Ultrahigh anti-impact and wear-resistant hydraulic runner concrete based on large-stage-difference ladder layer structure and preparation method of ultrahigh anti-impact and wear-resistant hydraulic runner concrete

Abstract

The invention provides ultrahigh anti-impact wear-resistant hydraulic runner concrete based on a large-stage-difference ladder layer structure and a preparation method of the ultrahigh anti-impact wear-resistant hydraulic runner concrete, and belongs to the technical field of hydraulic concrete. The concrete is composed of an anti-abrasion concrete surface layer, a transition layer and a concrete bottom layer. The surface layer is prepared from a plurality of components such as Portland cement, fly ash microspheres, silicon powder, steel fibers and super absorbent resin, and the strength grade of the surface layer reaches C120-C150. The transition layer is made of C80-C90 single-grading concrete, the elasticity modulus, the volume contractibility and other performance of the transition layer are precisely designed, and the huge performance difference between the surface layer and the bottom layer is effectively buffered. Through material-structure-process collaborative innovation, multiple mechanisms such as internal curing, expansion compensation and shrinkage reduction are comprehensively utilized, and a high-frequency vibration process after initial setting and before final setting is supplemented, so that the technical problems of weak interface bonding force and poor volume stability under the condition of large stage difference are successfully solved; and the prepared concrete has ultrahigh impact resistance and wear resistance and excellent crack resistance, and is suitable for strongly-scoured parts such as hydraulic building runners and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydraulic concrete, in particular to an ultra-high impact and wear resistant hydraulic runner concrete based on a large-differential stepped structure and a preparation method thereof. BACKGROUND

[0002] In the construction and repair process of hydraulic concrete structures such as dams, piers, stilling basins, etc., new and old concrete interfaces or large-area concrete layered pouring conditions are often encountered. In order to ensure the integrity and durability of the structure, high requirements are put forward for the interface bonding quality. The traditional construction practice and material design have a series of significant technical contradictions and limitations when dealing with this challenge.

[0003] Firstly, in order to control the hydration heat, reduce shrinkage cracks and meet the construction process requirements, a certain strength grade difference (industry practice is generally 2 grade differences) between the new poured concrete and the existing concrete is usually controlled. However, even if the grade difference is controlled, due to the differences in parameters such as elastic modulus and shrinkage performance of new and old concrete materials, the interface bonding force is still weak, which is easy to become a stress concentration area, and under the action of temperature change, dry-wet cycle and external load, it produces diseases such as separation and cracking, which seriously affects the safety of the structure.

[0004] In order to improve the interface bonding performance, one common method in the prior art is to design a stepped structure, for example, to use three layers of concrete with different mix proportions for transition pouring, in order to buffer the stress through the gradient change of performance. However, this method brings new problems in actual application: poor interface compatibility. Multi-layer materials mean that there are multiple interfaces with different performance differences, which not only increases the complexity of construction and quality control difficulty, but also the shrinkage and creep characteristics of each layer of material are inconsistent, which may induce micro-cracks at multiple interfaces, ultimately leading to the overall failure of the multi-layer system.

[0005] In view of the above problem of insufficient interface bonding force, the inventor thought of a remedial measure: immediately pouring the upper layer of concrete within the time window after the initial setting of the lower layer of concrete and before the final setting, and supplementing with high-frequency vibration. This aims to use the plasticity of the lower layer of concrete to make the two layers of materials intermix and penetrate, so as to achieve better mechanical interlocking. However, this technical means still has defects: firstly, the construction timing is difficult to accurately control, and the construction organization requirements are extremely high; secondly, and more importantly, high-frequency vibration will aggravate the settlement and bleeding of the cementitious material system, destroy the internal structure, cause the shrinkage performance of the concrete, especially the stepped material, to deteriorate, the volume stability to decrease, and the long-term shrinkage and cracking risk to increase.

[0006] Therefore, there is an urgent need for a solution that fundamentally solves the problem. The core is to design a new material that not only meets the mechanical and durability requirements of hydraulic concrete, but most importantly has excellent volume stability (low shrinkage, low creep), can form a strong and durable interface with existing concrete, and at the same time avoid complex multi-layer structure and harsh construction process requirements, so as to realize the persistent and reliable interface performance of hydraulic concrete structure. SUMMARY

[0007] The purpose of the present application is to provide an ultra-high impact and wear-resistant hydraulic flow channel concrete based on a large-differential gradient structure and a preparation method thereof, which is used to solve the above technical problems.

[0008] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions: The present application provides an ultra-high impact and wear-resistant hydraulic flow channel concrete based on a large-differential gradient structure, which is composed of an impact and wear-resistant concrete surface layer, a transition layer and a concrete bottom layer. The impact and wear-resistant concrete surface layer is prepared from raw materials containing the following mass fractions: 800~1200 parts of Portland cement; 150~210 parts of fly ash microbeads; 200~270 parts of silica powder; 196~265 parts of steel fiber; 28~40 parts of water reducing agent; 1000~1350 parts of aggregate; 0~10 parts of high water absorption resin; 0~130 parts of light burned magnesium oxide expanding agent; 0~500 parts of high water absorption aggregate; 0~25 parts of shrinkage reducing agent; 196~357 parts of water; The high water absorption resin, light burned magnesium oxide expanding agent, high water absorption aggregate and shrinkage reducing agent are not all 0.

