Novel aggregate-finished concrete and construction process thereof

Abstract

The application provides a new type of aggregate facing concrete and a construction process thereof, and belongs to the technical field of building engineering. The construction process comprises the following steps: preparing a pouring mold, pouring concrete according to a designed mixing ratio and leveling before initial setting; spraying a retarding agent prop by using a spray gun and naturally solidifying; and washing the retarding area by using a high-pressure water gun containing an ultrasonic generator until the aggregate is exposed. The method utilizes the synergistic effect of chemical softening and physical cavitation to achieve efficient stripping under low water pressure, solves the problems of uneven exposed aggregate depth, easy loosening and falling of the aggregate and blurred pattern boundary of the traditional exposed aggregate concrete, and realizes high-precision construction with the aggregate damage rate close to zero and the exposed aggregate depth deviation controlled within + / -0.5mm. The application has high construction efficiency, and the finished product has clear exposed aggregate, natural color and three-dimensional texture, and is suitable for high-quality decorative engineering such as municipal landscape ground paving.

Description

Technical Field

[0001] This invention relates to the field of building engineering technology, specifically to a novel aggregate-faced concrete and its construction process. Background Technology

[0002] With the continuous development of construction technology, modern architectural design increasingly pursues personalized expression and artistic texture. Traditional concrete surfaces, due to their monotonous color and bland texture, can no longer meet the current market's urgent demand for high-quality architectural aesthetics. Exposed aggregate concrete technology selectively removes the surface cement paste, exposing the color, texture, and three-dimensionality of natural aggregates, giving concrete a unique decorative appearance. This naturally exposed visual effect highly aligns with the trends of modern minimalism, industrial style, and site-specific design, becoming an important means of enhancing the quality of building facades.

[0003] Although exposed aggregate concrete is widely used, the existing on-site casting construction process still has many technical problems, which seriously restricts the improvement of its quality and efficiency. Specifically: (1) Long construction cycle and low efficiency: Traditional processes mostly adopt secondary surface treatment methods, which require waiting for the concrete to harden completely before high-pressure water washing or mechanical grinding. The process is complicated, time-consuming and labor-intensive, resulting in an extension of the overall construction period and seriously affecting the construction progress. (2) Difficulty in controlling the depth of exposed aggregate and poor uniformity: Existing technology lacks a precise control mechanism for washing time, pressure and angle, resulting in uneven distribution of exposed aggregate depth. Excessive exposed aggregate causes the aggregate to loosen and fall off, affecting structural safety; shallow exposed aggregate cannot present the ideal decorative effect and the surface is mottled. (3) High aggregate damage rate and impaired aesthetics: Traditional mechanical cleaning methods (such as high-pressure water gun impact, sandblasting, etc.) are often too forceful, which can easily cause physical damage such as chipping and cracking on the surface of the aggregate, destroying the original natural texture of the aggregate and reducing the overall aesthetics of the decorative surface. (4) Low pattern forming accuracy and blurred boundaries: When making complex patterns or mosaics, the existing process is difficult to achieve precise boundary control. The transition area between the pattern area and the background concrete is often unclear, resulting in the distortion of the decorative pattern and failing to meet the requirements of refined design. (5) High rework rate and waste of economic costs: Affected by the above-mentioned quality control problems, the finished product qualification rate of traditional process is low, and rework occurs frequently. This not only causes a lot of waste of raw materials and labor time, but also increases the overall cost of the project.

[0004] Currently, although there is research on the application of exposed aggregate technology in precast components, there is still a lack of a systematic solution in the field of cast-in-place concrete that can balance decorative effect and construction efficiency, which cannot meet the high requirements of modern construction projects for decorative concrete.

