Concrete anti-cracking and anti-seepage construction method for sewage treatment plant

Abstract

The invention relates to the technical field of sewage treatment plants, and discloses the following steps: selecting late-strength low-heat ordinary Portland cement or coal mine cement with the grade of 42.5 or above; a high-efficiency water reducing agent or a composite additive with a high-efficiency water reducing function and a high-performance expanding agent are added in concrete preparation; clean coarse aggregate with good natural continuous grading quantity is selected as the coarse aggregate to prepare concrete. The high-efficiency retarding type water reducing agent is adopted, so that the absolute cement consumption and water consumption are reduced, the workability and the pumpability of the concrete are improved, and the retarding time is prolonged; the high-performance expanding agent is doped, so that the concrete generates moderate expansion, and the stress structure in the concrete is changed to offset the tensile stress generated by shrinkage in the concrete hardening process, thereby avoiding or greatly reducing the cracking of the reinforced concrete structure; and a proper amount of mineral mixing materials such as high-quality fly ash and slag are doped to reduce the cement consumption, so that the total hydration heat of the cement is reduced, and cracks are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment plants, in particular to a concrete anti-cracking and anti-seepage construction method for sewage treatment plants. Background Art

[0002] Sewage treatment plant is one of the important buildings in water conservancy projects. Its main function is also called sewage treatment plant or sewage plant in the city. The treatment station located in the factory is often called a treatment station. When the effluent is put into the urban drainage pipe, the treatment station is actually a pretreatment facility. The wastewater treatment plant is a complex system composed of multiple unit processes. The cost and efficiency of each unit process are interrelated and affect each other, and ultimately determine the cost and efficiency of the entire system. Therefore, the anti-seepage design and construction of sewage treatment plants is one of the key technologies in water conservancy projects.

[0003] At present, there are two common methods for preventing seepage and cracking in sewage treatment plants: one is to set up an anti-seepage wall or anti-seepage curtain inside the sewage treatment plant, and the other is to set up an anti-seepage panel on the upstream surface of the sewage treatment plant. The former requires complex construction operations such as drilling and grouting inside the sewage treatment plant, which is costly, inefficient, and difficult to ensure quality; the latter only requires laying prefabricated reinforced concrete or prestressed concrete panels on the surface of the sewage treatment plant, which is simple, fast, and economical to construct.

[0004] However, the latter also has some problems. The main one is that the thermal stress and thermal deformation caused by the change of panel and ambient temperature may cause the panel to crack or fall off, affecting its anti-seepage effect and service life. In addition, due to the settlement and vibration of the sewage treatment plant itself, stress concentration and fatigue damage will be caused to the panel, increasing its cracking risk. Once the panel cracks or falls off, it will not only cause waste of resources and processing problems, but also endanger the safety and stability of the sewage treatment plant. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a concrete anti-cracking and anti-seepage construction method for a sewage treatment plant, which solves the above-mentioned problems.

[0006] The present invention provides the following technical solution: a concrete anti-cracking and anti-seepage construction method for a sewage treatment plant, characterized in that it comprises the following steps: selecting late-strength low-heat ordinary Portland cement or coal mine cement with a grade of 42.5 or above;

[0007] Add high-efficiency water reducing agent or composite admixture with high-efficiency water reducing function and high-performance expansion agent in concrete preparation;

[0008] Coarse aggregate: Choose clean coarse aggregate with good natural continuous grading to prepare concrete, and choose 5-25MM continuous grading stone to reduce concrete shrinkage, mud content <0.8%, and needle-shaped and flaky particles in the aggregate <10% by weight;

[0009] Fine aggregate should be medium-coarse sand, and the mud content should be controlled to be less than 2%. The coarse and fine aggregates should be washed to reduce the mud content as much as possible. When the temperature is high, the aggregates should be watered to cool down, and the temperature of concrete leaving the machine and entering the mold should be controlled to be less than 25℃.

[0010] Add high-quality fly ash, slag and other mineral admixtures;

[0011] The maximum water-cement ratio is ≤0.50, the minimum amount of cementitious material is 300 kg / cubic meter and not more than 400 kg / cubic meter. Pumped concrete is used with a sand ratio of 40% to 45%. Under the premise of pumpability, the sand ratio should be reduced as much as possible. The slump should be as small as possible while meeting the pumping conditions. The slump should be around 10 to 12 cm. The initial setting time is 8 hours and the final setting time is 12 hours.