[0009] Further, the thickness of the impact and wear-resistant concrete surface layer is 10~20cm, and the strength grade is C120~C150; the thickness of the transition layer is 10~20cm, and the strength grade is C80~C90; the thickness of the concrete bottom layer is 50~80cm, and the strength grade is C30~C40; The transition layer uses single grading, which is 5~20mm small stone; The concrete bottom layer uses two or three grades, two grades use 40mm medium stone and 20mm small stone; three grades use 80mm large stone, 40mm medium stone and 20mm small stone.

[0010] Further, the silicate cement is high-iron high-calcium silicate cement and / or high-iron low-calcium silicate cement, the Fe2O3 content of the high-iron high-calcium silicate cement is 5.84%, and the CaO content is 62.13%; the Fe2O3 content of the high-iron low-calcium silicate cement is 5.28%, and the CaO content is 61.25%.

[0011] Further, the specific surface area of the fly ash microsphere is greater than or equal to 1200 m 2 / kg, and the 28d activity index is greater than 90%.

[0012] Further, the water-binder ratio of the material in the anti-impact and wear-resistant concrete surface layer is 0.15-0.17.

[0013] Further, the aggregate is one or more of granite, basalt and marble, and the fineness modulus of the aggregate is 2.20-2.40.

[0014] Further, the high-water-absorption aggregate is fast-cooling high-titanium heavy slag sand, and the stone powder content is 8%; The apparent density of the water-absorbing resin is 890 kg / m 3 , and the water absorption multiple is 250 times of its own weight.

[0015] The application also provides a preparation method of the super-high anti-impact and wear-resistant hydraulic flow channel concrete based on the large-difference gradient layer structure. 1) Mix the high-water-absorption resin or high-water-absorption aggregate with part of the water to form a gel-like material; 2) Mix the aggregate, silicate cement, fly ash microsphere and silicon powder to obtain dry materials; 3) Mix the water-reducing agent, light-burned magnesium oxide expanding agent or shrinkage-reducing agent with the dry materials to form a mixture, then disperse the steel fibers in the mixture, and add part of the water to mix the materials uniformly; 4) Add the gel-like material to the materials in step 3), then add the remaining water, and mix uniformly to obtain the anti-impact and wear-resistant concrete surface layer slurry; 5) Pour the mixed concrete bottom layer material into a mold, and improve the surface density of the concrete bottom layer by high-frequency vibration; 6) Immediately after the initial setting of the concrete bottom layer material and before the final setting, pour the transition layer material, process the transition layer by the same high-frequency vibration, then pour the anti-impact and wear-resistant concrete surface layer slurry, tightly bond the anti-impact and wear-resistant concrete surface layer, the transition layer and the concrete bottom layer by high-frequency vibration, and then perform normal temperature curing to obtain the super-high anti-impact and wear-resistant hydraulic flow channel concrete based on the large-difference gradient layer structure.

[0016] Further, in step 1), the mass ratio of the high-water-absorption resin or high-water-absorption aggregate to part of the water is 1:9-1:11.

[0017] Further, the high-frequency vibration is carried out by using a high-frequency vibrating formwork, and the vibration frequency is 200-300 Hz.

[0018] The beneficial effects of the present application are: 1. Excellent interfacial bonding under large differential is successfully achieved: by designing a special single-grade transition layer with a strength grade of C80-C90, its elastic modulus (32-38 GPa), volume shrinkage (180d ≤500×10 -6 ), dry shrinkage (28d ≤0.020%), and autogenous volume change (28d, -50-50×10 -6 ) are precisely designed and controlled, effectively buffering the huge performance difference between the bottom layer concrete (C30-C40) and the surface layer ultra-high strength concrete (C120-C150), solving the industry problem of poor interfacial bonding force and easy void cracking caused by mismatch of elastic modulus and shrinkage behavior.

[0019] 2. The concrete is endowed with super-high impact and wear resistance: the surface layer is designed with ultra-high strength (C120-C150) and high fiber content (196-265 parts), and high-iron phase cement and high-hardness granite or basalt aggregate are selected, so that the surface layer has extremely high compressive strength and impact and wear resistance (up to more than 100 MPa), significantly improving the durability and service life of the hydraulic flow passage in harsh environments such as high-speed water flow and sediment scouring.

[0020] 3. The volume stability and crack resistance of the composite system are significantly improved: A variety of functional components such as high water absorption resin (SAP), light burned magnesium oxide expanding agent (MgO), high water absorption aggregate, and shrinkage reducing agent are innovatively introduced into the surface layer. These components effectively inhibit the early self-shrinkage and late dry shrinkage of ultra-high strength concrete through multiple synergistic mechanisms such as "internal curing", "expansion compensation", and "shrinkage reduction", significantly improving its volume stability and fundamentally reducing the risk of cracking.

[0021] 4. The low shrinkage and micro-expansion properties of the transition layer further ensure the dimensional stability and integrity of the entire gradient structure during long-term use.

