Solid waste lightweight aggregate low-shrinkage ultra-high performance concrete and preparation method thereof
By using lightweight solid waste aggregates and lightweight cement-based cementitious materials, combined with composite micro-expansion agents and high-fluidity fine aggregates, the problems of high weight and high cracking risk of UHPC have been solved, realizing the preparation of low-shrinkage ultra-high performance concrete, which is suitable for bridge and building applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FOSHAN TRANSPORTATION SCI & TECH CO LTD
- Filing Date
- 2025-12-31
- Publication Date
- 2026-05-12
AI Technical Summary
Traditional ultra-high performance concrete (UHPC) relies on high-energy-consuming silicate cement, resulting in large weight, high risk of shrinkage cracking, and high resource consumption, which limits its large-scale application.
By combining solid waste lightweight aggregates, lightweight cement-based cementitious materials, composite micro-expansion agents, and high-fluidity fine aggregates, the self-weight is reduced, and the self-shrinkage due to hydration loss is reduced through an internal curing mechanism, thereby improving volume stability and preventing cracking.
It reduces the self-weight and shrinkage cracking risk of UHPC, improves mechanical properties, increases resource utilization, and is suitable for bridges, buildings and other fields.
Smart Images
Figure SMS_1 
Figure SMS_2 
Figure SMS_3
Abstract
Description
Technical Field
[0001] This invention relates to lightweight ultra-high performance concrete building materials and their preparation methods, specifically to a solid waste lightweight aggregate ultra-high performance concrete and its preparation method. Background Technology
[0002] Ultra-high performance concrete (UHPC), with its compressive strength ≥150 MPa, extremely low permeability, and century-long durability, has become a core material for bridges, high-rise buildings, and repair projects. However, its traditional formulation heavily relies on energy-intensive silicate cement (accounting for more than 65%), natural quartz sand, and steel fibers, resulting in its heavy weight, high risk of shrinkage cracking, and high resource consumption, which severely restricts its large-scale application. Summary of the Invention
[0003] The problem to be solved by the present invention is to provide a low-shrinkage ultra-high performance concrete made of solid waste lightweight aggregate and its preparation method, which can reduce self-weight, has excellent mechanical properties, and forms an internal curing environment in UHPC, continuously releasing water to compensate for the self-shrinkage caused by cement hydration water loss, improve volume stability, and reduce the risk of cracking.
[0004] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: A low-shrinkage ultra-high performance concrete using solid waste lightweight aggregate comprises the following raw materials in parts by weight: 300-400 parts of solid waste mixed lightweight aggregate, 900-1000 parts of lightweight cementitious material, 65-75 parts of composite micro-expansion agent, 200-350 parts of high-fluidity fine aggregate, 25-35 parts of water-reducing agent, 0.1-3 parts of retarder, 15-156 parts of crack-resistant fiber, 200-250 parts of water, 3-6 parts of shrinkage-reducing agent, and 1-5 parts of defoamer; The lightweight cement-based cementitious material is composed of 45-55 parts cement, 2-8 parts silica fume, 15-25 parts fly ash microspheres, 10-25 parts fly ash and 2-5 parts slag powder. The composite micro-expansion agent is composed of magnesium oxide, calcium oxide and gypsum powder, and the weight ratio of magnesium oxide, calcium oxide and gypsum powder is 4:(2-3):(2-3).
[0005] Preferably, the silica fume has a SiO2 content greater than 92%, a 28-day activity index of 120-130%, and a water requirement ratio of 110-120%. The fly ash microspheres are low-density hollow cenospheres with a density of 1200-1500 kg / m³. 3 The activity index after 28 days is 100-110%, and the water requirement ratio is 90-100%. The 28-day activity index of the fly ash is 90-100%, and the water requirement ratio is 95-105%. The slag powder has a 28-day activity index of 98-108% and a water requirement ratio of 105-115%. The magnesium oxide has a magnesium oxide content of 88-92%, a moisture content of ≤1%, and an active reaction time of 200-300s; The calcium oxide content of the calcium oxide is 92-97%; The gypsum powder has a calcium sulfate dihydrate content ≥95%, a moisture content of less than 5%, and a fineness (45μm sieve residue) ≤15%. Preferably, the solid waste mixed lightweight aggregate is composed of clay ceramsite and coal gangue ceramsite, and the mass ratio of clay ceramsite to coal gangue ceramsite is (3~4):(6~7). The clay ceramsite has a particle size ratio of 1.18~2.36mm > 95%, a particle size ratio below 1.18mm ≤ 5%, a compressive strength ≥ 5MPa, and a compacted packing density of 600-650kg / m³. 3 The saturated water absorption rate is 5-7%; The coal gangue ceramsite has a particle size ratio of 1.18~0.075mm > 95%, a particle size ratio below 0.075mm ≤ 5%, a compressive strength ≥ 20MPa, and a compacted bulk density of 900-950kg / m³. 3 The saturated water absorption rate is 8-10%.
[0006] Preferably, the high-fluidity fine aggregate is composed of 180-220 parts of alumina microspheres, 350-380 parts of 16-26 mesh quartz sand, 180-220 parts of 40-70 mesh quartz sand, and 210-250 parts of 70-120 mesh quartz sand, with a compacted bulk density of 1500-1800 kg / m³. 3 .
[0007] Preferably, the crack-resistant fiber is copper-plated microfiber steel fiber or polyvinyl alcohol fiber; The copper-plated microfiber steel fibers are straight fibers with a diameter of 0.20~0.23mm, a length of 13~16mm, a tensile strength of 2500~2800MPa, and a density of 7500~8000kg / m³. 3 The admixture dosage is 117~156 kg per cubic meter of concrete; The polyvinyl alcohol fibers have a diameter of 30~100μm, a length of 9~12mm, and a density of 1200~1500kg / m³. 3 The admixture dosage is 15-30 kg per cubic meter of concrete.
[0008] Preferably, the water-reducing agent is a polycarboxylate-based high-performance water-reducing agent; The shrinkage-reducing agent is a polyether-based liquid shrinkage-reducing agent; The defoamer is a polyether and mineral oil composite powder defoamer; The retarder is a sodium citrate retarder.
[0009] Preferably, the present invention also provides a method for preparing low-shrinkage ultra-high performance concrete using lightweight aggregates from solid waste, comprising the following specific steps: (1) Weigh water, shrinkage reducer and defoamer according to the weight ratio. First heat the water, then add shrinkage reducer and defoamer, and stir at high speed to get a pre-wet impregnation solution. (2) Weigh the dry solid waste mixed lightweight aggregate according to the weight ratio, add the solid waste mixed lightweight aggregate to the pre-wetting impregnation liquid, and stir and soak it slowly to make the solid waste mixed lightweight aggregate fully absorb water and pre-wet it to obtain mixed product A; (3) Weigh the lightweight cement-based cementitious material, composite micro-expansion agent and high fluidity fine aggregate according to the weight ratio, add them to the mixture A, and stir evenly in a mixer to obtain the mixture B; (4) Weigh the water-reducing agent and retarder according to the weight ratio, add them to the mixed product B, stir evenly until a fluid state appears, and obtain the mixed product C; (5) Weigh out the anti-crack fiber according to the weight ratio, add it to the mixed product C, stir evenly to obtain the mixed product D; (6) The mixed product D is subjected to construction pouring, vibration, surface finishing and curing to obtain solid waste lightweight aggregate low shrinkage ultra-high performance concrete.
