What are the main methods for testing the strength of concrete and their characteristics?

Rebound method. With a rebound hammer.

The surface of the concrete structural component is inspected, and the rebound value is collected according to the data analysis.

The actual strength of the concrete is obtained. The rebound method is simple, convenient, and low-cost, and is a strength test method often used in the field, but the shortcomings are also obvious, the accuracy is poor, the artificial subjective factors are strong, and the real strength of the concrete structure can not be reflected at the same time. (For example, the surface of the structure is coated with a concrete reinforcing agent.)

, it is not possible to get real data with the rebound method)

Ultrasonic. The strength of concrete structures is measured with an ultrasonic detector, which can be used to test the strength of concrete.

It can also be used to detect concrete defects. The ultrasonic detector can make a relatively accurate judgment on the internal cavities of concrete, the range of undense areas, cracks, the thickness of the damaged layer, the quality of concrete bonds poured at different times and the homogeneity of concrete. However, the ultrasonic method will be affected by factors such as the reinforcement, aggregate, and humidity inside the concrete.

Drill core sampling method.

The core drilling method belongs to the breakage method to test the compressive strength of concrete.

The number of core drills on concrete components should not be too much, and it is necessary to avoid the concentrated force parts. The core drilling method is easy to cut off the steel bars inside the concrete components, resulting in the mechanical properties of the structure.

Decline. The height-diameter ratio of the core sample should be within the range, and the end of the core sample needs to be leveled, otherwise it will have a great impact on the detection results.

Maturity method. The concept of maturity is based on the temperature history of concrete, which can be used both for concrete quality control and for concrete compressive strength calculations. If the maturity index is the same, the compressive strength is also the same, and the strength value does not depend on the specific temperature or time.

As a non-destructive testing method, the maturity method has advantages over other field strength testing methods. Once the maturity curve is established correctly and reasonably, the results are accurate and reliable. What's more, this method is carried out in the concrete solidification process and can be concluded, and its aging advantage is self-evident.

The maturity method requires a built-in sensor in the concrete to continuously test the temperature of the concrete during the setting process. The operator only needs to mark the sensor and scan it to add it to the different sub-projects of the project to which it belongs, and fill in the location information. When installing, place the white label part of the sensor facing upwards and do not install the sensor more than 5cm from the concrete surface.

During the measurement process, the sensor will continuously collect the temperature inside the concrete and feed it back to the operator, who can view real-time temperature, maturity, strength and other data and corresponding charts through the mobile phone.

Breakage test: the test piece is destroyed with a testing machine, the concrete strength is tested by a press, or the concrete strength is tested in the laboratory by the lever principle, which is characterized by the fact that although the strength can be measured very accurately, the test piece will be scrapped after measurement.

Non-destructive test Concrete structure on-site testing technology: rebound method: non-destructive, the measured talks reflect the elastic properties of concrete, and also reflect the plastic properties of concrete to a certain extent, but can only accurately reflect the state of the surface layer of concrete 3cm thickness; Ultrasound-rebound synthesis method:

It not only reflects the elasticity of concrete but also reflects the plasticity of concrete, reflects both the surface state of concrete and the internal structure of concrete, and can reflect the strength of concrete more accurately from the surface to the inside; Drilling method: there is no need to establish the conversion relationship between a certain physical quantity and strength of concrete, but there is local damage to the original structure, which is a semi-damage test method; Pull-out method: semi-breakage test, the concrete pull-out strength is used to calculate the compressive strength of the cube.

Here's the answer:

1. Appearance inspection of building structure.

The visual inspection of the building should cover all the components of the structure. Firstly, by inspecting its appearance, it was preliminarily determined that there were common external defects such as honeycomb, hemp surface, holes and cracks on the surface of the structure. Secondly, by checking the size of the concrete components, and using the method of eye dust measurement to judge the size of the main components of the building structure; Again, by the way of the ruler.

Detect the concrete details, such as the verticality, elevation, axis position, cross-sectional size and other contents of the embedded parts; Finally, according to the environment in which the building is located, specific tests are carried out. For example, if the structure is located in the ** area or the seaside and other areas with serious corrosion, special tests should be carried out on the parts that may be damaged, and the results should be faithfully reflected in the test report and explained accordingly.

Second, the quality inspection of concrete materials.

