UHPC (Ultra High Performance Concrete) for reinforcing old damaged concrete and pouring method thereof
Through the application of gravel mixed silicate cement and sustained release water reducing agent, UHPC is solved in the problem of insufficient bonding strength and fast coagulation speed in the reinforcement of old damaged concrete, and the effects of uniform reinforcement and high tensile strength are achieved.
Patent Information
- Application Number
- CN202510280164.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-11
- Publication Date
- 2025-07-04
AI Technical Summary
When existing UHPC reinforces old damaged concrete, the difference in cement material leads to insufficient bonding strength, fast condensation speed leads to uneven pouring, and large-sized interfaces are difficult to stir, increasing the difficulty of maintenance.
Gravel mixed silicate cement is used as the reinforcement substrate to reduce the amount of silicate cement, and fill the ice with a sustained release water reducer. By alternately pouring the sustained release crushed ice and UHPC layers, the water-cement ratio and coagulation speed are controlled to ensure uniform coagulation.
The uniform reinforcement of old damaged concrete is achieved, the tensile strength is improved, the amount of silicate cement is reduced, the condensation speed is reduced, and the construction process is simplified.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of UHPC, and in particular to a UHPC for reinforcing old and damaged concrete and a pouring method thereof. Background Art
[0002] UHPC, fully known as ultra-high performance concrete, is an advanced building material with ultra-high strength, high durability and excellent toughness, and is widely used in fields such as bridges, buildings, and marine engineering. In the prior art, there is a situation of using UHPC to reinforce old and damaged concrete. However, due to the large gap between the two cement materials, in the pouring cavity surrounded by the damaged cement, the damaged cement will absorb the moisture in the UHPC, resulting in insufficient bonding strength between the two. After long-term use, the reinforced cement will show phenomena such as delamination or peeling. Moreover, due to the fast setting speed of UHPC, it is impossible to apply stirring and vibration operations during the pouring process of large-sized damaged interfaces, resulting in agglomeration phenomena often occurring before the pouring is completed, leading to uneven stress distribution between the reinforced parts and increasing the maintenance difficulty. Therefore, a UHPC for reinforcing old and damaged concrete and a pouring method thereof are needed. Summary of the Invention
[0003] The purpose of the present invention is to overcome the above deficiencies and provide a UHPC for reinforcing old and damaged concrete and a pouring method thereof, which have the advantages of being more suitable for reinforcing old and damaged concrete and having high tensile strength.
[0004] In the first aspect, the present invention provides a UHPC for reinforcing old and damaged concrete, and its components include, by components: 8-12 parts of portland cement, 2-4 parts of fully encrypted silica fume, 10-12 parts of heavy calcium carbonate, 8-10 parts of quartz sand, 4-6 parts of crushed stone, 0.5-0.7 part of admixture, 3.5-3.7 parts of water, and 1.3-1.5 parts of steel fiber.
[0005] Further, the components of the UHPC include, by components: 10 parts of portland cement, 3 parts of fully encrypted silica fume, 11 parts of heavy calcium carbonate, 9 parts of quartz sand, 5 parts of crushed stone, 0.6 part of admixture, 3.6 parts of water, and 1.4 parts of steel fiber.
[0006] Further, the components of the UHPC further include: 0.2-0.3 part of a slow-release water reducer.
[0007] Further, the slow-release water reducer needs to be pretreated separately before addition. The pretreatment method is to mix it with water to form a solution state, and then inject and fill it into ice cubes with cavities inside for freezing, and then crush the ice cubes to obtain slow-release crushed ice.
[0008] Further, the slow-release water reducer is a polycarboxylate water reducer.
[0009] Furthermore, the particle size of the quartz stone is 65 - 75 mesh.
[0010] Furthermore, the particle size range of the crushed stones is between 5 mm and 10 mm.
[0011] In a second aspect, the present invention provides a pouring method of UHPC for reinforcing old and damaged concrete. Based on the above-mentioned UHPC for reinforcing old and damaged concrete, it specifically includes the following steps:
[0012] S1: Grind the surface of the old and damaged concrete and then roughen it by chiseling.
[0013] S2: Arrange the pouring formwork according to the situation of the part to be reinforced, then wet the cavity formed by the formwork and the old and damaged concrete and lay a layer of slow-release crushed ice.