[0010] Preferably, in step (1), the heating temperature of the water is 40~50℃, the speed of high-speed stirring is 400r / min~600r / min, and the high-speed stirring time is 2~5min.
[0011] In step (2), the slow stirring speed is 20r / min to 60r / min, the slow stirring time is 1 to 5min, and the soaking time is 4 to 8h.
[0012] Preferably, in step (3), lightweight cement-based cementitious material, composite micro-expansion agent and high fluidity fine aggregate are weighed according to the weight ratio, added to the mixed product A, and stirred evenly in a mixer for a stirring time of t1 to obtain mixed product B; In step (4), the water-reducing agent and the retarder are weighed according to the weight ratio, added to the mixed product B, stirred evenly for t2 until a fluid state appears, and the mixed product C is obtained. In step (5), the anti-crack fiber is weighed according to the weight ratio, added to the mixed product C, stirred evenly, and stirred for t3 to obtain the mixed product D; t1+t2+t3≤10min.
[0013] Preferably, in step (6), the pouring spacing is controlled to be ≤1m, the curing method is steam curing, and the curing conditions are: constant temperature curing at 65-75℃ for 60-80h, or constant temperature curing at 85-95℃ for 40-50h.
[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) The solid waste lightweight aggregate low shrinkage ultra-high performance concrete provided by the present invention includes solid waste mixed lightweight aggregate, lightweight cement-based cementitious material, composite micro-expansion agent, high fluidity fine aggregate, water-reducing agent, retarder, crack-resistant fiber, water, shrinkage reduction agent and defoamer. It can solve the problems of traditional UHPC being heavy, having a high risk of shrinkage cracking, consuming a lot of resources and being expensive. Compared with traditional concrete, the solid waste lightweight aggregate low shrinkage ultra-high performance concrete provided by the present invention has a 16-26% reduction in self-weight and a 85%-88% reduction in shrinkage. It has excellent mechanical properties, turns solid waste materials into treasure, reduces carbon emissions, and improves resource utilization. It is suitable for applications such as ultra-high performance concrete bridge main beams, bridge deck paving, building composite slabs, and decorative curtain walls.
[0015] (2) The lightweight cement-based cementitious material used in this invention reduces the amount of cement and mineral powder used, thus reducing the total density of the cementitious material. Moreover, the solid waste mixed lightweight aggregate used in this invention is composed of clay ceramsite and coal gangue ceramsite sand, which significantly reduces the density and self-weight compared with the traditional solid waste mixed lightweight aggregate quartz sand system.
[0016] (3) The composite micro-expansion agent used in this invention is composed of magnesium oxide, calcium oxide and gypsum powder, taking into account the micro-expansion and stability characteristics of early and late hydration. Before the 7-day hydration period, calcium oxide plays a role in generating calcium hydroxide. After 7 days of hydration, magnesium oxide reacts with water to generate magnesium hydroxide, resulting in volume expansion. At the same time, gypsum provides SO₂. 4- With Ca 2+ The reaction produces ettringite, which slows down the volume expansion and prevents cracking.
[0017] On the other hand, the solid waste mixed lightweight aggregate used in this invention is a porous material. After being saturated with water, it compensates for moisture during cement hydration, forming an internal curing mechanism. This reduces self-shrinkage caused by water loss during hydration, improves volume stability, and lowers the risk of cracking. Therefore, the combined action of the composite micro-expansion agent and the solid waste mixed lightweight aggregate reduces the risk of shrinkage cracking in UHPC and also effectively prevents expansion cracking.
[0018] (4) The high-fluidity fine aggregate and solid waste mixed lightweight aggregate used in this invention are both composed of a combination of spherical particles and angular particles. Among them, spherical clay ceramsite and spherical alumina hollow microspheres provide a ball bearing effect for the UHPC system, ensuring good flow working condition; coal gangue ceramsite sand and quartz sand are angular particles, providing a framework for the system and enhancing the system strength. Detailed Implementation
[0019] The principles and features of the present invention are described below with reference to specific embodiments. The embodiments are only used to explain the present invention and are not intended to limit the scope of the present invention.
[0020] This invention provides a low-shrinkage ultra-high performance concrete using solid waste lightweight aggregate, comprising the following raw materials in parts by weight: 300-400 parts of solid waste mixed lightweight aggregate, 900-1000 parts of lightweight cementitious material, 65-75 parts of composite micro-expansion agent, 200-350 parts of high-fluidity fine aggregate, 25-35 parts of water-reducing agent, 0.1-3 parts of retarder, 15-156 parts of crack-resistant fiber, 200-250 parts of water, 3-6 parts of shrinkage-reducing agent, and 1-5 parts of defoamer; The lightweight cement-based cementitious material is composed of 45-55 parts cement, 2-8 parts silica fume, 15-25 parts fly ash microspheres, 10-25 parts fly ash and 2-5 parts slag powder. The composite micro-expansion agent is composed of magnesium oxide, calcium oxide and gypsum powder, and the weight ratio of magnesium oxide, calcium oxide and gypsum powder is 4:(2-3):(2-3).
[0021] Specifically, the present invention introduces a lightweight cement-based cementitious material into the formula, which is composed of 45-55 parts cement, 2-8 parts silica fume, 15-25 parts fly ash microspheres, 10-25 parts fly ash and 2-5 parts slag powder.
[0022] Among them, the cement with a higher density in the components is PI 52.5 or PII 52.5 type ordinary Portland cement. Compared with the traditional cementitious material system, the amount of cement and slag powder is reduced, and the total density of the cementitious material is reduced. At the same time, the solid waste mixed lightweight aggregate introduced in the formula is composed of clay ceramsite and coal gangue ceramsite sand. Compared with the traditional solid waste mixed lightweight aggregate quartz sand system, it has a lower density. Therefore, the self-weight of the solid waste lightweight aggregate low shrinkage high performance concrete provided by the present invention can be reduced.
[0023] Preferably, the silica fume has a SiO2 content greater than 92%, a 28-day activity index of 120-130%, and a water requirement ratio of 110-120%. As part of a lightweight cementitious material, the silica fume is a semi-dense, grayish-white powder that can fill the gaps between cement particles, achieving the "closest packing" of the cementitious material system. This significantly reduces the porosity of concrete, refines the pore size, and makes the concrete structure extremely dense. The high content and high activity of SiO2 react with calcium hydroxide, a cement hydration product, to generate additional, stronger, and more stable CSH gel, which can greatly improve the compressive and flexural strength of concrete.
