Concrete composite for quay barrel foundations

Abstract

The present invention provides a concrete compound for a barrel foundation in a dock, comprising the following raw materials: cement, sand, crushed stone, water, admixture, fly ash, mineral powder and water reducing agent, wherein the water-cement ratio of the compound is 0.35, the sand ratio is 42, the slump is 160-220 mm, and the expansion is 500±50 mm; the raw materials are mixed to obtain a concrete compound, and the concrete compound is stirred to obtain a pouring liquid for pouring a barrel foundation, the height of the barrel foundation is greater than 21 m, and during the barrel foundation curing, the inner side is cured by curing liquid and the outer side is cured by spraying water; the chloride ion content of the mixture of the concrete compound is ≤0.10%, and the electric flux (56d) is ≤1000C. The present invention adjusts the proportion, etc., so that the concrete compound meets the set requirements and meets the use of tall barrel foundations.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete composites, and in particular to a concrete composite for a barrel foundation in a dock. Background Art

[0002] In the prior art, there are many concrete composites for bucket foundations, but when the bucket foundation is larger, the strength of the concrete also changes. Most of the existing concrete is used for pouring low bucket foundations, and thus there is a lack of concrete composites for pouring higher bucket foundations. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a concrete composite for a bucket foundation in a dock to solve the above technical problems.

[0004] In order to solve the above technical problems, the technical solutions provided by the present invention are as follows:

[0005] The concrete compound used for the barrel foundation in the wharf includes the following raw materials: cement, sand, crushed stone, water, admixture, fly ash, mineral powder and water reducing agent. The water-cement ratio of the compound is 0.35, the sand ratio is 42, the slump is 160-220mm, and the expansion is 500±50mm;

[0006] The raw materials are mixed to obtain a concrete compound, and the concrete compound is stirred to obtain a pouring liquid for pouring a bucket foundation, wherein the height of the bucket foundation is greater than 21 m, and during the maintenance of the bucket foundation, the inner side is maintained by a curing liquid, and the outer side is maintained by spraying water;

[0007] The chloride ion content of the mixture of the concrete composite is ≤0.10%, and the electric flux (56d) is ≤1000C.

[0008] Furthermore, it also includes cementitious materials, the mass of which is 430kg, including 233kg-258kg of cement, 77kg-86kg of fly ash, 77kg-86kg of mineral powder, 769kg-776kg of sand, 1062-1072kg of crushed stone, 6.45kg of admixture, 147kg-150kg of water, and 43kg of water reducer.

[0009] Furthermore, the water reducing agent is compounded with a defoamer and combined with an air entraining agent. During use, inferior bubbles in the concrete are first eliminated, and then uniform bubbles are introduced to ensure the workability of the concrete.

[0010] Furthermore, after adding the air entraining agent to the water reducing agent, the air content is 2.0%-3.0%.

[0011] Furthermore, after the pouring liquid is poured, the slump loss over time is 10mm-20mm in 1h, and the initial setting time is extended to 8h to ensure that the pouring time of the lower barrel single-layer integral concrete is before the initial setting time.

[0012] Furthermore, the demolding time of the concrete is initially intended to make the demolding strength reach 7-8Mpa.

[0013] Furthermore, the barrel foundation comprises at least an upper barrel body and a lower barrel body, and the upper barrel body and the lower barrel body each comprise at least three casting layers, and in the three casting layers, the casting height of a single layer is 3-5m.

[0014] Furthermore, the barrel foundation forms a casting cavity by a tall formwork, the tall formwork is a steel formwork, and the demolding time of the concrete is such that the demolding strength reaches 7-8Mpa.

[0015] The present invention has the following beneficial effects:

[0016] The present invention adjusts the mix ratio, etc., so that the concrete compound meets the set requirements and meets the use of the tall bucket foundation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of the barrel foundation provided by the present invention;

[0018] In the figure:

[0019] 100, lower barrel body; 200, upper barrel body. DETAILED DESCRIPTION

[0020] The present invention is described in detail below in conjunction with the various embodiments shown in the accompanying drawings, but it should be noted that these embodiments are not limitations of the present invention, and any equivalent transformations or substitutions in functions, methods, or structures made by ordinary technicians in the field based on these embodiments are all within the scope of protection of the present invention.