[0014] S3: After mixing UHPC on-site, alternately pour and fill the slow-release crushed ice and UHPC in the order of slow-release crushed ice layer - UHPC layer - slow-release crushed ice layer - UHPC layer until the cavity formed by the formwork and the old and damaged concrete is filled.
[0015] S4: After pouring, cure its surface until the UHPC reaches 70% of the setting strength and then remove the formwork.
[0016] Furthermore, in step S3, the thickness ratio of the slow-release crushed ice layer to the UHPC layer is controlled at 1∶(5 - 8).
[0017] By adopting the above technical solutions, the beneficial effects of the present invention are as follows:
[0018] The present invention sets crushed stones mixed with portland cement as the reinforcement substrate, reduces the amount of portland cement while ensuring the reinforcement effect, and at the same time sets an appropriate water-cement ratio to slow down its setting speed while ensuring the fluidity and setting strength of UHPC. By setting a water reducer filled in the ice flakes to achieve temperature reduction during the cement setting process, and at the same time slowing down the setting speed of the cement around the damaged concrete to balance its strength after setting.
[0019] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. Detailed Embodiments
[0020] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.
[0021] In a first aspect, the present invention provides a UHPC for strengthening old and damaged concrete, which is prepared on-site according to the on-site usage amount. Its components by weight include: 8-12 parts of Portland cement, 2-4 parts of fully encrypted silica fume, 10-12 parts of heavy calcium carbonate, 8-10 parts of quartz sand, 4-6 parts of crushed stone, 0.5-0.7 parts of admixture, 3.5-3.7 parts of water, and 1.3-1.5 parts of steel fiber.
[0022] Among them, the Portland cement is P.II525 type cement; the fully encrypted silica fume is selected as 92 fully encrypted silica fume with a silica content greater than 92%; the particle size of quartz stone is 65-75 mesh, preferably 70 mesh; the particle size range of the crushed stone is between 5mm and 10mm.
[0023] Specifically, its components by weight specifically include: 10 parts of Portland cement, 3 parts of fully encrypted silica fume, 11 parts of heavy calcium carbonate, 9 parts of quartz sand, 5 parts of crushed stone, 0.6 parts of admixture, 3.6 parts of water, and 1.4 parts of steel fiber.
[0024] In order to increase the connection strength of the two concrete contact interfaces, the UHPC also includes, by weight: 0.2-0.3 parts of a sustained-release water reducer. In this embodiment, the sustained-release water reducer is a polycarboxylate water reducer. The sustained-release water reducer needs to be pretreated separately before addition. The pretreatment method is to mix it with water into a solution state, then inject and fill it into an ice cube with a cavity inside for freezing, and then break the ice cube to obtain sustained-release crushed ice.
[0025] In a second aspect, the present invention provides a pouring method for the UHPC for strengthening old and damaged concrete, which is based on the UHPC for strengthening old and damaged concrete described above, and specifically includes the following steps:
[0026] S1: Grind the surface of the old and damaged concrete and then roughen it by chiseling.
[0027] S2: Arrange the pouring formwork according to the situation of the part to be strengthened, and then wet the cavity formed by the formwork and the old and damaged concrete and lay a layer of sustained-release crushed ice.
[0028] S3: After mixing the UHPC on-site, alternately pour and fill the sustained-release crushed ice and the UHPC in the order of sustained-release crushed ice layer - UHPC layer - sustained-release crushed ice layer - UHPC layer until the cavity formed by the formwork and the old and damaged concrete is filled.
[0029] S4: After pouring, cure its surface until the UHPC reaches 70% of the setting strength and then remove the formwork.
[0030] Among them, in step S3, the thickness ratio of the sustained-release crushed ice layer to the UHPC layer is controlled at 1:(5-8), and preferably 1:6 in this embodiment.
[0031] Select 10 parts of portland cement, 3 parts of fully densified silica fume, 11 parts of heavy calcium carbonate, 9 parts of quartz sand, 5 parts of crushed stone, 0.6 part of admixture, 3.6 parts of water, and 1.4 parts of steel fiber. Prepare and test UHPC for strengthening damaged concrete according to the compressive strength test method in the "Technical Requirements for Ultra-High Performance Concrete (UHPC)" T / CECS10107-2020, and select the ages of 7 days and 28 days for compressive strength tests respectively to obtain Table 1 and Table 2 in sequence.