[0024] Preferably, the fly ash microspheres are low-density hollow cenospheres with a density of 1200-1500 kg / m³. 3 The 28-day activity index of the fly ash is 100-110%, and the water requirement ratio is 90-100%; the 28-day activity index of the fly ash is 90-100%, and the water requirement ratio is 95-105%; the 28-day activity index of the slag powder is 98-108%, and the water requirement ratio is 105-115%.
[0025] Fly ash and slag powder can also be used as part of lightweight cementitious materials, contributing to the strength of concrete. Among them, the highly active fly ash is Class F grade 1 fly ash, which can react with calcium hydroxide in the later stages of hydration to generate CSH, contributing to long-term strength and improving the microstructure. The highly active slag powder is S95 grade slag powder, which provides some strength after hydration. In addition, it can refine the pore structure of concrete, significantly improving its resistance to chloride ion penetration and sulfate attack.
[0026] Fly ash microspheres are low-density hollow cenospheres, which not only have low density but also low water demand. Due to their spherical shape and "ball effect", they can significantly reduce internal friction in concrete and improve the fluidity of concrete. Because of their low water demand, they hardly increase or may even reduce the amount of water used for mixing. They are an excellent water-reducing component and also help reduce the total density of cementitious materials and the self-weight of concrete.
[0027] This invention introduces a composite micro-expansion agent into the formulation, which is composed of magnesium oxide, calcium oxide, and gypsum powder in a weight ratio of 4:(2-3):(2-3). The composite micro-expansion agent balances the early and late-stage hydration micro-expansion and stability of concrete. Before the 7-day hydration period, the calcium oxide in its component reacts with water to form calcium hydroxide, which rapidly expands to compensate for the plastic shrinkage caused by surface moisture evaporation, providing early prestress and reducing surface cracking. After 7 days of hydration, the magnesium oxide in its component reacts with water to form magnesium hydroxide, resulting in volume expansion. Simultaneously, the gypsum powder in the component provides SO₂. 4- With Ca 2+ The reaction produces ettringite, which slows down the volume expansion and prevents the concrete from cracking.
[0028] Preferably, the weight ratio of magnesium oxide, calcium oxide, and gypsum powder is 42:29:29, the 28-day activity index of the composite micro-expansion agent is 90%, the 7-day restricted expansion rate is 0.015%, and the 28-day restricted expansion rate is 0.025%. Within the above ranges, the concrete undergoes micro-expansion, resulting in a denser internal structure, reduced porosity, and improved impermeability and durability, indirectly enhancing its resistance to cracking.
[0029] In addition, the solid waste mixed lightweight aggregate in the formulation of this invention is a porous material. After being saturated with water during concrete preparation, it can compensate for moisture during concrete hydration, forming an internal curing mechanism, thereby reducing self-shrinkage caused by hydration water loss. Therefore, the combined action mechanism of the composite micro-expansion agent and the solid waste mixed lightweight aggregate reduces the risk of shrinkage cracking in UHPC and also effectively prevents expansion cracking.
[0030] The composite micro-expansion agent uses calcium oxide, magnesium oxide, and gypsum powder in a specific ratio, achieving synergistic expansion through multiple mechanisms at different time stages, thus compensating for shrinkage throughout the entire hydration process of concrete in the early, middle, and late stages. Specifically, the magnesium oxide is type II magnesium oxide for hydraulic concrete, the calcium oxide is type I industrial calcium oxide, and the gypsum powder is first-grade flue gas desulfurization gypsum. Preferably, the magnesium oxide has a magnesium oxide content of 88-92%, a moisture content of ≤1%, and an active reaction time of 200-300 s; the calcium oxide has a calcium oxide content of 92-97%; and the gypsum powder has a calcium sulfate dihydrate content of ≥95%, a moisture content of less than 5%, and a fineness (45 μm sieve residue) of ≤15%.
[0031] Preferably, the solid waste mixed lightweight aggregate is composed of clay ceramsite and coal gangue ceramsite, and the mass ratio of clay ceramsite to coal gangue ceramsite is (3~4):(6~7). The clay ceramsite has a particle size ratio of 1.18~2.36mm > 95%, a particle size ratio below 1.18mm ≤ 5%, a compressive strength ≥ 5MPa, and a compacted packing density of 600-650kg / m³. 3 The saturated water absorption rate is 5-7%; The coal gangue ceramsite has a particle size ratio of 1.18~0.075mm > 95%, a particle size ratio below 0.075mm ≤ 5%, a compressive strength ≥ 20MPa, and a compacted bulk density of 900-950kg / m³. 3 The saturated water absorption rate is 8-10%.
[0032] Clay ceramsite is a spherical, porous ceramsite with 1-4 tails produced by high-temperature firing of solid waste clay, with a compacted bulk density of 600-650 kg / m³. 3 The compressive strength of the cylinder is ≥5MPa; the coal gangue ceramsite is an irregularly shaped porous 900-grade lightweight aggregate obtained from the crushing and screening of solid waste coal gangue ceramsite, with a compacted bulk density of 900-950kg / m³. 3 The compressive strength of the cylinder is ≥20MPa. Through reasonable design, the mass ratio of clay ceramsite to coal gangue ceramsite sand is controlled at (3~4):(6~7). Within this range, the average density of the mixed lightweight aggregate can be reduced. Compared with the traditional solid waste mixed lightweight aggregate quartz sand system, the density can be reduced from 1750kg / m³. 3 Decreased to 650 kg / m 3This can significantly reduce the self-weight of the low-shrinkage ultra-high performance concrete made from solid waste lightweight aggregates provided by this invention.
[0033] On the other hand, within the aforementioned range, spherical clay ceramsite provides a ball bearing effect for the UHPC system, ensuring good flow performance, while coal gangue ceramsite sand, being angular particles, provides a framework for the system and enhances its strength.
[0034] Preferably, the high-fluidity fine aggregate is composed of 180-220 parts of alumina microspheres, 350-380 parts of 16-26 mesh quartz sand, 180-220 parts of 40-70 mesh quartz sand, and 210-250 parts of 70-120 mesh quartz sand, with a compacted bulk density of 1500-1800 kg / m³. 3 Alumina microspheres and quartz sand, as part of high-fluidity fine aggregates, are a combination of spherical and angular particles. They work synergistically with solid waste mixed lightweight aggregates to provide stable strength to concrete.
[0035] In some embodiments, the alumina microspheres of the present invention are spherical particles with a Mohs hardness of 9, a purity of 92%, and a bulk density of 1700 kg / m³. 3 The three types of quartz sand are angular particles, all with a Mohs hardness of 7 and a bulk density of 1400~1450 kg / m³. 3 However, it is not limited to this.
