Construction method for improving wear resistance and durability of concrete by controlling thickness of concrete float

Abstract

The application discloses a construction method for improving wear resistance and durability of concrete by controlling thickness of concrete floating slurry, and comprises the following steps: S1, binding and pouring a steel bar net on a construction surface, pouring a first concrete slurry on the steel bar net, paving and vibrating, and obtaining base concrete; S2, pouring surface wear-resistant material before initial setting of the ordinary concrete formed in the step S1. The mortar layer and the floating slurry layer formed by the layered paving and pouring are thinner, the wear-resistant layer is tightly combined and solidified with the base concrete and the steel bar net, the connecting strength between the layered structures is high, the wear-resistant durability of the wear-resistant layer is greatly improved by using wear-resistant aggregate, the maintenance cycle is prolonged, the problem that it is difficult to control and prevent cracks of high-strength anti-impact wear-resistant concrete at high temperature is solved, the use amount of the wear-resistant concrete is reduced by 50% to 80% due to the layered position, the cost of the wear-resistant concrete is reduced, and the use amount of raw materials is reduced.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, and in particular to a construction method for improving the wear resistance and durability of concrete by controlling the thickness of concrete laitance. Background Technology

[0002] Concrete is a multi-material mixture composed of cement, admixtures, water, and sand and gravel aggregates. After being mixed into concrete, its components consist of mortar made of water, air, sand, cement, and admixtures, as well as small and medium stones.

[0003] Normally, concrete pouring requires high-frequency vibration to remove large air bubbles introduced during mixing, transportation, and placement, thus densifying the concrete. However, under certain vibration conditions, heavier aggregate particles will sink, while water, air, fly ash, lightweight particles from cement and fly ash, as well as small air bubbles introduced to improve concrete durability, will rise to the surface. Especially with pumped concrete and high-flowability concrete, a mortar layer and laitance (foamy slurry, generally a mixture of cement, fly ash, mineral powder, fine aggregate, etc., with water and air bubbles) often appear on the surface after pouring and vibration. Laitance is a result of mortar rising and coarse aggregate settling and segregating during concrete pouring, and it often occurs alongside bleeding. In hydraulic structures, it is used for erosion resistance, abrasion resistance, and air gap prevention. On the surface layer of a structure requiring corrosion resistance, the thickness of the mortar layer and laitance significantly affects the surface compressive strength, density, hardness, appearance quality, and durability of concrete. Thick laitance often means a substantial reduction in the impact and abrasion resistance of the concrete structure. In addition, the bleeding water generated by the concrete before initial setting will rise to the concrete surface or the lower surface of the aggregate, further reducing the surface compressive strength and abrasion resistance. Free water and air bubbles accumulating on the lower surface of the aggregate will reduce the bond strength between the cement paste and the aggregate surface. Under the impact of abrasive particles, the aggregate is easily pulled out and washed away as a whole, affecting the abrasion resistance and impact resistance of the concrete, and causing uneven wear on the concrete surface. Therefore, it is essential to reduce the thickness of laitance in the construction of hydraulic plane impact-resistant and abrasion-resistant concrete to improve the abrasion resistance and durability of concrete. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a technology to improve the wear resistance and durability of concrete by controlling the thickness of concrete laitance. This technology can minimize the laitance problem on the concrete surface, thereby ensuring the quality and safety of concrete structures.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A construction method for improving the wear resistance and durability of concrete by controlling the thickness of concrete laitance includes the following steps:

[0007] S1. Tie and pour the steel mesh on the construction surface, pour the first concrete slurry on the steel mesh, spread and vibrate it to obtain the base concrete;

[0008] S2. Before the initial setting of the ordinary concrete formed in step S1, pour a surface wear-resistant material. The surface wear-resistant material is impact-resistant and wear-resistant concrete or impact-resistant and wear-resistant cement mortar to form a surface wear-resistant layer.

[0009] S3. Vibrate and smooth the wear-resistant layer formed in step S2 according to the method specified for HF concrete, so that the surface flatness meets the specification requirements or the flatness error of the straightedge does not exceed 3mm.

[0010] S4. Repeat step S3 to obtain the surface wear-resistant concrete layer;

[0011] S5. Cover and cure the surface wear-resistant concrete layer.

[0012] Preferably, in step S1, the thickness of the base concrete layer is 50mm to 100mm lower than that of the surface reinforcement. The base concrete is poured in layers, with each layer being 30cm to 50cm thick. The number of layers is two to three. The height of the base concrete is 3 to 5cm lower than the height of the reinforcement mesh.