[0005] Therefore, developing a new, efficient, controllable, and low-damage on-site cast-in-place exposed aggregate concrete construction process has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] To address the technical problems of low construction efficiency, difficulty in controlling the depth of exposed aggregate, high aggregate damage rate, and blurred patterns in existing technologies, this invention aims to provide a novel aggregate-faced concrete and its construction process. This invention achieves a highly efficient, non-destructive, and high-precision exposed aggregate effect under low water pressure conditions through the synergistic effect of an ultrasonic generator and a decorative retarder, significantly improving decorative quality and construction efficiency.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A novel aggregate-finished concrete construction process, characterized by the following steps: (1) Prepare the casting mold, pour concrete according to the design mix ratio, and perform leveling treatment before the concrete sets to ensure that the concrete surface is flat. (2) Retarder coating: Use a spray gun to spray the decorative retarder onto the concrete surface. After the spraying is completed, the concrete will cure naturally. (3) Surface slurry washing: After the concrete has cured, use a high-pressure water gun to wash the slow-setting area until the aggregate is exposed.

[0008] Preferably, in step (1), the aggregate of the concrete is colored natural aggregate or uncolored aggregate with a particle size of 5-20mm, the aggregate is continuously graded, and the mud content is ≤1%.

[0009] Preferably, in order to obtain a pattern with a certain geometric texture, step (2) further includes laying a pattern cutout mold on the concrete surface before applying the retarder; the pattern cutout mold is laid after the concrete has initially set, after the first leveling is completed and the second finishing is done; the pattern cutout mold is made of a water-resistant and alkali-resistant flexible material with a thickness of 0.5-2mm.

[0010] Preferably, the amount of decorative retarder used in step (2) is 180-220 g / m². 2 This forms a uniform and appropriately thick slow-setting film, ensuring consistent exposed bone depth while reducing chemical costs and achieving a balance between economic benefits and decorative effects.

[0011] Preferably, the decorative retarder in step (2) is a water-based retarder, including at least one of sodium gluconate, sodium citrate, phosphate, and a thickener. The thickener is polyacrylamide, used to control the penetration depth of the retarder. The water-based system does not contain volatile organic compounds (VOCs), meets green building standards, is safe and environmentally friendly during construction, and the wastewater after rinsing is easy to treat and will not cause secondary pollution to the environment.

[0012] Preferably, the setting time of the decorative retarder in step (2) is 24-60h. This setting time ensures that the cement paste on the concrete surface is sufficiently softened, avoiding insufficient exposed aggregate depth due to too short a setting time, and also preventing damage to the strength of the deep concrete or overall disintegration during flushing due to too long a setting time.

[0013] Preferably, the spray gun in step (2) is an airless spray gun or an air-assisted spray gun. When using an air-assisted spray gun, the spraying pressure is ≤0.4MPa. Low-pressure atomization ensures fine droplets, reduces scattering, and improves film uniformity.

[0014] Preferably, during step (2) of spraying, the moving speed of the spray gun is 0.3-0.5m / s, the height of the spray gun from the concrete surface is 300-400mm, and the spraying angle is 60-75°.

[0015] Preferably, in step (3), the high-pressure water gun contains an ultrasonic generator, which uses the cavitation micro-jet generated by the ultrasonic waves in the liquid flow to perform microscopic shearing and peeling on the surface cement paste softened by the retarder, thereby reducing the pressure of the main water flow while avoiding mechanical damage to the aggregate in the unretarded area.

[0016] More preferably, the ultrasonic generator has a power of 20-40 kHz and a power density >50 W / cm². 2 .

[0017] More preferably, the pressure of the high-pressure water gun is 10-15 MPa. This pressure range is sufficient to peel away the surface mortar softened by the retarder, but not enough to damage the internal, unaffected aggregate structure. Too low a pressure will fail to clean properly, while too high a pressure may cause the aggregate to loosen and fall off.

[0018] This invention utilizes a retarder to disrupt the integrity of the cement crystal lattice, and ultrasonic waves further weaken the residual binding forces, creating a synergistic effect of chemical softening and physical cavitation. This achieves a non-destructive, high-precision exposed aggregate effect under low water pressure conditions. The exposed aggregate depth deviation is controlled within ±0.5mm, and the aggregate damage rate approaches zero.

[0019] Preferably, during the rinsing process in step (3), the high-pressure water gun is at a 45° angle to the concrete surface and 200-300mm away from the surface, moving at a uniform speed to achieve a balance between the exposed aggregate depth and the integrity of the aggregate.

