GB/T 4752-2002 Construction and operation procedures for household biogas digesters
Some standard content:
ICS_27.180
National Standard of the People's Republic of China
GB/T4752—2002
Replaces GB/T4752--1984
Operation rules for construction ofhousehold anerobie digesters2002-07-02 Issued
Silver Bureau of the People's Republic of China
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
2003-01-01 Implementation
GB/T4752-2002
In 1984, the former State Bureau of Standards issued GB/T4752-1984 "Operational Specifications for Construction of Water-Pressure Biogas Digesters for Rural Households", which was issued and implemented at the same time as GB/T4750-1984 "Standard Atlas of Water-Pressure Biogas Digesters for Rural Households" and GB/T4751-1984 "Quality Inspection and Acceptance Standards for Water-Pressure Biogas Digesters for Rural Households". In order to meet the higher requirements of scientific and technological progress and the needs of sustainable development of biogas industry, and the original "Standard Atlas of Water-Pressure Biogas Digesters for Rural Households" has been revised, this standard, which is implemented as a supporting standard, should also be revised accordingly. After 1990, the state issued some standards on building materials and construction technology for pools. This standard must be revised accordingly to maintain coordination between standards.
This standard retains the contents of GB/T4752-1984 that have been proven to be suitable for my country's current reality, and the following main contents are revised and supplemented:
The sealing layer of the biogas tank and the mortar ratio have been revised and adjusted; the construction chapters and sections of new technologies such as prefabricated reinforced concrete slab assembly biogas tank and separation gas storage flotation cover biogas tank have been added; the reference dosage tables of materials such as cast-in-place concrete meandering material, reinforced concrete slab assembly, cylindrical, ellipsoidal, and separation gas storage flotation cover biogas tank have been added;
Chapters such as reference standards and sealing layer construction (four-layer plastering method) have been added. This standard was proposed by the Science and Technology Education Department of the Ministry of Agriculture. This standard was drafted by the Kunming Rural Energy and Environmental Protection Office, and the Ministry of Agriculture Biogas Research Institute, Hubei Rural Energy Office, Hebei New Energy Office, Chongqing Wanzhou Tiancheng District Construction Committee, Guangxi Gongcheng County Rural Energy Office participated in the drafting. The main drafters of this standard are Zhang Wanjun, Zheng Qishou, Liu Jiali, Huang Chengxin, Zhu Jianxiang, Wang Chengzheng, Li Shujun, and Li Gongtao. This standard is entrusted to the Kunming Rural Energy and Environmental Protection Office for interpretation. The previous versions of the standards replaced by this standard are: GB/T4752-1984. 1 Scope
Construction and operation procedures for household biogas digesters
GB/T4752—2002
This standard specifies the technical requirements and overall acceptance of biogas digester site selection, quality requirements of biogas digester materials, earthwork, construction technology, and biogas digester sealing layer construction.
This standard is applicable to the construction of various biogas digesters designed according to GB/T4750. 2 Normative references
The clauses in the following documents become clauses of this standard through reference in this standard. For all dated references, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, parties to an agreement based on this standard are encouraged to study whether the latest versions of these documents can be used. For all undated references, the latest versions are applicable to this standard GB175—1999 Portland cement, ordinary Portland cement GB1344-1999 Slag Portland cement, pozzolanic Portland cement and fly ash Portland cement GB/T4750—2002 Standard atlas of household biogas digesters GB/T4751-2002 Quality inspection and acceptance specification for household biogas digesters GB5101-1998 Sintered ordinary bricks
GB50164--92
Concrete quality control
JGJ52-1992 Quality standard and test method for sand used in ordinary concrete JGJ53-1992 Quality standard and test method for crushed stone or pebble used in ordinary concrete 3 Construction preparation