[0013] Preferably, in step S2, the impact-resistant and wear-resistant concrete or impact-resistant and wear-resistant mortar contains quartz, corundum, hard tailings, basalt and granite, and the compressive strength is 40MPa to 80MPa. The surface wear-resistant layer is poured in layers.

[0014] Preferably, in step S2, the impact-resistant and wear-resistant concrete is mixed in the following weight ratio: 130-180 parts water, 200-500 parts cement, 30-150 parts fly ash, 20-50 parts silica fume, and 5-20 parts additives. In step S2, the impact-resistant and wear-resistant cement mortar is mixed in the following weight ratio: 200 parts water, 600 parts cement, 1200-1400 parts quartz sand, and admixtures, wherein the admixtures are 2%-6% of the cement content, and the water-cement ratio is 0.26-0.4.

[0015] Preferably, the water-cement ratio of the impact-resistant and wear-resistant concrete or the impact-resistant and wear-resistant cement mortar is 0.26 to 0.4, and the cement grade in the impact-resistant and wear-resistant concrete or the impact-resistant and wear-resistant cement mortar is not lower than C35.

[0016] Preferably, the slump of the impact-resistant and wear-resistant concrete in step S2 is 3-5 cm or 5-9 cm.

[0017] The present invention has the following beneficial effects:

[0018] 1. Compared with existing technologies, the wear-resistant concrete or mortar layer is formed by layered paving and pouring. After layered paving and pouring, the laitance layer formed by the lower layer is covered by the newly poured wear-resistant concrete slurry, which has virtually no impact on the wear resistance of the surface wear-resistant layer. The surface wear-resistant layer is poured with a small thickness, which is easy to vibrate and reduces the problems of thick concrete layers that are difficult to vibrate and compact, excessive vibration time, resulting in thick laitance, and unevenness in the planar direction. After layered paving and pouring, the final laitance thickness is reduced by at least 80% compared to the thickness of a single-pour laitance layer. Combined with changes in vibration and finishing methods, as well as structural modifications, the wear resistance and durability of concrete will be significantly improved to meet different usage scenarios and different durability requirements.

[0019] 2. Compared with existing technologies, the change in vibration method can not only reduce the thickness of laitance and improve the wear resistance and durability of the surface wear-resistant layer, but also make the concrete more uniform in the horizontal direction. Under the action of abrasion, the concrete can only be worn down and will not cause excessive uneven wear, which would lead to excessive unevenness in the recycling process and cavitation damage.

[0020] 3. Compared with existing technologies, the layered casting method allows for a smaller overall thickness of the wear-resistant layer, making temperature control easier to solve. This avoids the problem of excessive cement usage in high-strength wear-resistant concrete, which is prone to temperature cracking when the wear-resistant layer thickness is typically 500-1000mm. Furthermore, it avoids the need to use large amounts of fly ash in the wear-resistant concrete due to temperature control requirements, which significantly reduces the wear resistance, durability, and strength of the surface concrete.

[0021] 4. Compared with existing technologies, the use of hard aggregates can greatly reduce the total thickness of the wear-resistant layer and the amount of wear-resistant material used will be reduced accordingly. This greatly improves wear resistance and durability while the cost of the wear-resistant layer increases only slightly.

[0022] 5. Compared with existing technologies, this technology can solve the problem of using aggregates such as limestone, marble, dolomite, low-strength sandstone, argillaceous rock, aggregates with poor particle size, high content of needle-like and flaky particles, and large fluctuations in water content as aggregates for wear-resistant concrete in some projects. It can also solve the problem of low compressive strength and low crushing index of rock aggregates in some projects, making it impossible to prepare high compressive strength concrete as required by specifications. At the same time, it can provide a more reliable solution to the problem of wear resistance and durability, and meet the different requirements for wear resistance and durability under different flow rates, different sand contents and different sand hardness, different water and sand passing conditions, and different maintenance conditions.

[0023] 6. Compared with existing technologies, the aggregate in the wear-resistant layer is replaced with wear-resistant and uniformly hard aggregate, thereby solving the problems of poor uniformity of hardness of some engineering aggregates and uneven surface of concrete after wear, and avoiding the occurrence of cavitation damage caused by unevenness exceeding the specification.

[0024] 7. Compared with existing technologies, this technology can solve the problems of high price of organic materials, limited application to thin layers, poor weather resistance and durability, large difference in linear expansion coefficient between base concrete and surface organic material leading to easy detachment and peeling, and insufficient wear resistance and durability in some projects that use polyurea layer and epoxy mortar layer on the surface of wear-resistant concrete as a method to extend the wear resistance and durability of the wear-resistant layer. In addition, it can solve the problems of difficult construction, toxicity and need for secondary construction of epoxy mortar. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below.