[0036] Preferably, the crack-resistant fiber is copper-plated microfiber steel fiber or polyvinyl alcohol fiber; The copper-plated microfiber steel fibers are straight fibers with a diameter of 0.20~0.23mm, a length of 13~16mm, a tensile strength of 2500~2800MPa, and a density of 7500~8000kg / m³. 3 The admixture dosage is 117~156 kg per cubic meter of concrete; The polyvinyl alcohol fibers have a diameter of 30~100μm, a length of 9~12mm, and a density of 1200~1500kg / m³. 3 The admixture dosage is 15-30 kg per cubic meter of concrete.
[0037] The copper-plated microfiber steel fiber of this invention is a straight fiber that can significantly improve the tensile, flexural and toughness of concrete, greatly enhancing its flexural strength, fracture toughness, impact resistance and fatigue resistance. The polyvinyl alcohol fiber is a milky white hard fiber with excellent ability to inhibit shrinkage cracks, forming a high-density micro-support system in the concrete, effectively resisting capillary tension caused by bleeding and settlement, and greatly reducing or even eliminating plastic shrinkage cracks.
[0038] Preferably, the water-reducing agent is a polycarboxylate-based high-performance water-reducing agent; the shrinkage-reducing agent is a polyether-based liquid shrinkage-reducing agent; the defoamer is a polyether-mineral oil composite powder defoamer; and the retarder is a sodium citrate-based retarder, but not limited thereto.
[0039] More preferably, the polycarboxylate-based high-performance water-reducing agent has a solid content of 35% and a water reduction rate of ≥30%. It can be adsorbed onto the surface of cement particles and, through electrostatic repulsion and steric hindrance, disrupts the flocculated structure of concrete, releasing the trapped free water. This significantly reduces the amount of mixing water while maintaining the fluidity of the concrete. The polyether-based liquid shrinkage-reducing agent can significantly reduce the surface tension of pore water in concrete, greatly reducing the negative pressure formed in the capillaries, thus weakening the driving force of shrinkage and inhibiting concrete shrinkage from the source. The polyether and mineral oil composite... The powdered defoamer is a hydrophobic substance that can quickly spread on the surface of the bubble liquid film, reduce local surface tension, remove irregular and unstable large bubbles entrained during mixing and pouring, reduce ineffective pores, and make the concrete structure denser, thereby improving compressive strength and impermeability. The sodium citrate retarder is a chemical admixture that can prolong the setting time of concrete without significantly affecting its later strength. Through mechanisms such as adsorption, film formation, precipitation, or changing the morphology of hydration products, it significantly reduces the internal and external temperature difference and temperature stress, greatly reducing the risk of early temperature cracks.
[0040] Accordingly, the present invention also provides a method for preparing low-shrinkage ultra-high performance concrete using lightweight aggregates from solid waste, comprising the following specific steps: (1) Weigh water, shrinkage reducer and defoamer according to the weight ratio. First heat the water, then add shrinkage reducer and defoamer, and stir at high speed to get a pre-wet impregnation solution. Preferably, in step (1), the heating temperature of the water is 40~50℃, the speed of high-speed stirring is 400r / min~600r / min, and the high-speed stirring time is 2~5min.
[0041] More preferably, in step (1), the heating temperature of the water is 42~48℃, the speed of high-speed stirring is 450r / min~550r / min, and the high-speed stirring time is 2~5min.
[0042] (2) Weigh the dry solid waste mixed lightweight aggregate according to the weight ratio, add the solid waste mixed lightweight aggregate to the pre-wetting impregnation liquid, and stir and soak it slowly to make the solid waste mixed lightweight aggregate fully absorb water and pre-wet it to obtain mixed product A; Preferably, in step (2), the slow stirring speed is 20r / min to 60r / min, the slow stirring time is 1 to 5min, and the soaking time is 4 to 8h.
[0043] More preferably, in step (2), the slow stirring speed is 30r / min to 50r / min, the slow stirring time is 2 to 5 min, and the soaking time is 5 to 7 h.
[0044] (3) Weigh the lightweight cement-based cementitious material, composite micro-expansion agent and high fluidity fine aggregate according to the weight ratio, add them to the mixture A, and stir evenly in a mixer to obtain the mixture B; (4) Weigh the water-reducing agent and retarder according to the weight ratio, add them to the mixed product B, stir evenly until a fluid state appears, and obtain the mixed product C; (5) Weigh out the anti-crack fiber according to the weight ratio, add it to the mixed product C, stir evenly to obtain the mixed product D; Preferably, in step (3), lightweight cement-based cementitious material, composite micro-expansion agent and high fluidity fine aggregate are weighed according to the weight ratio, added to the mixed product A, and stirred evenly in a mixer for a stirring time of t1 to obtain mixed product B; In step (4), the water-reducing agent and the retarder are weighed according to the weight ratio, added to the mixed product B, stirred evenly for t2 until a fluid state appears, and the mixed product C is obtained. In step (5), the anti-crack fiber is weighed according to the weight ratio, added to the mixed product C, stirred evenly, and stirred for t3 to obtain the mixed product D; t1+t2+t3≤10min.
[0045] It should be noted that, compared with traditional preparation methods, the preparation method of low-shrinkage ultra-high performance concrete using solid waste lightweight aggregate provided by this invention first prepares a pre-wet impregnation liquid composed of shrinkage-reducing agent and defoamer under high-speed stirring. Then, the solid waste mixed lightweight aggregate is fully immersed in the pre-wet impregnation liquid, allowing the solid waste mixed lightweight aggregate to fully absorb water and pre-wet. In this process, since the solid waste mixed lightweight aggregate is a porous material, slow stirring and controlled soaking time allow the solid waste mixed lightweight aggregate to absorb water to saturation. The shrinkage-reducing agent and defoamer are incorporated into the lightweight aggregate along with the pre-wet impregnation liquid. The synergistic mechanism allows the concrete to continuously compensate for water during the hydration process, forming an internal curing mechanism, thereby reducing the self-shrinkage caused by hydration water loss and maintaining the compressive strength of the concrete. In addition, the mixing time t1+t2+t3 in the mixer must be controlled within 10 minutes. This is because excessive mixing time will accelerate the hydration reaction between cement and water, causing the concrete to lose its plasticity too early, become thick or dry, reduce fluidity, and make construction difficult. Moreover, premature hydration may cause the concrete to start setting before pouring, affecting the later strength development and even causing the strength to fail to meet the standard.
[0046] (6) The mixed product D is subjected to construction pouring, vibration, surface finishing and curing to obtain solid waste lightweight aggregate low shrinkage ultra-high performance concrete.