[0022] 5. The construction process is optimized to ensure the interlayer bonding quality: the best time window for pouring the surface layer after the initial setting and before the final setting of the bottom layer concrete is determined, and a high-frequency vibration (200-300 Hz) process is used. This process can take advantage of the plastic state of the bottom layer material to achieve full mixing and mechanical engagement of the two layers of material, forming a firm interfacial bond (gradient interface), while the addition of functional components offsets the potential negative effects of high-frequency vibration, ensuring the final engineering quality.

[0023] 6. Provide flexible material adaptability and excellent construction performance: various functional components (SAP, MgO, high water absorption aggregate, shrinkage reducing agent) in the surface layer formula can be flexibly compounded and optimized according to the actual engineering requirements (such as different emphasis on crack resistance, wear resistance, fluidity), and the preparation method can effectively solve the problems of high viscosity of ultra-high strength concrete and easy agglomeration of steel fiber, and obtain a surface layer slurry with good workability, which is easy to construct and pour.

[0024] In summary, the present application prepares a hydraulic flow channel concrete with ultra-high impact and wear resistance, excellent volume stability and interface bonding performance through the trinity innovation of "material design-structure design-process design", which has significantly better comprehensive performance than traditional technology and has great engineering application value. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Figure is the influence of SAP content on the mechanical properties of ultra-high performance concrete; Figure 2 Figure is the influence of SAP content on the dry shrinkage of ultra-high performance concrete; Figure 3 Figure is the influence of MgO expansion agent content on the mechanical properties of ultra-high performance concrete; Figure 4 Figure is the influence of MgO expansion agent content on the dry shrinkage of ultra-high performance concrete; Figure 5 Figure is the influence of high water absorption aggregate content on the mechanical properties of ultra-high performance concrete; Figure 6 Figure is the influence of shrinkage reducing agent content on the mechanical properties of ultra-high performance concrete; Figure 7 Figure is the influence of different improvement measures on the performance of ultra-high performance concrete: (a) compressive strength; (b) dry shrinkage rate; Figure 8 Figure is the impact and wear resistance strength column chart of the concrete of comparative example 1; Figure 9 Figure is a schematic diagram of the ultra-high impact and wear resistant hydraulic flow channel concrete based on the large-differential gradient layer structure of the present application, wherein 1 is the impact and wear resistant concrete surface layer, 2 is the gradient layer interface, and 3 is the concrete bottom layer. DETAILED DESCRIPTION

[0026] The present application provides an ultra-high impact and wear resistant hydraulic flow channel concrete based on a large-differential gradient layer structure, which is composed of an impact and wear resistant concrete surface layer, a transition layer and a concrete bottom layer. The impact and wear resistant concrete surface layer is prepared from raw materials containing the following mass fractions: portland cement 800~1200 parts; Fly ash microbead 150~210 parts; Silica powder 200~270 parts; Steel fiber 196~265 parts; Water reducing agent 28~40 parts; Aggregate 1000~1350 parts; Super absorbent resin 0~10 parts; Light burned magnesium oxide expansion agent 0~130 parts; Super absorbent aggregate 0~500 parts; Shrinkage reducing agent 0~25 parts; Water 196~357 parts; The super absorbent resin, light burned magnesium oxide expansion agent, super absorbent aggregate and shrinkage reducing agent are not simultaneously 0.

[0027] In the present application, the amount of the portland cement is preferably 802~1080 parts by mass, and further preferably 1000~1080 parts by mass.

[0028] In the present application, the amount of the fly ash microbead is preferably 150~203 parts by mass, and further preferably 180~203 parts by mass.

[0029] In the present application, the amount of the silica powder is preferably 250~270 parts by mass.

[0030] In the present application, the amount of the steel fiber is preferably 200~265 parts by mass.

[0031] In the present application, the amount of the water reducing agent is preferably 28.8~39 parts by mass, and further preferably 30~35 parts by mass.

[0032] In the present application, the amount of the aggregate is preferably 1200~1350 parts by mass.

[0033] In the present application, the amount of the super absorbent resin is preferably 3.1~9.3 parts by mass, and further preferably 3.1~6.2 parts by mass.

[0034] In the present application, the amount of the light burned magnesium oxide expansion agent is preferably 77.7~124.2 parts by mass, and further preferably 93.2~108.7 parts by mass.

[0035] In the present application, the amount of the super absorbent aggregate is preferably 80~483 parts by mass, and further preferably 160~322 parts by mass.

[0036] In the present application, the amount of the shrinkage reducing agent is preferably 12.5-23.3 parts by mass, and more preferably 12.5-15.5 parts by mass.

[0037] In the present application, the amount of water is preferably 200-357 parts by mass.

[0038] In the present application, the thickness of the impact-resistant and abrasion-resistant concrete surface layer is 10-20 cm, and the strength grade is C120-C150; the thickness of the transition layer is 10-20 cm, and the strength grade is C80-C90; the thickness of the concrete bottom layer is 50-80 cm, and the strength grade is C30-C40. The transition layer is single-graded, and the small stones are 5-20 mm; The concrete bottom layer is double-graded or triple-graded, the double-graded uses 40 mm medium stones and 20 mm small stones, and the triple-graded uses 80 mm large stones, 40 mm medium stones and 20 mm small stones.

