A construction process for reducing surface porosity in fair-faced concrete and water-reducing concrete

Abstract

This invention relates to a construction process for reducing surface porosity in fair-faced concrete and to water-reducing concrete, specifically relating to the field of fair-faced concrete. The construction process includes: spraying a water-reducing agent onto the surface of a template coated with template paint, followed by concrete pouring, curing, and demolding to obtain fair-faced concrete. The construction process provided by this invention improves the surface properties of water-reducing concrete by placing the water-reducing agent between the template agent and the water-reducing concrete, rather than adding it into the concrete itself, thereby reducing surface porosity and ensuring an excellent appearance.

Description

Technical Field

[0001] This invention relates to the field of fair-faced concrete, specifically to a construction process for reducing surface porosity in fair-faced concrete and water-reducing concrete. Background Technology

[0002] At present, improving the surface quality of concrete components is an important prerequisite for high-quality concrete engineering. Appropriate pouring and vibration processes and concrete materials that meet the specifications and service environment can avoid common defects such as honeycomb, pitting, delamination and efflorescence. However, fair-faced concrete has higher requirements for its surface quality. Fair-faced concrete has a decorative function, and in addition to requiring surface flatness, it also requires that surface pores be minimized.

[0003] Traditional methods mainly optimize materials and vibration processes, including:

[0004] (1) Add defoaming agent or add defoaming component to water-reducing agent;

[0005] (2) Use self-compacting or self-leveling concrete;

[0006] (3) Use an attached plate vibrator to enhance the removal of air bubbles from the concrete surface.

[0007] However, the most commonly used method (1) is liquid-phase modified silicone polyether defoamer or defoaming component, which usually increases the cost by RMB 15-20 per cubic meter of concrete, which is relatively high. In addition, some polycarboxylate superplasticizers and defoamers have poor compatibility and cannot be used at the same time. Method (2) has a more significant increase in cost and is usually used in special parts such as floors and running tracks. Method (3) has the lowest cost and better effect, but it is only suitable for large surfaces. For complex, irregular, densely reinforced structures or parts, the plate vibrator cannot achieve the effect of removing surface pores. Moreover, due to reflected waves, resonance and other reasons, it may even locally aggravate the accumulation of pores and affect the appearance of concrete.

[0008] As for the surface treatment methods of concrete after demolding and hardening, these are mid-to-late stage treatment and repair processes. In essence, they are designed to address the problems that occurred when the concrete material was poured and formed before hardening. Therefore, the methods to improve surface quality should be based on solving the root causes of the problems, especially for fair-faced concrete projects that emphasize self-finished finishes.

[0009] However, current methods for reducing porosity still suffer from problems such as unstable porosity reduction and high costs. Therefore, there is an urgent need for a method that can directly reduce the porosity of fair-faced concrete while treating only the concrete surface. Summary of the Invention

[0010] In view of the problems existing in the prior art, the purpose of the present invention is to provide a construction process and water-reducing concrete for reducing the porosity of fair-faced concrete surfaces, so as to solve the problems that current methods for reducing porosity still have issues such as unstable porosity reduction and high cost.

[0011] To achieve this objective, the present invention adopts the following technical solution:

[0012] In a first aspect, the present invention provides a construction process for reducing porosity on the surface of fair-faced concrete, the construction process comprising:

[0013] A water-reducing agent is sprayed onto the surface of the template after it has been coated with template paint. Then, concrete is poured, cured, and demolded in sequence to obtain fair-faced concrete.

[0014] The construction process provided by this invention improves the surface properties of water-reducing concrete by placing the water-reducing agent between the formwork agent and the water-reducing concrete, rather than adding it into the water-reducing concrete, thereby reducing the porosity of the water-reducing concrete surface and ensuring that the water-reducing concrete has an excellent appearance.

[0015] As a preferred technical solution of the present invention, the template for applying template paint includes: a template obtained after applying template paint and drying for 20-40 minutes.

[0016] As a preferred embodiment of the present invention, the water-reducing agent has a water reduction rate of ≥25%.

[0017] Preferably, the water-reducing agent has a bleeding rate of ≤70%.

[0018] Preferably, the air content of the water-reducing agent is ≤6%.

[0019] As a preferred embodiment of the present invention, the solid content of the water-reducing agent is 8-12%.

[0020] As a preferred embodiment of the present invention, the dosage of the water-reducing agent is 12-15 mg / L. 2 / kg.

[0021] As a preferred technical solution of the present invention, the concrete pouring is completed within 12 hours after the spraying is completed.

[0022] As a preferred technical solution of the present invention, the spraying method includes one of air spraying, high-pressure spraying or brushing.

[0023] As a preferred technical solution of the present invention, the working temperature of the concrete pouring is 0-30℃.

