Cement concrete pavement repairing material and preparation method thereof

Abstract

This invention discloses a cement concrete pavement repair material and its preparation method, belonging to the field of road engineering technology. By weight, the raw materials of the cement concrete pavement repair material include: 100 parts silicate cement, 200-250 parts sand, 15-20 parts alkali activator, 7-10 parts fluorosilicate, 3-5 parts organic alcohol amine, 30-40 parts lithium slag powder, 1-2 parts calcium carbonate micron powder, 1-1.5 parts polycarboxylate superplasticizer, and 35-45 parts water. The cement concrete pavement repair material provided by this invention possesses the characteristics of early strength and rapid hardening, making it highly suitable for repairing cracked cement concrete pavements. Using the cement concrete pavement repair material provided by this invention to repair cracked cement concrete pavements can significantly shorten the time of traffic closure. Simultaneously, the repaired pavement exhibits good durability and can be used for a long period.

Description

Technical Field

[0001] This invention belongs to the field of road engineering technology, specifically relating to a cement concrete pavement repair material and its preparation method. Background Technology

[0002] Cement concrete pavement is a common rigid pavement structure, mainly composed of cement, aggregates, water, and necessary admixtures mixed and poured in a certain proportion. Its typical structure includes a surface layer, base layer, subbase layer, and subgrade, using a slab structure to distribute vehicle loads over a large area of ​​the underlying soil. Due to its high strength, good durability, low long-term maintenance requirements, and less dependence on petroleum asphalt, cement concrete pavement is widely used in highways, urban roads, airport runways, and areas with heavy traffic.

[0003] Due to its rigidity, cement concrete pavements are highly sensitive to external loads and prone to various forms of cracking, affecting the overall performance and service life of the pavement structure. If pavement repairs are not carried out promptly, repeated vehicle traffic will worsen the situation, causing cracks to develop or forming depressions, impacting driving safety and even leading to traffic accidents. Ultimately, this can result in roadbed settlement and the abandonment of the entire highway section. Therefore, cracks and damage in cement concrete pavements require timely repair.

[0004] To minimize economic losses caused by road closures during cement concrete pavement repairs, the shorter the time before the repaired pavement is open to traffic, the better. This requires repair materials to have short setting and curing times, rapid hardening and early strength, while also possessing good mechanical strength and durability to meet usage requirements. A common approach is to add accelerators such as fluorosilicates. However, while the addition of fluorosilicates can significantly accelerate cement hydration and shorten setting time, fluoride ions may participate in the formation of some loosely structured hydration products or interfere with the normal development of the dominant strength phase—calcium silicate hydrate (CSH) gel—forming during silicate cement hydration. This can lead to slower strength growth and reduced strength retention in concrete after 28 days or longer, negatively impacting the later-stage strength of the cement concrete. Summary of the Invention

[0005] The purpose of this invention is to provide a cement concrete pavement repair material and its preparation method. Addressing the drawback of commonly used fluorosilicate accelerators negatively impacting the later-stage strength of cement concrete, this invention optimizes the cement concrete formulation by combining fluorosilicates with organic alcohol amines and introducing lithium slag powder and calcium carbonate micropowder. This approach retains the rapid-hardening and early-strength characteristics of cement concrete without affecting its later-stage strength.

[0006] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of this invention is to provide a cement concrete pavement repair material, which, by weight, comprises: 100 parts silicate cement, 200-250 parts sand, 15-20 parts alkali activator, 7-10 parts fluorosilicate, 3-5 parts organic alcohol amine, 30-40 parts lithium slag powder, 1-2 parts calcium carbonate powder, 1-1.5 parts polycarboxylate superplasticizer, and 35-45 parts water.

[0007] In order to obtain a repair material with early strength and rapid hardening suitable for repairing cement concrete pavements, this invention selects to introduce the accelerator fluorosilicate into cement concrete. However, in view of the defect that the addition of fluorosilicate has an adverse effect on the later strength of cement concrete, this invention further combines organic alcohol amines and introduces lithium slag powder and calcium carbonate micro powder. By reasonably optimizing the cement concrete formula, the cement concrete can maintain its rapid hardening and early strength characteristics without affecting its later strength, and may even improve it to a certain extent.

[0008] Preferably, the sand is manufactured sand with a fineness modulus of 2.3 to 3.0.

[0009] Preferably, the alkali activator is water glass with a modulus of 1.1 to 1.4.

[0010] Preferably, the fluorosilicate comprises magnesium fluorosilicate and / or sodium fluorosilicate.

[0011] Preferably, the organic alcohol amine includes monoethanolamine and / or diethanolamine.

[0012] Preferably, the specific surface area of ​​the lithium slag powder is 600~800m². 2 / kg.

[0013] Preferably, the average particle size of the calcium carbonate micro powder is 1~10μm.

