Colored black iron powder micro-expansion self-compaction bare concrete and construction method thereof

Abstract

The invention belongs to the technical field of concrete, and particularly relates to colored black iron powder micro-expansion self-compaction bare concrete which comprises cement, coal ash, fibers, an expanding agent, fine aggregate, coarse aggregate, black iron powder, an additive and water, the fine aggregate is two-zone shaping medium sand, the coarse aggregate is shaping pebbles, the particle size of the pebbles is 5-20 mm, the black iron powder is continuously graded, and the additive is water. The admixture comprises the following raw materials: a water reducing agent, a viscosity reducer, a slump retaining agent, a workability improving agent, a retarder and a defoaming agent, and the doping amount of the admixture is 2.2%-2.7% of the weight part of the cementing material (cement, fly ash and the expanding agent). The invention further provides a construction method of the colored black iron powder micro-expansion self-compaction bare concrete. The method can reduce and even avoid surface defects of concrete, particularly controls bubbles and colors on the surface of the concrete, controls shrinkage cracks of the bare concrete, has crack resistance, is low in hydration heat, and avoids temperature difference cracks of the bare concrete in the early stage.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete, and in particular relates to a colored black iron powder micro-expansion self-compacting plain concrete and a preparation method thereof. Background Art

[0002] Fair-faced concrete is concrete that directly uses the natural texture of concrete after molding as a finishing effect. Since fair-faced concrete is concrete used as a finishing surface, the requirements for appearance of fair-faced concrete are extremely high. Common appearance defects of existing fair-faced concrete are: surface bubble problem and crack problem. The bubble problem is caused by incomplete discharge of pores inside the concrete, and the crack problem is caused by cracking caused by shrinkage of the concrete itself and temperature difference cracks caused by excessive hydration heat. In order to solve the appearance problem of fair-faced concrete, we propose a colored black iron powder micro-expansion self-compacting fair-faced concrete and a preparation method thereof. Summary of the invention

[0003] The purpose of the present invention is to provide a colored black iron powder micro-expansion self-compacting plain concrete and a preparation method thereof, so as to solve the problems existing in the background technology.

[0004] In order to achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0005] A colored black iron powder slightly expanded self-compacting plain concrete, comprising the following raw materials:

[0006] Cement, fly ash, fiber, expansion agent, fine aggregate, coarse aggregate, black iron powder, admixture, water, among which,

[0007] The fly ash is Grade I fly ash;

[0008] The fine aggregate is machine-made sand and the machine-made sand adopts two-zone shaped medium sand, with a powder content of ≤15%, MB value <1.25, and a fineness modulus of 2.6-2.9;

[0009] The coarse aggregate is shaped stone and the stone particle size is 5-20mm continuously graded;

[0010] The weight proportions of the raw materials of the plain concrete are as follows:

[0011] 300-340 parts of cement;

[0012] 80-90 parts of fly ash;

[0013] 1-3 servings of fiber;

[0014] 30-40 parts of expansion agent;

[0015] 860-900 parts of machine-made sand;

[0016] 880-940 pieces of stone;

[0017] 8 parts of black iron powder;

[0018] 150-170 parts of water;

[0019] The admixtures include the following raw materials: water reducing agent, viscosity reducing agent, slump retaining agent, workability improving agent, retarder, defoaming agent;

[0020] The addition amount of the admixture is 2.2%-2.7% of the weight of the cementitious material (cement, fly ash and expansion agent).

[0021] The mud content of the gravel is not more than 1%, wherein the fine material particle size is 5-10mm and the weight component is 210-270 parts, and the coarse material particle size is 10-20mm and the weight component is 670-730 parts.

[0022] The fiber is a polypropylene fiber with a diameter not greater than 100um and a tensile strength not less than 540Mpa.

[0023] The weight proportion of each raw material of the admixture relative to the cementitious material (cement, fly ash and expansion agent) is:

[0024] Water reducing agent 0.7%;

[0025] Viscosity reducer 0.6%;

[0026] Collapse inhibitor 0.6%;

[0027] Workability improver 0.4%;

[0028] Retarder 0.4%;

[0029] Defoaming agent 0.003%.

[0030] The expansion of the plain concrete is 500 mm-550 mm, the slump is 200±30 mm, and the slump loss value within 120 minutes is less than 20 mm.

