: the force sensor is a disc type pressure sensor.

As a preferable scheme: the first connecting piece is provided with an adjusting screw, the adjusting screw is arranged at the central axis of the first connecting piece, and a rocker is arranged outside the adjusting screw in a matching manner.

A test method by using a cement-based material shrinkage stress detection device is characterized by comprising the following steps: the test method comprises the following steps:

installing a mold: inserting a steel column into the sleeve, holding one end of the steel column by hand and pushing the steel column until the front end of the steel column abuts against the second flange, and stopping pushing;

filling concrete into the mould and tamping, and taking out the steel column from the sleeve after the concrete is vibrated to be compact;

a limiting ring is arranged in the second flange, a force measuring sensor is arranged in the limiting ring, the force measuring sensor is arranged in the second flange through the limiting ring, the central axis of the force measuring sensor is enabled to be coincident with the central axis of the second flange, then the cylinder end of the disc type cylinder is inserted into the sleeve until the cylinder end of the disc type cylinder abuts against the force measuring sensor, the pushing is stopped, and then the first flange is arranged on the mold;

a group of positioning nails is arranged on the disc type column body to adjust the initial position of the disc type column body in the concrete, simultaneously enhance the connection strength of the disc type column body and the concrete, and record the initial reading of the force measuring sensor;

and recording the readings of the force sensors at different ages, and subtracting the initial readings of the force sensors to obtain the self-contraction stress of the concrete in the normal-temperature or high-temperature environment.

As a preferable scheme: respectively disassembling the first flange and the second flange from a mould, sequentially taking out the disc type cylinder, the sleeve and the concrete, disassembling the force measuring sensor from the second flange, installing the force measuring sensor at an adjusting screw of the first flange, reinstalling the second flange on one end of the mould, reinstalling the disc type cylinder on the mould, ensuring that the cylinder of the disc type cylinder penetrates through the bottom plate and is tightly pressed on the second flange, filling the concrete in the mould and tamping, and installing the force measuring sensor on the other end of the mould after the concrete is tamped;

placing a mould with a first flange, a second flange, a force measuring sensor and a disc type column body in a low-temperature environment for detection, arranging a group of positioning nails on the disc type column body to adjust the initial position of the disc type column body in concrete, enhancing the connection strength of the disc type column body and the concrete, and simultaneously recording the initial reading of the force measuring sensor;

and recording the readings of the force sensors at different ages, and subtracting the initial readings of the force sensors to obtain the frost heaving stress of the concrete in the negative temperature environment.

The invention has the beneficial effects that:

the quantitative detection of the self-contraction stress of the cement-based material is realized through mutual matching of the die, the first connecting piece, the second connecting piece, the disc type cylinder, the sleeve, the force measuring sensor and the two groups of positioning nails, the acquisition mode is simple and direct, a tedious calculation process is omitted, the acquired data of the self-contraction stress of the cement-based material are more accurate, and the comprehensive evaluation on the crack resistance of the cement-based material is facilitated.

The device can realize the shrinkage (frost heaving) stress detection of the cement-based material in a high-temperature, normal-temperature or negative-temperature environment, realize the full-temperature detection process of the internal stress of the cement-based material, effectively realize the multi-purpose detection effect of the device and ensure accurate and reliable detection results.

The detection method has the characteristics of high efficiency, simple operation steps, low operation difficulty, time saving and labor saving.

The method can be suitable for detection in engineering laboratories, and provides basic data for the design of the concrete mixing ratio.

The invention is particularly suitable for detecting the shrinkage stress of the simulated construction site concrete, and carries out a laboratory simulation test according to the actual temperature of the construction site concrete to obtain a more real and reliable shrinkage stress value of the concrete, thereby having important application values for preventing the early cracking of the concrete, improving the engineering quality and prolonging the service life.

The invention has simple structure design, easy assembly, low manufacturing cost, reliable detection structure and easy popularization and use.

Description of the drawings:

for ease of illustration, the invention is described in detail by the following detailed description and the accompanying drawings.

FIG. 1 is a sectional view of a front view of a testing device according to the present invention in a horizontal arrangement, wherein the testing device is used for testing the shrinkage stress of concrete under high temperature and normal temperature conditions;

FIG. 2 is a cross-sectional view of a front view of the testing device of the present invention in a vertical configuration;

FIG. 3 is a sectional view of a front view of the testing device of the present invention in a horizontal configuration, wherein the testing device is used for detecting the shrinkage stress of concrete in a negative temperature environment;

FIG. 4 is a schematic front view of a steel column;

FIG. 5 is a graph showing the trend of the shrinkage stress of normal temperature concrete during the testing process of the present invention.

The labels in the figure are as follows:

1-a mould; 1-1-outer cylinder; 1-2-a base plate; 1-3-annular boss; 2-a first connecting member; 3-a second connector; 4-disc column; 4-1-disk body; 4-2-column; 5-sleeving a pipe; 6-a force transducer; 7-positioning nails; 8-concrete; 9-a first sealing ring; 10-a second sealing ring; 11-steel column; 12-a stop collar; 13-adjusting screws; 14-Rocker.

The specific implementation mode is as follows:

in order that the objects, aspects and advantages of the invention will become more apparent, the invention will be described by way of example only, and in connection with the accompanying drawings. It is to be understood that such description is merely illustrative and not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.