[0047] Preferably, in step (6), the pouring spacing is controlled to be ≤1m, the curing method is steam curing, and the curing conditions are: constant temperature curing at 65-75℃ for 60-80h, or constant temperature curing at 85-95℃ for 40-50h.
[0048] In summary, the solid waste lightweight aggregate low-shrinkage ultra-high performance concrete prepared by the method of this invention ensures that the concrete can uniformly and quickly fill every corner of the mold by controlling the pouring spacing, reducing the amount of manual leveling work required, thereby avoiding defects such as voids, honeycomb, and pitted surfaces caused by insufficient or excessive vibration. The use of steam curing under specific curing conditions, with its high temperature and humidity environment, greatly inhibits the early plastic shrinkage and drying shrinkage of the concrete.
[0049] The solid waste lightweight aggregate low-shrinkage ultra-high performance concrete provided by this invention can solve the problems of traditional UHPC, such as large self-weight, high risk of shrinkage cracking, large resource consumption, and high cost. Compared with traditional concrete, the solid waste lightweight aggregate low-shrinkage ultra-high performance concrete provided by this invention has a 16-26% reduction in self-weight and an 85-88% reduction in shrinkage. It turns solid waste materials into treasure, reduces carbon emissions, and improves resource utilization. It is suitable for applications such as ultra-high performance concrete bridge main beams, bridge deck pavement, building composite slabs, and decorative curtain walls.
[0050] Example 1 1. Preparation This embodiment 1 provides a low-shrinkage ultra-high performance concrete using solid waste lightweight aggregate, comprising the following raw materials in parts by weight: 400 parts of solid waste mixed lightweight aggregate, 911.4 parts of lightweight cementitious material, 68.6 parts of composite micro-expansion agent, 200 parts of high-fluidity fine aggregate, 29.4 parts of water-reducing agent, 0.98 parts of retarder, 15 parts of crack-resistant fiber, 215.6 parts of water, 4.9 parts of shrinkage-reducing agent, and 2.94 parts of defoamer; The lightweight cement-based cementitious material is composed of 53.8 parts cement, 5.4 parts silica fume, 19.4 parts fly ash microspheres, 16.1 parts fly ash, and 5.4 parts slag powder. The cement is PI 52.5 ordinary Portland cement; the silica fume has a SiO2 content greater than 92%, a 28-day activity index of 120%, a water requirement ratio of 110%, and is a semi-dense grayish-white powder; the fly ash microspheres are low-density hollow cenospheres with a density of 1500 kg / m³. 3 The 28-day activity index is 100%, and the water requirement ratio is 90%; the fly ash is Class F Grade 1 fly ash, with a 28-day activity index of 90% and a water requirement ratio of 95%; the slag powder is S95 grade ore powder, with a 28-day activity index of 98% and a water requirement ratio of 105%. The composite micro-expansion agent is composed of 42 parts magnesium oxide, 29 parts calcium oxide, and 29 parts gypsum powder. Its 28-day activity index is 90%, its 7-day restricted expansion rate is 0.015%, and its 28-day restricted expansion rate is 0.025%. Specifically, the magnesium oxide is Type II magnesium oxide for hydraulic concrete, with a magnesium oxide content of 90%, a moisture content ≤1%, and an activity reaction time of 200-300 seconds; the calcium oxide is Class I industrial calcium oxide, with a calcium oxide content of 95%; and the gypsum powder is Grade I flue gas desulfurization gypsum, with a calcium sulfate dihydrate content ≥95%, a moisture content less than 5%, and a fineness (45μm sieve residue) ≤15%. The solid waste mixed lightweight aggregate is composed of clay ceramsite and coal gangue ceramsite in a mass ratio of 4:6. The clay ceramsite is spherical porous ceramsite with 1-4 tails produced by high-temperature firing of solid waste clay. Its particle size distribution is >95% (1.18-2.36mm), and its particle size distribution is ≤5% (below 1.18mm). The compressive strength is 5MPa, and the compacted bulk density is 650kg / m³. 3 The saturated water absorption rate is 7%; the coal gangue ceramsite is an irregularly shaped porous 900-grade lightweight aggregate obtained by crushing and screening solid waste coal gangue ceramsite particles, with a particle size of 1.18-0.075mm accounting for >95%, and a particle size of less than 0.075mm accounting for ≤5%, a cylinder compressive strength of 20MPa, and a compacted bulk density of 950kg / m³. 3 The saturated water absorption rate is 10%. The high-flowability fine aggregate consists of 200 parts alumina microspheres, 362 parts 16-26 mesh quartz sand, 201 parts 40-70 mesh quartz sand, and 238 parts 70-120 mesh quartz sand, with a compacted bulk density of 1800 kg / m³. 3 ; The crack-resistant fiber is copper-plated microfiber steel fiber or polyvinyl alcohol fiber; The water-reducing agent is a polycarboxylate-based high-performance water-reducing agent; The shrinkage-reducing agent is a polyether-based liquid shrinkage-reducing agent; The defoamer is a polyether and mineral oil composite powder defoamer; The retarder is a sodium citrate retarder.
[0051] This embodiment 1 also provides a method for preparing low-shrinkage ultra-high performance concrete using lightweight aggregates from solid waste, including the following specific steps: (1) Weigh out water, shrinkage reducer and defoamer. First heat the water to 50°C, then add shrinkage reducer and defoamer. Use a high-speed stirring device to stir at a speed of 500r / min for 3 minutes to obtain pre-wet impregnation solution. (2) Weigh the dry solid waste mixed light aggregate, add the solid waste mixed light aggregate to the pre-wetting impregnation liquid, stir slowly at a speed of 40 r / min for 1 min, and soak for 6 h to allow the solid waste mixed light aggregate to fully absorb water and pre-wet, and obtain mixed product A; (3) Weigh the lightweight cement-based cementitious material, composite micro-expansion agent and high fluidity fine aggregate, add them to the mixture A, and stir in a mixer for 1 minute to obtain the mixture B; (4) Weigh out the water-reducing agent and the retarder, add them to the mixture B, stir for 4 minutes until a fluid state appears, and obtain the mixture C; (5) Weigh out the anti-crack fiber, add it to the mixture C, stir for 5 minutes to obtain the mixture D; (6) The mixed product D is poured for construction, with the pouring interval controlled within 1m. After vibration and surface finishing, it is then steam cured at 90℃ for 48h to obtain solid waste lightweight aggregate low shrinkage ultra-high performance concrete.
[0052] 2. Testing The low-shrinkage ultra-high performance concrete made from solid waste lightweight aggregate prepared in Example 1 was evaluated using the following specific test methods: (1) Workability test: The bulk density, spread and 1-hour spread loss of solid waste lightweight aggregate low shrinkage ultra-high performance concrete mixture were tested according to the requirements of GB / T 50080. (2) Test block preparation: According to the requirements of GB / T 31387, test blocks for compressive strength, flexural strength, tensile strength, axial compressive strength and drying shrinkage are formed. When forming, the solid waste lightweight aggregate low shrinkage ultra-high performance concrete mixture is poured from one side and the test block is shaken from side to side until no air bubbles emerge. Cover with a moisturizing film and cure for 24 hours.