[0039] In the present application, the elastic modulus of the transition layer is 32-38 GPa, the volume shrinkage (180 d) is ≤500×10 -6 , the dry shrinkage (28 d) is ≤0.02%, and the self-volume change (28 d) is -50×10 -6 -50×10 -6 .

[0040] In the present application, the portland cement is high-iron high-calcium portland cement and / or high-iron low-calcium portland cement, the content of Fe2O3 in the high-iron high-calcium portland cement is 5.84%, and the content of CaO is 62.13%; the content of Fe2O3 in the high-iron low-calcium portland cement is 5.28%, and the content of CaO is 61.25%.

[0041] In the present application, the specific surface area of the fly ash microbeads is ≥1200 m 2 / kg, and the 28 d activity index is >90%.

[0042] In the present application, the water-binder ratio of the materials in the impact-resistant and abrasion-resistant concrete surface layer is 0.15-0.17, and preferably 0.15, 0.16 or 0.17.

[0043] In the present application, the aggregate is one or more of granite, basalt and marble, and the fineness modulus of the aggregate is 2.20-2.40, and preferably 2.30.

[0044] In the present application, the high-water-absorption aggregate is fast-cooling high-titanium heavy slag sand, and the content of stone powder is 8%; The apparent density of the water-absorption resin is 890 kg / m 3, the water absorption multiple is 250 times of its own weight.

[0045] The application also provides a preparation method of the super-high impact and wear-resistant hydraulic flow channel concrete based on the large-difference gradient layer structure. 1) mixing the super-absorbent resin or super-absorbent aggregate with part of water to form a gel-like material; 2) mixing the aggregate, Portland cement, fly ash microbeads and silicon powder to obtain dry materials; 3) mixing the water reducing agent, light-burned magnesium oxide expanding agent or shrinkage reducing agent with the dry materials to form a mixture, then dispersing the steel fibers in the mixture, and adding part of water to mix the materials uniformly; 4) adding the gel-like material to the materials in step 3), then adding the remaining water and mixing uniformly to obtain the impact and wear-resistant concrete surface layer slurry; 5) pouring the mixed concrete bottom layer material into a mold, and improving the surface density of the concrete bottom layer by high-frequency vibration; 6) immediately pouring the transition layer material after the initial setting of the concrete bottom layer material and before the final setting, treating the transition layer by the same high-frequency vibration, then pouring the impact and wear-resistant concrete surface layer slurry, tightly combining the impact and wear-resistant concrete surface layer, the transition layer and the concrete bottom layer by high-frequency vibration, and then performing normal temperature curing to obtain the super-high impact and wear-resistant hydraulic flow channel concrete based on the large-difference gradient layer structure.

[0046] In the application, in step 1), the mass ratio of the super-absorbent resin or super-absorbent aggregate to part of water is 1:9-11, preferably 1:10.

[0047] In the application, the high-frequency vibration is performed by using a high-frequency vibration formwork, and the vibration frequency is 200-300 Hz, preferably 200-250 Hz.

[0048] In the application, the high-frequency vibration formwork is the formwork with built-in high-frequency vibration for concrete construction disclosed in application No. 202010679223.0.

[0049] The technical solutions provided by the application will be described in detail below in combination with embodiments, but they should not be understood as limitations on the protection scope of the application.

[0050] The physical properties of the raw materials used in the application are as follows: High-iron high-calcium Portland cement (referred to as HFC1) and high-iron low-calcium Portland cement (referred to as HFC2), C4AF≥15% and C3S≤50% in HFC1; C4AF≥15% and C3S≤35% in HFC2.

[0051] Fly ash microbeads: fly ash microbeads produced by Tianjin Zhucheng New Material Co., Ltd., specific surface area≥1200m2 / kg, 28d activity index >90%; silicon powder (SF) from Eken International Trade (Shanghai) Co., Ltd.

[0052] Steel fiber: diameter 0.18mm, length 13mm, tensile strength 1800MPa.

[0053] Water reducing agent: polycarboxylic acid superplasticizer for ultra-high performance concrete, solid content 35%, water reducing rate 35%.

[0054] The high water absorption resin (SAP) used in the application is from Sinopharm Group, with an apparent density of 890kg / m 3 , water absorption in deionized water is 250 times its own weight, and water absorption in alkaline solution is 40 times its own weight.

[0055] The light-burned MgO used in the application is from a certain special building material limited liability company in Wuhan.

[0056] The high water absorption aggregate used in the application is fast-cooled high-titanium heavy slag sand produced in Panzhihua, with a stone powder content of 8% and a saturated surface dry water absorption rate of 12.0%.

[0057] The shrinkage reducing agent used in the application is from Jiangsu Subote New Material Co., Ltd. The density is 1.013g / cm 3 , and the 7d, 28d and 60d shrinkage rates are 45.4%, 39.6% and 35.2% respectively.

[0058] Example 1

[0059] The batching table of the anti-impact and wear concrete surface layer is as follows Table 1: Table 1 Concrete batching table (kg / m 3 )

[0060] In the above batching table, the cement is HFC1, and the aggregate is granite.