[0021] See attached Figure 1 As shown, the case in the present invention is used in a local confidentiality project, and the specific case is introduced as follows:

[0022] First, the project introduction.

[0023] This project is located in a certain operating area of ​​Shanghai International Shipping Center. The container terminal project workboat terminal adopts barrel foundation and the components are produced in the prefabrication plant.

[0024] See attached Figure 1As shown, the barrel foundation in this embodiment consists of a lower barrel body 100 and an upper barrel body 200. The long axis of the lower barrel body 100 is 40 / 36.6m, the short axis is 20m, the height is 10-14m, the outer barrel wall thickness is 400mm, the lower barrel top cover plate thickness is 300mm, and the cast-in-place surface layer is 200mm. The barrel is divided into 15 / 12 compartments by partitions, and the partition thickness is 300mm. There are 2 partitions arranged along the long axis direction of the barrel body and 4 / 3 partitions arranged along the short axis direction.

[0025] The upper barrel body 200 is rectangular, 20m long, 14m / 13.6m wide, 9-12.5m high, the outer barrel body wall thickness is 400mm, and the barrel body is divided into 6 compartments by 3 partitions, and the partition thickness is 300mm.

[0026] In this embodiment, taking the highest barrel foundation lower barrel 14m + upper barrel 12.5m as an example, the barrel foundation is manufactured in layers on a production pedestal, and concrete is poured 7 times from bottom to top, including 3 times for the lower barrel body, 1 time for the top cover plate and 3 times for the upper barrel body.

[0027] The lower barrel body is divided into 3 layers. The steel bars are tied on the pedestal in sequence and then cast in the formwork. The top plate of the lower barrel adopts the composite plate construction process. After the prefabricated plate is installed, the cast-in-place surface layer is carried out. The upper barrel body steel bars are hoisted onto the lower barrel body after the overall tying in the special area, and cast in 3 layers.

[0028] The lower barrel body is layered as follows: the first layer is 5.3m, the second layer is 4m, and the third layer is 4.2m. It is constructed to the bottom of the cover plate. After the prefabricated cover plate is installed, a 0.5m cast-in-place cover plate layer is poured. The upper barrel body is poured in 3 layers, the first layer is 2m, the second layer is 5.25m, and the third layer is 5.25m.

[0029] During pouring, the first pouring layer to the seventh pouring layer are formed sequentially from bottom to top.

[0030] Next, the concrete composite in this embodiment is introduced.

[0031] The concrete structures of this project all use high-durability concrete. High-durability concrete should have high resistance to chloride ion penetration, high dimensional stability and good workability; it should comply with the relevant provisions of the "Water Transport Engineering Concrete Quality Control Standard", "Water Transport Engineering Concrete Construction Specification" and "Water Transport Engineering Structure Durability Design Standard".

[0032] The relevant technical requirements for adding harbor concrete anti-corrosion enhancer (CPA) to the barrel cover plate under the barrel foundation and the concrete structure above are as follows:

[0033] a. Specific surface area ≥ 300m2 / kg.

[0034] b. Setting time: initial setting time ≥ 45 minutes, final setting time ≤ 10 hours.

[0035] c. Standard test limit expansion rate (10% internal doping): 7 days in water> 0.025%; 21 days in air> -0.015%.

[0036] d. Compressive strength ratio: According to the strength test method of GB / T 50081, the 7-day strength ratio shall be ≥90%; the 28-day strength ratio shall be ≥100%.

[0037] e. Chloride ion permeability resistance (C) <1000 coulomb.

[0038] f. The dosage of anti-corrosion enhancer is 40kg / m3.