[0026] A construction method for improving the wear resistance and durability of concrete by controlling the thickness of concrete laitance includes the following steps:

[0027] S1. Tie and pour the steel mesh on the construction surface, pour the first concrete slurry on the steel mesh, spread and vibrate it to obtain the base concrete. Since the elevation of the base is lower than that of the concrete surface layer, the laitance will not affect the wear resistance of the surface concrete after being covered with wear-resistant layer material.

[0028] S2. Before the initial setting of the ordinary concrete formed in step S1, pour a surface wear-resistant material. The surface wear-resistant material is impact-resistant and wear-resistant concrete or impact-resistant and wear-resistant cement mortar to form a surface wear-resistant layer. Pouring the wear-resistant layer concrete before the initial setting of the first concrete can solidify the base concrete and the surface wear-resistant layer into a whole, improve the bonding strength between the two, and tightly bond with the steel mesh to improve the overall strength of the concrete structure.

[0029] S3. The wear-resistant surface layer formed in step S2 is vibrated and smoothed according to the method specified in HF concrete to ensure that the surface flatness meets the specification requirements or the flatness error of the straightedge does not exceed 3mm. That is, first, the evenly spread surface wear-resistant layer is smoothed with a vibrating beam or a scraper, and then it is smoothed with an immersion vibrator and smoothed three times (coarse smoothing, fine smoothing and fine smoothing) to make the wear-resistant layer uniform and flat.

[0030] S4. Repeat step S3 to obtain the surface wear-resistant concrete layer;

[0031] S5. Cover the surface with the wear-resistant concrete layer to maintain moisture and heat.

[0032] In step S1, the thickness of the base concrete layer is 50mm to 100mm lower than that of the surface reinforcement. The base concrete is poured in layers, with each layer being 30cm to 50cm thick. The layers are poured two to three times. The height of the base concrete is 3 to 5cm lower than the height of the reinforcing mesh, allowing the reinforcing mesh to penetrate the surface wear-resistant concrete layer, enhancing its strength, and connecting the surface wear-resistant concrete layer and the base concrete layer to form a unified structure, thus improving the overall strength of the concrete structure. The height of the base concrete is lower than the height of the reinforcing mesh by a certain amount, preferably 1 to 2 times greater than the maximum particle size of the wear-resistant material.

[0033] In step S2, the impact-resistant and wear-resistant concrete or mortar contains wear-resistant aggregates such as quartz, corundum, hard tailings, basalt, and granite (the mass ratio of quartz, basalt, and granite can be determined according to the project conditions, the price and ease of procurement of each wear-resistant aggregate, and the concrete structure). The compressive strength is 40MPa to 80MPa. The surface wear-resistant layer is poured in layers. In step S2, the impact-resistant and wear-resistant cement mortar is mixed according to the following weight ratios: 130-180 parts water, 200-500 parts cement, 30-150 parts fly ash, 20-50 parts silica fume, and 5-20 parts additives. In step S2, the impact-resistant and wear-resistant cement mortar is mixed according to the following weight ratios: 200 parts water, 600 parts cement, 1200-1400 parts quartz sand, and admixtures. The admixtures are 2%-6% of the cement content, and the water-cement ratio is 0.26-0. 4. The water-cement ratio of impact-resistant and wear-resistant concrete or impact-resistant and wear-resistant mortar is 0.26 to 0.4. The cement grade in impact-resistant and wear-resistant concrete and impact-resistant and wear-resistant cement mortar is not lower than C35, and can reach C60 or C70. When the surface wear-resistant layer is a wear-resistant cement mortar layer, its aggregate can be one or more of quartz sand, corundum, and brown corundum mixed together. In this case, the surface wear-resistant layer may also have a different bonding position with the foundation concrete and wear-resistant layer in steps S1 and S2. For example, if the bonding surface is above the steel mesh, the thickness of the wear-resistant layer can also be reduced.

[0034] If the surface wear-resistant layer is concrete, fly ash may be omitted or used sparingly in the mix design. Wear-resistant concrete may have the smallest possible slump, a smaller maximum aggregate size, or even fine stone concrete or wear-resistant mortar.

[0035] When the surface wear-resistant layer concrete must be pumped, a multi-point unloading and placement method should be adopted. The concrete should be compacted using special vibrators and vibration methods for HF concrete, so that the thickness of the slurry in the wear-resistant layer concrete is significantly reduced compared to the thickness of the slurry in concrete poured using conventional construction methods.

[0036] In step S2, the slump of the impact-resistant and wear-resistant concrete is 3-5 cm or 5-9 cm.