[0031] The present invention also provides a construction method of colored black iron powder micro-expansion self-compacting plain concrete, the construction method comprising:

[0032] S1. Inspection before pouring:

[0033] Check the slump of plain concrete, whether the concrete appearance and color are abnormal, whether there is bleeding, and whether there is stratification and segregation;

[0034] Before pouring the plain concrete, the casting formwork should be kept clean and free of water, and the bottom of the formwork should be sealed tightly to prevent leakage;

[0035] S2. Concrete pouring:

[0036] Pour and vibrate the plain concrete according to the construction requirements;

[0037] Specifically, it includes wall casting process and special-shaped shell casting process, among which:

[0038] S2.1, Wall casting process:

[0039] ① The pouring flow starts from the corner. First, pour cement mortar with the same composition as the plain concrete at the root and pour it evenly into the mold with a shovel;

[0040] ② Use the method of layered pouring and layered vibration to fully eliminate the bubbles in the plain concrete;

[0041] S2.2, Casting process of special-shaped shell:

[0042] ① Casting of the shell column foot part shall be carried out in a symmetrical manner by casting the concrete of the shell column foot at the same time;

[0043] ② Shell roof casting: the shell roof is cast by overmolding.

[0044] S3. Concrete curing:

[0045] Within 12 hours after the pouring of plain concrete, it is necessary to carry out thermal insulation and moisture retention maintenance to avoid temperature difference cracks and plastic cracks in the plain concrete.

[0046] The beneficial effects of the present invention are as follows:

[0047] 1. The viscosity reducer and workability improver in the admixture mainly reduce the viscosity of concrete, improve the workability of concrete, and make it easy to remove the pores inside the concrete. Together with the defoamer in the admixture, the generated bubbles can be eliminated, thereby achieving the purpose of reducing bubbles;

[0048] 2. The expansion agent added to the plain concrete can compensate for the shrinkage of the plain concrete, thereby controlling the cracking problem caused by the shrinkage of the concrete itself;

[0049] 3. The machine-made sand adopts two-zone shaped medium sand, with powder content ≤15%, MB value <1.25, and fineness modulus 2.6-2.9, which can reduce the amount of cement and water, thereby reducing the temperature rise of concrete and reducing the shrinkage of concrete;

[0050] 4. The added polypropylene fiber increases the crack resistance of concrete;

[0051] 5. The fly ash added to cement can reduce the hydration heat, improve the workability of concrete and increase the pumpability of plain concrete;

[0052] 6. The gravel is selected with a particle size of 5-10mm and 10-20mm, and the mud content is not more than 1%. The secondary grading is adopted to increase the amount of aggregate and reduce the void ratio. The amount of cement can be appropriately reduced, thereby reducing the total amount of hydration heat release;

[0053] 7. The retarder in the admixture appropriately prolongs the initial setting time of concrete, delays the release of cement hydration heat, reduces the temperature rise of concrete, avoids excessive hydration heat and causes temperature difference cracks in the plain concrete at an early stage, and the addition of fly ash can also increase the strength of the plain concrete after hardening. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The present invention is further illustrated by means of the non-limiting examples given in the accompanying drawings.

[0055] Figure 1 Schematic diagram to verify the effect of fine particle content of manufactured sand on fair-faced concrete;

[0056] Figure 2 Schematic diagram to verify the effect of black iron powder mixed with oil on plain concrete;

[0057] Figure 3 Schematic diagram to verify the effect of different amounts of black iron powder on plain concrete;

[0058] Figure 4 Schematic diagram to verify the appearance of the bare concrete after demoulding;

[0059] Figure 5 This is a schematic diagram of the slump inspection of plain concrete;

[0060] Figure 6 This is a schematic diagram of checking the slump, expansion and fluidity of plain concrete;

[0061] Figure 7 It is a schematic diagram of construction example 2 of the construction process of the present invention. DETAILED DESCRIPTION

[0062] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0063] The present invention provides a color black iron powder micro-expansion self-compacting plain concrete, comprising the following raw materials:

[0064] Cement, fly ash, fiber, expansion agent, fine aggregate, coarse aggregate, black iron powder, admixture, water, among which,

[0065] The fly ash adopts first-grade fly ash;

[0066] The fine aggregate is machine-made sand and the machine-made sand adopts two-zone shaped medium sand, with powder content ≤15%, MB value <1.25, and fineness modulus 2.6-2.9;

[0067] The coarse aggregate is shaped stone with a particle size of 5-20 mm and continuous grading; the mud content of the stone is not more than 1%, wherein the fine material particle size is 5-10 mm and the weight component is 210-270 parts, and the coarse material particle size is 10-20 mm and the weight component is 670-730 parts.