[0061] From Table 1 and Figure 1 , it can be seen that adding different amounts of SAP will result in different degrees of reduction in 3d compressive strength. At 3d, the compressive strengths of SG1, SG2 and SG3 are 84.2%, 69.2% and 63.4% of SG0 respectively. With the extension of the age, the compressive strength of ultra-high performance concrete with SAP gradually approaches that of the blank sample. At 28d, the compressive strengths of SG1, SG2 and SG3 are 102.1%, 83.1% and 71.3% of SG0 respectively. At 180d, the compressive strengths of SG1, SG2 and SG3 are 102.0%, 91.2% and 83.7% of SG0 respectively.

[0062] FromFigure 2 It can be seen that before 6 days of age, the drying shrinkage of ultra-high performance concrete with different dosages of SAP showed a gradually increasing trend, but was lower than that of the control sample. The drying shrinkage rates of SG1, SG2, and SG3 at 6 days of age were 0.006%, 0.025%, and 0.028% lower than that of SG0, respectively. From 6 days to 3 meters of age, the drying shrinkage of ultra-high performance concrete with different dosages of SAP showed a gradually decreasing trend. This is mainly because the moisture absorbed by SAP is gradually released, resulting in a slight decrease in the drying shrinkage rate, which is close to the evolution law of internal humidity. At 5 meters of age, the drying shrinkage rates of ultra-high performance concrete with SAP were all lower than that of the control sample. The drying shrinkage rates of SG1, SG2, and SG3 at 5 meters of age were 0.012%, 0.019%, and 0.020% lower than that of SG0, respectively. This shows that, under appropriate dosage conditions, SAP can improve the fluidity of ultra-high performance concrete without affecting its long-term mechanical properties, and can also reduce the drying shrinkage rate of ultra-high performance concrete to a certain extent. The reason why adding SAP reduces the drying shrinkage rate of ultra-high performance concrete can be attributed to the fact that SAP has a high migration rate in an alkaline environment after absorbing water, and is more easily lost than free water in capillaries. The drying stress generated in the specimens containing SAP is relatively low, so its drying shrinkage is relatively small.

[0063] The 28-day impact and abrasion resistance of the surface layer obtained by curing SG1 samples using different curing methods were as follows: Standard curing 167h·(kg / m) 2 ) -1 Steam curing for 169 hours (kg / m²) 2 ) -1 Dry heat curing for 152 hours (kg / m²) 2 ) -1 Steam curing for 171 hours (kg / m²) 2 ) -1 .

[0064] Example 2

[0065] The batching table for the impact-resistant concrete surface layer is shown in Table 2 below: Table 2 Concrete mix design (kg / m³) 3 )

[0066] In the above ingredient list, the cement is HFC1 and the aggregate is granite.

[0067] Depend on Figure 3It is evident that incorporating different amounts of MgO expansive agent leads to a certain degree of decrease in the compressive strength of ultra-high performance concrete. Compared with the blank sample, the compressive strength of PG1, PG2, PG3, and PG4 decreased by 5.6%, 3.3%, 9.7%, and 4.3% at 180 days, respectively. This indicates that the incorporation of MgO expansive agent will have a certain adverse effect on the mechanical properties of ultra-high performance concrete. This is mainly due to the competition between MgO expansive agent particles and cement particles for water molecules, resulting in a decrease in the bonding force of cement hydration products, thereby affecting the mechanical properties of ultra-high performance concrete.

[0068] Depend on Figure 4 It can be seen that the addition of MgO expansive agent can effectively reduce the drying shrinkage rate of ultra-high performance concrete. At 5m age, the drying shrinkage rates of PG1, PG2, PG3, and PG4 are 0.015%, 0.021%, 0.027%, and 0.043% lower than that of SG0, respectively. This indicates that the higher the dosage of MgO expansive agent, the greater the final expansion, and the more significant its compensation effect on ultra-high performance concrete.

[0069] Example 3

[0070] The batching table for the impact-resistant concrete surface layer is shown in Table 3 below: Table 3 Concrete mix design (kg / m³) 3 )

[0071] In the above ingredient list, the cement is HFC1 and the aggregate is granite.

[0072] Depend on Figure 5 It is evident that replacing standard sand with highly absorbent aggregate leads to a certain degree of decrease in the compressive strength of ultra-high performance concrete, and the higher the replacement amount, the more pronounced the decrease. Compared with the blank sample, the compressive strength of GG1, GG2, GG3, and GG4 at 180 days decreased by 1.1%, 4.7%, 8.1%, and 11.3%, respectively. This indicates that replacing standard sand with highly absorbent aggregate will have a certain adverse effect on the mechanical properties of ultra-high performance concrete. This is mainly because as hydration progresses, the water in the highly absorbent aggregate is continuously released, leading to a continuous decrease in the actual water-cement ratio of ultra-high performance concrete, thus affecting its mechanical properties to some extent.