[0053] (3) Remove the mold, move the test block into the steam curing chamber, and cure at a constant temperature of 90℃ for 48 hours. After curing, move it into the standard curing room until the test age of 28 days and then conduct the test.
[0054] Table 1 shows the performance indicators of Example 1. The tested solid waste lightweight aggregate low-shrinkage ultra-high performance concrete mixture has a bulk density of 1849 kg / m³. 3 The output expansion is 740 mm, the expansion loss over 1 hour is 740 mm, the 28-day compressive strength is 101.4 MPa, the 28-day flexural strength is 12.4 MPa, the 28-day tensile strength is 6.5 MPa, the 28-day axial compressive strength is 99.7 MPa, and the 28-day drying shrinkage is 42 με.
[0055] Table 1 shows the performance indicators of Example 1.
[0056] Example 2 1. Preparation Unlike Example 1, Example 2 provides a low-shrinkage ultra-high performance concrete made from solid waste lightweight aggregate, comprising the following raw materials in parts by weight: 350 parts of solid waste mixed lightweight aggregate, 944.9 parts of lightweight cementitious material, 71.1 parts of composite micro-expansion agent, 223.5 parts of high-fluidity fine aggregate, 30.5 parts of water-reducing agent, 1.02 parts of retarder, 117 parts of crack-resistant fiber, 223.5 parts of water, 5.08 parts of shrinkage-reducing agent, and 3.05 parts of defoamer.
[0057] The lightweight cement-based cementitious material is composed of 50 parts cement, 6.5 parts silica fume, 20.1 parts fly ash microspheres, 18.2 parts fly ash, and 5.2 parts slag powder. The cement is PI 52.5 ordinary Portland cement; the silica fume has a SiO2 content greater than 92%, a 28-day activity index of 120%, a water requirement ratio of 110%, and is a semi-dense grayish-white powder; the fly ash microspheres are low-density hollow cenospheres with a density of 1500 kg / m³. 3 The 28-day activity index is 100%, and the water requirement ratio is 90%; the fly ash is Class F Grade 1 fly ash, with a 28-day activity index of 90% and a water requirement ratio of 95%; the slag powder is S95 grade ore powder, with a 28-day activity index of 98% and a water requirement ratio of 105%. The solid waste mixed lightweight aggregate is composed of clay ceramsite and coal gangue ceramsite sand in a mass ratio of 3.5:6.5.
[0058] This embodiment 2 also provides a method for preparing low-shrinkage ultra-high performance concrete using solid waste lightweight aggregates, including the following specific steps: (1) Weigh out water, shrinkage reducer and defoamer. First heat the water to 40°C, then add shrinkage reducer and defoamer. Use a high-speed stirring device to stir at a stirring speed of 400r / min for 5 minutes to obtain pre-wet impregnation solution. (2) Weigh the dry solid waste mixed light aggregate, add the solid waste mixed light aggregate to the pre-wetting impregnation liquid, stir slowly at a speed of 60 r / min for 3 min, and soak for 8 h to allow the solid waste mixed light aggregate to fully absorb water and pre-wet, and obtain mixed product A; (3) Weigh the lightweight cement-based cementitious material, composite micro-expansion agent and high fluidity fine aggregate, add them to the mixture A, and stir in a mixer for 2 minutes to obtain the mixture B; (4) Weigh out the water-reducing agent and the retarder, add them to the mixture B, stir for 4 minutes until a fluid state appears, and obtain the mixture C; (5) Weigh out the anti-crack fiber, add it to the mixture C, stir for 4 min to obtain the mixture D; (6) The mixed product D is poured for construction, with the pouring interval controlled within 1m. After vibration and surface finishing, it is cured at a constant temperature of 65℃ for 72h to obtain solid waste lightweight aggregate low shrinkage ultra-high performance concrete.
[0059] 2. Testing The low-shrinkage ultra-high performance concrete made from solid waste lightweight aggregate prepared in Example 2 was evaluated using the following specific test methods: (1) Workability test: The bulk density, spread and 1-hour spread loss of solid waste lightweight aggregate low shrinkage ultra-high performance concrete mixture were tested according to the requirements of GB / T 50080. (2) Test block preparation: According to the requirements of GB / T 31387, test blocks for compressive strength, flexural strength, tensile strength, axial compressive strength and drying shrinkage are formed. When forming, the solid waste lightweight aggregate low shrinkage ultra-high performance concrete mixture is poured from one side and the test block is shaken from side to side until no air bubbles emerge. Cover with a moisturizing film and cure for 24 hours.
[0060] (3) Remove the mold, move the test block into the steam curing chamber, and cure at a constant temperature of 65℃ for 72 hours. After curing, move it into the standard curing room until the test age of 28 days and then conduct the test.
[0061] Table 2 shows the performance indicators of Example 2. The tested solid waste lightweight aggregate low-shrinkage ultra-high performance concrete mixture has a bulk density of 2000 kg / m³. 3 The output expansion is 700mm, the expansion loss over 1 hour is 680mm, the 28-day compressive strength is 117MPa, the 28-day flexural strength is 16.5MPa, the 28-day tensile strength is 7.2MPa, the 28-day axial compressive strength is 110.3MPa, and the 28-day drying shrinkage is 50με.
[0062] Table 2 shows the performance indicators of Example 2.
[0063] Example 3 1. Preparation Unlike Example 1, Example 3 provides a low-shrinkage ultra-high performance concrete made from solid waste lightweight aggregate, comprising the following raw materials: 300 parts of solid waste mixed lightweight aggregate, 997.2 parts of lightweight cementitious material, 72.8 parts of composite micro-expansion agent, 334 parts of high-fluidity fine aggregate, 31.2 parts of water-reducing agent, 1.04 parts of retarder, 156 parts of crack-resistant fiber, 228.8 parts of water, 5.2 parts of shrinkage-reducing agent, and 3.12 parts of defoamer.
[0064] The lightweight cement-based cementitious material is composed of 50 parts cement, 6.5 parts silica fume, 20.1 parts fly ash microspheres, 18.2 parts fly ash, and 5.2 parts slag powder. The cement is PI 52.5 ordinary Portland cement; the silica fume has a SiO2 content greater than 92%, a 28-day activity index of 120%, a water requirement ratio of 110%, and is a semi-dense grayish-white powder; the fly ash microspheres are low-density hollow cenospheres with a density of 1500 kg / m³. 3 The 28-day activity index is 100%, and the water requirement ratio is 90%; the fly ash is Class F Grade 1 fly ash, with a 28-day activity index of 90% and a water requirement ratio of 95%; the slag powder is S95 grade ore powder, with a 28-day activity index of 98% and a water requirement ratio of 105%. The solid waste mixed lightweight aggregate is composed of clay ceramsite and coal gangue ceramsite sand in a mass ratio of 3:7.