[0020] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention employs a process combining retarder coating and high-pressure water rinsing, and introduces ultrasonic cavitation effect. Through the synergistic effect of chemical retarding and softening with ultrasonic microjets, the impact stress on the aggregate surface is reduced, enabling efficient slurry stripping under lower water pressure and improving construction efficiency. Experimental results show that this method controls the aggregate damage rate to 0%, significantly reducing the risk of aggregate edge chipping compared to traditional processes, and fully preserving the color, edges, and texture of the natural aggregate.

[0021] 2. This invention precisely controls the amount of retarder and utilizes the micro-jet and cavitation effects generated by ultrasound to assist in the peeling of cement paste, enabling the ideal exposed aggregate depth to be achieved even under low water pressure conditions; it achieves uniform exposed aggregate depth with the deviation controlled within ±0.5mm, solving the technical problems of inconsistent exposed aggregate depth and mottled surface in traditional processes, and ensuring the overall consistency of the decorative surface.

[0022] 3. This invention achieves a decorative effect of complex patterns by precisely combining the patterned hollow mold with the retarder and the ultrasonic cleaning capability of the boundary area. The patterned area is clearly defined from the background concrete, and the distribution of stones presents a perfect patterned effect, meeting the high standards of modern architecture for personalized and refined decoration.

[0023] 4. The process parameters of this invention are highly controllable, ensuring stable and reliable construction quality with a near-zero rework rate. Combined with improved construction efficiency, it significantly reduces project costs, resulting in substantial economic benefits. This process is widely applicable to various scenarios such as wall decoration, floor paving, landscape construction, and anti-slip garden paths. It can present the frosted texture of fine aggregates and the textured surface of coarse aggregates according to design requirements, and can also create personalized patterns.

[0024] 5. This process eliminates the need for an additional decorative layer, directly showcasing the original texture of the concrete, reducing material consumption and resource waste. At the same time, the resulting surface structure is dense, exhibiting excellent resistance to dust and peeling, significantly reducing the frequency of later maintenance. It presents both environmental and economic value, and endows the building facade with long-lasting vitality and aesthetics. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings: Figure 1 This is a flowchart of the construction process of this invention; Figure 2 This is a construction effect diagram of the present invention. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] Unless otherwise specified, the experimental methods used in the examples and comparative examples are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0028] Example 1: This embodiment takes a municipal landscape engineering ground paving project as an example and provides a new type of aggregate-faced concrete construction process, including the following steps: (1) Concrete mix design C30 colored exposed aggregate concrete was used, with the following mass ratio of components: cement: sand: aggregate: water: admixture = 1:1.5:3.5:0.4:0.02; the aggregate used was colored granite with a particle size of 5-15mm, continuously graded, and with a mud content of 0.8%. (2) Concrete pouring and leveling Prepare the casting mold, pour concrete according to the design mix ratio, and pour the concrete to a thickness of 150mm. Before the concrete sets, use a power trowel to level it, ensuring that the surface flatness deviation is no more than 3mm / 2m.

[0029] (3) Laying out pattern cutout mold According to the design drawings, make a geometric pattern cutout mold. The cutout mold is made of 0.8mm thick alkali-resistant rubber material. After the concrete has initially set, the first leveling is completed and the second finishing is done, accurately lay the pattern cutout mold on the designated area of ​​the concrete surface to ensure that the mold is tightly attached to the concrete surface without air bubbles or wrinkles.

[0030] (4) Retarder coating The decorative retarder was evenly sprayed onto the hollowed-out areas of the pattern using an airless spray gun. During spraying, the gun's moving speed was controlled at 0.4 m / s, the gun height above the concrete surface was 350 mm, the spraying angle was 70°, and the retarder dosage was 200 g / m². 2 Ensure complete coverage of the concrete surface; The retarder is composed of sodium gluconate, sodium citrate, phosphate (sodium tripolyphosphate), thickener, and water in a mass ratio of 30:20:12.5:5:32.5, and the retarding time is 36 hours.