3.1 Selection of pool shape According to the technical requirements of GB/T4750, combined with the types, quantities and population of fermentation raw materials provided by users, geological and hydrological conditions, climate, difficulty in selecting pool materials, construction technology level and other characteristics, the pool shape and pool volume should be selected according to local conditions. 3.2 Pool site selection should be done in such a way that the pig pit, toilet and biogas tank are connected to each other so that human and livestock feces can flow into the pool by themselves; the distance between the pool site and the stove should be as close as possible, generally controlled within 25m; try to choose a place that is sheltered from the wind and facing the sun, with solid soil, low groundwater level and convenient discharge. 3.3 Draft a construction plan to determine the construction process according to the pool structure design; prepare enough pool materials; and make technical preparations before construction. 3.3.14m3~10m2 cast-in-place concrete meandering distribution biogas pool material reference table (see Table 1). 3.3.24m3~10m3 prefabricated reinforced concrete slab assembly biogas pool material reference table (see Table 2). 3.3.34m3~10m3 cast-in-place concrete cylindrical biogas pool material reference table (see Table 3). 3.3.44m2~10m3 ellipsoidal biogas pool material reference table (Table 4). 3.3.56m3~10m2 separation air storage flotation cover biogas pool material consumption table (Table 5). 4 Requirements for pool construction materials
4.1 Cement: Portland cement is preferred, and slag Portland cement, pozzolana Portland cement or fly ash Portland cement can also be used. The performance indicators of cement must comply with the provisions of GB175 and GB1344, and cement with a cement strength grade of 325 or 425 is preferred. 4.2 The cement should be delivered to the site with a factory certificate or a test report, and its type, grade, and date of delivery should be inspected and accepted. When there is doubt about the quality of cement or the cement has been delivered for more than three months, the test should be reviewed and used according to the test results. 4.3 The maximum particle size of the gravel shall not exceed one-fourth of the minimum size of the structural section, and shall not exceed one-fourth of the minimum distance between steel bars. For concrete solid slabs, the maximum particle size of the gravel should not exceed one-half of the slab thickness and shall not exceed 20mm to 40mm. Table 14m3~10m3 cast-in-place concrete meander distribution biogas tank material reference consumption table Volume/m3
Volume/m3
Volume/m3
Volume/
Concrete
Cement/kg
Medium sand/m3
Crushed stone/m3
Volume/m
Pool body plastering
Cement/kg
Medium sand/m3
Cement slurry
Cement/kg
Total material consumption
Cement/ kg
4m3~10m3 Prefabricated reinforced concrete slab assembled biogas pool material reference table Concrete
Cement/
Volume/m3
Ellipsoid AI type
Ellipsoid AI type
Zhongsha/
Crushed stone/
Volume/
Pool body plastering
Cement/
Zhongsha/
Cement/
Cement/
Total materials
Zhongsha/
Zhongsha/m2
Crushed stone/m3
Crushed stone Stone/
4m3~10m3 cast-in-place concrete cylindrical biogas tank material reference table concrete
cement/kg medium sand/m2
volume/m
crushed stone/m3
volume/m3
tank body plastering
cement/kg
medium sand/m2
cement slurry
cement/kg
cast-in-place concrete ellipsoidal biogas tank material reference table concrete/m3
cement/kg
sand/m3
stone/m3| |tt||Iron wire/
Total material consumption
Cement/kg
Sodium silicate/kg
Medium sand/m3
Paraffin/kg
Rebar/
Crushed stone/m3
Ellipsoidal BI type
Volume/m3
Concrete/m3
Table 4 (continued)
Cement/kg
Sand/m3
Stone/m
Note 1: All materials in the table are calculated based on the gas production rate of 0.2m2/(m2·d), without loss. Note 2: The volume ratio of plaster mortar is 1:2.5 and 1:3.0 two types, this table is calculated by average. Note 3: The particle size of crushed stone is 5mm~20mm.
Note 4: This table is calculated according to the actual volume.
Sodium silicate/kg
Table 56m3~10m3 separation gas storage flotation cover biogas tank material reference consumption table tank volume/m3
Concrete engineering
Volume/m2|Cement/kg
Medium sand/m3
Pebble/m3
Area/m3
Sealing engineering
Cement/kg
Note: This table is calculated according to the actual volume, without loss; the table does not include the material consumption of manure storage tanks. 4.4
The stones used in biogas tank concrete should comply with the provisions of JGJ53, and the sand used in biogas tank concrete should comply with the provisions of JGJ52, and medium sand should be used. 4.6 Water should be drinking water.
Medium sand/m3
GB/T4752-2002
Paraffin/kg
Cement/kg
4.7 Bricks should be solid bricks, which should comply with the provisions of GB5101. The strength grade of bricks should be above MU7.5.