[0039] Laboratory mix ratio:

[0040] According to the design requirements, after raw material comparison and mix trial, the mix ratio is determined as shown in Table 1 below. The lower barrel structure adopts the 1# mix ratio, and the lower barrel cover plate and the above concrete structure adopt the 2# mix ratio.

[0041] Table 1;

[0042]

[0043] In this embodiment, the mixing ingredient list for the concrete composite is shown in Table 2.

[0044] Table 2:

[0045]

[0046] In this embodiment, a mix ratio design report is conducted for the examples in Table 1 to obtain Table 3.

[0047] Table 3:

[0048]

[0049] It can be seen from Table 3 that the technical conditions obtained by the entire ratio meet the requirements.

[0050] Again, this embodiment also includes research on optimization of mix ratio, etc., as follows: 1) Research on the quality of raw materials.

[0051] The requirements for raw sand (mechanical sand) are shown in Table 4:

[0052] Table 4;

[0053]

[0054]

[0055] The requirements for raw material gravel are shown in Table 5:

[0056] Table 5

[0057]

[0058] The requirements for raw material gravel are shown in Table 6:

[0059] Table 6

[0060]

[0061] The requirements for raw fly ash are shown in Table 7:

[0062] Table 7

[0063]

[0064]

[0065] The requirements for raw mineral powder are shown in Table 8:

[0066] Table 8

[0067]

[0068] The concrete mix ratio used in the bucket foundation is shown in Table 9 below (kg / m 3 );

[0069] Table 9

[0070]

[0071] The water reducer in this embodiment is GTS-501 high performance polycarboxylate water reducer series, which is a new type of high performance water reducer and is a green environmentally friendly product. Compared with other types of water reducers, it has the advantages of good compatibility with cement, ultra-high water reduction rate, small slump loss, high compressive strength ratio, denser concrete, bright surface, high durability, etc. It is suitable for high performance concrete, high strength concrete, self-compacting concrete, and large admixture concrete. Polycarboxylate water reducer is mainly suitable for railway and highway precast beams, cast-in-place beams, large cylinders, nuclear power plants, high-grade concrete for industrial and civil buildings, and concrete with special requirements for appearance.

[0072] The technical performance of the water reducing agent in this embodiment:

[0073] 1. The water reduction rate of polycarboxylate water reducer can reach more than 25%, and the cement paste fluidity is ≥230mm;

[0074] 2. The setting time of concrete can be adjusted according to construction requirements; the slump is basically free of loss in 1 hour;

[0075] 3. Concrete mixed with polycarboxylate water reducer can save 15-20% of cement under the condition of the same performance, and effectively control the shrinkage and creep of concrete in the later stage;

[0076] 4. The early strength of concrete mixed with polycarboxylate water reducer develops quickly, and the later strength is significantly improved;

[0077] 5. The addition of polycarboxylate water-reducing agent can effectively reduce the water-cement ratio of concrete, effectively control the shrinkage of concrete in the later stage, as well as the frost resistance and durability of concrete, and improve the steam-cured strength of concrete;

[0078] 6. Concrete mixed with polycarboxylate water reducer can achieve solid inside and bright outside, with enhanced anti-seepage ability and bright surface. It greatly improves the visual effect of concrete and the ability of the surface to resist soft water scouring;

[0079] 7. This product does not contain chloride salts and has no corrosion effect on steel bars; the content of sodium sulfate and alkali is low.

[0080] Polycarboxylate water-reducing agent products must be stored in plastic tanks at the construction site and added to concrete after measurement and stirred for 2 to 5 minutes. The dosage is 1.0-1.5% of the mass of the cementitious material.

[0081] The design of the concrete mix ratio of the bucket foundation has not yet been optimized. The main reason is that the strength of the bucket foundation concrete on site is significantly different from the strength of the standard curing room test block in the laboratory. The 28d compressive strength of the standard test block concrete reaches (50-60)Mpa, and the 28d rebound strength of the on-site structural entity concrete is 40-45Mpa. The deviation is 10-15Mpa.