[0031] (5) Concrete curing After the retarder is sprayed, immediately cover and protect the sprayed area, and allow it to cure naturally for 36 hours; (6) Surface slurry washing After curing, the slow-curing area was rinsed with a high-pressure water gun equipped with an integrated ultrasonic generator. The ultrasonic generator had a power of 30kHz and a power density of 60W / cm³. 2 The high-pressure water gun has a pressure of 12MPa. When rinsing, keep the water gun at a 45° angle to the concrete surface and 240mm away from the surface. Move the water gun at a uniform speed to rinse until the aggregate is exposed evenly, the color is natural, the texture is clear, and the boundary between the patterned area and the background concrete is distinct. (7) Sealed curing After rinsing, perform regular water curing for 7 days to ensure the full development of the concrete's internal strength; once the concrete surface is completely dry, apply a uniform layer of propylene polyurethane sealant.

[0032] Measurements showed that there was no detachment of exposed aggregate, the average depth of exposed aggregate was 2.5 mm, the deviation of exposed aggregate depth was -0.5 mm, and the aggregate damage rate was 0%.

[0033] Example 2: Similar to Example 1, except that the mass ratio of each component in the retarder was changed. The effect of the mass ratio of each component in the retarder on the aggregate properties was investigated. The results are shown in Table 1.

[0034] Table 1

[0035] Table 1 shows that the average depth and deviation of exposed grit depth exhibit a certain regularity as the mass ratio of each component in the retarder changes. This is particularly true when the retarder dosage is 200 g / m³. 2 Under a washing water pressure of 12 MPa, when the retarder composition is 30:20:12.5:5:32.5, the average exposed aggregate depth is 3.2 mm, the exposed aggregate depth deviation is 0.2 mm, and the aggregate damage rate is 0%. If the retarder composition ratio deviates from the above range, it will lead to an increase in the exposed aggregate depth deviation, an increased risk of aggregate detachment, and an increased aggregate damage rate, thereby affecting the final finishing effect.

[0036] Example 3: Based on Example 2, the effects of retarder dosage and washing water pressure on aggregate properties were investigated. The results are shown in Table 2.

[0037] Table 2

[0038] Table 2 shows that when the retarder dosage is 200 g / m³, 2Under a water pressure of 10 MPa, when the retarder composition is 30:20:12.5:5:32.5 or 32.5:20:12.5:5:30, the exposed aggregate effect is better, specifically with moderate exposed aggregate depth (2.4 mm or 3.2 mm), small depth deviation (-0.6 mm or 0.2 mm), no aggregate detachment, and a damage rate of 0%. If the proportion of retarder components deviates from the above range, it will lead to increased deviation in exposed aggregate depth, increased risk of aggregate detachment, and increased aggregate damage rate, thus affecting the final finishing effect.

[0039] Example 4: Based on Example 3, the effects of different retarder dosages and washing water pressures on aggregate properties were investigated. The results are shown in Table 3.

[0040] Table 3

[0041] Table 3 shows that when the retarder dosage is 220 g / m³, 2 Under a washing water pressure of 10 MPa, the best exposed aggregate effect is achieved when the retarder component ratio is 30-35:20:12.5:5:27.5-32.5. Specifically, the exposed aggregate depth is moderate (3.0 mm, 3.3 mm, or 3.2 mm), the depth deviation is small (0 mm, 0.3 mm, or 0.2 mm), there is no aggregate detachment, and the damage rate is 0%. If the retarder component ratio deviates from the above optimal range, it will lead to an increase in the exposed aggregate depth deviation, an increased risk of aggregate detachment, and an increased aggregate damage rate, thereby affecting the final finishing effect.

[0042] Comparative Example 1: Similar to Example 1, except that the nozzle of the high-pressure water gun used in step (6) does not have an ultrasonic generator and the water pressure is 12 MPa.

[0043] After construction was completed, it was found that most of the aggregates were exposed, but some aggregates were covered with a thin layer of unwashed slurry, which made the aggregate outlines blurred; the average depth of exposed aggregates was 1.3 mm, the deviation of exposed aggregate depth was 1.7 mm, and the aggregate damage rate was 0%.