[0014] Preferably, the polycarboxylate superplasticizer is a high-efficiency polycarboxylate superplasticizer.

[0015] The second technical solution of the present invention provides a method for preparing the above-mentioned cement concrete pavement repair material, comprising the following steps: First, mix silicate cement and sand evenly, then add fluorosilicate, lithium slag powder and calcium carbonate powder and stir evenly; mix alkali activator, organic alcohol amine, polycarboxylate superplasticizer and water and stir evenly; finally, mix all materials together and stir to obtain the cement concrete pavement repair material.

[0016] The third technical solution of the present invention provides an application of the above-mentioned cement concrete pavement repair material in repairing cracked cement concrete pavements.

[0017] The beneficial technical effects of the present invention are as follows: This invention provides a cement concrete pavement repair material with early strength and rapid hardening characteristics, making it highly suitable for repairing cracked cement concrete pavements. Using this repair material can significantly shorten the time required for traffic closure. Furthermore, the repaired pavement exhibits good durability and can be used for a long period. Detailed Implementation

[0018] Cement concrete pavement, widely used in modern road engineering, plays a crucial role in the construction of various highways, urban roads, and airport runways due to its significant advantages such as high strength, good stability, and high durability. However, with increasing traffic volume, heavier vehicle loads, and longer service life, cement concrete pavements inevitably develop various defects, such as cracks, potholes, and misalignments, severely affecting pavement performance and driving safety. Therefore, timely and effective repair of damaged cement concrete pavements has become a key aspect of ensuring normal road operation. From early simple partial excavation and repaving to the later adoption of various new repair materials and processes, cement concrete pavement repair technology has continuously developed and improved, aiming to achieve fast, efficient, and durable repair results while minimizing traffic disruption.

[0019] Among cement concrete pavement repair materials, there are traditional cement concrete repair materials with the same mix proportions as the pavement to be repaired. While these materials have good compatibility with the original pavement, they require a long curing time (usually 7-14 days to reach sufficient strength for traffic reopening), causing significant traffic disruption. Furthermore, polymer-modified cement concrete repair materials, although exhibiting significantly improved bond strength and stronger adhesion to the original base layer, suffer from expensive polymer additives that may soften under high temperatures. While general early-strength, fast-setting cement concrete pavement repair materials can also achieve rapid traffic reopening, they often suffer from insufficient later-stage strength and poor durability.

[0020] The cement concrete pavement repair material provided by this invention is not only inexpensive, but also has good repair effect and durability.

[0021] The core concept is that when fluorosilicates are added to cement concrete as an admixture, they can significantly accelerate the hydration rate of the main minerals in cement. This process promotes the earlier and greater generation of hydration products. By accelerating the hydration rate, fluorosilicates help reduce porosity in the initial setting stage of concrete, forming a denser cement paste structure at an earlier stage, thus enhancing the material's density and early hardness.

[0022] Furthermore, the added organic alcohol amines can promote the later-stage hydration of tricalcium aluminate (C3A) and tetracalcium aluminoferrite (C4AF), ensuring their later-stage strength; the added calcium carbonate micro powder can guide cement concrete to form a denser CSH gel, reducing the structurally loose hydration products induced by fluorosilicates.

[0023] Lithium slag powder contains a large amount of active SiO2 and Al2O3. These active SiO2 and Al2O3 can react with Ca(OH)2 produced during cement hydration to form pozzolanic material, thereby improving the mid-to-late-stage strength of cement concrete. Additionally, lithium slag powder has a high SO4 content. 2- It can combine with cement hydration products—calcium aluminate hydrate—to form ettringite micro-expansion products, which can compensate for the shrinkage caused by cement during the curing process, thereby improving the bonding performance between cement concrete pavement repair materials and the pavement.

[0024] Based on the above inventive concept, this invention proposes a rapid-hardening cement concrete pavement repair material, which, by weight, comprises: 100 parts silicate cement, 200-250 parts sand, 15-20 parts alkali activator, 7-10 parts fluorosilicate, 3-5 parts organic alcohol amine, 30-40 parts lithium slag powder, 1-2 parts calcium carbonate powder, 1-1.5 parts polycarboxylate superplasticizer, and 35-45 parts water.

[0025] In the preparation process, silicate cement and sand are first mixed evenly, then fluorosilicate, lithium slag powder, and calcium carbonate micro powder are added and stirred evenly; alkali activator, organic alcohol amine, polycarboxylate superplasticizer, and water are mixed and stirred evenly; finally, all materials are mixed together and stirred to obtain the cement concrete pavement repair material. During mixing, a large amount of silicate cement and sand are mixed evenly first, and then a small amount of functional solid components are added to avoid uneven dispersion of the functional solid components in the resulting cement concrete pavement repair material.