[0073] This invention utilizes highly absorbent aggregates to replace standard sand, effectively reducing the drying shrinkage rate of ultra-high performance concrete (UHVPC). At 2 meters, the reduction in drying shrinkage rate of UHVPC using highly absorbent aggregates is most significant. Specifically, the drying shrinkage rates of GG1, GG2, GG3, and GG4 are 0.038%, 0.042%, 0.041%, and 0.042% lower than SG0, respectively. This is because the water adsorbed by the highly absorbent aggregates is gradually released, reducing the drying shrinkage rate of UHVPC to some extent. As the age increases, the trend of highly absorbent aggregates reducing the drying shrinkage rate of UHVPC gradually becomes less significant. At 5 meters, the drying shrinkage rates of GG1, GG2, GG3, and GG4 are 0.023%, 0.027%, 0.016%, and 0.014% lower than SG0, respectively. This demonstrates that the reduction in drying shrinkage rate of UHVPC using highly absorbent aggregates is age-dependent. Furthermore, when the replacement rate of superabsorbent aggregate is 10%, the drying shrinkage rate of ultra-high performance concrete decreases most significantly at 5m age.

[0074] Example 4

[0075] The batching table for the impact-resistant concrete surface layer is shown in Table 4 below: Table 4 Concrete Mixing Table (kg / m³) 3 )

[0076] In the above ingredient list, the cement is HFC1 and the aggregate is granite.

[0077] Depend on Figure 6 It is evident that the addition of shrinkage-reducing agents leads to a decrease in the compressive strength of ultra-high performance concrete (UHVPC), with the decrease becoming more pronounced at higher dosages. At 3 days of age, the compressive strengths of JG1, JG2, and JG3 decreased by 16.4%, 18.7%, and 29.2% compared to SG0, respectively. With increasing age, the compressive strength of UHVPC with added shrinkage-reducing agents gradually approached that of the control sample. At 180 days of age, the compressive strengths of JG1, JG2, and JG3 decreased by 4.7%, 6.9%, and 12.9% compared to SG0, respectively. This is because, on the one hand, the addition of shrinkage-reducing agents lowers the hydration rate of the cementitious materials in UHVPC, reducing the generation of hydration products; on the other hand, the addition of shrinkage-reducing agents increases the air content of UHVPC, increasing the proportion of harmful pores. This negatively impacts the mechanical properties of UHVPC.

[0078] The shrinkage reducing admixture can effectively reduce the dry shrinkage of the ultra-high performance concrete, and the effect of reducing the dry shrinkage at the early age is more obvious. At the age of 3d, the dry shrinkage of JG1, JG2 and JG3 is reduced by 0.045%, 0.048% and 0.052% respectively compared with SG0. With the extension of the age, the trend of reducing the dry shrinkage of the ultra-high performance concrete by the shrinkage reducing admixture gradually weakens. At the age of 5m, the dry shrinkage of JG1, JG2 and JG3 is reduced by 0.030%, 0.030% and 0.034% respectively compared with SG0. The incorporation of the shrinkage reducing admixture can effectively maintain the humidity of the pore solution in the ultra-high performance concrete, and effectively reduce the capillary pore tension and the negative pressure generated thereby.

[0079] Example 5

[0080] Preparation of an ultra-high impact and wear-resistant hydraulic flow channel concrete based on a large-differential gradient layer structure: The material of the SG1 sample in Example 1 is used as the impact and wear-resistant concrete surface layer material, and the specific preparation process is as follows: 1) The concrete bottom layer material with a strength grade of C30 is designed according to the conventional mixing ratio and mixed (80mm large stones, 40mm medium stones and 20mm small stones are used in three-stage distribution), and is ready for use.

[0081] 2) The superabsorbent resin is mixed with water, and stirred until the superabsorbent resin is fully water-absorbed and swelled to form a uniform gel-like material, which is ready for use. The mass ratio of SAP to water is about 1:10; 3) The granite aggregate, HFC1 cement, silicon powder and fly ash beads are poured into a forced mixer, and dry mixing is performed for 5 minutes until all the powders and aggregates are uniformly mixed to obtain dry materials; 4) The water reducing agent is added to the dry materials, and the mixer is started. During the mixing process, the steel fibers are slowly and uniformly added to ensure that the fibers are fully dispersed without clumping. Then the mixing water is added, and the mixing is continued for 8 minutes to form a uniform mixture with uniformly distributed fibers; 5) The prepared SAP gel-like material is added to the mixer, the remaining mixing water is slowly added, and the mixing is continued for 10 minutes until all the materials are uniformly mixed, and the slurry reaches the state of extreme homogeneity, i.e. the impact and wear-resistant concrete surface layer slurry is obtained. The water-binder ratio of the slurry is 0.19; 6) The mixed C30 concrete bottom layer material is poured into a forming mold, and a high-frequency vibrating template with a frequency of 250Hz is used for vibration to improve the density of the bottom surface and create good conditions for subsequent bonding; 7) closely observe the state of the concrete bottom layer, after initial setting, before final setting (i.e. the surface has no obvious water film, but the finger still can leave a fingerprint when pressed), immediately pour the transition layer material (single grade: 5~10mm sand) into the mold, also use 250Hz high frequency vibration template to process the transition layer, then pour the prepared anti-impact and wear surface layer slurry on it. Similarly, use 250Hz high frequency vibration template to vibrate the surface layer, so that the surface layer slurry, transition layer and bottom layer concrete are fully penetrated, mixed, realize strong mechanical interlocking, and form a firm ladder interface.