Medium sand/m
4.8 The strength grade of precast concrete panels should be greater than C15, and the specifications should be the same, the size should be accurate, and the shape should be regular without defects. 4.9 Masonry mortar:
Pebbles/m3
The sand used for mortar should be sieved and should not contain grass roots and other debris. The mix ratio of mortar should be determined by test. The construction mix ratio of mortar should adopt mass ratio, and the strength grade should adopt MU7.5. The allowable deviation of material weighing is ±2%. If mechanical stirring is used for mortar mixing, the mixing time shall not be less than 90s from the time of material addition. For manual mixing, no visible original sand particles shall be found, and the color shall be uniform.
Sand shall be used immediately after mixing, and shall be used up within 3 hours after mixing. If the maximum temperature during construction exceeds 30℃, it shall be used up within 2hc) after mixing.
4.10 Admixtures. Admixtures may be added to biogas tank concrete, and early strength agents and water reducers that can increase the impermeability and strength of concrete are preferably added. They shall comply with relevant standards and can only be used after being tested and meeting the requirements. Air entraining agents and air-entraining water reducers shall not be added. 5 Earthwork
5.1 Pit excavation shall be carried out in accordance with the following conditions
5.1.1 If the pit site has groundwater or not and the soil has natural moisture, the straight wall excavation depth of the pit should be less than the allowable value specified in Table 6; when the pit excavation depth is less than the allowable value in Table 6, the pit may be excavated with straight walls. Table 6 Maximum allowable height of lower wall excavation of pit
In artificial fill and sand
In silt and gravel
In clay
No groundwater, soil with natural moisture/m1.00
With groundwater
GB/T4752—2002
5.1.2 When the pond is built in an area without groundwater, the soil has natural moisture, the soil structure is uniform, and the excavation depth of the pit is less than 5m or when it is built in an area with groundwater and the excavation depth of the pit is less than 3m, the excavation can be carried out by slope according to the provisions of Table 7. Table 7 Pit excavation ratio
5.2 Pit excavation layout
Silty soil
5.2.1 For straight-wall excavation of a pit, in order to save labor and materials, it is advisable to use the pit wall as a mold: Slope
a) For cylindrical and meandering distribution pools, the area above the upper ring beam is laid out according to the slope excavation pit, and the area below the ring beam is laid out according to the requirements of mold forming;
The upper hemisphere of the ellipsoidal pool is generally laid out according to the main pool. The diameter is enlarged by 0.6m and laid out as the construction working surface. The lower hemisphere is laid out according to the geometric size of the pool shape. b)
Prefabricated board biogas pit, according to the geometric size of the biogas pit selected by GB/T4750, plus the backfill soil of 15cm width c)
Lay out. When the soil of the brick biogas pit is good, the bricks are laid close to the pit wall with original mortar, leaving no back tamping position; When laying out the pit, first determine the center pile and elevation reference pile. The center pile and elevation reference pile should be firm and unchanged; d)
The pit should be excavated according to the layout size. The soil formwork should not be disturbed when excavating the pit, and heavy objects and abandoned soil should not be piled on the edge of the pit. If there is water in the ground, drainage measures such as diversion ditches, water collection wells and bottomless glass bottles in meander distribution pools should be adopted to remove the accumulated water in time and divert it away from the construction site; excavation and construction should be done quickly to avoid rainstorms. 5.3 Special foundation treatment
5.3.1 Silt: After the silt foundation is excavated, it should be compacted with large stones, then filled with slag or crushed stone, and then poured with a layer of 1:5.5 cement mortar.
