Low-temperature-resistant concrete and preparation method thereof

Abstract

The invention provides low-temperature-resistant concrete and a preparation method thereof. The low-temperature-resistant concrete is prepared from the following raw materials: aggregate, polyvinyl alcohol, polypropylene fibers and a flow modifier, wherein the Marshall stability of the low-temperature-resistant concrete is not less than 25 kN, the porosity is 18.0-20.0%, the breaking bending-tensile stress is not less than 5 MPa, the low-temperature breaking stiffness modulus is not less than 404.18 MPa, the freeze-thaw splitting strength is not less than 1 MPa, the standard flying loss is not more than 15%, and the water immersion flying loss is not more than 20%.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete, and in particular relates to low-temperature resistant concrete and a preparation method thereof. Background Art

[0002] As one of the most widely used civil engineering materials, concrete has good plasticity, economy and durability, and plays an important role in our daily life. The rapid development of concrete has greatly improved people's living and production standards, and it is an indispensable role in social infrastructure projects.

[0003] However, it also has disadvantages that cannot be ignored. Concrete has low ductility, poor deformation capacity, and is prone to brittle failure. In addition, the strength of traditional concrete is greatly affected by temperature and humidity. In a high temperature environment, it is easy to cause volume expansion when heated, and cracks and other defects are easy to occur inside the matrix. When concrete is used in a low temperature environment, the low temperature will cause the cement hydration reaction time to be prolonged, which will eventually affect the initial setting time and final setting time of the concrete, seriously affecting the progress of construction. In addition, the low temperature environment will cause the concrete to frost heave, thereby reducing the concrete's anti-freeze performance and the concrete's anti-cracking performance.

[0004] Concrete materials are very brittle and will produce cracks during pouring, which indirectly affects the mechanical properties of the material. High-performance concrete usually has low water-cement content, which makes the early plastic shrinkage of concrete very serious. Therefore, in view of the defects of traditional concrete, it is necessary to develop a low-temperature resistant high-performance concrete to ensure excellent mechanical properties and durability at room temperature, and to maintain good mechanical properties at low temperatures, so as to ensure good structural integrity after a sudden drop in ambient temperature. Summary of the invention

[0005] The invention provides a low temperature resistant concrete and a preparation method thereof, which are used to solve the problem in the prior art that the mechanical properties of concrete are poor in a low temperature environment.

[0006] In a first aspect, the present invention provides a low-temperature resistant concrete, wherein the raw materials of the low-temperature resistant concrete include aggregate, polyvinyl alcohol, polypropylene fiber and flow modifier; wherein the Marshall stability of the low-temperature resistant concrete is not less than 25 kN, the porosity is 18.0-20.0%, the breaking flexural stress is not less than 5 MPa, the low-temperature breaking stiffness modulus is not less than 404.18 MPa, the freeze-thaw splitting strength is not less than 1 MPa, the standard scattering loss is not more than 15%, and the immersion scattering loss is not more than 20%.

[0007] Compared with the prior art, the beneficial effects of the present invention are as follows: by adding aggregate, polyvinyl alcohol, polypropylene fiber and flow modifier, the water-soluble high molecular polymer polyvinyl alcohol in the low-temperature resistant concrete is increased, so that a film covering the aggregate particles is formed in the concrete to prevent the expansion caused by moisture during freezing, and the concrete reinforcing material polypropylene fiber is added, and synergistically acts with polyvinyl alcohol and the flow modifier to improve the frost resistance of the concrete, and at the same time changes the structure of the concrete, thereby reducing the stress caused by frost heave, so that the concrete has excellent frost resistance, low-temperature strength, freeze-thaw cracking resistance, anti-slip performance and temperature stability.

[0008] Furthermore, the raw materials of the low-temperature resistant concrete include, by mass, 90-94 parts of aggregate, 0.05-0.2 parts of polyvinyl alcohol, 0.1-0.5 parts of polypropylene fiber, 0.4-0.6 parts of flow modifier, 4-5 parts of cement and 4-5 parts of water.