[0012] Preferably, the bottom slab pouring is divided into zones according to the post-pouring strips, and a number of pouring strips are determined in each zone. Each pouring strip uses a ceiling pump, a ground pump or a combination of the two according to the actual situation on site, and the number of pumps configured is determined by the volume of concrete poured in each zone.

[0013] Preferably, according to the actual situation that a slope is naturally formed when concrete is pumped, three vibrators are arranged in front, middle and back of each casting belt, the first one is arranged at the concrete unloading point, the second one is arranged at the foot of the concrete slope, and the third one is arranged in the middle of the slope.

[0014] Preferably, during the pouring and vibration process, the upwelling seepage water and floating slurry will flow down the concrete slope to the slope angle pit. Therefore, when the concrete cushion layer is constructed, a slope of 1 / 1000 is made along the long direction of the foundation, so that most of the seepage water flows along the slope of the cushion layer to the side of the foundation pit.

[0015] Preferably, after the base plate is poured, the concrete is initially leveled with an aluminum alloy bar, and the wire mesh is laid and fixed with hooked steel bars as the pouring progresses. The surface is smoothed with a wooden trowel in time. After the concrete absorbs water, it is rubbed flat twice with a wooden trowel to close the shrinkage cracks in the concrete surface layer.

[0016] Preferably, the post-cast belt adopts a quick-closing net. When vibrating concrete, the vibrating rod is 300 to 500 meters away from the edge of the net. At the same time, attention should be paid to observe so that the concrete slurry emerges from the quick-closing net. The continuous cloth thickness exceeds 1m, and multiple discharge ports are arranged around the cylinder to evenly drop concrete. The distance between each discharge port is not more than 4m. During operation, the concrete should be caught quickly and pulled out slowly. The vibration points are arranged in a plum blossom shape. The vibration time of each point is about 40 seconds. The steel at the hidden columns and hidden beams is densely packed to strengthen the vibration.

[0017] Preferably, water storage film curing is carried out 8 hours after final setting to reduce the temperature difference between the inside and outside during the temperature rise stage, prevent the generation of temperature cracks, and prevent the concrete surface from dehydrating and generating shrinkage cracks, so that the cement can be hydrated smoothly.

[0018] Preferably, crack inspection is performed on the concrete structure regularly, and cracks are promptly dealt with when discovered; for crack repair, for cracks with smaller widths, surface sealing methods can be used for treatment, such as applying waterproof coatings, embedding water-stopping materials, etc.; for cracks with larger widths, chemical grouting or pressure grouting methods can be used for repair.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The concrete anti-cracking and anti-seepage construction method used in the sewage treatment plant adopts a high-efficiency slow-setting water-reducing agent to reduce the absolute cement and water consumption, improve the workability and pumpability of concrete, and extend the slow-setting time; high-performance expansion agent is added to make the concrete expand moderately, change the stress structure inside the concrete, and offset the tensile stress caused by shrinkage during the hardening process of the concrete, thereby avoiding or greatly reducing the cracking of the reinforced concrete structure; a proper amount of high-quality fly ash, slag and other mineral mixing materials are added to reduce the amount of cement, thereby reducing the total hydration heat of cement and reducing the occurrence of cracks; the first one is arranged at the concrete unloading point, mainly to solve the compaction of the upper concrete due to the dense spacing of the bottom skin steel bars; the second one is arranged at the foot of the concrete slope to ensure the compaction of the lower concrete; the third one is in the middle of the slope to ensure the slope and compactness of the concrete, and as the concrete pouring work moves forward, the vibrator also keeps up accordingly to ensure the quality of the concrete of the entire height of the slope formed during pouring, improve the compactness of the concrete, and reduce the gaps between concrete aggregates.