[0068] The weight proportions of each raw material of plain concrete are:

[0069] 300-340 parts of cement;

[0070] 80-90 parts of fly ash;

[0071] 1-3 servings of fiber;

[0072] 30-40 parts of expansion agent;

[0073] 860-900 parts of machine-made sand;

[0074] 880-940 pieces of stone;

[0075] 8 parts of black iron powder;

[0076] 150-170 parts of water;

[0077] Admixtures include the following raw materials: water reducing agent, viscosity reducing agent, slump retaining agent, workability improving agent, retarder, defoaming agent;

[0078] The amount of admixture added is 2.2%-2.7% by weight of the cementitious material (cement, fly ash and expansion agent), of which

[0079] The weight proportion of each raw material of the admixture relative to the cementitious material (cement, fly ash and expansion agent) is:

[0080] Water reducing agent 0.7%;

[0081] Viscosity reducer 0.6%;

[0082] Collapse inhibitor 0.6%;

[0083] Workability improver 0.4%;

[0084] Retarder 0.4%;

[0085] Defoaming agent 0.003%.

[0086] In the implementation process of the present invention, cement needs to be from the same manufacturer, the same brand, and the same strength grade, and other raw materials need to be purchased from the same batch to avoid color difference; the stone particle size is 5-20mm and has a continuous particle size, the color is uniform, the mud content is ≤1%, the mud block content is ≤0.5%, and the needle and flake particle content is ≤15%. The concrete is debugged according to a fixed mix ratio without color difference; the machine-made sand uses two-zone shaped medium sand, and the powder content is required to be ≤15%, the MB value is <1.25, the fineness modulus is 2.6-2.9, and the color is uniform; the fly ash material requires the same manufacturer and the same specification model of Grade I fly ash; the expansion of the plain concrete is 500mm-550mm, the slump of the plain concrete is 200±30mm, the slump should be stable, and the slump loss value within 120min is less than 20mm;

[0087] This type of plain concrete is mainly used to control the appearance of concrete and reduce the appearance defects of plain concrete. Specifically, the purpose of reducing appearance defects is achieved from the following aspects:

[0088] ①Exterior of bare concrete:

[0089] The viscosity reducer and workability improver mainly reduce the viscosity of concrete, improve the workability of concrete, make it easy to remove the pores inside the concrete, and cooperate with the defoamer in the admixture to eliminate the bubbles, thereby achieving the purpose of reducing bubbles, improving the strength of concrete, reducing the number of bubbles on the surface after pouring, and improving the visual quality of concrete. If not added, there will be more bubbles on the surface of concrete after pouring, affecting the overall visual quality and reducing the strength of concrete;

[0090] ②Cracks in plain concrete:

[0091] In order to control the cracking problem caused by the shrinkage of concrete itself, the expansion agent added to the plain concrete can play a role in compensating the shrinkage of the plain concrete. If the expansion agent is not added, the concrete is prone to shrinkage and cracking, leakage occurs, and its use function and durability are reduced;

[0092] The machine-made sand adopts two-zone shaped medium sand, and the high-quality medium sand is selected. The powder content in the sand is ≤15%, the MB value is <1.25, and the fineness modulus is between 2.6-2.9, which can reduce the amount of cement and water, thereby reducing the temperature rise of concrete and reducing the shrinkage of concrete;

[0093] Adding a certain amount of polypropylene fiber can increase the crack resistance and flexural strength of concrete, control the generation and expansion of concrete cracks, and reduce the cracking of concrete. If it is not added, the concrete is prone to shrinkage cracking or stress cracking, leakage occurs, and its use function and durability are reduced;

[0094] At the same time, fly ash mixed with cement can reduce the hydration heat, improve the workability of concrete and increase the pumpability of plain concrete;

[0095] The gravel is selected with a particle size of 5-10mm and 10-20mm, and the mud content is not more than 1%. The secondary grading is adopted to increase the amount of aggregate and reduce the void ratio, which can appropriately reduce the amount of cement, thereby reducing the total amount of hydration heat release;

[0096] The retarder in the admixture appropriately prolongs the initial setting time of concrete, delays the release of cement hydration heat, reduces the temperature rise of concrete, avoids excessive hydration heat and causes temperature difference cracks in the plain concrete at an early stage, and the addition of fly ash can also increase the strength of the plain concrete after hardening.