[0032] Table 1 Compressive Strength Test Table of UHPC with an Age of 7 Days
[0033]
[0034] Table 2 Compressive Strength Test Table of UHPC with an Age of 28 Days
[0035]
[0036] The flexural strength of the UHPC module at 7 days is shown in Table 3:
[0037]
[0038]
[0039] The flexural strength of the UHPC module at 28 days is shown in Table 4:
[0040]
[0041] It can be seen from the above experimental data that the UHPC in the present invention still maintains a relatively high compressive strength and its compressive strength increases steadily with the increase of the age.
[0042] It should be understood that the embodiments disclosed in the present invention are not limited to the specific processing steps or materials disclosed herein, but should extend to equivalent alternatives of such features understood by those of ordinary skill in the relevant art. It should also be understood that the terms used herein are only for the purpose of describing specific embodiments and do not mean to limit.
[0043] The "embodiments" mentioned in the specification mean that the specific features or characteristics described in connection with the embodiments are included in at least one embodiment of the present invention. Therefore, the phrases or "embodiments" that appear throughout the specification do not necessarily all refer to the same embodiment.
[0044] In addition, the described features or characteristics may be combined in any other suitable manner into one or more embodiments. In the above description, some specific details such as thickness, quantity, etc. are provided to give a comprehensive understanding of the embodiments of the present invention. However, those skilled in the relevant art will understand that the present invention can be implemented without one or more of the above specific details or can also be implemented using other methods, components, materials, etc.
Claims
1. A UHPC for strengthening old and damaged concrete, characterized in that, Its components by weight include: 8 - 12 parts of portland cement, 2 - 4 parts of fully densified silica fume, 10 - 12 parts of heavy calcium carbonate, 8 - 10 parts of quartz sand, 4 - 6 parts of crushed stone, 0.5 - 0.7 parts of admixture, 3.5 - 3.7 parts of water, and 1.3 - 1.5 parts of steel fiber.
2. The UHPC for strengthening old and damaged concrete according to claim 1, wherein Its components by weight include: 10 parts of portland cement, 3 parts of fully densified silica fume, 11 parts of heavy calcium carbonate, 9 parts of quartz sand, 5 parts of crushed stone, 0.6 parts of admixture, 3.6 parts of water, and 1.4 parts of steel fiber.
3. The UHPC for strengthening old and damaged concrete according to claim 1, wherein Its components by weight further include: 0.2 - 0.3 parts of slow - release water - reducing agent.
4. The UHPC for strengthening old and damaged concrete according to claim 3, characterized in that, The slow - release water - reducing agent needs to be pretreated separately before addition. The pretreatment method is to mix it with water into a solution state, then inject and fill it into an ice cube with a cavity inside and freeze it, and then crush the ice cube to obtain slow - release crushed ice.
5. The UHPC for reinforcing old and damaged concrete according to claim 4, wherein, This slow - release water - reducing agent is a polycarboxylate water - reducing agent.
6. The UHPC for reinforcing old and damaged concrete according to claim 1, wherein, The particle size of quartz stone is 65 - 75 mesh.
7. The UHPC for strengthening old and damaged concrete according to claim 1, wherein The particle size range of the crushed stone is between 5mm - 10mm.
8. A pouring method of UHPC for strengthening old and damaged concrete, characterized in that, The UHPC for strengthening old and damaged concrete according to claim 3 specifically includes the following steps: S1: Grind the surface of the old and damaged concrete and then roughen it by chiseling. S2: Arrange formwork according to the situation of the part to be strengthened, then wet the cavity formed by the formwork and the old and damaged concrete and lay a layer of slow - release crushed ice. S3: After mixing UHPC on - site, alternately pour and fill the slow - release crushed ice and UHPC in the order of slow - release crushed ice layer - UHPC layer - slow - release crushed ice layer - UHPC layer until the cavity formed by the formwork and the old and damaged concrete is filled. S4: After pouring, cure its surface until the UHPC reaches 70% of the setting strength and then remove the formwork.
9. A pouring method of UHPC for strengthening old and damaged concrete, characterized in that, In step S3, the thickness ratio of the slow - release crushed ice layer to the UHPC layer is controlled at 1∶(5 - 8).