[0021] 2. The concrete anti-cracking and anti-seepage construction method used in sewage treatment plants can reduce the temperature difference between the inside and outside during the heating stage, prevent temperature cracks, prevent the dehydration of the concrete surface and the shrinkage cracks, make the cement hydrate smoothly, and improve the concrete's crack resistance. The wire rods of the exterior wall formwork are loosened 24 hours after pouring the concrete to form a certain gap between the exterior wall formwork and the exterior wall formwork, and then water is poured in the gap for maintenance to avoid excessive evaporation of water on the concrete surface and ensure the humidity of the ground. The pouring sequence is set as "one slope, thin layer pouring, sequential advancement, and one-time to the top" method. This pouring method can better adapt to the pumping process, avoid frequent dismantling, flushing and extension of the concrete delivery pipeline, thereby improving the pumping efficiency, simplifying the water seepage treatment of the concrete, and ensuring that the upper and lower concrete does not exceed the initial setting time. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A flow chart of the structure of the present invention;

[0023] Figure 2A flow chart of the structure of the present invention;

[0024] Figure 3 Flowchart of the structure of the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] See also Figure 1-Figure 3 , a concrete anti-cracking and anti-seepage construction method for a sewage treatment plant, characterized in that it comprises the following steps: selecting late-strength low-heat ordinary Portland cement or coal mine cement with a grade of 42.5 or above;

[0027] Add high-efficiency water reducing agent or composite admixture with high-efficiency water reducing function and high-performance expansion agent in concrete preparation;

[0028] Coarse aggregate: Choose clean coarse aggregate with good natural continuous grading to prepare concrete, and choose 5-25MM continuous grading stone to reduce concrete shrinkage, mud content <0.8%, and needle-shaped and flaky particles in the aggregate <10% by weight;

[0029] Fine aggregate should be medium-coarse sand, and the mud content should be controlled to be less than 2%. The coarse and fine aggregates should be washed to reduce the mud content as much as possible. When the temperature is high, the aggregates should be watered to cool down, and the temperature of concrete leaving the machine and entering the mold should be controlled to be less than 25℃.

[0030] Add high-quality fly ash, slag and other mineral admixtures;

[0031] The maximum water-cement ratio is ≤0.50, the minimum amount of cementitious material is 300 kg / cubic meter and not more than 400 kg / cubic meter. Pumped concrete is used with a sand ratio of 40% to 45%. Under the premise of pumpability, the sand ratio should be reduced as much as possible. The slump should be as small as possible while meeting the pumping conditions. The slump should be around 10 to 12 cm. The initial setting time is 8 hours and the final setting time is 12 hours.

[0032] In this embodiment, a high-efficiency slow-setting water-reducing agent is used to reduce the absolute cement and water consumption, improve the workability and pumpability of concrete, and extend the slow-setting time; a high-performance expansive agent is added to cause the concrete to expand moderately, change the stress structure inside the concrete, and offset the tensile stress caused by shrinkage during the hardening of the concrete, thereby avoiding or greatly reducing the cracking of the reinforced concrete structure; an appropriate amount of high-quality fly ash, slag and other mineral additives are added to reduce the amount of cement, thereby reducing the total hydration heat of cement and reducing the occurrence of cracks.

[0033] Furthermore, the bottom slab pouring is divided into zones according to the post-pouring strips, and a number of pouring strips are determined in each zone. Each pouring strip uses a ceiling pump, a ground pump or a combination of the two according to the actual situation on site, and the number of pumps configured is determined by the volume of concrete poured in each zone.

[0034] In this embodiment, the pouring sequence is set as the method of "one slope, thin layer pouring, gradual advancement, and reaching the top in one time". This pouring method can better adapt to the pumping process, avoid frequent dismantling, flushing and extension of the concrete delivery pipeline, thereby improving the pumping efficiency, simplifying the concrete seepage treatment, and ensuring that the upper and lower concrete does not exceed the initial setting time.

[0035] Furthermore, according to the actual situation that a slope is naturally formed when concrete is pumped, three vibrators are arranged in front, middle and back of each casting zone, the first one is arranged at the concrete unloading point, the second one is arranged at the foot of the concrete slope, and the third one is arranged in the middle of the slope.