[0097] ③The color of plain concrete:

[0098] All raw materials of concrete are from the same manufacturer and the same batch to ensure uniform color of raw materials;

[0099] The addition of black iron powder to the plain concrete can adjust the color of the concrete, making its appearance better after demolding;

[0100] ④Strength of plain concrete:

[0101] The viscosity reducer is used to reduce the viscosity of concrete, reduce surface tension, change the sedimentation rate of concrete, ensure the stability of concrete itself, and improve the construction performance of concrete. If it is not added, the viscosity and fluidity of concrete will decrease, the operability of concrete will decrease, quality defects will occur, and the overall construction quality cannot be guaranteed;

[0102] Workability improver is used to improve the workability of concrete, ensure that the slump, expansion and flowability of concrete meet the requirements of on-site construction, and ensure that the concrete itself is stable and easy to construct. If it is not added, the workability of concrete is poor, aggregate separation and water seepage will occur, the flowability is poor, concrete defects are prone to occur, and the quality of plain concrete pouring is affected;

[0103] Water reducer is used to reduce the mixing water consumption, lower the water-cement ratio, reduce the cement dosage, improve fluidity, reduce the shrinkage and cracking of concrete, and increase the strength of concrete. If it is not added, the concrete workability is poor, and hollows, bubbles, and cracks are prone to occur, which reduces the strength of the concrete and fails to meet the on-site fluidity requirements.

[0104] The purpose of retarder is to delay the setting time of concrete, keep the concrete plastic for a longer period of time, adjust the setting time of concrete, give the site enough time for pouring, and reduce the early shrinkage time of concrete and the occurrence of concrete cracks. If it is not added, the shell construction in summer, the temperature is high, the pouring speed is slow, which will directly affect the pouring of concrete and cause early cracking;

[0105] The purpose of adding slump-preserving agent is to maintain the fluidity and workability of concrete, improve the cohesion of concrete, reduce the bleeding of concrete, ensure that the slump of plain concrete is not lost before pouring, and improve and maintain the fluidity of concrete. If it is not added, the slump of concrete will be lost too quickly during transportation, the slump on site cannot be controlled, the slump on site is unstable, and the quality of concrete is affected.

[0106] This paper verifies the influence of various raw materials on the performance of plain concrete:

[0107] 1. The influence of fine particle content of machine-made sand on the performance of plain concrete:

[0108] Two different types of zone 2 medium sand were used for verification, and the test results are as follows:

[0109]

[0110] The concrete exiting the machine with two types of machine-made sand is shown in the figure below. Figure 1 As shown, it can be seen from the test data and the concrete machine images that although the machine-made sands are all medium sands in the second zone with a powder content ≤15%, the concrete state of machine-made sand 2# is obviously better, mainly because the sieve bottom content and stone powder content of machine-made sand 2# are higher than those of machine-made sand 1#; therefore, in the selection of machine-made sand, on the basis of meeting the powder content ≤15%, machine-made sand with higher sieve bottom content and stone powder content is preferred.

[0111] 2. The influence of black iron powder on the performance of plain concrete:

[0112] ①Three different black iron powder samples were selected, among which sample 1# was mixed with carbon powder, sample 2# was black iron powder mixed with oil, and sample 3# was pure black iron powder without impurities. The test results are as follows:

[0113]

[0114] From the above test data and Figure 2 As shown: Sample 1# contains carbon powder, which results in a high amount of concrete admixtures, a large slump loss, and a black concrete color; Sample 2# contains oil stains, so black oil spots will appear on the surface of the concrete after it leaves the machine, seriously affecting the appearance of plain concrete 1; Sample 3# is pure black iron powder without any impurities, and the concrete state and appearance are normal. Therefore, when selecting black iron powder, pure black iron powder without any impurities should be selected.

[0115] ②The influence of black iron powder dosage on the appearance of concrete:

[0116] Different amounts of black iron powder were selected for verification, and the results are as follows Figure 3As shown, it can be seen that: with the increase of black iron powder content, the color of concrete will gradually deepen, so the amount of black iron powder needs to be added in appropriate amounts according to actual needs;

[0117] At the same time, the test was carried out on the bare concrete with black iron powder added to verify the appearance changes of the bare concrete, such as Figure 4 As shown, it can be seen that after the concrete is demolded, the appearance will be further improved. Therefore, the addition of black iron powder can further improve the appearance of the hardened plain concrete to achieve the effect of gray concrete. At the same time, the plain concrete has no bubbles and no cracks.