The quality inspection of concrete materials includes many aspects: First, the compressive strength of concrete materials. At present, the methods commonly used to test the strength of concrete include core drilling method and rebound method.

As a common non-destructive testing method, the rebound method should strictly follow the relevant operation specifications in the "Technical Regulations for Testing the Compressive Strength of Concrete by Rebound Method" during operation.

Ensure that the axis of the rebound hammer is perpendicular to the surface of the structure during the inspection, and apply pressure slowly to ensure that the reading is stable. Second, concrete raw material testing. Concrete is a composite material formed by mixing a variety of raw materials, so the quality of raw materials directly determines the quality of concrete structures.

Water, cement, sand, and gravel are several common raw materials for concrete, which are used in house construction projects.

When the above-mentioned raw materials enter the site, they should be inspected as necessary, such as the performance and grade of cement, the gradation of coarse and fine aggregates, and whether the sand and gravel contain impurities, etc., which should be focused on, which is also the basis for the design of concrete mix ratio.

3. Structural floor slab thickness detection.

As a component that directly bears the load, the thickness of the floor slab is closely related to the size of the load that can be withheld. Therefore, in the inspection and pure measurement work, the thickness of the floor slab of the building structure should also be measured, not only to meet the needs of future use, but also to meet the basic quality requirements.

Usually in different rooms and compartment spans, random sampling is used for testing, and once a non-compliance is found, it should be immediately surveyed and rectified.

Fourth, steel bar material testing.

The material testing of steel bars is mainly divided into two parts: mechanical property testing and welding quality testing. For the test item of mechanical properties of steel bars, the part can be randomly selected according to the total amount of testing for sampling testing, so as to ensure the effect.

It can also take into account the comprehensiveness of the detection; For the quality inspection of steel bars, first of all, visually check whether there are problems such as steel bar welding is not firm and fractured on the surface, and if the problem is found in the test, further testing must be done on the same batch of steel bars to ensure that its quality is reliable.

Methods for assessing the strength of concrete:

1. Statistical methods with known variance: the formula specified in the "Concrete Strength Inspection and Evaluation Standard" GB T50107 2010 is used for evaluation.

The sample capacity of a test batch should be 3 consecutive sets of specimens, and its strength should meet the following requirements at the same time:

mƒcu≥ƒcu，k＋ （

cu，min≥ƒcu，k－ （

When the concrete strength grade is not higher than C20, its minimum strength value should meet the following requirements:

cu，min≥，k （

When the concrete strength grade is higher than C20, the minimum strength value should meet the following requirements:

cu，min≥，k （

2. Statistical method with unknown variance: the formula specified in the "Concrete Strength Inspection and Evaluation Standard" GB T50107 2010 is used for evaluation.

When the sample size is not less than 10 groups, its intensity should meet the following requirements at the same time:

mƒcu≥ƒcu，k＋λ1●sƒcu （

cu，min≥λ2●ƒcu，k （

When the calculated value of the strength standard difference of the test batch concrete is less than that of cu, it should be taken. 1. 2 According to the concrete strength inspection and evaluation standard GB T50107 2010 table selection.

3. Non-statistical methods: the formula specified in the "Concrete Strength Inspection and Evaluation Standards" GB T50107 2010 is used for evaluation.

When the sample size is less than 10 groups, its intensity should meet the following requirements at the same time:

mƒcu≥＋λ3●ƒcu，k （

cu，min≥λ4●ƒcu，k （

4 take. Concrete strength grade C60, 3, C60, 3.

There are three methods to detect the strength test of mixed limb concrete: the first is to detect the concrete strength by the afterloading pull-out method, the second is to detect the concrete strength by the rebound method, and the third is to detect the strength of the concrete by the pressure method, which 15910665564 Wanggong.

Concrete Posture Puller.

Concrete rebound hammer.

Concrete presses.

The on-site testing methods for the strength of concrete structures can be divided into non-damaged or deliberate and local damage methods.

1. Non-breakage method.

1.Rebound method.

The rebound method is a method to estimate the compressive strength of concrete based on the correlation between its rebound value, carbonization depth and compressive strength.

2.Ultrasound-rebound synthesis method:

The ultrasonic rebound comprehensive method is a method based on the correlation between the ultrasonic propagation velocity and rebound value and the compressive strength of concrete, and comprehensively reflects the compressive strength of concrete with the sound velocity and rebound value.