[0082] The study found that the appearance quality of the prefabricated barrel foundation at this stage has obvious black and white stratification, black and white defects of the ring structure body, sand lines from top to bottom in the structure, concrete surface sticking to the mold, bubbles and other quality defects. We are about to enter the summer concrete construction. For the high formwork and thin-walled concrete structure of the barrel foundation, the summer formula optimization of the concrete mix ratio is required, mainly the concrete collapse resistance, workability, initial setting time, final setting time, and concrete trial mixing issues such as determining the demolding strength according to the on-site demolding time. In order to solve the appearance quality defects of the barrel foundation and meet the evaluation standards. The cementitious materials of the concrete mix ratio will not be optimized for the time being, and the concrete mix ratio design will be optimized after the rebound strength of the on-site solid structure reaches a stable level.

[0083] In this embodiment, in order to solve the problem of obvious black and white boundary stratification of bucket foundation, the collapse protection performance, initial setting time and final setting time of concrete mix ratio can be optimized. At present, the concrete collapse loss of bucket foundation is relatively large, and the collapse loss of concrete mixture in 30 minutes is about (40-60) mm, the initial setting time is 5h30min-6h, and the final setting time is 7h-7h30min. In addition, the initial setting time will be further shortened by the influence of external weather temperature. According to the performance indicators of concrete mixture at this stage, it is planned to improve the collapse protection performance of concrete mixture, and the slump loss over time in 1h is 10mm-20mm, and the initial setting time is extended to 8h to ensure that the pouring time of the single-layer integral concrete of the lower bucket is before the initial setting time.

[0084] In this embodiment, the solution for the concrete bonding formwork of the bucket foundation is as follows:

[0085] 1) The concrete structure bonding formwork is considered from four aspects;

[0086] 2) Improve the demoulding strength of concrete;

[0087] 3) The barrel foundation has a high and large formwork with strong adhesion. The compressive strength is measured by the test blocks under the same conditions on site. The compressive strength is 4.8Mpa when the formwork is removed for 16 hours. It is planned to increase the strength by (2-3)Mpa according to the on-site conditions and observe the effect without extending the time.

[0088] 4) Release agent: Missing or insufficient application of release agent will cause concrete to stick to the mold.

[0089] For the concrete formwork solution for bucket foundation, four aspects are considered for concrete structure formwork:

[0090] 1) Delay the demoulding time of concrete

[0091] 2) After optimizing the concrete mix ratio slump time, initial setting time, and final setting time, it is recommended to delay the demolding time as much as possible (if the formwork turnover conditions are met, delay it by 4-6 hours after the initial setting time of the concrete is optimized) to improve the early strength of the concrete. Delaying the demolding time is also very beneficial to the growth of the mid- and late-stage strength of the concrete.

[0092] 3) Stainless steel formwork: After polishing, the stainless steel formwork has enhanced adhesion due to the oxide layer on its surface, so consider using formwork paint.

[0093] Solutions for bubbles on the surface of barrel foundation:

[0094] 1) Compound water reducer with defoaming ingredients

[0095] 2) Add defoaming agent to the water reducer and combine it with the air entraining agent in a certain proportion to first eliminate the inferior bubbles in the concrete, and then introduce uniform bubbles to ensure the workability of the concrete. It is recommended to control the air content at 2.0%-3.0%.

[0096] 3) Influence of ammonia in fly ash: There is a certain amount of ammonia gas in the fly ash in the concrete raw materials of this project, which will produce a large number of inferior bubbles. In addition to the compound defoaming agent, the slump of the concrete mixture is guaranteed to be certain when it leaves the machine and the collapse of the concrete is strictly controlled, so that harmful bubbles can be discharged as much as possible before pouring, and the discharge of bubbles is facilitated during the pouring and vibration process.

[0097] 4) Casting and vibration process: Casting and vibration shall be carried out strictly in accordance with the requirements of the construction team, and no missing or insufficient vibration is allowed. Many large bubbles were found on site, showing an elliptical upward discharge trend, but due to insufficient vibration, the bubbles were not discharged.