[0118] 3. Test of admixture dosage of plain concrete:

[0119]

[0120] Since the construction sites have different requirements for the slump and expansion of concrete, concrete tests with different admixture dosages are carried out before each concrete pouring. Based on the test data, the concrete is factory-controlled according to the slump and expansion required by the construction site. The plain concrete is required to have good workability, the slump should be controlled within 10S, and there should be no water seepage during the concrete placement process.

[0121] Based on the above technical solution, the following preparation example is formed:

[0122] Preparation Example 1:

[0123] Table of ingredients of raw materials for plain concrete:

[0124]

[0125] The test was conducted according to JGJ55-2011, and the data are as follows:

[0126]

[0127] Conclusion: It meets the C40 strength requirement, the P6 impermeability grade requirement and the slump requirement of 200±30mm. Preparation Example 2:

[0128] Table of ingredients of raw materials for plain concrete:

[0129]

[0130] The test was conducted according to JGJ55-2011, and the data are as follows:

[0131]

[0132]

[0133] Conclusion: It meets the C40 strength requirement, the P6 water resistance grade requirement and the slump requirement of 200±30mm.

[0134] In Preparation Example 1 and Preparation Example 2, the admixture components are as follows:

[0135] Serial number name Specifications Addition amount (ratio to cementitious material) Remark 1 Water reducing agent NJ400 0.7％ 2 Viscosity reducer PC-1 0.6％ 3 Collapse inhibitor PT6407 0.6％ 4 Workability Improver PT-E 0.4％ 5 Retarder Polycarboxylic acid series 0.4％ 6 Defoaming agent Model 912Z 0.003％

[0136] Based on the above technical solution, the present invention also provides a construction method of colored black iron powder micro-expansion self-compacting plain concrete, the construction method comprising:

[0137] S1. Inspection before pouring:

[0138] Check the slump of plain concrete, whether the concrete appearance and color are abnormal, whether there is bleeding, and whether there is stratification and segregation;

[0139] Before pouring the plain concrete, the casting formwork should be kept clean and free of water, and the bottom of the formwork should be sealed tightly to prevent leakage;

[0140] S2. Concrete pouring:

[0141] The plain concrete is poured and vibrated according to the construction requirements, including the wall pouring process and the special-shaped shell pouring process, among which:

[0142] S2.1, Wall casting process:

[0143] ① The pouring flow starts from the corner. First, pour cement mortar with the same composition as the plain concrete at the root and pour it evenly into the mold with a shovel;

[0144] ② Use the method of layered pouring and layered vibration to fully eliminate the bubbles in the plain concrete;

[0145] S2.2, Casting process of special-shaped shell:

[0146] ① Casting of the shell column foot part shall be carried out in a symmetrical manner by casting the concrete of the shell column foot at the same time;

[0147] ②Casing of the shell roof: the shell roof is cast by overmolding;

[0148] S3. Concrete curing:

[0149] Within 12 hours after the pouring of plain concrete, it is necessary to carry out thermal insulation and moisture retention maintenance to avoid temperature difference cracks and plastic cracks in the plain concrete.

[0150] The following is a construction example for reference:

[0151] Construction example 1, taking a construction site as an example:

[0152] 1. Inspection before pouring:

[0153] Strictly implement the concrete delivery inspection system, and the personnel at the commercial concrete mixing station shall inspect each truckload to the personnel assigned by the on-site concrete foreman. The clear concrete entering the construction site shall be checked for slump, concrete appearance and color, presence of water seepage, and no stratification or segregation.

[0154] ① Such as Figure 5 As shown, the slump check is:

[0155] Place the slump bucket on a flat surface (can be an iron plate or a wooden board), pour clear water concrete into the bucket, and tamp it every time it reaches a height of about 100mm;

[0156] Pour in three layers, tamp evenly 25 times with a tamping rod after each layer is filled, and smooth it out after tamping;

[0157] Then pull up the bucket, lift the slump bucket and place it aside, let the plain concrete collapse naturally, place a straight ruler on the mouth of the bucket, and then use a ruler or tape measure to measure the height from the mouth of the bucket to the highest point of the plain concrete, which is the slump. The vertical lifting process of the slump bucket should be completed within 5s-10s; the entire process from starting to load to lifting the slump bucket should be carried out uninterruptedly.