[0024] The vibration methods used in concrete pouring include internal vibration and / or external vibration.

[0025] Secondly, the present invention provides a water-reducing concrete, which is obtained by using the construction process for reducing surface porosity of fair-faced concrete as described in the first aspect, wherein the pore density of the water-reducing concrete is ≤10⁸ m³ / s. -2 Pore ​​area density ≤ 2.316 cm³ 2 / m 2 .

[0026] Compared with existing technical solutions, the present invention has the following beneficial effects:

[0027] (1) The dosage is calculated based on the concrete area, and the cost is much lower than that of using defoamer.

[0028] (2) It is a pretreatment before pouring, which can take into account complex, irregular, and densely reinforced concrete structures and parts.

[0029] (3) No additional equipment is required, and the short-term cost investment is far lower than that of the attached plate vibrator.

[0030] (4) Using the construction process provided by this invention, the pore density of the resulting water-reducing concrete is ≤10⁸ m³ / s. -2 Pore ​​area density ≤ 2.316 cm³ 2 / m 2 Attached Figure Description

[0031] Figure 1 These are surface photographs of the fair-faced concrete obtained by the construction process of Embodiment 1 of the present invention;

[0032] Figure 2 This is a photograph of the surface of the fair-faced concrete obtained by the construction process of Comparative Example 1 of this invention;

[0033] Figure 3 This is a statistical diagram of the pore size of the fair-faced concrete surface obtained by the construction process corresponding to Embodiment 1 and Comparative Example 1 of the present invention;

[0034] Figure 4 This is a statistical diagram of the surface pore distribution of fair-faced concrete obtained by the construction process corresponding to Embodiment 1 and Comparative Example 1 of the present invention.

[0035] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims. Detailed Implementation

[0036] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0037] This embodiment provides a construction process for reducing porosity on the surface of fair-faced concrete, the construction process including:

[0038] A water-reducing agent is sprayed onto the surface of the template after it has been coated with template paint. Then, concrete is poured, cured, and demolded in sequence to obtain fair-faced concrete.

[0039] The template for applying the template paint includes a template obtained after the template has been coated with template paint and dried for 20-40 minutes, for example, 20 minutes, 22 minutes, 24 minutes, 26 minutes, 28 minutes, 30 minutes, 32 minutes, 34 minutes, 36 minutes, 38 minutes or 40 minutes, etc., but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0040] In this invention, applying a template paint increases the probability that damage will occur within the interface, i.e., within the template paint layer, during demolding, thus making the concrete surface smoother. The specific template paint can be selected and designed according to the requirements of the cement pouring field, such as Changsha Yousheng YS-1 template paint, Hunan Yipin HD-1 template paint, or Henan Lingjun LJ-1 template paint, etc.

[0041] Wherein, the water-reducing agent has a water reduction rate of ≥25%, for example, it can be 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%, etc., but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0042] Wherein, the water-reducing agent has a water bleeding rate of ≤70%, for example, it can be 70%, 68%, 66%, 64%, 62%, 60%, 58%, 56%, 54%, 52% or 50%, etc., but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0043] Wherein, the air content of the water-reducing agent is ≤6%, for example, it can be 6%, 5.8%, 5.6%, 5.4%, 5.2%, 5%, 4.8%, 4.6%, 4.4%, 4.2% or 4%, etc., but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0044] For example, the water-reducing agent is selected as a liquid standard polycarboxylate water-reducing agent according to GB 8076-2008.

[0045] The solid content of the water-reducing agent is 8-12%, for example, it can be 8%, 8.2%, 8.4%, 8.6%, 8.8%, 9%, 9.2%, 9.4%, 9.6%, 9.8%, 10%, 10.2%, 10.2%, 10.4%, 10.6%, 10.8%, 11%, 11.2%, 11.4%, 11.6%, 11.8%, or 12%, etc., but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0046] In this invention, solid content refers to the percentage content by mass.

[0047] The dosage of the water-reducing agent is 12-15 mg / L. 2 / kg, for example, could be 12m 2 / kg, 12.2m 2 / kg, 12.4m 2 / kg, 12.6m 2 / kg, 12.8m 2 / kg, 13m 2 / kg, 13.2m 2 / kg, 13.4m 2 / kg, 13.6m 2 / kg, 13.8m 2 / kg, 14m 2 / kg, 14.2m 2 / kg, 14.4m 2 / kg, 14.6m 2 / kg, 14.8m 2 / kg or 15m 2 / kg, etc., but not limited to the listed values; other unlisted values ​​within this range also meet the requirements.

[0048] In this invention, m 2 / kg refers to the contact area between concrete and formwork per square meter. 2 A certain amount of water-reducing agent is sprayed onto it.

