Double fast concrete for frame bridge jacking sliding plate construction and preparation method thereof

Abstract

The application discloses a kind of double fast concrete for frame bridge jacking slide plate construction and preparation method. The C50 double fast concrete prepared by using the additive, with ARIT CASH aluminum-silicon hybrid hydrated calcium silicate nanocrystal core as early strength agent, realizes the rapid strength development of 4 hours compressive strength ≥5MPa, 24 hours compressive strength ≥40MPa by optimizing mix proportion and using stage-by-stage casting process. The application solves the problems of limited early strength effect, insufficient synergy of additive components, lack of environmental adaptability and not considering intermittent working conditions in the prior art, and can meet the requirements of rapid construction of frame bridge jacking slide plate in railway operation gap, which is of great significance to ensure normal operation of existing railway.

Description

Technical Field

[0001] This invention relates to the field of concrete admixtures and concrete technology, specifically to a fast-acting concrete for jacking slide plate construction of frame bridges and its preparation method. Background Technology

[0002] The jacking construction of a frame bridge passing under an existing railway is a key engineering technology for solving the problem of traffic line intersections. The sliding plate, as the basic platform for jacking the frame bridge, directly affects the jacking attitude control. To ensure the normal operation of the existing railway, the sliding plate extension construction must be completed quickly during railway operation breaks—typically within a 1-2 hour window between train passages. This requires the poured concrete to reach its initial sliding strength (≥5MPa) within 4 hours and the sliding plate's design strength (≥40MPa) within 24 hours.

[0003] In existing technologies, early-strength concrete often employs a composite system of inorganic salts (such as sodium sulfate and calcium nitrate) and alkanolamines (such as triethanolamine). However, its early-strength effect is limited, with a 24-hour strength of only 25–30 MPa, which cannot meet the requirement of ≥5 MPa for rapid traffic opening within 4 hours. Furthermore, it has poor compatibility with polycarboxylate superplasticizers, leading to easy stratification during long-term storage. Although some studies have used nano-CSH nucleation early-strength agents, the matching problem with specific polycarboxylate superplasticizer systems has not been solved, nor has a complete concrete mix design and construction process suitable for the specific conditions of slide block construction in frame bridge jacking projects been provided. In addition, existing polycarboxylate superplasticizer compounding schemes often involve 2–3 types of mother liquor, lacking a multi-type mother liquor synergy and a precise control system for multi-component admixtures, and failing to consider intermittent construction conditions and environmental adaptability.

[0004] Therefore, there is an urgent need to provide a complete set of dual-fast concrete technology solutions for the jacking-in sliding plate construction scenario of frame bridges, which uses a compound of nanocrystalline nucleus-based early-strength agents and various types of polycarboxylate mother liquor as the core to meet the requirements of rapid strength development. Summary of the Invention

[0005] The technical problem this invention aims to solve is to overcome the shortcomings of existing technologies, such as limited early-strength effect of early-strength concrete, insufficient synergy of admixture components, lack of environmental adaptability, and failure to consider intermittent construction conditions. This invention provides a dual-fast concrete for jacking-in sliding plate construction of frame bridges and its preparation method. The present invention adopts the following technical solution: A type of fast-acting concrete for jacking slide plate construction of frame bridges is characterized by the following raw materials by weight: cement 516-607 kg / m³, slag powder 0-91 kg / m³, natural sand 200-300 kg / m³, manufactured sand 300-500 kg / m³, crushed stone 900-1100 kg / m³, water 100-300 kg / m³, admixture 10-20 kg / m³, and early-strength agent 30.35-60.70 kg / m³; wherein the early-strength agent is ARIT® CASH aluminum-silicon hybrid hydrated calcium silicate nanocrystal nucleus early-strength agent.

[0006] Its raw materials, by weight, include: cement 516-607 kg / m³, slag powder 91 kg / m³, natural sand 264 kg / m³, manufactured sand 395 kg / m³, crushed stone 989 kg / m³, water 170 kg / m³, admixture 13.96 kg / m³, and early strength agent 30.35-60.70 kg / m³.

[0007] A method for preparing dual-fast concrete for jacking slide plate construction of frame bridges, as described above, is characterized in that... Step 1: Place cement, slag powder, natural sand, manufactured sand, crushed stone and water into a concrete mixer and mix them. Step 2: Mix the admixture and the early strength agent to obtain a mixture; Step 3: Add the mixture from Step 2 to Step 1 and mix to obtain double-fast concrete.

[0008] The method for preparing double-fast concrete for jacking slide plate construction of frame bridges, as described above, is characterized in that, in step three, when the time from the discharge of the double-fast concrete to the end of the pouring is within 1.5 hours, the mixture from step two is added and mixed all at once.