[0065] This embodiment 3 also provides a method for preparing low-shrinkage ultra-high performance concrete using lightweight aggregates from solid waste, including the following specific steps: (1) Weigh out water, shrinkage reducer and defoamer. First heat the water to 40°C, then add shrinkage reducer and defoamer. Use a high-speed stirring device to stir at a stirring speed of 600r / min for 2 minutes to obtain pre-wet impregnation solution. (2) Weigh the dry solid waste mixed light aggregate, add the solid waste mixed light aggregate to the pre-wetting impregnation liquid, stir slowly at a speed of 20 r / min for 5 min, and soak for 4 h to allow the solid waste mixed light aggregate to fully absorb water and pre-wet, and obtain mixed product A; (3) Weigh the lightweight cement-based cementitious material, composite micro-expansion agent and high fluidity fine aggregate, add them to the mixture A, and stir in a mixer for 3 minutes to obtain the mixture B; (4) Weigh out the water-reducing agent and the retarder, add them to the mixture B, stir for 3 minutes until a fluid state appears, and obtain the mixture C; (5) Weigh out the anti-crack fiber, add it to the mixture C, stir for 3 minutes to obtain the mixture D; (6) The mixed product D is poured for construction, with the pouring interval controlled within 1m. After vibration and surface finishing, it is then steam cured at 90℃ for 48h to obtain solid waste lightweight aggregate low shrinkage ultra-high performance concrete.
[0066] 2. Testing The low-shrinkage ultra-high performance concrete made from solid waste lightweight aggregate prepared in Example 3 was evaluated using the following specific test methods: (1) Workability test: The bulk density, spread and 1-hour spread loss of solid waste lightweight aggregate low shrinkage ultra-high performance concrete mixture were tested according to the requirements of GB / T 50080. (2) Test block preparation: According to the requirements of GB / T 31387, test blocks for compressive strength, flexural strength, tensile strength, axial compressive strength and drying shrinkage are formed. When forming, the solid waste lightweight aggregate low shrinkage ultra-high performance concrete mixture is poured from one side and the test block is shaken from side to side until no air bubbles emerge. Cover with a moisturizing film and cure for 24 hours.
[0067] (3) Remove the mold, move the test block into the steam curing chamber, and cure at a constant temperature of 90℃ for 48 hours. After curing, move it into the standard curing room until the test age of 28 days and then conduct the test.
[0068] Table 3 shows the performance indicators of Example 3. The tested solid waste lightweight aggregate low-shrinkage ultra-high performance concrete mixture has a bulk density of 2099 kg / m³. 3 The output expansion is 700mm, the expansion loss over 1 hour is 660mm, the 28-day compressive strength is 126MPa, the 28-day flexural strength is 20.1MPa, the 28-day tensile strength is 8.2MPa, the 28-day axial compressive strength is 112MPa, and the 28-day drying shrinkage is 43με.
[0069] Table 3 shows the performance indicators of Example 3.
[0070] Comparative Example 1 A traditional ultra-high performance concrete comprises the following raw materials: 630 parts of PⅡ52.5 cement, 155.7 parts of silica fume, 100.5 parts of microspheres, 85.4 parts of mineral powder, 475.2 parts of 16-26 mesh quartz sand, 508.3 parts of 40-70 mesh quartz sand, 121.6 parts of 100-200 mesh quartz sand, 221 parts of water, 30.05 parts of water-reducing agent, 0.5 parts of defoamer, 0.6 parts of retarder, 2.55 parts of shrinkage reducer, and 156 parts of copper-plated steel fiber.
[0071] The traditional method for preparing ultra-high performance concrete includes the following specific steps: Weigh out cement, silica fume, microspheres, mineral powder, 16-26 mesh quartz sand, 40-70 mesh quartz sand, and 100-200 mesh quartz sand and add them to the mixer. Then add water, water-reducing agent, defoamer, retarder, and shrinkage reducer. Mix for 4 minutes until a fluid state is reached. Then add copper-plated steel fibers and continue mixing for 5 minutes. The total mixing time should be controlled within 10 minutes to obtain traditional high-performance concrete.
[0072] 2. Testing The conventional ultra-high performance concrete prepared according to the present invention was evaluated using the following specific testing methods: (1) Workability test: Test the bulk density, spread and 1-hour spread loss of the mixture according to the requirements of GB / T 50080; (2) Test block preparation: According to the requirements of GB / T 31387, test blocks for compressive strength, flexural strength, tensile strength, axial compressive strength and drying shrinkage are prepared. When preparing, the traditional ultra-high performance concrete mixture is poured from one side and the test block is shaken from side to side until no air bubbles emerge. Cover with a moisturizing film and cure for 24 hours.
[0073] (3) Remove the mold, move the test block into the steam curing chamber, and cure at a constant temperature of 90℃ for 48 hours. After curing, move it into the standard curing room until the test age of 28 days and then conduct the test.
[0074] Table 4 shows the performance indicators of Comparative Example 1.
[0075] Table 4 shows a comparison of performance indicators for the comparative examples. Tests showed that the bulk density of the prepared traditional ultra-high performance concrete mixture was 2500 kg / m³. 3 The output expansion is 700mm, the expansion loss over 1 hour is 700mm, the 28-day compressive strength is 135MPa, the 28-day flexural strength is 16MPa, the 28-day tensile strength is 7.5MPa, the 28-day axial compressive strength is 122MPa, and the 28-day drying shrinkage is 350με.
[0076] Experimental results show that the workability of the low-shrinkage ultra-high performance concrete made from solid waste lightweight aggregates prepared in Examples 1-3 of this invention meets the application requirements. Compared with the traditional ultra-high performance concrete in the comparative example, the bulk density is significantly reduced by 16-26%. Although the mechanical properties are somewhat reduced, they still meet the C100 and C120 grade levels required by the specifications. Importantly, the 28-day drying shrinkage values of Examples 1-3 of this invention are significantly reduced. Compared with the 28-day drying shrinkage value of 350 με in the comparative example, the 28-day drying shrinkage value of Examples 1-3 of this invention is only 42-50 με, a reduction of 85%-88%. This indicates that the low-shrinkage ultra-high performance concrete made from solid waste lightweight aggregates provided by this invention significantly improves the crack resistance of ultra-high performance concrete.