[0044] Comparative Example 2: Similar to Example 1, the difference is that the nozzle of the high-pressure water gun used in step (6) does not have an ultrasonic generator. In order to ensure the rinsing effect, the water pressure is adjusted to 18MPa.

[0045] After construction was completed, measurements showed that there was no detachment of exposed aggregate, the average depth of exposed aggregate was 2.1 mm, the deviation of exposed aggregate depth was 0.9 mm, and the aggregate damage rate was 4.2%.

[0046] The results from the above embodiments and comparative examples show that Example 1, utilizing the cavitation microjets generated by the ultrasonic generator module, successfully disrupted the interfacial bond between cement paste and aggregate under a low water pressure of 12 MPa. The average exposed aggregate depth reached 2.5 mm, with a depth deviation controlled within -0.5 mm, and the aggregate damage rate was 0%. In Comparative Example 1, under the same water pressure, due to the lack of ultrasonic cavitation shearing effect, macroscopic water flow alone could not effectively peel off the dense softened layer formed by the retarder, resulting in an exposed aggregate depth of only 1.3 mm and a depth deviation as high as 1.7 mm, with severe surface residue. This indicates that simply reducing the water pressure cannot guarantee cleaning quality. Although Comparative Example 2 increased the water pressure to 18 MPa, achieving an exposed aggregate depth of 2.1 mm, the aggregate damage rate was as high as 4.2%, with a depth deviation of 0.9 mm. This demonstrates that while simply increasing the water pressure can increase the exposed aggregate depth, it inevitably causes mechanical damage to the aggregate.

[0047] In summary, this invention achieves high-quality construction of exposed aggregate concrete by adjusting the retarder ratio and process parameters, and by introducing an ultrasonic generator. It offers advantages such as significantly improved decorative effect, reduced aggregate damage, and prevention of aggregate detachment. The ultrasonic technology and the chemical softening effect of the retarder produce a significant synergistic effect, enabling high-quality, high-precision, non-destructive exposed aggregate results under low water pressure and high efficiency conditions. Furthermore, this invention offers high process flexibility, simple and efficient construction, and is suitable for various scenarios such as municipal landscape engineering paving, demonstrating significant engineering application value.

[0048] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A novel aggregate-finished concrete construction process, characterized in that, Includes the following steps: (1) Prepare the casting mold, pour concrete according to the design mix ratio, and perform leveling treatment before the concrete sets to ensure that the concrete surface is flat. (2) Retarder coating: Use a spray gun to spray the decorative retarder onto the concrete surface. After the spraying is completed, the concrete will cure naturally. (3) Surface slurry washing: After the concrete has cured, use a high-pressure water gun to wash the slow-setting area until the aggregate is exposed.

2. The construction process according to claim 1, characterized in that, Step (2) further includes applying a patterned perforated mold to the concrete surface before applying the retarder.

3. The construction process according to claim 1, characterized in that, The pattern cutout mold is made of a water- and alkali-resistant flexible material with a thickness of 0.5-2mm.

4. The construction process according to claim 1, characterized in that, The amount of decorative retarder used in step (2) is 180-220 g / m³. 2 .

5. The construction process according to claim 1, characterized in that, The decorative retarder in step (2) is an aqueous retarder selected from at least one of sodium gluconate, sodium citrate and phosphate, with a retarding time of 24-60h.

6. The construction process according to claim 1, characterized in that, During the spraying process in step (2), the moving speed of the spray gun is 0.3-0.5m / s, the height of the spray gun from the concrete surface is 300-400mm, and the spraying angle is 60-75°.

7. The construction process according to claim 1, characterized in that, In step (3), the high-pressure water gun contains an ultrasonic generator; the power of the ultrasonic generator is 20-40kHz, and the power density is >50W / cm³. 2 .

8. The construction process according to claim 7, characterized in that, The pressure of the high-pressure water gun is 10-15 MPa.

9. The construction process according to claim 1, characterized in that, During the rinsing process in step (3), the high-pressure water gun is at a 45° angle to the concrete surface and 200-300mm away from the surface, moving at a uniform speed to rinse.

10. A novel aggregate-faced concrete, prepared using the construction process described in any one of claims 1-9.

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