[0009] The method for preparing double-fast concrete for jacking slide plate construction of frame bridges, as described above, is characterized in that, in step three, when the time from the discharge of the double-fast concrete to the end of the pouring exceeds 1.5 hours, the mixture is added and mixed in two batches. The first batch of 50% to 70% is added and mixed, and the second batch of 30% to 50% is added before pouring.

[0010] The method for preparing double-fast concrete for jacking slide plate construction of frame bridges, as described above, is characterized in that the mixing time in step three is 30-120 seconds.

[0011] The admixture consists of 30%–45% polycarboxylate mother liquor, 2%–3% retarder, 0.5%–1.5% viscosity modifier, 1.0%–2.0% regulator, 0.1%–0.3% air-entraining agent, 0.05%–0.15% defoamer, and water; The polycarboxylate mother liquor is composed of 55%–65% high water-reducing mother liquor, 15%–25% viscosity-reducing mother liquor, 20%–25% high slump-retaining and slow-release mother liquor, and 0%–5% comprehensive mother liquor.

[0012] The retarder is white sugar, and the regulator is sodium gluconate; Beneficial effects: 1. Significant early strength effect of nanocrystalline nuclei: The ARIT® CASH aluminum-silicon hybrid hydrated calcium silicate nanocrystalline nuclei early strength agent has a better early strength effect than traditional inorganic salt / alkanolamine early strength agents (4h≥5MPa, 24h≥40MPa), better compatibility with cementitious materials, and the mechanism of nanocrystalline nuclei inducing hydration reaction to accelerate the early strength effect is scientific and reasonable.

[0013] 2. Precise blending of four types of mother liquor to match nanocrystalline cores: The unique blending system of high water-reducing type + viscosity-reducing type + high slump-retaining slow-release type mother liquor achieves optimal compatibility with nanocrystalline core early strength agent, providing high water reduction rate while ensuring performance is maintained within 2 hours.

[0014] 3. Synergistic regulation of admixtures: The full-component system of two-component retarder (A1 controls setting time + A2 improves workability) + air-entraining agent (introduces uniform air bubbles) + defoamer (eliminates harmful large air bubbles) + viscosity modifier (reduces material sensitivity) achieves comprehensive optimization of concrete workability, mechanical properties and durability.

[0015] 4. Staged addition adapts to construction conditions: The staged addition process of the early strength agent (≤1.5h in one go / >1.5h in two parts) solves the effectiveness problem of nanocrystalline early strength agent within a long transportation / waiting time window, and greatly improves construction adaptability.

[0016] 5. Full ambient temperature coverage: Establish a mix proportion adjustment scheme for four environmental conditions from 10 to 25℃ to effectively cope with the challenges of different seasons and construction environments.

[0017] 6. Rapid opening to traffic ensures railway operation: Concrete with a 4-hour strength ≥ 5MPa can quickly begin jacking operations during train operation intervals, minimizing the impact on existing railway operations. Detailed Implementation

[0018] The present invention will be further described below with reference to specific embodiments.

[0019] A type of fast-acting concrete for jacking slide plate construction of frame bridges is characterized by the following raw materials by weight: cement 516-607 kg / m³, slag powder 0-91 kg / m³, natural sand 200-300 kg / m³, manufactured sand 300-500 kg / m³, crushed stone 900-1100 kg / m³, water 100-300 kg / m³, admixture 10-20 kg / m³, and early-strength agent 30.35-60.70 kg / m³; wherein the early-strength agent is ARIT® CASH aluminum-silicon hybrid hydrated calcium silicate nanocrystal nucleus early-strength agent.

[0020] Its raw materials, by weight, include: cement 516-607 kg / m³, slag powder 91 kg / m³, natural sand 264 kg / m³, manufactured sand 395 kg / m³, crushed stone 989 kg / m³, water 170 kg / m³, admixture 13.96 kg / m³, and early strength agent 30.35-60.70 kg / m³.

[0021] A method for preparing dual-fast concrete for jacking slide plate construction of frame bridges, as described above, is characterized in that... Step 1: Place cement, slag powder, natural sand, manufactured sand, crushed stone and water into a concrete mixer and mix them. Step 2: Mix the admixture and the early strength agent to obtain a mixture; Step 3: Add the mixture from Step 2 to Step 1 and mix to obtain double-fast concrete.

[0022] The method for preparing double-fast concrete for jacking slide plate construction of frame bridges, as described above, is characterized in that, in step three, when the time from the discharge of the double-fast concrete to the end of the pouring is within 1.5 hours, the mixture from step two is added and mixed all at once.