[0049] The concrete pouring shall be completed within 12 hours after the spraying is finished. For example, it can be 12h, 11h, 10h, 9h, 8h, 7h, 6h, 5h, 4h, 3h, 2h or 1h, but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0050] The spraying method includes one of air spraying, high-pressure spraying, or brushing.

[0051] The concrete pouring operation temperature is 0-30℃, for example, it can be 0℃, 2℃, 4℃, 6℃, 8℃, 10℃, 12℃, 14℃, 16℃, 18℃, 20℃, 22℃, 24℃, 26℃, 28℃ or 30℃, etc., but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0052] The vibration method in the concrete pouring includes internal vibration and / or external vibration.

[0053] In this invention, internal vibration refers to inserting a vibrator into the concrete to vibrate, while external vibration refers to vibrating on the surface of the concrete, i.e., outside, such as attached vibration and surface vibration.

[0054] Furthermore, the present invention provides a molded water-reducing concrete, which is obtained by employing the aforementioned construction process for reducing surface porosity of fair-faced concrete, wherein the pore density of the molded water-reducing concrete is ≤10⁸ m³ / s. -2 Pore ​​area density ≤ 2.316 cm³ 2 / m 2 .

[0055] Furthermore, to illustrate the excellent effect of the construction process for reducing surface porosity in fair-faced concrete provided by the present invention, the following practical example is used for explanation:

[0056] Example 1

[0057] This embodiment provides a construction process for reducing porosity on the surface of fair-faced concrete, the construction process including:

[0058] After the template paint (Changsha Yousheng YS-1 template paint) has dried for 30 minutes, the template surface is treated with 13m... 2 / kg is the dosage basis for high-pressure spraying of liquid standard polycarboxylate superplasticizer (Sika) conforming to GB 8076-2008 and with a solid content of 10% at 10℃. 8305 (diluted to a solid content of 10%), then concrete is poured. During the concrete pouring process, internal vibration, curing, and demolding are carried out to obtain fair-faced concrete.

[0059] Example 2

[0060] This embodiment provides a construction process for reducing porosity on the surface of fair-faced concrete, the construction process including:

[0061] After the template paint (Hunan Yipin HD-1 template paint) has dried for 35 minutes, the template surface is sprayed with 14m... 2 / kg is the dosage basis for air spraying of a liquid standard polycarboxylate superplasticizer (Sika) conforming to GB 8076-2008 with a solid content of 9% at 20℃. 540P (diluted to a solid content of 9%), then concrete is poured. During the concrete pouring process, external vibration, curing, and demolding are carried out to obtain fair-faced concrete.

[0062] Example 3

[0063] This embodiment provides a construction process for reducing porosity on the surface of fair-faced concrete, the construction process including:

[0064] After the template paint (Henan Lingjun LJ-1 template paint) has dried for 20 minutes, the template surface is sprayed with 15m... 2 / kg is the dosage basis for applying a liquid standard polycarboxylate superplasticizer (Sika) conforming to GB 8076-2008 and with a solid content of 12% at 15℃. 8305 (diluted to a solid content of 12%), then concrete is poured. During the concrete pouring process, external vibration, curing, and demolding are carried out to obtain fair-faced concrete.

[0065] Example 4

[0066] This embodiment provides a construction process for reducing porosity on the surface of fair-faced concrete, the construction process including:

[0067] After the template paint (Changsha Yousheng YS-1 template paint) has dried for 40 minutes, the template surface is sprayed with 12m... 2 / kg is the dosage basis. At 25℃, a liquid standard polycarboxylate superplasticizer (Guangdong Hongqiang CSP-18, diluted to 8% solid content) conforming to GB 8076-2008 is sprayed under high pressure. After that, concrete is poured. During the concrete pouring, internal vibration, curing and demolding are carried out to obtain fair-faced concrete.

[0068] Example 5

[0069] The only difference from Example 1 is that the water-reducing agent used is replaced with an equal amount of Shandong Xinbaihe Chemical MZS01 calcium lignosulfonate water-reducing agent.

[0070] Example 6

[0071] The only difference from Example 1 is that the water-reducing agent used is replaced with an equal amount and equal solids content of Kezhijie Point-N100(I) naphthalene-based high-efficiency water-reducing agent.

[0072] Example 7

[0073] The only difference from Example 1 is that the water-reducing agent used is replaced with an equal amount of BASF with the same solids content. F10 melamine-based water-reducing agent.

[0074] Example 8

[0075] The only difference from Example 1 is that the water-reducing agent used is replaced with an equal amount and equal solids content of Kezhijie Point-800 aminosulfonate-based high-efficiency water-reducing agent.

[0076] Example 9

[0077] The only difference from Example 1 is that the water-reducing agent used is replaced with an equal amount and equal solids content of Lichenglier LC-SAF-BZ fatty acid-based high-efficiency water-reducing agent.