[0026] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0027] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0028] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0029] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0030] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0031] Unless otherwise specified, "parts" in this invention refers to "parts by weight". The silicate cement used in the embodiments and comparative examples of this invention is 42.5 grade ordinary silicate cement.

[0032] The fineness modulus of the manufactured sand used in the embodiments and comparative examples of this invention is 2.5.

[0033] The modulus of the water glass used in the embodiments and comparative examples of this invention is 1.2.

[0034] The lithium slag powder used in the embodiments and comparative examples of this invention is lithium slag that has been dried and ground to a specific surface area of ​​700 m². 2 The lithium slag powder per kg has a SiO2 content of 42%, an Al2O3 content of 26%, and an SO3 content of 17%.

[0035] The average particle size of the calcium carbonate micro powder used in the embodiments and comparative examples of this invention is 5 μm.

[0036] All raw materials used in this invention are commercially available products.

[0037] Example 1 Preparation of cement concrete pavement repair materials: Prepare the raw materials according to the following proportions: 100 parts silicate cement, 230 parts manufactured sand, 20 parts water glass, 8 parts sodium fluorosilicate, 5 parts diethanolamine, 35 parts lithium slag powder, 1.5 parts calcium carbonate powder, 1 part polycarboxylate superplasticizer, and 40 parts water. Add silicate cement and manufactured sand to a concrete mixer and mix for 10 minutes. Then add sodium fluorosilicate, lithium slag powder and calcium carbonate powder and continue mixing for 10 minutes to ensure that all components are evenly mixed. Next, pour the pre-mixed mixture of water glass, diethanolamine, polycarboxylate superplasticizer and water into the concrete mixer and continue mixing for 15 minutes to obtain cement concrete pavement repair material.

[0038] Example 2 Preparation of cement concrete pavement repair materials: Prepare the raw materials according to the following proportions: 100 parts silicate cement, 200 parts manufactured sand, 20 parts water glass, 8 parts sodium fluorosilicate, 4 parts monoethanolamine, 37 parts lithium slag powder, 1.5 parts calcium carbonate powder, 1 part polycarboxylate superplasticizer, and 37 parts water. Add silicate cement and manufactured sand to a concrete mixer and mix for 10 minutes. Then add sodium fluorosilicate, lithium slag powder and calcium carbonate powder and continue mixing for 10 minutes to ensure that all components are evenly mixed. Next, pour the pre-mixed mixture of water glass, monoethanolamine, polycarboxylate superplasticizer and water into the concrete mixer and continue mixing for 15 minutes to obtain cement concrete pavement repair material.

[0039] Example 3 Preparation of cement concrete pavement repair materials: Prepare the raw materials according to the following proportions: 100 parts silicate cement, 250 parts manufactured sand, 15 parts water glass, 10 parts magnesium fluorosilicate, 3 parts diethanolamine, 38 parts lithium slag powder, 1.5 parts calcium carbonate micro powder, 1 part polycarboxylate superplasticizer, and 45 parts water. Silicate cement and manufactured sand are added to a concrete mixer and mixed for 10 minutes. Then magnesium fluorosilicate, lithium slag powder and calcium carbonate powder are added and mixed for another 10 minutes to ensure that all components are evenly mixed. Then, a mixture of pre-mixed water glass, diethanolamine, polycarboxylate superplasticizer and water is poured into the concrete mixer and mixed for another 15 minutes to obtain cement concrete pavement repair material.

[0040] Comparative Example 1 Preparation of cement concrete pavement repair material (the difference from Example 1 is that diethanolamine is omitted): Prepare the raw materials according to the following proportions: 100 parts silicate cement, 230 parts manufactured sand, 20 parts water glass, 8 parts sodium fluorosilicate, 35 parts lithium slag powder, 1.5 parts calcium carbonate powder, 1 part polycarboxylate superplasticizer, and 40 parts water. Add silicate cement and manufactured sand to a concrete mixer and mix for 10 minutes. Then add sodium fluorosilicate, lithium slag powder and calcium carbonate powder and continue mixing for 10 minutes to ensure that all components are evenly mixed. Next, pour the pre-mixed mixture of water glass, polycarboxylate superplasticizer and water into the concrete mixer and continue mixing for 15 minutes to obtain cement concrete pavement repair material.

[0041] Comparative Example 2 Preparation of cement concrete pavement repair material (the difference from Example 1 is that lithium slag powder is omitted): Prepare the raw materials according to the following proportions: 100 parts silicate cement, 230 parts manufactured sand, 20 parts water glass, 8 parts sodium fluorosilicate, 5 parts diethanolamine, 1.5 parts calcium carbonate powder, 1 part polycarboxylate superplasticizer, and 40 parts water. Add silicate cement and manufactured sand to a concrete mixer and mix for 10 minutes. Then add sodium fluorosilicate and calcium carbonate powder and continue mixing for 10 minutes to ensure that all components are evenly mixed. Next, pour the pre-mixed mixture of water glass, diethanolamine, polycarboxylate superplasticizer and water into the concrete mixer and continue mixing for 15 minutes to obtain cement concrete pavement repair material.