[0037] The functional principle of this invention can be explained through the following operation: the foundation concrete is generally thick, ranging from 100cm to 300cm, and is mostly poured in layers, with each layer being 30cm to 50cm thick;

[0038] The surface layer of wear-resistant concrete is generally 100cm thick. It is usually poured in two or three layers. The last layer is 30-50cm thick and is spread to the design elevation in one go. Then, it is compacted with an immersion vibrator. The wear-resistant concrete vibrated by the immersion vibrator has poor uniformity in both vertical and horizontal directions and a thicker laitance. After spreading using this technique, the top concrete layer is relatively thin. Vibration beams or concrete vibratory scrapers can be used for compaction. The mortar layer and laitance layer formed by the pouring are even thinner, especially when pumped, and are more uniform in the horizontal direction.

[0039] The location of the bonding surface ensures that the wear-resistant layer is thinner and the amount of material used is smaller, while also ensuring that the wear-resistant layer, the reinforcing steel, and the base concrete solidify into a whole, so that the connection strength between the layered structures is high. After multiple layers of paving and pouring, the thickness of the mortar layer and laitance formed on the final surface is reduced by at least 50% compared to the thickness of the mortar layer and laitance layer poured to the surface in one thicker pour.

[0040] Meanwhile, the surface wear-resistant concrete layer uses a smaller slump, such as 3-5 cm or 5-9 cm, to reduce the thickness of the mortar layer and laitance.

[0041] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A construction method for improving the wear resistance and durability of concrete by controlling the thickness of concrete laitance, characterized in that, Includes the following steps: S1. Tie and pour a steel mesh on the construction surface, and pour the first concrete slurry on the steel mesh. The first concrete slurry is ordinary concrete. Spread and vibrate to obtain the base concrete. The base concrete is poured in layers, with each layer being 30cm to 50cm thick. The number of layers is two to three. The height of the base concrete is 3 to 5cm lower than the height of the steel mesh. S2. Before the initial setting of the ordinary concrete formed in step S1, a surface wear-resistant material is poured. The surface wear-resistant material is impact-resistant and wear-resistant concrete or impact-resistant and wear-resistant cement mortar to form a surface wear-resistant layer. The surface wear-resistant layer is poured in layers. The location of the bonding surface ensures that the wear-resistant layer is thinner and the amount of material used is smaller. At the same time, it ensures that the wear-resistant layer is solidified into a whole with the steel reinforcement and the base concrete, so that the connection strength between the layered structures is high. After multiple layers of paving and pouring, the thickness of the mortar layer and laitance formed on the final surface is reduced compared with the thickness of the mortar layer and laitance layer poured to the surface in one thicker pour. S3. Vibrate and smooth the wear-resistant layer formed in step S2 according to the method specified for HF concrete, so that the surface flatness meets the specification requirements or the flatness error of the straightedge does not exceed 3mm. S4. Repeat step S3 to obtain the surface wear-resistant concrete layer; S5. Cover and cure the surface wear-resistant concrete layer.

2. The construction method for improving the wear resistance and durability of concrete by controlling the thickness of concrete laitance according to claim 1, characterized in that: In step S2, the impact-resistant and wear-resistant concrete or impact-resistant and wear-resistant cement mortar contains quartz, corundum, hard tailings, basalt and granite, and the compressive strength is 40MPa to 80MPa.

3. The construction method for improving the wear resistance and durability of concrete by controlling the thickness of concrete laitance according to claim 2, characterized in that: In step S2, the impact-resistant and wear-resistant concrete is mixed according to the following weight ratio: 130-180 parts water, 200-500 parts cement, 30-150 parts fly ash, 20-50 parts silica fume, and 5-20 parts additives. In step S2, the impact-resistant and wear-resistant cement mortar is mixed according to the following weight ratio: 200 parts water, 600 parts cement, 1200-1400 parts quartz sand, and admixtures. The admixtures are 2%-6% of the cement content, and the water-cement ratio is 0.26-0.

4.

4. The construction method for improving the wear resistance and durability of concrete by controlling the thickness of concrete laitance according to claim 3, characterized in that: The water-cement ratio of the impact-resistant and wear-resistant concrete or the impact-resistant and wear-resistant cement mortar is 0.26 to 0.4, and the cement grade in the impact-resistant and wear-resistant concrete or the impact-resistant and wear-resistant cement mortar is not lower than C35.

5. The construction method for improving the wear resistance and durability of concrete by controlling the thickness of concrete laitance according to claim 1, characterized in that: In step S2, the slump of the impact-resistant and wear-resistant concrete is 3-5 cm or 5-9 cm.