[0009] Furthermore, the mass percentage of the aggregate with a particle size of 0.1-15 mm accounts for 90-94% of the aggregate.

[0010] Furthermore, in the aggregate, the particles with diameters of 0.1-3 mm, 3-10 mm, and 10-15 mm account for 25-35%, 25-35%, and 30-50%, respectively.

[0011] Furthermore, the mass percentages of the aggregate with particle sizes of 0.001-0.075 mm, 0.075-0.15 mm, 0.15-0.3 mm, 0.3-0.6 mm, 0.6-1.18 mm, 1.18-2.36 mm, 2.36-4.75 mm, 4.75-9.5 mm, 9.5-13.2 mm and 13.2-16 mm are 5-6%, 3-5%, 2-5%, 4.5-5%, 5-5.5%, 5-8%, 12-15%, 15-18%, 20-25% and 15-20% respectively.

[0012] Furthermore, the polypropylene fiber has a fineness of 1.5-2.5 dtex and a length of 1.5-200 mm.

[0013] Furthermore, the flow improver includes at least one of asphalt emulsion and rubber.

[0014] In a second aspect, the present invention provides a method for preparing low-temperature resistant concrete, which is used to prepare the low-temperature resistant concrete according to any one of the first aspects, comprising the following steps: The raw material system including aggregate, polyvinyl alcohol, polypropylene fiber and flow modifier is mixed, stirred and heat-insulated to obtain the low-temperature resistant concrete.

[0015] Furthermore, the stirring process has a rotation speed of 10-20 rpm and a time of 1-3 min.

[0016] Furthermore, the temperature of the heat preservation treatment is 180-200° C. and the time is 12-14 days. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] In a first aspect, the present invention provides a low-temperature resistant concrete, wherein the raw materials of the low-temperature resistant concrete include aggregate, polyvinyl alcohol, polypropylene fiber and flow modifier; wherein the Marshall stability of the low-temperature resistant concrete is not less than 25 kN (using LHWD-6 automatic Marshall stability tester), the porosity is 18.0~20.0% (measured by mass method), the breaking flexural stress is not less than 5 MPa, the low-temperature breaking stiffness modulus is not less than 404.18 MPa, the freeze-thaw splitting strength is not less than 1 MPa, the standard scattering loss is not more than 15%, and the immersion scattering loss is not more than 20%.

[0019] The above parameters are obtained by testing at -30℃.

[0020] The low-temperature resistant concrete provided by the present invention increases the water-soluble high-molecular polymer polyvinyl alcohol in the low-temperature resistant concrete by adding aggregate, polyvinyl alcohol, polypropylene fiber and flow modifier therein, so that a film covering aggregate particles is formed in the concrete to prevent expansion caused by moisture during freezing, and polypropylene fiber, a concrete reinforcing material, is added and synergistically acts with polyvinyl alcohol and the flow modifier to improve the frost resistance of the concrete and change the structure of the concrete, thereby reducing the stress caused by frost heave, so that the concrete has excellent frost resistance, low-temperature strength, freeze-thaw crack resistance, anti-slip performance and temperature stability.

[0021] Furthermore, to achieve the above performance, the raw materials of the low-temperature resistant concrete include, by mass, 90-94 parts of aggregate, 0.05-0.2 parts of polyvinyl alcohol, 0.1-0.5 parts of polypropylene fiber, 0.4-0.6 parts of flow modifier, 4-5 parts of cement and 4-5 parts of water.

[0022] Optionally, the mass percentage of the aggregate with a particle size of 0.1-15 mm accounts for 90-94% of the aggregate.

[0023] In a specific embodiment, the mass percentage of the aggregate with particle sizes of 0.1-3 mm, 3-10 mm, and 10-15 mm is 25-35%, 25-35%, and 30-50%, respectively.