5.3.2 Quicksand: After the quicksand foundation is excavated, the bottom elevation of the pit shall not be lower than 0.5m below the groundwater level. If the depth is greater than 0.5m above the groundwater level, technical measures should be taken to lower the groundwater level outside the pit, or the site should be relocated to avoid it. 5.3.3 Expansive soil or collapsible loess should be replaced with good soil or drainage and waterproofing measures should be set up. 6 Construction of cast-in-place concrete biogas tanks
6.1 Excavation of pits
Large excavation formwork and pouring method. Select the size of the biogas tank according to GB/T4750 and excavate the entire tank. The outer formwork of the tank wall uses the original soil wall; the inner formwork of the tank wall and the tank cover can be steel formwork, brick formwork, wooden formwork, etc. After supporting the formwork, pour the concrete and form it in one go. The concrete pouring should be continuous, uniform and symmetrical, and vibrated and compacted. The tank cover pouring procedure is from bottom to top, and the top surface of the tank cover is compacted and smoothed with the original slurry. 6.2 Formwork
6.2.1 External formwork: The external formwork of the meandering material biogas tank and the cylindrical tank bottom, tank wall and the lower hemisphere of the spherical and ellipsoidal biogas tank. For pits suitable for straight wall excavation, the pit wall is used as the external formwork. 6.2.2 Inner mold: The inner mold of the meandering material biogas tank and the cylindrical tank wall, tank cover and the upper hemisphere of the ellipsoidal biogas tank can be made of steel mold, brick mold or wooden mold. When laying brick molds, the bricks should be watered to keep them moist, keep the inside damp and the outside dry, and prevent mortar leakage from the masonry joints. 6.3 The formwork and its support
should meet the following requirements:
a) Ensure the correct shape, size and corresponding position of each part of the biogas tank structure and components; b) Have sufficient strength, rigidity and stability to reliably withstand the positive pressure and lateral pressure of the newly poured concrete, as well as the loads generated by construction personnel and construction equipment during the construction process; c) The structure is simple and easy to assemble and disassemble, and it is convenient for the binding and installation of steel bars and the pouring and maintenance of concrete and other process requirements; 4
d) The template joints are tight and must not leak mortar.
6.4 Mix ratio of concrete
GB/T4752—2002
6.4.1 The mix ratio of concrete construction shall be determined according to the design concrete strength grade, quality inspection, concrete construction and workability and the requirements of trying to improve its anti-seepage capacity, and shall comply with the principles of reasonable use of materials and economy. 6.4.2 The maximum water-cement ratio of concrete shall not exceed 0.65, and the minimum cement dosage per cubic meter of concrete shall not be less than 275kg. 6.4.3 The slump of concrete shall be controlled within 2cm~4cm during pouring. 6.4.4 The deviation of weighing raw materials of concrete shall not exceed the allowable deviation specified in Table 8. Table 8 Allowable deviation of material weighing
Material name
Stone, sand and gravel
Water, admixture
6.5 Requirements for concrete mixing
Allowable deviation/%
When mechanical mixing is used for concrete mixing, the shortest time shall not be less than 90s. When manual mixing is adopted, the mixed concrete shall be uniform in color and shall not have visible original gravel and sand. 6.6 Inspection of formwork and support
The formwork and its support, steel bars and embedded parts shall be inspected and recorded. Concrete can be poured only after they meet the design requirements. 6.7 Inspection before pouring concrete
The debris in the formwork and the oil stains on the steel bars shall be cleaned up, the gaps and holes in the formwork shall be sealed, and the wooden formwork shall be watered and moistened, but no water shall be accumulated.
6.8 Requirements for concrete pouring
The free height of concrete pouring from a height shall not exceed 2m. 6.9 Requirements for pouring concrete cleaning
When pouring the bottom concrete of the pool, silt and debris shall be removed, and drainage and waterproofing measures shall be taken. Dry non-cohesive soil shall be moistened with water. 6.10 Temperature requirements for pouring concrete
Concrete should not be poured when it is raining or snowing or the temperature is below 0℃. When pouring is required, effective measures should be taken to ensure the quality of concrete. 6.11 Procedure requirements for pouring concrete
The pouring of biogas tank concrete adopts a spiral rising procedure to pour and form it in one go. It is required to be vibrated and compacted, without defects such as honeycombs, pits, cracks, etc., and construction records should be kept.
6.12 Temperature requirements for pouring concrete
After the concrete is mixed, when the temperature is not higher than 25℃, it should be poured within 120 minutes. When the temperature is higher than 25℃, it should be poured within 90 minutes.
6.13 Concrete maintenance
6.13.1 The poured concrete should be covered within 12 hours and watered after 24 hours. Watering is not allowed when the average temperature of the day is below 5℃.
