Disease causes and treatment of cement concrete pavement joint fragmentation

1. Causes: 1) The debris on the bottom surface of the edge of the cement concrete pavement plate of the construction is not cleaned, resulting in the formation of a free surface there, or the spacing of the reinforcement bar of the force transmission rod is too large or the steel bar is too small, so that the plate edge is squeezed and broken under the repeated action of the wheel load.

2) the edge of the cement concrete pavement plate of the first construction is in order to catch up with the construction period when the curing age is insufficient, when pouring the adjacent plate, the finished product protection is not done, and the three-roller machine directly rolls on it and walks the operation, causes the concrete inside of the edge of the cement concrete pavement slab to be destroyed before reaching the strength, and is quickly reflected to the surface under the action of wheel load to produce local concrete spalling, fragmentation.

2. Solution:

1) The expansion joints that are broken or cracked are more serious should be chiseled in full depth within the width range of 10 30cm larger than the damage range, the section length of the whole plate and the longitudinal extension width of the surface, and the position of the force transmission rod should be re-corrected, and the reinforcement mesh should be added if necessary to re-set the expansion joints. In order to open to traffic earlier, it is recommended to use early-strength concrete for repair.

2) For the shrinkage joint spalling and serious damage, it should be chiseled and cleaned up at a certain depth of not less than 5cm width, and then repaired with concrete mixed with polymer. The more commonly used is to extract water-soluble epoxy resin into the mixture, and the dosage is generally 1 2 of the amount of cement, which can effectively reduce the water-cement ratio, improve frost resistance and durability, and have obvious improvement effects on adhesion performance, impact resistance and fatigue resistance.

3) For the case that the shrinkage joint peeling is not serious, you can continue to use it first and strengthen the usual inspection and maintenance to slow down its development, and then treat it according to the above methods when the peeling and damage is serious to a certain extent after a period of use.

Causes of pavement joint disease.

The fracture of the joint is due to the offset of the position of the force transmission rod during the construction process, resulting in the sliding end and the fixed end can not be freely expanded, or the expansion joint force transmission rod is not sleeved to leave enough holes, or the expansion joint is blocked by mortar, silk weaving and other sundries, resulting in the plate body on one side of the joint being crushed and cracked.

The loss of caulk is due to the fact that the caulk is not replaced with a new one in time after aging, or the material of the caulk itself is poor, and the adhesion with the concrete is not strong.

How to deal with seam chipping.

The joint is the weak link of the cement concrete pavement, and both sides of the joint are easy to be crushed by inclined shear. On the highway with heavy traffic, the transverse shrinkage joints are generally provided with force transmission rods, but with the fragmentation of the joints, the force transmission rods also fail one after another, and the constraints between adjacent concrete slabs disappear, thereby increasing the degree of freedom of the slabs. The cement concrete expansion joint has a fairly high failure rate due to the lack of parallelism in the installation of the force transmission rod, the missing sleeve, the asphalt coating of the force transmission rod is too thick or falling off, the joint is too wide, and the filler in the joint is aging and dissipating.

Due to the failure of the joints, the likelihood of reflective cracks in the asphalt overlay on the concrete slab increases.

It is mainly caused by poor substrate treatment and overload. Deal with the base low and heavy pouring.

It can be solved with diagenetic mortar.

In recent years, the cement concrete pavement in Huaihua area has developed rapidly, and it is found that the joints of the pavement are seriously damaged in use, which not only affects the driving stability and comfort, but also is not easy to repair, and affects the service life of the cement concrete pavement.

1. Analysis of the causes of joint failure of cement concrete pavement.

The joint failure is mainly manifested as the edge breaking and misalignment of the concrete slab at the joint, and the bursting and breaking of the edge of the concrete plate. There are three causes of joint failure: failure of joint sealing, excessive traffic loads, and insufficient strength of the base and concrete.

Seam seal failure is the main cause, which interacts with other causes of failure. Factors that cause seam seal failure include: environmental factors (rain, sunlight, high temperatures, hard objects, dirty objects); traffic load action; the performance and quality of the sealing material; seam construction, dimensions; the strength and water stability of the base layer; Incorrect construction methods.

1) Rain, sunlight and high temperature will accelerate the aging of sealing materials, and the adhesion will decrease, resulting in falling off and losing the sealing and waterproof properties. Water enters the base layer through the gap, reducing the strength of the base layer;

2) After hard objects and dirt enter the seam, the sealing material will occupy the seam space and be extruded. The large temperature increase makes the length of the concrete slab elongate more, which causes the edge of the slab to burst, break or bulge at the joints.

3) When the vehicle passes through the joint, the jumping car makes the plate with water on the bottom surface appear to absorb the mud, and the frequent mud drawing will hollow out the bottom base material of the slab, so that the joint of the road slab is broken and damaged;

4) For joints without force transmission rods, insufficient strength of the base layer and poor water stability will accelerate the failure of the concrete slab at the edge of the joint;

5) Low-quality sealing materials, heat loss, cold hardness, brittleness, and reduced adhesion, so that the seam loses its waterproof performance;

6) Incorrect construction will reduce or even lose the waterproof effect of good sealing materials. For example, the seams are not clean, etc.