[0158] ② If Figure 6 As shown, the standard method for identifying the appearance of plain concrete is:

[0159] The surface does not seep water, and the fluidity (collapse) lasts about 10 seconds;

[0160] When spreading the plain concrete, it is best to expose one third of the stones;

[0161] The plain concrete does not stratify or segregate, the shovel does not feel like it is sinking to the bottom, and it is easy to turn over.

[0162] 2. Wall concrete pouring:

[0163] ① The pouring direction of the wall's plain concrete starts from the corner. First, pour 30mm thick cement mortar with the same composition as the plain concrete at the root, and evenly pour it into the mold with a shovel. Be careful not to use a bucket or pumping pipe to pour it directly into the formwork, so as to avoid the mortar splashing onto the formwork and solidifying, resulting in spots on the surface of the plain concrete after demolding. Note that the mortar should not be laid too early or too open, so as to avoid the formation of cold joints between the mortar and the plain concrete, which will affect the appearance. The material should be poured while the mortar is poured;

[0164] ② Use a Φ50 vibrating rod to vibrate the plain concrete. When pouring the plain concrete, use a ruler to control the layer thickness, feed and vibrate the concrete in layers;

[0165] The pouring thickness of each layer of plain concrete should be strictly controlled within 500mm. The vibration points of plain concrete should be distributed from the middle to the edge, and the rods must be evenly distributed, interlocked, and should be carried out continuously with pouring;

[0166] The upper layer of plain concrete should be vibrated before the lower layer of plain concrete begins to set. The vibrator should be inserted into the lower layer 50-100mm. When vibrating, attention should be paid to "insert quickly and withdraw slowly". The vibration time is generally controlled at about 20s to 30s. The surface of the upper layer of plain concrete should be based on the appearance of floating slurry, no longer sinking, and no more bubbles.

[0167] ③ The vibrating rod twitches slightly up and down during the vibration process, and the upper and lower clear water concrete vibrates evenly, so that the bubbles in the clear water concrete fully float up and dissipate;

[0168] ⑤ When vibrating with a vibrating rod, in order to reduce bubbles on the surface of the plain concrete, after the first vibration is completed, the plain concrete should be vibrated for the second time before pouring the upper layer of plain concrete;

[0169] ⑥ The interval between two pourings of clear water concrete should not exceed 30 minutes; before the second pouring, the 50-100mm thick clear water concrete layer on the top of the lower clear water concrete should be re-vibrated to combine the two pours of clear water concrete into a dense whole. At the same time, it should be noted that if the vibration sinking of the vibrating rod can no longer penetrate the lower clear water concrete, the second layer of clear water concrete cannot be poured directly, and joint treatment should be carried out;

[0170] ⑦ During the vibration process, avoid prying the formwork and steel bars. The vibration time of each vibration point should be until the surface of the clear water concrete no longer sinks and no bubbles escape;

[0171] ⑧ The time from the completion of mixing of the clear water concrete mixture to entering the mold should not exceed 90 minutes. It is strictly forbidden to add water or admixtures other than those in the mix ratio.

[0172] Construction Example 2: Figure 7 Take the casting of special-shaped shell in a certain place as an example:

[0173] ① Casting of the shell column foot part shall be carried out in a symmetrical manner by casting the concrete of the shell column foot at the same time;

[0174] Specific pouring construction requirements are as follows:

[0175] a) Before pouring concrete, open the vibrator in advance and then pour;

[0176] b) Drainage holes are opened at the base of the shell, and the plain concrete panel is fully moistened by water 2 hours before pouring concrete;

[0177] c) When pouring, pour the concrete at the base of the symmetrical shell column at the same time to reduce the impact of the horizontal thrust on the shell during pouring;

[0178] d) When pouring concrete, lay plastic film on the inner formwork to prevent concrete from contaminating the upper formwork;

[0179] e) Layered pouring, the steel bars need to be corrected after each pouring;

[0180] f) For the densely reinforced area at the bottom of the shell, a 150*150 vibration opening with a spacing of 1000mm is opened on the outer template, and fine stone concrete is poured at the bottom;

[0181] g) To ensure compaction, the vibration points of the shell wall are increased and moved at a distance of about 500mm;

[0182] ②Casing of the shell roof: the shell roof is cast by overmolding;

[0183] Since the curvature of the special-shaped shell is large, the curvature is different, there are structures such as hidden beams, and the steel bars are dense, in order to avoid quality defects such as honeycomb dog holes, the specific pouring construction requirements are as follows:

[0184] a) Set a 300mm*200mm feed opening and vibrating opening on the roof shell, with a horizontal spacing of 1000mm and a vertical spacing of 3000mm; Figure 7 As shown, the B shell material discharge port and vibration port are set at the roof area B and the fourth construction section of the inner facade column foot, and the A shell material discharge port and vibration port are set at the roof area and the fifth construction section of the inner facade column foot.