[0036] In this embodiment, the first stage is arranged at the concrete unloading point, mainly to solve the compaction of the upper concrete due to the dense spacing of the bottom skin steel bars. The second stage is arranged at the foot of the concrete slope to ensure the compaction of the lower concrete. The third stage is in the middle of the slope to ensure the slope and compactness of the concrete. As the concrete pouring work moves forward, the vibrator also keeps up accordingly to ensure the quality of the concrete of the entire height of the slope formed during pouring, improve the compactness of the concrete, and reduce the gaps between the concrete aggregates.

[0037] Furthermore, during the pouring and vibration process, the upwelling seepage water and floating slurry will flow down the concrete slope to the slope angle pit. Therefore, when constructing the concrete cushion layer, a slope of 1 / 1000 is made along the long direction of the foundation, so that most of the seepage water flows along the slope of the cushion layer to the side of the foundation pit.

[0038] In this embodiment, a slope of 1 / 1000 is made along the long direction of the foundation, so that most of the seepage water flows along the slope of the cushion layer to the side of the foundation pit. At this time, the concrete pouring direction is changed, that is, it is poured back from the other top to intersect with the original slope to form a sump. As the pouring of concrete progresses, the sump gradually shrinks into a pool in the middle. At this time, a submersible pump can be used to drain the accumulated water to an open ditch outside the pit to prevent the accumulation of seepage water.

[0039] Furthermore, after the base plate is poured, the concrete is initially leveled with an aluminum alloy bar, and the wire mesh is laid and fixed with hooked steel bars as the pouring progresses. The surface is smoothed with a wooden trowel in time. After the concrete absorbs water, it is rubbed flat twice with a wooden trowel to close the shrinkage cracks in the concrete surface layer.

[0040] Furthermore, the post-cast joint adopts a quick-closing net. When vibrating the concrete, the vibrating rod is 300 to 500 meters away from the edge of the net. At the same time, attention should be paid to make the concrete slurry emerge from the quick-closing net. The continuous laying thickness exceeds 1m. Multiple discharge ports are arranged around the cylinder to evenly drop concrete. The distance between each discharge port is not more than 4m. During operation, the concrete should be caught quickly and pulled out slowly. The vibration points are arranged in a plum blossom shape. The vibration time at each point is about 40 seconds. The steel at the hidden columns and hidden beams is densely packed to strengthen the vibration.

[0041] In this embodiment, a relatively large opening is left in the simplified shear wall. Before pouring concrete, a vibration hole should be left in advance on the template under the hole. When pouring concrete, a dedicated person should vibrate the concrete below to ensure that the concrete under the opening is dense.

[0042] Furthermore, water storage film maintenance is carried out 8 hours after final setting to reduce the temperature difference between the inside and outside during the heating stage, prevent the formation of temperature cracks, and prevent the concrete surface from dehydrating and causing shrinkage cracks, so that the cement can be hydrated smoothly.

[0043] In this embodiment, the temperature difference between the inside and outside during the heating stage is reduced to prevent the generation of temperature cracks, and the concrete surface can be prevented from dehydrating and generating shrinkage cracks, so that the cement can be smoothly hydrated and the crack resistance of the concrete can be improved. The tension rods of the exterior wall formwork are loosened 24 hours after pouring the concrete to form a certain gap between the exterior wall formwork and the concrete, and then water is sprayed in the gap for maintenance to avoid excessive evaporation of moisture on the concrete surface and to ensure the humidity of the ground.

[0044] Furthermore, crack inspection should be carried out on concrete structures regularly, and cracks should be dealt with in time if found; for crack repair, for cracks with smaller width, surface sealing method can be used for treatment, such as applying waterproof coating, embedding water-stopping materials, etc.; for cracks with larger width, chemical grouting method or pressure grouting method can be used for repair.

[0045] In the description of the present invention, it is necessary to understand that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0046] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0047] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] In the present invention, unless otherwise clearly specified and limited, the first feature "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "one scheme", "some schemes", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the scheme or example are included in at least one scheme or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same scheme or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more schemes or examples in a suitable manner.