[0082] After pouring, immediately cover the surface with plastic film, and maintain in a normal temperature (20±2°C) and humid environment for 28 days, and keep the surface of the concrete continuously wet during the period.

[0083] The obtained concrete structure and performance: Concrete bottom layer: thickness 68cm, strength grade C30.

[0084] Transition layer: naturally formed performance gradient transition zone at the interface, 15cm.

[0085] Anti-impact and wear concrete surface layer: thickness 15cm, strength grade up to C120 or above, with ultra-high impact and wear resistance (>100MPa) and excellent volume stability.

[0086] Comparative Example 1

[0087] The ingredient table of the anti-impact and wear concrete surface layer is as follows Table 5: Table 5 Concrete ingredient table (kg / m 3 )

[0088] The compressive strength and growth rate of the above concrete are compared as follows Table 6: Table 6 Comparison of compressive strength and growth rate

[0089] The anti-impact and wear strength of the ultra-high performance concrete prepared by different aggregates is studied, and the specific results are shown in Figure 8 The anti-impact and wear strength of the ultra-high performance concrete prepared by different aggregates is 68.5h / (kg / m 2 )~82.8h / (kg / m 2 ). Compared with different cements, the anti-impact and wear strength of UH1, UH2 and UH3 is 6.3h / (kg / m 2 ), 6.6h / (kg / m 2 ) and 4.9h / (kg / m 2This indicates that ultra-high performance concrete prepared with high-calcium cement from high-speed rail has a higher impact and abrasion resistance than that prepared with low-calcium cement from high-speed rail. Comparing different aggregates, UH1 has a higher impact and abrasion resistance than UH2 and UH3 by 2.97 h / (kg / m³). 2 ) and 9.36h / (kg / m 2 UH4 is 3.27 h / (kg / m³) higher than UH5 and UH6, respectively. 2 ) and 7.97h / (kg / m 2 This indicates that ultra-high performance concrete prepared from granite has the highest impact and abrasion resistance, while ultra-high performance concrete prepared from marble has the lowest impact and abrasion resistance, which is similar to the pattern observed in compressive strength.

[0090] This invention compares the compressive strength and shrinkage rate of different volume stability improvement measures; specific results are shown in [link to results]. Figure 7 .Depend on Figure 7 (a) It can be seen that different measures to improve volume stability all reduce the compressive strength of ultra-high performance concrete to some extent. At 180 days, the compressive strengths of SG2, PG4, GG2, and JG3 are 18.1 MPa, 8.8 MPa, 9.6 MPa, and 26.6 MPa lower than that of SG0, respectively. The addition of MgO expansive agent and the use of high-absorbency aggregate to replace standard sand have the lowest reduction in compressive strength of ultra-high performance concrete. The addition of shrinkage-reducing agents has the most significant reduction in compressive strength. Figure 7 (b) It can be seen that at 180 days, the drying shrinkage rates of SG2, PG4, GG2, and JG3 are reduced by 19%, 43%, 34%, and 27% respectively compared to SG0. Therefore, adding 8% MgO expansion agent has the most significant effect in reducing the drying shrinkage rate of ultra-high performance concrete (UHVPC), and can substantially reduce it. Replacing standard sand with 10% high-absorbency aggregate is the second most effective method, followed by adding 1.5% shrinkage-reducing agent, while adding 0.6% SAP has the least effective effect.

[0091] From the above experimental results, we can conclude that: (1) For ultra-high performance concrete, compared with different aggregates, ultra-high performance concrete prepared with granite aggregate has the highest compressive strength and impact abrasion resistance, while ultra-high performance concrete prepared with marble aggregate has the lowest compressive strength and impact abrasion resistance. Compared with different cements, ultra-high performance concrete prepared with HFC1 has a higher impact abrasion resistance than that prepared with HFC2. The impact abrasion resistance of ultra-high performance concrete prepared with HFC1 is 4.9 h / (kg / m²) higher than that prepared with HFC2. 2 ~6.6h / (kg / m 2 ).

[0092] (2) The 28-day impact and abrasion resistance of the ultra-high performance concrete prepared by HFC1 is 73.4 (h / (kg / m²)).2 )~82.8(h / (kg / m 2 ), the 28d final crack impact energy is 84.1kJ~105.4kJ. The 28d abrasion resistance of the super high performance concrete prepared by the HFC2 is 68.5(h / (kg / m 2 )~76.5(h / (kg / m 2 ), the 28d final crack impact energy is 74.9kJ~98.8kJ.

[0093] (3) The MgO expansive agent with 8% can most obviously reduce the dry shrinkage rate of the super high performance concrete, and can greatly reduce the dry shrinkage rate of the UHPC. The high water absorption aggregate with 10% can reduce the dry shrinkage rate of the super high performance concrete, and the effect is second; the shrinkage reducing agent with 1.5% can reduce the dry shrinkage rate of the super high performance concrete, and the effect is third; the SAP with 0.6% can reduce the dry shrinkage rate of the super high performance concrete, and the effect is worst.