2 Properties of the sealing material Type F9201.

The information provided by the Chongqing Highway Science Research of the Ministry of Communications and our test results show that the F9201 sealing material has excellent high temperature stability, low temperature deformation, adhesion, aging resistance (including thermal aging and weather aging) and water resistance, and is convenient for construction.

Summary. 1. Basal reasons. The concrete floor is below the base surface of the concrete, and the flatness of the base surface determines whether the concrete plate can be evenly stressed, and when encountering heavy loads, there will be different thicknesses of the plates and different bearing capacity, resulting in the fracture of the demarcation part due to the different strength of the force.

2. Cement problem. Cement is the main component of concrete, is the guarantee of concrete strength, if the use of expired cement or unqualified cement products, the concrete floor will be very prone to cracking and sand and dust drawbacks. 3. Aggregate problem.

Aggregates need to be added to concrete, mainly sand and gravel, but there are many choices of aggregates, and the size and material are different. If you choose fine sand and gravel (such as fine stone concrete used for the surface layer), it will be easy to sand and dust due to the increased shrinkage of the concrete. To reduce the possibility of concrete sanding, materials that are clean, contain less activated silica, and are continuously graded should be selected as much as possible.

4. The problem of water-cement ratio. Concrete is composed of water, cement, sand, and gravel, and the general ratio is required. The proportion of solid, liquid and gaseous states is 80%, 18% and 2% respectively.

1. What are the reasons for the formation of cracks in cement concrete pavement? What is the specific treatment?

1. Basal reasons. The concrete floor is below the base surface of the concrete, and the flatness of the base surface determines whether the concrete plate can be evenly stressed, and when encountering heavy loads, there will be different thicknesses of the slab Xiaoqing block, different bearing capacity, and different stress strengths caused by the leakage lead to the fracture of the demarcation part. 2. Cement problem.

Cement is the main component of concrete, is the guarantee of concrete strength, if the use of expired cement or unqualified cement products, the concrete floor will be very prone to cracking and sand and dust drawbacks. 3. Aggregate problem. Aggregates need to be added to concrete, mainly sand and gravel, but there are many choices of aggregates, and the size and material are different.

If Kaishen rot fruit is selected with fine sand and gravel (such as fine stone concrete used for the surface layer), it will be easy to sand and dust due to the increase of concrete shrinkage. To reduce the possibility of concrete sanding, materials that are clean, contain less activated silica, and are continuously graded should be selected as much as possible. 4. The problem of water-cement ratio.

Concrete is composed of water, cement, sand, and gravel, and the general ratio is required. The proportion of solid, liquid and gaseous states is 80%, 18% and 2% respectively.

The specific methods are 1. Mark all the cracks first, which can not only remind vehicles and passers-by to take a detour, but also make it more convenient to repair the operation. 2. Prepare the materials required for repair, and check the specific situation of the crack. If the sealing part is cracked and deformed, it is necessary to cut the seam and then clean and rinse it, but if it is only the seam is deformed or broken, it will be cleaned and rinsed directly.

3. After all cracks are cleaned and flushed, the repair materials can be adjusted according to the proportion, and stirred evenly. Then fill or pour the repair material into the crack, and then do the sealing treatment. 4. Finally, after the repair material is completely hardened, the reminder sign can be taken away and opened to traffic.

Hope it helps.

Have a great day.

The bond strength between the cement surface and the aggregate is about 40 70 of the tensile strength of the cement stone, indicating that the bond between the cement and the aggregate contact surface is the weak link inside the concrete. In the process of concrete condensation, hail such as the cement stone loses water and shrinks, and the crescent-shaped bond crack is produced at the interface between the cement and the larger aggregate, and with the continuous improvement of the strength of the steel and concrete used in modern engineering, the calculation theory and design method are becoming more and more accurate and perfect, and the cross-sectional size designed according to the ultimate state of bearing capacity is relatively reduced. In the practical phase, the reinforcement stress is greatly increased, which leads to a decrease in the stiffness of the concrete.

The increase of crack development width affects the normal use and durability, so the calculation and control of deformation and crack are becoming more and more important. In order to effectively prevent and control cracks, it is necessary to first identify the cause of cracks.

1. The main reason.

1) Cracks caused by loads and constraints or applied deformations.

2) Cracks formed during construction.

3) Cracks caused by the composition of concrete.

4) Cracks caused by use and environmental conditions.

5) Cracks caused by construction technology, temperature and humidity, deformation, transportation and other reasons. Although cracks are generally allowed in buildings, during the use of buildings, excessively wide cracks not only destroy the appearance of the structure and cause uneasiness to users, but also the cracks that are too wide may cause corrosion of steel bars.

2. The relationship between crack width and influencing factors.

1) The greater the tensile stress of the tensile steel bar, the greater the crack width.

2) The thicker the diameter of the tensile reinforcement (or the larger the ratio of the reinforcement diameter to the reinforcement ratio), the greater the crack width.

3) If the tensile reinforcement is a light round reinforcement, the crack width is larger than that of the thread source sensitive reinforcement and other deformed reinforcements.

4) The larger the crack spacing, the greater the crack width.

5) The thicker the concrete protective layer of the tensile reinforcement, the greater the crack width.