[0024] In another specific embodiment, the mass percentages of the aggregate with particle sizes of 0.001-0.075 mm, 0.075-0.15 mm, 0.15-0.3 mm, 0.3-0.6 mm, 0.6-1.18 mm, 1.18-2.36 mm, 2.36-4.75 mm, 4.75-9.5 mm, 9.5-13.2 mm and 13.2-16 mm are 5-6%, 3-5%, 2-5%, 4.5-5%, 5-5.5%, 5-8%, 12-15%, 15-18%, 20-25% and 15-20% respectively.

[0025] It can be understood that evenly mixing aggregates of different particle sizes can further improve the frost resistance, low-temperature strength, freeze-thaw cracking resistance, anti-slip performance and temperature stability of concrete.

[0026] Specifically, the fineness of the polypropylene fiber is 1.5-2.5 dtex, and the length is 1.5-200 mm.

[0027] By further limiting the size of the polypropylene fiber, the synergistic effect with polyvinyl alcohol and the flow modifier can be further enhanced, the frost resistance of the concrete can be further improved, and the stress caused by frost heave can be further reduced.

[0028] Optionally, the flow improver includes at least one of asphalt emulsion and rubber.

[0029] Among them, asphalt emulsion, polypropylene fiber and polyvinyl alcohol can further synergistically improve the crack resistance of concrete, effectively control the microcracks caused by factors such as concrete plastic shrinkage, drying shrinkage, temperature changes, and form a waterproof layer to further improve the concrete's resistance to freeze-thaw cracking.

[0030] In a second aspect, the present invention provides a method for preparing low-temperature resistant concrete, which is used to prepare the low-temperature resistant concrete of the first aspect, comprising the following steps: A raw material system including aggregate, polyvinyl alcohol, polypropylene fiber and flow modifier is mixed, stirred and steam-insulated to obtain low-temperature resistant concrete.

[0031] Furthermore, the stirring process has a rotation speed of 10-20 rpm and a time of 1-3 min.

[0032] Furthermore, the temperature of the steam heat preservation and moisture retention treatment is 180-200°C, and the time is 12-14 days.

[0033] By further limiting each execution parameter, it is possible to further ensure that the raw material system is mixed evenly, further accelerate the hydration reaction, and further improve the strength and temperature stability of the concrete.

[0034] Hereinafter, a low-temperature resistant concrete and a preparation method thereof provided by the present invention are described in detail through specific embodiments. Example

[0035] Mix the raw material system including 90 parts of aggregate, 0.1 parts of polyvinyl alcohol, 0.3 parts of polypropylene fiber, 0.5 parts of asphalt emulsion, 5 parts of cement and 5 parts of water. According to the above proportions, weigh each raw material accurately and put it into the mixing equipment. Stir at a speed of 10rpm for 3 minutes to make the various raw materials preliminarily mixed and evenly mixed, and then lay it. After paving, keep it warm and moisturize it under 190℃ steam for 14 days, and obtain low-temperature resistant concrete after solidification; Among them, the mass percentages of the aggregate with particle sizes of 0.001-0.075mm, 0.075-0.15mm, 0.15-0.3mm, 0.3-0.6mm, 0.6-1.18mm, 1.18-2.36mm, 2.36-4.75mm, 4.75-9.5mm, 9.5-13.2mm and 13.2-16mm are 6%, 3%, 2.5%, 5%, 5.5%, 8%, 15%, 28%, 22% and 5% respectively; The thickness of the polypropylene fiber is 2 dtex and the length is 50 mm. Example

[0036] The difference between this embodiment and embodiment 1 is that the amount of polyvinyl alcohol added is 0.5 parts. Example

[0037] The difference between this embodiment and embodiment 1 is that the amount of polypropylene fiber added is 1 part. Example

[0038] The difference between this embodiment and embodiment 1 is that the amount of asphalt emulsion added is 1 part. Example

[0039] Compared with Example 1, the difference between this embodiment and this embodiment is that the particle sizes of 0.001~0.075mm, 0.075~0.15mm, 0.15~0.3mm, 0.3~0.6mm, 0.6~1.18mm, 1.18~2.36mm, 2.36~4.75mm, 4.75~9.5mm, 9.5~13.2mm and 13.2~16mm in the aggregate account for 5%, 5%, 5%, 5%, 5%, 5%, 5%, 12%, 18%, 25% and 15% of the mass percentage of the aggregate respectively. Example

[0040] The difference between this embodiment and embodiment 1 is that the diameter of the polypropylene fiber is 3.5 dtex and the length is 250 mm.