6.13.2 The watering and curing time of concrete shall not be less than 7 days for concrete made of Portland cement, ordinary Portland cement or slag Portland cement, and shall not be less than 14 days for concrete made of volcanic ash, fly ash Portland cement and admixtures. 6.13.3 It is not allowed to step on or install formwork and brackets on the poured concrete before the strength reaches 1.5MPa. 7 Pool bottom construction
First, compact the original soil of the pool foundation, then lay the pebble cushion layer, and pour the cement mortar with a ratio of 1:5.5, and then pour the pool bottom concrete. It is required to vibrate and smooth the pool bottom into a curved shape.
GB/T4752—2002
8Construction of inlet and outlet pipes
Construction of inlet and outlet pipes and water pressure room and backfilling soil should be carried out at the same elevation as the main pool, and attention should be paid to the concrete reinforcement of the inlet and outlet pipes inserted into the pool wall.
9Construction of biogas pools and prefabricated reinforced concrete slabs 9.1 The following should be noted when masonry the wall of a cylindrical biogas pool using the "movable wheel rod method":
a) Bricks should be soaked in water first to keep the surface dry and the inside wet; b) Brick masonry should be horizontal and vertical, with the inner mouth tightly pressed and the outer mouth firmly embedded, the mortar full, and the vertical joints staggered; c) Pay attention to watering and curing the masonry to avoid dehydration of the mortar joints; d) If there is no condition to build close to the pit wall, the backfill soil outside the pool wall should be backfilled densely. The moisture content of backfill soil should be controlled between 20% and 25%, and 30% of crushed stone, lime slag or broken bricks and tiles with a particle size of less than 40mm can be added; symmetrical and uniform backfill and compaction should be carried out, and backfilling should be carried out while masonry is being built.
9.2 Construction of upper ring beam
On the top of the built pool wall, make a mortar leveling layer, and then support the formwork. When using tool-type curved wooden formwork, the concrete should be moved and poured in sections, and it should be tamped and compacted, and smoothed as it is beaten. 9.3 Masonry of pool cover
After the upper ring beam is poured, the pool cover masonry construction should be carried out immediately, or the pool cover can be masonry after the strength of the ring beam concrete reaches 70% of the design strength grade. For brick masonry or small concrete prefabricated block biogas tanks, the "formless suspended masonry arch method" can be used for masonry construction. For the construction of prefabricated board concrete pool cover, the formwork method should be used.
9.4 Precast reinforced concrete slab and assembly construction The concrete pouring mix ratio, curing, and formwork of the precast slab concrete shall be carried out in accordance with the requirements of 6.2, 6.4, and 6.13. 9.5 Precast reinforced concrete slab assembly The construction of the biogas tank is to first pour the bottom ring beam concrete, and then assemble it according to the number of the pool wall and pool arch precast slabs and the position and direction of the inlet and outlet pipes. The key is to pay attention to the verticality and horizontality of each part to meet the requirements, and pay special attention to the firm and dense bonding of the joints. 10 Formwork removal
10.1 When removing the side formwork, the concrete strength should be no less than 40% of the concrete design strength grade. When removing the load-bearing formwork, the concrete strength should be no less than 75% of the concrete design strength grade. 10.2 During the process of removing the formwork, care should be taken to protect the concrete surface and edges from being damaged by removing the formwork. If the concrete is found to have quality problems that affect the structure and impermeability, the removal should be suspended. Removal can be continued after treatment. 11 Backfill soil