2. Partial damage method.

1.Core drilling method.

The core drilling method is a method that uses a special drilling rig to drill a core sample from the structure and infer the strength of the structural concrete according to the compressive strength of the core sample.

2.Pull out method.

The pull-out method is a local damage detection method, the test is to pre-embed an anchor made of metal into the unhardened concrete pouring component, or drill into the concrete component of the hardened concrete and bury an anchor, and then according to the tensile force when the anchor is pulled out, to calculate the compressive strength of the concrete.

3.Shear pressing method.

The shear compression method is to use a special extrusion jack to apply pressure to the edge of the concrete component, so that the edge of the component produces local shear compression failure, and the concrete strength of the component is inferred according to the size of its local bearing pressure, and the local failure surface after detection is smaller, which does not affect the bearing capacity of the sage base component itself.

1. Concrete is the most important material for construction projects, and the strength of concrete determines the quality basis of construction projects. There are many ways to test the strength of concrete, and the more commonly used ones are rebound method, ultrasonic rebound method, core drilling method, pull-out method, ultrasonic method, etc.

2. Concrete (concrete, stone arrow) is a composite material made of gel materials, aggregates and water in appropriate proportions, and then hardened for a certain period of time, which is the world's most widely used artificial civil building materials.

3. Concrete has high hardness, wide range of raw materials and low cost, and is widely used in buildings, highways, military projects, nuclear power plants and other structures.

There are a lot of details that need to be paid attention to by concrete Shizhou's file workers, and if you don't pay attention to it, it will affect the later building construction, so you should have a cognition of the strength of concrete in advance. So what are the concrete strength testing methods, and what to pay attention to in concrete construction, do you know it? Now let's take a look.

1. What are the concrete strength testing methods?

1. The rebound method tests the strength of concrete by measuring the carbonization depth and rebound value of concrete; 2. Ultrasonic method can not only detect the strength of concrete, but also detect concrete defects; 3. The ultrasonic rebound comprehensive method can measure the strength of the concrete to know the change of concrete strength; 4. Radar method, using electromagnetic waves to detect the strength of concrete.

Second, what to pay attention to in concrete construction.

1. In the process of deploying concrete, it is necessary to make relevant preparations, design construction plans and temperature control measures, so as to detect the internal temperature of concrete in time. In addition, during the period of protection of concrete, it is necessary to do a good job of temperature measurement and make necessary protection adjustments to the concrete in time.

2. When pouring concrete, if there is a non-conforming pouring phenomenon, it needs to be maintained by professional construction personnel in time, and it can be continued to be used only after it is processed. At the construction site of concrete, it is not allowed to add water to the inside of the concrete without permission, otherwise it is easy to cause the concrete to fail to meet the hardness requirements and affect the use.

3. The time of pouring the core for the first time is best fixed at night, which can reduce the temperature of the concrete into the mold and reduce the time required for pouring during the day. If you are going to pour it during the day, you need to do a shading process. When the pouring reaches the height requirements, it needs to be covered with a plastic bag.

What are the concrete strength testing methods, and what to pay attention to in concrete construction, I will introduce it here, do you understand it? There are several methods for testing the strength of concrete, and the key is to pay attention to the details to avoid unnecessary trouble.

1. The test block method is to pour the mixed concrete into the specified cube test mold during construction, and after vibration or insertion, it is cured for 28 days according to the specified temperature and humidity, and the compressive strength test is carried out.

2. The core drilling method is to drill the core sample with a diamond drill bit on a representative concrete structure, and after processing, sawing, grinding or leveling at both ends, it is made into a circular grip cylinder for compressive strength measurement.

3. The rebound method, the surface hardness of the concrete is measured by the rebound meter, and then the compressive strength is inferred by combining the carbonization depth of the concrete.

4. Ultrasonic testing method, ultrasonic testing can make a more accurate judgment on the location and scope of cavities, unmatched or compacted areas in concrete, crack depth, thickness of surface damage layer, quality of concrete bond poured at different times and concrete homogeneity.

5. Afterloading pull-out method, post-installation pull-out method to detect the strength of concrete, drilling holes, grinding grooves, embedding anchors and installing pull-out instruments on the hardened concrete surface for pull-out test, measuring the ultimate pull-out force, and testing the concrete strength according to the correlation between the pre-established pull-out force and the concrete strength of the concrete Zhiqing concrete.