[0023] The method for preparing double-fast concrete for jacking slide plate construction of frame bridges, as described above, is characterized in that, in step three, when the time from the discharge of the double-fast concrete to the end of the pouring exceeds 1.5 hours, the mixture is added and mixed in two batches. The first batch of 50% to 70% is added and mixed, and the second batch of 30% to 50% is added before pouring.

[0024] The method for preparing double-fast concrete for jacking slide plate construction of frame bridges, as described above, is characterized in that the mixing time in step three is 30-120 seconds.

[0025] The admixture consists of 30%–45% polycarboxylate mother liquor, 2%–3% retarder, 0.5%–1.5% viscosity modifier, 1.0%–2.0% regulator, 0.1%–0.3% air-entraining agent, 0.05%–0.15% defoamer, and water; The polycarboxylate mother liquor is composed of 55%–65% high water-reducing mother liquor, 15%–25% viscosity-reducing mother liquor, 20%–25% high slump-retaining and slow-release mother liquor, and 0%–5% comprehensive mother liquor.

[0026] The retarder is white sugar, and the regulator is sodium gluconate; Preferably, the strength development curve of the fast concrete is: 4h≥5MPa, 8h≥20MPa, 12h≥30MPa, 24h≥40MPa, 7d≥60MPa.

[0027] Preferably, the raw material ratio is adjusted according to the ambient temperature during construction: When the ambient temperature is 25℃, the composition is 516 parts cement, 91 parts slag powder, and 30.35 parts early strength agent. When the ambient temperature is 20℃, the composition is 546 parts cement, 61 parts slag powder, and 30.35 parts early strength agent. When the ambient temperature is 15℃, there are 607 parts of cement, 0 parts of slag powder, and 48.56 parts of early strength agent. When the ambient temperature is 10℃, the composition is 607 parts cement, 0 parts slag powder, and 60.70 parts early strength agent.

[0028] Example 1: Standard operating conditions (temperature 25℃, humidity 75%, with light) This embodiment provides a C50 fast-setting concrete, the raw materials of which include, by weight: 170 parts water, 516 parts cement, 91 parts slag powder, 264 parts natural sand, 395 parts manufactured sand, 989 parts crushed stone, 13.96 parts water-reducing agent, and 30.35 parts early-strength agent.

[0029] The water-reducing agent mentioned above is the admixture of the present invention, and the formulation is as follows: the polycarboxylate mother liquor is composed of 60% high water-reducing mother liquor, 20% viscosity-reducing mother liquor, and 20% high slump-retaining slow-release mother liquor; the admixture contains 35% polycarboxylate mother liquor, 2.5% retarder, 1.0% viscosity modifier, 1.5% regulator, 0.2% air-entraining agent, 0.1% defoamer, and the remainder is water.

[0030] The early strength agent is ARIT® CASH aluminum-silicon hybrid hydrated calcium silicate nanocrystal early strength agent, and the dosage is 5% of the total amount of cementitious material.

[0031] Preparation method: Weigh each component according to the ratio, extend the stirring time to 100s, and add the early strength agent at one time.

[0032] Performance test results: 4h strength is 5.2MPa, 8h strength is 21.5MPa, 12h strength is 31.8MPa, 24h strength is 42.3MPa, and 7d strength is 63.5MPa.

[0033] Example 2: Low temperature conditions (temperature 15℃, humidity 70%, no light) The difference between this embodiment and Embodiment 1 is that the raw materials by weight include: 170 parts water, 607 parts cement, 264 parts natural sand, 395 parts manufactured sand, 989 parts crushed stone, 13.96 parts water-reducing agent, and 48.56 parts early-strength agent; no slag powder is added.

[0034] The early strength agent is added at a rate of 8% of the total amount of cementitious materials.

[0035] Preparation method: Weigh each component according to the ratio, extend the stirring time to 110s. Since the transportation and pouring time exceeds 1.5h, the early strength agent is added in two parts: 60% is added during the early stirring and 40% is added before pouring.

[0036] Performance test results: 4h strength is 5.1MPa, 8h strength is 20.8MPa, 12h strength is 30.5MPa, 24h strength is 41.2MPa, and 7d strength is 61.8MPa.

[0037] Example 3: Medium operating conditions (temperature 20°C, humidity 70%, diffused light) The difference between this embodiment and Embodiment 1 is that the raw materials, by weight, include: 170 parts water, 546 parts cement, 61 parts slag powder, 264 parts natural sand, 395 parts manufactured sand, 989 parts crushed stone, 13.96 parts water-reducing agent, and 30.35 parts early-strength agent.

[0038] The early strength agent is added at a rate of 5% of the total amount of cementitious materials.

[0039] Preparation method: Weigh each component according to the formula, extend the stirring time to 105s, and add the early strength agent at one time.