[0098] 5) Release agent: The release agent should be applied evenly. The outer wall of the barrel foundation should use a water-based release agent. The application of the release agent should be carefully checked before closing the mold.

[0099] Solution to the ring strip defect of barrel foundation:

[0100] 1) Vibration technology: The single-layer pouring height of the barrel foundation concrete is 5m, the first layer of the lower barrel is 4m and the wall thickness is 30cm. Excluding the thickness of the steel bar protective layer and the thickness of the longitudinal and transverse steel bars, the barrel wall can be vibrated to a width of about 16cm. The diameter of the 70-type vibrating rod is 70mm, which is very easy to touch the steel bars, increasing the water-cement ratio of the concrete near the steel bars. The moisture of the barrel wall concrete migrates to the vicinity of the steel bars, resulting in a decrease in the water-cement ratio of the concrete near the steel bars on the outer surface, resulting in the appearance of linear black marks. It is recommended to optimize the vibration technology so that the vibrating rod does not touch the steel bars.

[0101] 2) Stainless steel formwork: According to the surface comparison of the bucket foundation cast at the workboat dock, this type of ring-shaped strip defects did not appear when the steel formwork was used instead of the stainless steel formwork. It is suspected that the ring-shaped strip defects of the bucket foundation were caused by the combined effect of the stainless steel formwork and the vibration process. The ring-shaped strip defects are mainly distributed about two meters above the lower part of the bucket foundation, and gradually weaken above two meters. In this case, formwork paint can also be used for isolation, and at the same time, the situation of concrete sticking to the formwork will be greatly improved.

[0102] Design requirements for summer concrete mix optimization:

[0103] 1. The slump of concrete is 200±20mm and the expansion is 500±50mm.

[0104] 2. Air content of concrete 2.0%-3.0%

[0105] 3. The concrete slump retention time is 60 minutes. The concrete slump loss over time is (10-20) mm, and then the concrete shrinks gradually. Before shrinking, no water seepage, slurry bleeding, aggregate separation, etc. should occur. The concrete cohesion, water retention and workability must meet the construction requirements.

[0106] 4. The initial setting time of 8h meets the pouring time of single-layer bucket foundation concrete.

[0107] 5. Determine the demolding time of concrete, and initially plan to make the demolding strength reach 7-8Mpa based on the demolding time of concrete.

[0108] Finally, the concrete pouring in the present invention is introduced.

[0109] Concrete is centrally supplied by mixing stations, transported horizontally by tank trucks, and pumped into molds by pump trucks.

[0110] The production capacity of two 4-cubic-meter mixers is 160 cubic meters per hour, the pouring speed is 70 cubic meters per hour, the first layer with the largest volume is about 367 cubic meters, and the planned pouring time is 5-6 hours.

[0111] During pouring, two pump trucks pour symmetrically, placing materials in layers from the outer circle to the partition wall. The first layer is controlled at a height of 80cm, and the remaining layers are placed at a height of no more than 50cm.

[0112] The concrete pump truck is configured with 2 units of 47m+53m each. The bucket foundation is 25.5m high, the structure is 40m wide, and the distance from one side to the center is 20m. The length of the pump truck can meet the construction requirements.

[0113] Since the lower barrel is divided into 15 compartments, in order to ensure that the vibration is in place, the vibrating personnel need to carry out construction work in the compartments, with 2 to 3 people and 2 vibrating rods in each compartment, and the vibration length each time is 12-13 meters.

[0114] When vibrating concrete, the vibration time of each vibration point is until the concrete is compacted until the surface shows floating slurry and no longer sinks; when vibrating concrete, first outside and then inside, the vibration interval is 300mm, and the continuous vibration time of each vibration point is 15-20s, until the concrete surface shows cement slurry and no longer sinks. The vibrating rod is inserted vertically into the concrete, and it is inserted quickly and pulled out slowly, and pumped up and down to ensure that the upper and lower layers of concrete are combined into a whole. The vibrating rod is inserted into the lower layer of concrete for 5-10cm; to ensure that the vibrator is inserted into the concrete to an appropriate length, a marking line is tied to the vibrating rod hose, with a spacing of 50cm. The vibration time of each vibration point is 2 seconds. When each layer is ashed to the top, a secondary vibration is carried out to remove the floating slurry and ensure that the top of each layer is not loose. And use 5cm*5cm*50cm long wooden strips to press the groove to ensure the connection of the upper and lower layers of concrete.