[0049] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A concrete anti-cracking and anti-seepage construction method for a sewage treatment plant, characterized in that: The following steps are involved: Use late-strength low-heat ordinary Portland cement or coal mine cement with a grade of 42.5 or above; Add high-efficiency water reducing agent or composite admixture with high-efficiency water reducing function and high-performance expansion agent in concrete preparation; Coarse aggregate: Choose clean coarse aggregate with good natural continuous grading to prepare concrete, and choose 5-25MM continuous grading stone to reduce concrete shrinkage, mud content <0.8%, and needle-shaped and flaky particles in the aggregate <10% by weight; Fine aggregate should be medium-coarse sand, and the mud content should be controlled to be less than 2%. The coarse and fine aggregates should be washed to reduce the mud content as much as possible. When the temperature is high, the aggregates should be watered to cool down, and the temperature of concrete leaving the machine and entering the mold should be controlled to be less than 25℃. Add high-quality fly ash, slag and other mineral admixtures; The maximum water-cement ratio is ≤0.50, the minimum amount of cementitious material is 300 kg / cubic meter and not more than 400 kg / cubic meter. Pumped concrete is used with a sand ratio of 40% to 45%. Under the premise of pumpability, the sand ratio should be reduced as much as possible. The slump should be as small as possible while meeting the pumping conditions. The slump should be around 10 to 12 cm. The initial setting time is 8 hours and the final setting time is 12 hours.

2. The concrete anti-cracking and anti-seepage construction method for a sewage treatment plant according to claim 1, characterized in that: The bottom slab pouring is divided into zones according to the post-pouring strips. Several pouring strips are determined in each zone. Each pouring strip uses overhead pumps, ground pumps or a combination of the two according to the actual situation on site. The number of pumps configured is determined by the volume of concrete poured in each zone.

3. The concrete anti-cracking and anti-seepage construction method for a sewage treatment plant according to claim 1, characterized in that: According to the actual situation that a slope is naturally formed when concrete is pumped, three vibrators are arranged in front, middle and back of each casting belt. The first one is arranged at the concrete unloading point, the second one is arranged at the foot of the concrete slope, and the third one is arranged in the middle of the slope.

4. The concrete anti-cracking and anti-seepage construction method for a sewage treatment plant according to claim 1, characterized in that: During the pouring and vibration process, the upwelling seepage water and floating slurry will flow down the concrete slope to the slope angle pit. Therefore, when constructing the concrete cushion layer, a slope of 1 / 1000 is made along the long direction of the foundation, so that most of the seepage water flows along the slope of the cushion layer to the side of the foundation pit.

5. The concrete anti-cracking and anti-seepage construction method for a sewage treatment plant according to claim 1, characterized in that: After the base plate is poured, the concrete is initially leveled with an aluminum alloy bar. The wire mesh is then laid and fixed with hooked steel bars as the pouring progresses. The surface is smoothed with a wooden trowel in time. After the concrete has absorbed water, it is rubbed flat twice with a wooden trowel to close the shrinkage cracks in the concrete surface layer.

6. The concrete anti-cracking and anti-seepage construction method for a sewage treatment plant according to claim 1, characterized in that: The post-cast joint adopts a quick-closing net. When vibrating concrete, the vibrating rod should be 300 to 500 meters away from the edge of the net. At the same time, attention should be paid to make the concrete slurry emerge from the quick-closing net. The continuous fabric thickness exceeds 1m. Multiple discharge ports are arranged around the cylinder to evenly drop concrete. The distance between each discharge port is not more than 4m. During operation, the concrete should be caught quickly and pulled out slowly. The vibration points are arranged in a plum blossom shape. The vibration time at each point is about 40 seconds. The steel at the hidden columns and hidden beams is densely packed to strengthen the vibration.

7. The concrete anti-cracking and anti-seepage construction method for a sewage treatment plant according to claim 1, characterized in that: Water storage film maintenance is carried out 8 hours after final setting to reduce the temperature difference between the inside and outside during the heating stage, prevent the formation of temperature cracks, and prevent the concrete surface from dehydrating and causing shrinkage cracks, so that the cement can be hydrated smoothly.

8. The concrete anti-cracking and anti-seepage construction method for a sewage treatment plant according to claim 1, characterized in that: Crack inspection: Regularly inspect the concrete structure and deal with cracks in time if found; for crack repair, for cracks with smaller width, surface sealing method can be used for treatment, such as applying waterproof coating, embedding water-stopping materials, etc.; for cracks with larger width, chemical grouting method or pressure grouting method can be used for repair.

Images