[0185] b) A 500mm high discharge funnel is set at the discharge port, and protective agent is used to repair the weakened vibration port in the later stage.

[0186] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A color black iron powder micro-expansion self-compacting plain concrete, characterized by: Including the following ingredients: Cement, fly ash, fiber, expansion agent, fine aggregate, coarse aggregate, black iron powder, admixture, water, among which, The fly ash is Grade I fly ash; The fine aggregate is machine-made sand and the machine-made sand adopts two-zone shaped medium sand, with a powder content of ≤15%, MB value <1.25, and a fineness modulus of 2.6-2.9; The coarse aggregate is shaped stone and the stone particle size is 5-20mm continuously graded; The weight proportions of the raw materials of the plain concrete are as follows: 300-340 parts of cement; 80-90 parts of fly ash; 1-3 servings of fiber; 30-40 parts of expansion agent; 860-900 parts of machine-made sand; 880-940 pieces of stone; 8 parts of black iron powder; 150-170 parts of water; The admixtures include the following raw materials: water reducing agent, viscosity reducing agent, slump retaining agent, workability improving agent, retarder, defoaming agent; The addition amount of the admixture is 2.2%-2.7% of the weight of the cementitious material (cement, fly ash and expansion agent).

2. The color black iron powder micro-expansion self-compacting plain concrete according to claim 1, characterized in that: The mud content of the gravel is not more than 1%, wherein the fine material particle size is 5-10mm and the weight component is 210-270 parts, and the coarse material particle size is 10-20mm and the weight component is 670-730 parts.

3. The color black iron powder micro-expansion self-compacting plain concrete according to claim 2, characterized in that: The fiber is a polypropylene fiber with a diameter not greater than 100um and a tensile strength not less than 540Mpa.

4. The color black iron powder micro-expansion self-compacting plain concrete according to claim 3, characterized in that: The weight proportion of each raw material of the admixture relative to the cementitious material (cement, fly ash and expansion agent) is: Water reducing agent 0.7%; Viscosity reducer 0.6%; Collapse inhibitor 0.6%; Workability improver 0.4%; Retarder 0.4%; Defoaming agent 0.003%.

5. The color black iron powder micro-expansion self-compacting plain concrete according to claim 4, characterized in that: The expansion of the plain concrete is 500 mm-550 mm, the slump is 200±30 mm, and the slump loss value within 120 minutes is less than 20 mm.

6. A construction method of colored black iron powder micro-expansion self-compacting plain concrete, comprising the colored black iron powder micro-expansion self-compacting plain concrete according to any one of claims 1 to 5, characterized in that: The construction method comprises: S1. Inspection before pouring: Check the slump, expansion, collapse time of the plain concrete, whether the concrete appearance and color are abnormal, whether there is bleeding, and whether there is stratification and segregation; Before pouring the plain concrete, the casting formwork should be kept clean and free of water, and the bottom of the formwork should be sealed tightly to prevent leakage; S2. Concrete pouring: Pour and vibrate the plain concrete according to the requirements of Construction 2; S3. Concrete curing: Within 12 hours after the pouring of plain concrete, it is necessary to carry out thermal insulation and moisture retention maintenance to avoid temperature difference cracks and plastic cracks in the plain concrete.

7. The construction method of a colored black iron powder micro-expansion self-compacting plain concrete according to claim 6, characterized in that: The "concrete pouring" specifically includes the wall pouring process and the special-shaped shell pouring process, wherein: S2.1, Wall casting process: ① The pouring flow starts from the corner. First, pour cement mortar with the same composition as the plain concrete at the root and pour it evenly into the mold with a shovel; ② Use the method of layered pouring and layered vibration to fully eliminate the bubbles in the plain concrete; S2.2, Casting process of special-shaped shell: ① Casting of the shell column foot part shall be carried out in a symmetrical manner by casting the concrete of the shell column foot at the same time; ② Shell roof casting: the shell roof is cast by overmolding.

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