Backfill soil should be mainly good soil, and attention should be paid to symmetrical and uniform backfilling and layered compaction. Backfill soil on the arch cover should be carried out after the concrete strength reaches 75% of the design strength grade to avoid local impact. 12 Sealing layer construction
12.1 Base treatment
12.1.1 Treatment of concrete base After the formwork is removed, immediately roughen the surface with a wire brush and rinse it with water before plastering. 12.1.2 When there are uneven surfaces, honeycomb holes and other phenomena on the concrete base, they should be treated according to different situations. 6
Plain ash layer 2mm mortar layer 10mm
Figure 1 Treatment of uneven concrete base
Plain ash 2mm
Mortar layer
GB/T4752—2002
Figure 2 Treatment of holes in concrete base
When the depth of the unevenness is greater than 10mm, first use a drill to chisel it into a slope, brush it with a wire brush and then clean it with water, apply 2mm of plain ash, and then apply a mortar leveling layer (see Figure 1). After applying, sweep the mortar surface horizontally to make it a rough surface. If the depth is large, wait for the mortar to solidify (usually every 12 hours) and then apply 2mm of ash, and then apply mortar until it is flush with the concrete plane. When there are honeycomb holes on the surface of the base, the loose stones should be removed with a drill first, and the edges around the holes should be cut into slopes, cleaned with water, and then 2mm ash and 10mm cement mortar are applied alternately until it is flush with the base, and the last layer of mortar surface is horizontally applied into a rough surface. After the mortar solidifies, a waterproof layer is made together with the concrete surface (see Figure 2). When the honeycomb surface is not deep and the ear stones are firmly bonded, it needs to be rinsed with water, and then 1:1 cement mortar is pressed and smoothed, and the mortar surface is brushed (see Figure 3). For masonry, the masonry joints need to be cut into 1cm deep right-angle grooves (not rounded corners) (see Figure 4). Unqualified joint picking
1:1 cement mortar filling
Figure 3 Concrete base honeycomb treatment
Sub-joint unqualified
Treatment of masonry joints
12.1.2.1 The block base treatment needs to remove the mortar and other dirt left on the surface and rinse with water. 12.1.2.2 After the base treatment is completed, it should be fully soaked with water. 12.2 Four-layer plastering method
Construction requirements of the four-layer plastering method for the rigid anti-seepage layer of the biogas tank (see Table 9) Table 9 Construction requirements of the four-layer plastering method
First layer of plain ash
Second layer of cement mortar
Thickness 10mm
Third layer of cement mortar
Thickness 4~5mm
Water-cement ratio
Cement: sand is
Cement: sand is
Operation requirements
Brush with thick cement slurry.
1: Carry out when the plain ash is initially set, that is, when the plain ash is dry enough to be pressed into the cement slurry layer by fingers for one-fourth to two-tenths, and make the cement mortar thinly pressed into the plain ash layer about one-fourth, so that the first and second layers are firmly combined.
2. Before the cement mortar is initially set, smooth and compact the surface with a wooden trowel. 1. The operation method is the same as the second layer. During the evaporation of water, use a wooden trowel to apply 1 to 2 times in batches to increase the density, and then press it. 2. The interval between each application should be determined according to the humidity, temperature and ventilation conditions at the construction site.
Binding layer
Plays the role of skeleton and protective ashWww.bzxZ.net
Plays the role of skeleton and waterproof.
GB/T 4752—2002
Thickness of the fourth ash layer
Water-cement ratio
12.3 Operation requirements for sealing layer construction
Table 9 (continued)
Operation requirements
1. Use an iron trowel to scrape back and forth twice. First, apply 1mm thick ash as the binding layer to fill the pores of the base layer to increase the bonding force of the waterproof layer. Then, apply 1mm thick ash. The thickness should be uniform. After each scraping of the ash, use rubber or plastic cloth to absorb water in time (rub carefully).