[0041] Comparative Example 1 The difference between this comparative example and Example 1 is that no polypropylene alcohol is added.

[0042] Comparative Example 2 The difference between this comparative example and Example 1 is that no polypropylene fiber is added.

[0043] Comparative Example 3 The difference between this comparative example and Example 1 is that no asphalt emulsion is added.

[0044] Test Example 1 The above examples and comparative examples were tested and the results are shown in Table 1.

[0045] Table 1 It can be seen from this that the low-temperature resistant concrete provided by the present invention has good practical properties such as low-temperature performance and antifreeze performance, which makes the construction of low-temperature resistant improved concrete more convenient and prolongs the life of the finished concrete product.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein by equivalents. If these modifications and variations fall within the scope of the claims of the present invention and their equivalent technologies, they should be considered to be within the protection scope of the present invention.

Claims

1. A low temperature resistant concrete, characterized in that: The raw materials of the low-temperature resistant concrete include aggregate, polyvinyl alcohol, polypropylene fiber and flow modifier; wherein, the Marshall stability of the low-temperature resistant concrete is not less than 25kN, the porosity is 18.0-20.0%, the breaking flexural stress is not less than 5MPa, the low-temperature breaking stiffness modulus is not less than 404.18MPa, the freeze-thaw splitting strength is not less than 1MPa, the standard scattering loss is not more than 15%, and the immersion scattering loss is not more than 20%.

2. The low temperature resistant concrete according to claim 1, characterized in that: The raw materials of the low-temperature resistant concrete include, by mass, 90-94 parts of aggregate, 0.05-0.2 parts of polyvinyl alcohol, 0.1-0.5 parts of polypropylene fiber, 0.4-0.6 parts of flow modifier, 4-5 parts of cement and 4-5 parts of water.

3. The low temperature resistant concrete according to claim 1, characterized in that: The mass percentage of the aggregate with a particle size of 0.1-15 mm accounts for 90-94% of the aggregate.

4. The low temperature resistant concrete according to claim 3, characterized in that: The aggregates with particle sizes of 0.1-3 mm, 3-10 mm and 10-15 mm account for 25-35%, 25-35% and 30-50% respectively.

5. The low temperature resistant concrete according to claim 4, characterized in that: The mass percentages of the aggregate with particle sizes of 0.001-0.075mm, 0.075-0.15mm, 0.15-0.3mm, 0.3-0.6mm, 0.6-1.18mm, 1.18-2.36mm, 2.36-4.75mm, 4.75-9.5mm, 9.5-13.2mm and 13.2-16mm are 5-6%, 3-5%, 2-5%, 4.5-5%, 5-5.5%, 5-8%, 12-15%, 15-18%, 20-25% and 15-20% respectively.

6. The low temperature resistant concrete according to claim 1, characterized in that: The polypropylene fiber has a fineness of 1.5-2.5 dtex and a length of 1.5-200 mm.

7. The low temperature resistant concrete according to any one of claims 1 to 6, characterized in that: The flow improver includes at least one of asphalt emulsion and rubber.

8. A method for preparing low temperature resistant concrete, used for preparing the low temperature resistant concrete according to any one of claims 1 to 7, characterized in that: The following steps are involved: The raw material system including aggregate, polyvinyl alcohol, polypropylene fiber and flow modifier is mixed, stirred and heat-insulated to obtain the low-temperature resistant concrete.

9. The method for preparing low temperature resistant concrete according to claim 8, characterized in that: The stirring process is performed at a rotation speed of 10-20 rpm and a time of 1-3 min.

10. The method for preparing low temperature resistant concrete according to claim 8 or 9, characterized in that: The temperature of the heat preservation treatment is 180-200° C. and the time is 12-14 days.