[0078] Example 10

[0079] The only difference from Example 1 is that the solid content of the water-reducing agent used is 20%.

[0080] Example 11

[0081] The only difference from Example 1 is that the solid content of the water-reducing agent used is 5%.

[0082] Example 12

[0083] The only difference from Example 1 is that the amount of water-reducing agent used is 10m³. 2 / kg.

[0084] Example 13

[0085] The only difference from Example 1 is that the amount of water-reducing agent used is 20m³. 2 / kg.

[0086] Comparative Example 1

[0087] The only difference from Example 1 is that the template surface is not sprayed with liquid standard polycarboxylate superplasticizer.

[0088] Comparative Example 2

[0089] The only difference from Example 1 is that the water-reducing agent used is mixed into the concrete in equal amounts before concrete pouring.

[0090] Using the above construction process, C35 ordinary commercial concrete (mass ratio of silicate cement 2.5: slag powder S95: Class II fly ash: water: natural sand (fineness modulus = 2.5): crushed stone (5-25mm): high-performance water-reducing agent 1:0.37:0.24:0.68:2.99:4.02:0.02) was used. The distribution of pore size and pore area on the concrete surface was statistically analyzed using photography and image processing software. The template paint, template, concrete, pouring process, and vibration process of each test group were completely consistent. The pore distribution results of the water-reducing concrete are shown in Table 1 below.

[0091] Table 1

[0092]

[0093]

[0094] As shown in Table 1, the solution provided by this invention, by applying polycarboxylate superplasticizer, improves the fluidity of the cement paste on the formwork side during concrete vibration, making it easier for the cement paste to flow at the interface and level during vibration. This results in higher surface smoothness at the interface with the formwork paint, smaller and fewer pores, and even smaller and fewer pores on the concrete surface after demolding. Excessive use of both polycarboxylate superplasticizer and formwork paint diminishes their effect on reducing pores on the concrete surface, significantly increasing costs. Therefore, the recommended dosage for efficient use of both the formwork paint and the sprayed polycarboxylate superplasticizer is defined as the inflection point where pore density and pore area density gradually decrease with increasing dosage.

[0095] Among them, the surface photograph of the fair-faced concrete obtained by the construction process in Example 1 is as follows: Figure 1 As shown, a photograph of the surface of the fair-faced concrete obtained by the construction process in Comparative Example 1 is as follows. Figure 2 As shown, the statistical diagrams of pore size on the surface of fair-faced concrete obtained by the corresponding construction processes in Example 1 and Comparative Example 1 are as follows: Figure 3 As shown, the statistical diagrams of the pore distribution on the surface of fair-faced concrete obtained by the corresponding construction processes in Example 1 and Comparative Example 1 are as follows: Figure 4 As shown in the figure, spraying polycarboxylate superplasticizer onto the steel mold after the template paint has dried is beneficial to reducing the surface pore density, pore area density, and overall pore size distribution of the concrete after demolding.

[0096] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0097] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0098] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A construction process for reducing porosity on the surface of fair-faced concrete, characterized in that, The construction process includes: A water-reducing agent is sprayed onto the surface of the template after it has been coated with template paint. Then, concrete is poured, cured, and demolded in sequence to obtain fair-faced concrete.

2. The construction process as described in claim 1, characterized in that, The template for applying the template paint includes: the template obtained after the template has been coated with template paint and dried for 20-40 minutes.

3. The construction process as described in claim 1, characterized in that, The water-reducing agent has a water reduction rate of ≥25%.

4. The construction process as described in claim 1, characterized in that, The water-reducing agent has a bleeding rate of ≤70%.

5. The construction process as described in claim 1, characterized in that, The air content of the water-reducing agent is ≤6%.

6. The construction process as described in claim 1, characterized in that, The solid content of the water-reducing agent is 8-12%.

7. The construction process as described in claim 1, characterized in that, The dosage of the water-reducing agent is 12-15m³. 2 / kg.

8. The construction process as described in claim 1, characterized in that, Concrete pouring shall be completed within 12 hours after the spraying is finished.

9. The construction process as described in claim 1, characterized in that, The spraying method includes one of air spraying, high-pressure spraying, or brushing.

10. The construction process as described in claim 1, characterized in that, The working temperature for concrete pouring is 0-30℃.

11. The construction process as described in claim 1, characterized in that, The vibration methods used in concrete pouring include internal vibration and / or external vibration.

12. A water-reducing concrete, characterized in that, The water-reducing concrete is obtained using the construction process for reducing surface porosity of fair-faced concrete as described in any one of claims 1-11, and the pore density of the water-reducing concrete is ≤10⁸ m³ / s. -2 Pore ​​area density ≤ 2.316 cm³ 2 / m 2 .

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