[0115] (3) Concrete curing

[0116] After the surface concrete is poured, it should be covered with geotextiles or other materials with good water retention in time to prevent water loss due to wind drying and sun exposure. Moisturizing maintenance should be started immediately after hardening.

[0117] 12 hours before removing the formwork, loosen the fastening nuts of the side formwork to allow the curing water to seep down along the surface where the formwork and concrete are separated to cure the concrete side. When the temperature is low, pay attention to covering with insulation materials to keep the concrete moist and warm. During the entire curing period, especially in the initial stage of curing from final setting to removing the formwork, ensure that the concrete is in a temperature and humidity environment that is conducive to hardening and strength growth. Curing at room temperature for at least 14 days.

[0118] The inner side of the barrel is maintained with curing liquid, and the outer side is maintained with water spraying.

[0119] Through the above scheme, the construction of a larger barrel foundation can be realized.

[0120] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0121] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A concrete composite for barrel foundations in docks, characterized in that The raw materials include cement, sand, crushed stone, water, admixture, fly ash, mineral powder and water reducing agent. The water-cement ratio of the composite is 0.35, the sand ratio is 42, the slump is 160-220mm, and the expansion is 500±50mm. The raw materials are mixed to obtain a concrete compound, and the concrete compound is stirred to obtain a pouring liquid for pouring a bucket foundation, wherein the height of the bucket foundation is greater than 21 m, and during the maintenance of the bucket foundation, the inner side is maintained by a curing liquid, and the outer side is maintained by spraying water; The concrete composite has a mixture chloride ion content of ≤0.10% and an electrical flux (56d) of ≤1000C.

2. The concrete composite for barrel foundation in a dock according to claim 1, characterized in that: It also includes cementitious materials, the mass of which is 430kg, including 233kg-258kg of cement, 77kg-86kg of fly ash, 77kg-86kg of mineral powder, 769kg-776kg of sand, 1062-1072kg of crushed stone, 6.45kg of admixture, 147kg-150kg of water and 43kg of water reducer.

3. The concrete composite for barrel foundation in a dock according to claim 1, characterized in that: The water reducing agent is compounded with a defoamer and combined with an air entraining agent. During use, inferior bubbles in the concrete are first eliminated, and then uniform bubbles are introduced to ensure the workability of the concrete.

4. The concrete composite for barrel foundation in a dock according to claim 3, characterized in that: After adding the air entraining agent into the water reducing agent, the air content is 2.0%-3.0%.

5. The concrete composite for barrel foundation in dock according to claim 1, characterized in that: After the pouring liquid is poured, the slump loss over time is 10mm-20mm in 1h, and the initial setting time is extended to 8h to ensure that the pouring time of the lower barrel single-layer integral concrete is before the initial setting time.

6. The concrete composite for barrel foundation in a dock according to claim 1, characterized in that: The demolding time of the concrete is initially planned to make the demolding strength reach 7-8Mpa based on the demolding time of the concrete.

7. The concrete composite for barrel foundation in a dock according to claim 1, characterized in that: The barrel foundation comprises at least an upper barrel body and a lower barrel body, and the upper barrel body and the lower barrel body each comprise at least three casting layers, and in the three casting layers, a single casting height is 3-5m.

8. The concrete composite for barrel foundation in a dock according to claim 7, characterized in that The bucket foundation is formed with a casting cavity by a tall formwork, the tall formwork is a steel formwork, and the concrete demolding time is such that the demolding strength reaches 7-8Mpa.

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