[0042] Comparative Example 3 Preparation of cement concrete pavement repair material (the difference from Example 1 is that calcium carbonate powder is omitted): Prepare the raw materials according to the following proportions: 100 parts silicate cement, 230 parts manufactured sand, 20 parts water glass, 8 parts sodium fluorosilicate, 5 parts diethanolamine, 35 parts lithium slag powder, 1 part polycarboxylate superplasticizer, and 40 parts water. Add silicate cement and manufactured sand to a concrete mixer and mix for 10 minutes. Then add sodium fluorosilicate and lithium slag powder and continue mixing for 10 minutes to ensure that all components are evenly mixed. Next, pour the pre-mixed mixture of water glass, diethanolamine, polycarboxylate superplasticizer and water into the concrete mixer and continue mixing for 15 minutes to obtain cement concrete pavement repair material.

[0043] According to the standards GB / T 50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures" and GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete", the initial setting time, final setting time, compressive strength and flexural strength of the cement concrete pavement repair materials prepared in Examples 1-3 and Comparative Examples 1-3 were tested. The test results are shown in Table 1.

[0044] Table 1 Performance test results of cement concrete pavement repair materials in each group As can be seen from Table 1, omitting the organic alcohol amines in cement concrete pavement repair materials prolongs the initial and final setting times, while reducing early strength and later strength.

[0045] Even after omitting lithium slag powder from cement concrete pavement repair materials, the early strength characteristics of the materials are still retained, but the later strength is significantly reduced.

[0046] Even after omitting calcium carbonate powder from cement concrete pavement repair materials, the early strength characteristics of the cement concrete pavement repair materials are still retained, but there is a certain loss in both early and late strength.

[0047] The cement concrete pavement repair material provided by this invention can achieve a compressive strength of over 30MPa and a flexural strength of over 3.1MPa after 1 day. It has the characteristics of fast hardening and early strength, and can meet the requirements for opening to traffic in 1 day.

[0048] The bonding performance of the cement concrete pavement repair materials prepared in Examples 1-3 and Comparative Examples 1-3 was tested according to the standard "Concrete Interface Treatment Agent" JC / T 907-2002. The test results are shown in Table 2.

[0049] Table 2 Bond strength of cement concrete pavement repair materials in each group As can be seen from Table 2, the addition of lithium slag powder to cement concrete pavement repair materials has a significant impact on the bonding performance of cement concrete.

[0050] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A cement concrete pavement repair material, characterized in that, By weight, the raw materials include: 100 parts silicate cement, 200-250 parts sand, 15-20 parts alkali activator, 7-10 parts fluorosilicate, 3-5 parts organic alcohol amine, 30-40 parts lithium slag powder, 1-2 parts calcium carbonate powder, 1-1.5 parts polycarboxylate superplasticizer, and 35-45 parts water.

2. The cement concrete pavement repair material according to claim 1, characterized in that, The sand is manufactured sand with a fineness modulus of 2.3 to 3.

0.

3. The cement concrete pavement repair material according to claim 1, characterized in that, The alkaline activator is water glass with a modulus of 1.1 to 1.

4.

4. The cement concrete pavement repair material according to claim 1, characterized in that, The fluorosilicates include magnesium fluorosilicate and / or sodium fluorosilicate.

5. The cement concrete pavement repair material according to claim 1, characterized in that, The organic alcohol amines include monoethanolamine and / or diethanolamine.

6. The cement concrete pavement repair material according to claim 1, characterized in that, The specific surface area of ​​the lithium slag powder is 600~800 m². 2 / kg.

7. The cement concrete pavement repair material according to claim 1, characterized in that, The average particle size of the calcium carbonate micro powder is 1~10μm.

8. The cement concrete pavement repair material according to claim 1, characterized in that, The polycarboxylate superplasticizer is a high-efficiency polycarboxylate superplasticizer.

9. A method for preparing the cement concrete pavement repair material according to any one of claims 1 to 8, characterized in that, Includes the following steps: First, mix silicate cement and sand evenly, then add fluorosilicate, lithium slag powder and calcium carbonate powder and stir evenly; mix alkali activator, organic alcohol amine, polycarboxylate superplasticizer and water and stir evenly; finally, mix all materials together and stir to obtain the cement concrete pavement repair material.

10. The application of the cement concrete pavement repair material according to any one of claims 1 to 8 in repairing cracked cement concrete pavements.

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