2. Use a wet brush or a row brush to dip the cement slurry and brush it evenly and horizontally on the surface of the ash layer to block and fill the capillary pores and increase the impermeability. Finally, brush the slurry 1 to 2 times to form a sealing layer. Function
Waterproof and sealing function
12.3.1 During construction, it is necessary to apply and compact the layers alternately so that most of the capillary pores of each layer are cut off, so that the remaining small amount of capillary pores cannot form a connected water seepage pore network, and ensure that the waterproof layer has a high anti-seepage and waterproof performance. 12.3.2 During construction, it should be noted that the ash layer and the mortar layer should be completed on the same day. That is, the first two layers of the waterproof layer are basically operated continuously, and the last two layers are operated continuously. Do not leave the ash for too long after applying it or apply cement mortar the next day. 12.3.3 For the surface finishing with ash, the ash layer should be thin and uniform, not too thick, otherwise it will cause accumulation, reduce the bonding strength and easily peel. After finishing, it is not advisable to dryly sprinkle cement powder, so as to avoid the uneven thickness of the ash layer affecting the bonding. 12.3.4 For the cement mortar, use a wooden trowel to press it back and forth to make it penetrate into the ash layer. If it is not pressed thoroughly, it will affect the bonding between the two layers. In the process of kneading and smoothing the mortar, it is strictly forbidden to add water, otherwise the mortar will be unevenly wet and easy to crack. 12.3.5 For the cement mortar, before the initial setting of the cement mortar, when 70% of the water is absorbed (that is, when you press it with your fingers, a little water appears and it is not easy to press into hand marks), you can start the pressing work. Pressing is to smooth and compact it with a wooden trowel. When pressing, the following points should be noted: a) the mortar should not be too wet;
b) pressing should not be too early, but not later than the initial setting; c) pressing should be done with an iron plate instead of scraping with the edge. Pressing is usually done in two passes, the first pass should have a coarse surface, and the second pass should have a fine surface, so that the mortar is dense, strong and not prone to sanding. 13 Construction of coating sealing layer
13.1 The coating shall be a sealing coating that has been identified by the provincial and ministerial levels. The material performance requirements shall be good elasticity and plasticity, non-toxicity, acid and alkali resistance, strong adhesion to the moist base, good elongation, good durability, and can be painted. 13.2 The coating construction requirements and construction precautions shall be carried out in accordance with the instructions for use of the purchased products. 14 Construction of purchased air floating cover
14.1 Welding the floating cover frame: The 1m3~2m2 floating cover frame adopts a DN25 water-gas pipe as a guide sleeve and a DN15 water-gas pipe as a central guide shaft; the 3m3~4m2 floating cover frame adopts a DN4o water-gas pipe as a guide guide and a DN2s water-gas pipe as a central guide shaft. The bottom of the sleeve is 5mm lower than the frame, and the top is 15mm higher than the top of the frame. 14.2 Construction of the top plate of the floating cover: First, level the site, draw a circle 100mm to 150mm larger than the size of the floating cover, use red bricks to level the circumference, lay it regularly, fill the circle with river sand and compact it to form a cone. The height of the cone is: 10mm for 1m3 to 2m2 floating cover; 20mm for 3m3 to 4m3 floating cover. At the air guide pipe, it needs to sink a little to form a cone to enhance the firmness of the air guide pipe. Then lay a layer of plastic film on it, put the floating cover frame on it, calibrate it, and flatten it with 1:2 cement mortar according to the designed thickness of the top plate. When it is initially set, sprinkle cement ash and smooth it repeatedly. Along the edge of the top plate, cut it into a 45° bevel according to the designed size and keep it rough so that it can be firmly glued to the wall of the floating cover. 14.3 Formwork: After the top plate is finally set, use 53mm bricks to form a mold with the inner diameter of the guide sleeve floating cover as the radius. The brick mold should be close to the steel frame, and clay slurry should be used for mortar. When the mold is 100mm~120mm away from the mouth of the floating cover wall, the mold is inclined to the sleeve 20mm~30mm to thicken the mouth of the cover wall. 8
After the mold body is built, use clay slurry to smooth the masonry joints, and brush lime water once after it dries slightly. GB/T4752—2002
14.4 Make the floating cover wall: first cut off the plastic film on the outer edge of the mold according to the outer diameter of the floating cover, clean it, and lay 100mm on the circumferential rough edge of the top plate with 1:2 cement mortar. Then paint from bottom to top along the mold body, with a thickness of 20mm~30mm. The cement mortar should be dry, with a water-cement ratio of 0.4~0.45. The construction cannot be stopped and the painting should be completed at one time. After the cover wall is initially set, sprinkle dry cement ash to compact and polish it to eliminate pores and carry out maintenance. 14.5 Internal seal: After the final setting of the floating cover, remove the brick mold, scrape off the debris on the cover wall, and clean it. At the connection between the top plate and the cover wall, use 1:1 cement mortar to make a 50mm to 60mm high bevel. Use 1:2 cement mortar to press the inner surface of the cover wall once, with a thickness of about 5mm, compact and smooth it to eliminate bubbles and sand holes. After the final setting, brush the cement slurry two to three times to make the cover wall flat and smooth. 14.6 Water seal pool pressure test: Fill the water seal pool with clean water, mark the water level line after the pool body is soaked, and observe for 12 hours. When the water level does not change significantly, it indicates that the water seal pool is not leaking.