[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A low-shrinkage, ultra-high-performance concrete using lightweight aggregates from solid waste, characterized in that, The raw materials include the following parts by weight: 300-400 parts of solid waste mixed lightweight aggregate, 900-1000 parts of lightweight cement-based cementitious material, 65-75 parts of composite micro-expansion agent, 200-350 parts of high-fluidity fine aggregate, 25-35 parts of water-reducing agent, 0.1-3 parts of retarder, 15-156 parts of crack-resistant fiber, 200-250 parts of water, 3-6 parts of shrinkage reducing agent, and 1-5 parts of defoamer; The lightweight cement-based cementitious material is composed of 45-55 parts cement, 2-8 parts silica fume, 15-25 parts fly ash microspheres, 10-25 parts fly ash and 2-5 parts slag powder. The composite micro-expansion agent is composed of magnesium oxide, calcium oxide and gypsum powder, and the weight ratio of magnesium oxide, calcium oxide and gypsum powder is 4:(2-3):(2-3).
2. The solid waste lightweight aggregate low-shrinkage ultra-high performance concrete according to claim 1, characterized in that, The silica fume has a SiO2 content greater than 92%, a 28-day activity index of 120-130%, and a water requirement ratio of 110-120%. The fly ash microspheres are low-density hollow cenospheres with a density of 1200-1500 kg / m³. 3 The activity index after 28 days is 100-110%, and the water requirement ratio is 90-100%. The 28-day activity index of the fly ash is 90-100%, and the water requirement ratio is 95-105%. The slag powder has a 28-day activity index of 98-108% and a water requirement ratio of 105-115%. The magnesium oxide has a magnesium oxide content of 88-92%, a moisture content of ≤1%, and an active reaction time of 200-300s; The calcium oxide content of the calcium oxide is 92-97%; The gypsum powder has a calcium sulfate dihydrate content of ≥95% and a moisture content of less than 5%.
3. The low-shrinkage ultra-high performance concrete using lightweight aggregates from solid waste according to claim 1, characterized in that, The solid waste mixed lightweight aggregate is composed of clay ceramsite and coal gangue ceramsite, and the mass ratio of clay ceramsite to coal gangue ceramsite is (3~4):(6~7). The clay ceramsite has a particle size ratio of 1.18~2.36mm > 95%, a particle size ratio below 1.18mm ≤ 5%, a compressive strength ≥ 5MPa, and a compacted bulk density of 600-650kg / m³. 3 The saturated water absorption rate is 5-7%; The coal gangue ceramsite has a particle size of 1.18~0.075mm accounting for >95%, a particle size below 0.075mm accounting for ≤5%, a compressive strength of ≥20MPa, and a compacted bulk density of 900-950kg / m³. 3 The saturated water absorption rate is 8-10%.
4. The low-shrinkage ultra-high performance concrete using lightweight aggregates from solid waste according to claim 1, characterized in that, The high-flowability fine aggregate is composed of 180-220 parts alumina microspheres, 350-380 parts 16-26 mesh quartz sand, 180-220 parts 40-70 mesh quartz sand, and 210-250 parts 70-120 mesh quartz sand, with a compacted bulk density of 1500-1800 kg / m³. 3 .
5. The low-shrinkage ultra-high performance concrete using lightweight aggregates from solid waste according to claim 1, characterized in that, The crack-resistant fiber is copper-plated microfiber steel fiber or polyvinyl alcohol fiber; The copper-plated microfiber steel fibers are straight fibers with a diameter of 0.20~0.23mm, a length of 13~16mm, a tensile strength of 2500~2800MPa, and a density of 7500~8000kg / m³. 3 The admixture dosage is 117~156 kg per cubic meter of concrete; The polyvinyl alcohol fibers have a diameter of 30~100μm, a length of 9~12mm, and a density of 1200~1500kg / m³. 3 The admixture dosage is 15-30 kg per cubic meter of concrete.
6. The low-shrinkage ultra-high performance concrete using lightweight aggregates from solid waste according to claim 1, characterized in that, The water-reducing agent is a polycarboxylate-based high-performance water-reducing agent; The shrinkage-reducing agent is a polyether-based liquid shrinkage-reducing agent; The defoamer is a polyether and mineral oil composite powder defoamer; The retarder is a sodium citrate retarder.
7. A method for preparing low-shrinkage ultra-high performance concrete using lightweight aggregates from solid waste as described in any one of claims 1-6, comprising the following specific steps: (1) Weigh water, shrinkage reducer and defoamer according to the weight ratio. First heat the water, then add shrinkage reducer and defoamer, and stir at high speed to get a pre-wet impregnation solution. (2) Weigh the dry solid waste mixed lightweight aggregate according to the weight ratio, add the solid waste mixed lightweight aggregate to the pre-wetting impregnation liquid, and stir and soak it slowly to make the solid waste mixed lightweight aggregate fully absorb water and pre-wet it to obtain mixed product A; (3) Weigh the lightweight cement-based cementitious material, composite micro-expansion agent and high fluidity fine aggregate according to the weight ratio, add them to the mixture A, and stir evenly in a mixer to obtain the mixture B; (4) Weigh the water-reducing agent and retarder according to the weight ratio, add them to the mixed product B, stir evenly until a fluid state appears, and obtain the mixed product C; (5) Weigh out the anti-crack fiber according to the weight ratio, add it to the mixed product C, stir evenly to obtain the mixed product D; (6) The mixed product D is subjected to construction pouring, vibration, surface finishing and curing to obtain solid waste lightweight aggregate low shrinkage ultra-high performance concrete.
8. The method for preparing low-shrinkage ultra-high performance concrete using lightweight aggregates from solid waste according to claim 7, characterized in that, In step (1), the water is heated to a temperature of 40-50°C, the high-speed stirring speed is 400-600 r / min, and the high-speed stirring time is 2-5 min. In step (2), the slow stirring speed is 20r / min to 60r / min, the slow stirring time is 1 to 5min, and the soaking time is 4 to 8h.
9. The method for preparing low-shrinkage ultra-high performance concrete using lightweight aggregates from solid waste according to claim 7, characterized in that, In step (3), lightweight cement-based cementitious material, composite micro-expansion agent and high fluidity fine aggregate are weighed according to the weight ratio, added to the mixed product A, and stirred evenly in a mixer for a time of t1 to obtain mixed product B. In step (4), the water-reducing agent and the retarder are weighed according to the weight ratio, added to the mixed product B, stirred evenly for t2 until a fluid state appears, and the mixed product C is obtained. In step (5), the anti-crack fiber is weighed according to the weight ratio, added to the mixed product C, stirred evenly, and stirred for t3 to obtain the mixed product D; t1+t2+t3≤10min.
10. The method for preparing low-shrinkage ultra-high performance concrete using lightweight aggregates from solid waste according to claim 7, characterized in that, In step (6), the pouring spacing is controlled to be ≤1m, the curing method is steam curing, and the curing conditions are: constant temperature curing at 65-75℃ for 60-80h, or constant temperature curing at 85-95℃ for 40-50h.