[0094] The above only is the preferred embodiment of the present application, it should be pointed out, for the ordinary skilled in the art, without departing from the principles of the present application, can also make a number of improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. An ultra-high impact and abrasion resistant hydraulic passageway concrete based on a large step graded ladder structure, characterized in that, The super-high impact and wear-resistant hydraulic flow channel concrete is composed of an impact and wear-resistant concrete surface layer, a transition layer and a concrete bottom layer; The impact and wear-resistant concrete surface layer is prepared from raw materials in the following mass fractions: portland cement 800-1200 parts; fly ash microbeads 150-210 parts; silicon powder 200-270 parts; steel fiber 196-265 parts; water reducing agent 28-40 parts; aggregate 1000-1350 parts; high water absorption resin 0-10 parts; light-burned magnesium oxide expanding agent 0-130 parts; high water absorption aggregate 0-500 parts; shrinkage reducing agent 0-25 parts; water 196-357 parts; The high water absorption resin, light-burned magnesium oxide expanding agent, high water absorption aggregate and shrinkage reducing agent are not all 0.

2. The super-abrasion-resistant hydraulic flume concrete based on a large-differential graded structure according to claim 1, characterized in that, The thickness of the impact and wear-resistant concrete surface layer is 10-20 cm, and the strength grade is C120-C150; the thickness of the transition layer is 10-20 cm, and the strength grade is C80-C90; the thickness of the concrete bottom layer is 50-80 cm, and the strength grade is C30-C40; The transition layer is single-graded, and the small stones are 5-20 mm; The concrete bottom layer is double-graded or triple-graded, the double-graded uses medium stones of 40 mm and small stones of 20 mm, and the triple-graded uses large stones of 80 mm, medium stones of 40 mm and small stones of 20 mm.

3. The super-abrasion-resistant hydraulic flume concrete based on a large-differential graded structure according to claim 1 or 2, characterized in that, The portland cement is high-iron high-calcium portland cement and / or high-iron low-calcium portland cement, the content of Fe2O3 in the high-iron high-calcium portland cement is 5.84%, and the content of CaO is 62.13%; the content of Fe2O3 in the high-iron low-calcium portland cement is 5.28%, and the content of CaO is 61.25%.

4. The super-abrasion-resistant hydraulic flume concrete based on a large-differential graded structure according to claim 3, characterized in that, The specific surface area of the fly ash cenospheres is ≥ 1200 m 2 / kg, 28d activity index > 90%.

5. The super-abrasion-resistant hydraulic flume concrete based on a large-differential graded structure according to claim 3, characterized in that, The water-binder ratio of the materials in the impact and wear-resistant concrete surface layer is 0.15-0.

17.

6. The super-abrasion-resistant hydraulic flume concrete based on a large-differential graded structure according to claim 4, characterized in that, The aggregate is one or more of granite, basalt and marble, and the fineness modulus of the aggregate is 2.20-2.

40.

7. The super-abrasion-resistant hydraulic flume concrete based on a large-differential graded structure according to claim 1 or 4 or 6, characterized in that, The high water absorption aggregate is fast-cooling high-titanium heavy slag sand, and the stone powder content is 8%; The apparent density of the water-absorbing resin is 890 kg / m 3 , and the water-absorption multiple is 250 times the weight of itself.

8. The method of manufacturing the ultra-high impact and abrasion resistant hydraulic flow channel concrete based on the large-gap stepped structure according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: 1) mixing the high water absorption resin or high water absorption aggregate with part of the water to form a gel-like material; 2) mixing the aggregate, portland cement, fly ash microbeads and silicon powder to obtain dry materials; 3) mixing the water reducing agent, light-burned magnesium oxide expanding agent or shrinkage reducing agent with the dry materials to form a mixture, then dispersing the steel fiber in the mixture, and adding part of the water to uniformly mix the materials; 4) adding the gel-like material to the materials of step 3), then adding the remaining water to uniformly mix to obtain the impact and wear-resistant concrete surface layer slurry; 5) pouring the mixed concrete bottom layer material into a mold, and improving the surface density of the concrete bottom layer by high-frequency vibration; 6) immediately pouring the transition layer material after the initial setting and before the final setting of the concrete bottom layer material, treating the transition layer by the same high-frequency vibration, then pouring the impact and wear-resistant concrete surface layer slurry, tightly combining the impact and wear-resistant concrete surface layer, the transition layer and the concrete bottom layer by high-frequency vibration, and then performing normal temperature curing to obtain the super-high impact and wear-resistant hydraulic flow channel concrete based on the large-differential gradient layer structure.

9. The production method according to claim 8, characterized by, In step 1), the mass ratio of the high water absorption resin or high water absorption aggregate to part of the water is 1:9-1:

11.

10. The method of claim 9, wherein, The high-frequency vibration is performed by using a high-frequency vibrating formwork, and the vibration frequency is 200 Hz-300 Hz. The high-frequency vibration is performed by using a high-frequency vibrating formwork, and the vibration frequency is 200 Hz-300 Hz.

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