14.7 Install the floating cover: After the floating cover has been maintained for 28 days, it can be installed. Move the floating cover to the side of the water seal pool and slowly put it into the water, and exhaust it through the air guide pipe. When the float cover falls to about 200mm from the bottom of the pool, turn off the air guide pipe, install the central guide shaft and guide frame, tighten the nut, and finally expel all the air.
14.8 Float cover pressure test: After installing the float cover, install the pressure gauge on the air guide pipe, then pump air into the float cover, and carefully observe the surface of the float cover to check for leaks. When the float cover rises to the maximum height, stop pumping air, observe steadily for 24 hours, and when the water column difference of the pressure gauge drops within 3%, the anti-seepage performance meets the requirements.
.14.9 Separation of air storage float cover The size of the float cover and water seal tank of the biogas tank is selected as shown in Table 10; the materials of the float cover and water seal tank are shown in Table 11. Table 106 m3 ~ 10 m3 separation gas storage float cover biogas tank and water seal tank size selection table Volume/m3
Gas production rate/
m2/(m2.d)
Inner diameter/mm
2001300
Net depth/mm1300135014001450
Inner diameter/mm10001000
Net height/mm
Total volume/m||tt| |Effective volume
volume/m3
volume,
production project
cement/medium sand/
1150013001400
4501500
1m3～4m3separation air flotation cover biogas tank and water seal tank material reference table slurry
cement/
cement/
Note: The materials in the table do not include the steel consumption of the flotation cover and water seal tank. Overall quality inspection and acceptance
Concrete engineering
Cement/
Volume/
Medium sand/
Pebbles/
0.1400.280
0.2500.500
0.2890.586
Inspect and accept according to GB/T4751. All that meet the requirements can be delivered to users for use. Plastering engineering
14501550
Cement/Medium sand/
Cement/
Nash/
Medium sand/
0.3300.260
0.4660.396
0.5900.500
0.6890.5669 The size selection of the floating cover and water seal tank of the separation gas storage floating cover biogas tank is shown in Table 10; the materials of the floating cover and water seal tank are shown in Table 11. Table 106 m3 ~ 10 m3 separation gas storage floating cover biogas tank and water seal tank size selection table Volume/m3
Gas production rate/
m2/(m2.d)
Inner diameter/mm
2001300
Net depth/mm1300135014001450
Inner diameter/mm10001000
Net height/mm
Total volume/m||tt| |Effective volume
volume/m3
volume,
production project
cement/medium sand/
1150013001400
4501500
1m3～4m3separation air flotation cover biogas tank and water seal tank material reference table slurry
cement/
cement/
Note: The materials in the table do not include the steel consumption of the flotation cover and water seal tank. Overall quality inspection and acceptance
Concrete engineering
Cement/
Volume/
Medium sand/
Pebbles/
0.1400.280
0.2500.500
0.2890.586
Inspect and accept according to GB/T4751. All that meet the requirements can be delivered to users for use. Plastering engineering
14501550
Cement/Medium sand/
Cement/
Nash/
Medium sand/
0.3300.260
0.4660.396
0.5900.500
0.6890.5669 The size selection of the floating cover and water seal tank of the separation gas storage floating cover biogas tank is shown in Table 10; the materials of the floating cover and water seal tank are shown in Table 11. Table 106 m3 ~ 10 m3 separation gas storage floating cover biogas tank and water seal tank size selection table Volume/m3
Gas production rate/
m2/(m2.d)
Inner diameter/mm
2001300
Net depth/mm1300135014001450
Inner diameter/mm10001000
Net height/mm
Total volume/m||tt| |Effective volume
volume/m3
volume,
production project
cement/medium sand/
1150013001400
4501500
1m3～4m3separation air flotation cover biogas tank and water seal tank material reference table slurry
cement/
cement/
Note: The materials in the table do not include the steel consumption of the flotation cover and water seal tank. Overall quality inspection and acceptance
Concrete engineering
Cement/
Volume/
Medium sand/
Pebbles/
0.1400.280
0.2500.500
0.2890.586
Inspect and accept according to GB/T4751. All that meet the requirements can be delivered to users for use. Plastering engineering
14501550
Cement/Medium sand/
Cement/
Nash/
Medium sand/
0.3300.260
0.4660.396
0.5900.500
0.6890.566
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