[0040] Performance test results: 4h strength is 5.3MPa, 8h strength is 22.1MPa, 12h strength is 32.5MPa, 24h strength is 43.1MPa, and 7d strength is 64.2MPa.

[0041] Example 4: Extreme low temperature conditions (temperature 10°C, humidity 50%, no light) The difference between this embodiment and Embodiment 1 is that the raw materials, by weight, include: 170 parts water, 607 parts cement, 264 parts natural sand, 395 parts manufactured sand, 989 parts crushed stone, 13.96 parts water-reducing agent, and 60.70 parts early-strength agent; no slag powder is added.

[0042] The early strength agent is added at a rate of 10% of the total amount of cementitious materials.

[0043] Preparation method: Weigh each component according to the ratio, extend the stirring time to 120s. Since the transportation and pouring time exceeds 1.5h, the early strength agent is added in two parts: 70% is added during the early stirring and 30% is added before pouring.

[0044] Performance test results: 4h strength is 5.0MPa, 8h strength is 20.2MPa, 12h strength is 30.1MPa, 24h strength is 40.5MPa, and 7d strength is 60.8MPa.

[0045] Comparative Example 1: Traditional Early-Strength System The difference between this comparative example and Example 1 is that: the early strength agent used is a composite early strength agent of sodium sulfate and triethanolamine, with a dosage of 5% of the total amount of cementitious materials; and the water-reducing agent used is a common polycarboxylate water-reducing agent.

[0046] Performance test results: 4h strength is 2.1MPa, 8h strength is 10.5MPa, 12h strength is 18.3MPa, 24h strength is 28.6MPa, and 7d strength is 45.2MPa.

[0047] Comparative Example 2: Unblended four types of mother liquor The difference between this comparative example and Example 1 is that only a high water-reducing mother liquor was used as the water-reducing agent, and no viscosity-reducing or high slump-retaining slow-release mother liquor was added.

[0048] Performance test results: The concrete has high viscosity, with a slump loss of 30% in 1 hour, a strength of 4.2 MPa in 4 hours, and a strength of 35.8 MPa in 24 hours.

[0049] As can be seen from the test results of Examples 1-4 and Comparative Examples 1-2, the C50 fast-strength concrete provided by the present invention achieves rapid strength development of ≥5MPa in 4h and ≥40MPa in 24h through the synergistic effect of nanocrystalline nucleus early strength agent and four types of polycarboxylate mother liquor compound system. It also has excellent workability, adapts to different construction environments and working conditions, and is significantly superior to the prior art.

[0050] It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A type of fast-moving concrete for jacking slide plate construction of frame bridges, characterized in that, The raw materials, by weight, include: cement 516–607 kg / m³, slag powder 0–91 kg / m³, natural sand 200–300 kg / m³, manufactured sand 300–500 kg / m³, crushed stone 900–1100 kg / m³, water 100–300 kg / m³, admixtures 10–20 kg / m³, and early-strength agent 30.35–60.70 kg / m³; the early-strength agent is ARIT® CASH aluminum-silicon hybrid hydrated calcium silicate nanocrystal early-strength agent.

2. The dual-speed concrete for jacking slide plate construction of frame bridges as described in claim 1, characterized in that, Its raw materials, by weight, include: cement 516-607 kg / m³, slag powder 91 kg / m³, natural sand 264 kg / m³, manufactured sand 395 kg / m³, crushed stone 989 kg / m³, water 170 kg / m³, admixture 13.96 kg / m³, and early strength agent 30.35-60.70 kg / m³.

3. A method for preparing dual-fast concrete for jacking slide plate construction of frame bridges as described in claims 1-2, characterized in that, Step 1: Place cement, slag powder, natural sand, manufactured sand, crushed stone and water into a concrete mixer and mix them. Step 2: Mix the admixture and the early strength agent to obtain a mixture; Step 3: Add the mixture from Step 2 to Step 1 and mix to obtain double-fast concrete.

4. The method for preparing dual-fast concrete for jacking slide plate construction of frame bridges as described in claim 3, characterized in that, Step 3: If the time from the discharge of the double-fast concrete machine to the end of the pouring is within 1.5 hours, the mixture from Step 2 is added into the mixture all at once.

5. The method for preparing dual-fast concrete for jacking slide plate construction of frame bridges as described in claim 3, characterized in that, Step 3: When the time from the discharge of the quick-setting concrete to the end of the pouring exceeds 1.5 hours, the mixture is added in two batches for mixing. The first batch of 50% to 70% is added for mixing, and the second batch of 30% to 50% is added before pouring.

6. The method for preparing dual-fast concrete for jacking slide plate construction of frame bridges as described in claim 3, characterized in that, The stirring time in step three is 30-120 seconds.