Construction technology for reducing air holes in surface of bare concrete and water-reducing concrete

Abstract

The invention relates to a construction technology for reducing air holes in the surface of fair-faced concrete and water-reducing concrete, in particular to the field of fair-faced concrete.The construction technology comprises the steps that a water reducing agent is sprayed to the surface of a formwork painted with formwork paint, then concrete pouring, curing and demolding are conducted in sequence, and the fair-faced concrete is obtained. According to the construction process provided by the invention, the water reducing agent is arranged between the template agent and the water-reducing concrete instead of being added into the water-reducing concrete, so that the surface performance of the water-reducing concrete is improved, pores in the surface of the water-reducing concrete are reduced, and the water-reducing concrete is ensured to have an excellent appearance.

Description

Technical Field

[0001] The invention relates to the field of plain concrete, and in particular to a construction process for reducing pores on the surface of plain concrete and water-reducing concrete. Background Art

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

[0003] The traditional method is mainly optimized from the perspective of materials and vibration technology, including:

[0004] (1) Adding defoaming agent or adding defoaming components 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 bubbles from the concrete surface.

[0007] However, method (1) most commonly uses liquid-modified silicone polyether defoamers or defoaming components, which usually increase the cost of each cubic meter of concrete by (15-20) yuan, which is relatively expensive. In addition, some polycarboxylic acid water reducers and defoamers have poor compatibility and cannot be used at the same time. Method (2) has a more obvious cost increase and is usually used in special areas such as floors and runways. Method (3) has the lowest cost and better effect, but is only suitable for large surfaces. For complex, special-shaped, densely reinforced structures or areas, the flat plate vibrator cannot achieve the effect of expelling surface pores, and due to reflected waves, resonance, etc., it may even locally aggravate the aggregation of pores, affecting the appearance of the concrete.

[0008] As for the surface treatment method of concrete after demolding and hardening, it belongs to the mid-to-late stage treatment and repair process. Its essence is to make up for the problems that occurred when the concrete material was cast and formed before hardening. Therefore, the method to improve the surface quality should solve the problem from the root, especially the plain concrete project that emphasizes self-finishing finish.

[0009] However, the current methods for reducing pores still have problems such as unstable pore reduction and high cost. Therefore, there is an urgent need for a method for fair-faced concrete that can directly reduce the porosity of concrete while only treating 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 for reducing pores on the surface of plain concrete and water-reducing concrete, so as to solve the problems of unstable pore reduction and high cost in the current pore reduction method.

[0011] To achieve this object, the present invention adopts the following technical solutions:

[0012] In a first aspect, the present invention provides a construction process for reducing pores on the surface of plain concrete, the construction process comprising:

[0013] A water reducing agent is sprayed on the surface of the formwork painted with formwork paint, and then concrete pouring, curing and demoulding are carried out in sequence to obtain plain concrete.

[0014] The construction process provided by the present invention improves the surface performance of the water-reducing concrete and reduces the pores on the surface of the water-reducing concrete by placing the water-reducing agent between the formwork agent and the water-reducing concrete instead of adding it into the water-reducing concrete, thereby ensuring that the water-reducing concrete has an excellent appearance.

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

[0016] As a preferred technical solution of the present invention, the water reducing rate of the water reducing agent is ≥25%.

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

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

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

[0020] As a preferred technical solution of the present invention, the amount of the water reducing agent is 12-15m 2 / kg.

[0021] As a preferred technical solution of the present invention, 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°C.

[0024] The vibrating method during concrete pouring includes internal vibration and / or external vibration.

[0025] In a second aspect, the present invention provides a water-reducing concrete, wherein the water-reducing concrete is obtained by using the construction process for reducing the pores on the surface of the plain concrete as described in the first aspect, and the pore density of the water-reducing concrete is ≤108m -2 , pore area density ≤ 2.316cm 2 / m 2 .

[0026] Compared with the prior art solutions, the present invention has the following beneficial effects:

[0027] (1) The amount is calculated based on the concrete area, and the cost investment is much lower than using a defoaming agent.

[0028] (2) As a pre-treatment before pouring, it can take into account the complex, special-shaped, and densely reinforced concrete structures and parts.

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

[0030] (4) The pore density of the water-reducing concrete obtained by the construction process provided by the present invention is ≤108m -2 , pore area density ≤ 2.316cm 2 / m 2 BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a surface photograph of the plain concrete obtained by the construction process of Example 1 of the present invention;

[0032] Figure 2 This is a surface photograph of the plain concrete obtained by the construction process of Comparative Example 1 of the present invention;

[0033] Figure 3 Statistical diagram of pore diameters on the surface of the plain concrete obtained by the corresponding construction processes of Example 1 of the present invention and Comparative Example 1;

[0034] Figure 4 It is a statistical diagram of pore distribution on the surface of the plain concrete obtained by the corresponding construction processes of Example 1 of the present invention and Comparative Example 1.

[0035] The present invention is further described in detail below. However, the following examples are only 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 shall be subject to the claims. DETAILED DESCRIPTION

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

[0037] This embodiment provides a construction process for reducing pores on the surface of plain concrete, the construction process comprising:

[0038] A water reducing agent is sprayed on the surface of the formwork painted with formwork paint, and then concrete pouring, curing and demoulding are carried out in sequence to obtain plain concrete.

[0039] Among them, the template coated with template paint includes: a template obtained by drying for 20-40 minutes after the template is coated with template paint, for example, it can be 20min, 22min, 24min, 26min, 28min, 30min, 32min, 34min, 36min, 38min or 40min, etc., but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0040] In the present invention, the probability of damage occurring in the interface, that is, in the template paint layer, during demoulding is increased by applying the template paint, which is more conducive to a smooth concrete surface. 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.

[0041] Among them, the water reduction rate of the water reducer is ≥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 the range also meet the requirements.

[0042] The water seepage rate of the water reducer is ≤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 values ​​not listed within the range also meet the requirements.

[0043] Among them, the air content of the water reducer 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, and other unlisted values ​​within the range also meet the requirements.

[0044] Exemplarily, the water reducer is a liquid standard polycarboxylate water reducer according to GB 8076-2008.

[0045] Wherein, the solid content of the water reducer 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, and other values ​​not listed within the range also meet the requirements.

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

[0047] Wherein, the dosage of the water reducing agent is 12-15m 2 / kg, for example, it can 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 values ​​not listed within this range also meet the requirements.

[0048] In the present invention, m 2 / kg refers to the contact area between concrete and formwork is 1m 2 Spray a certain amount of water reducing agent on the surface.

[0049] Among them, concrete pouring is completed within 12 hours after the spraying is completed, 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, and other unlisted values ​​within the range also meet the requirements.

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

[0051] Among them, the operating temperature of concrete pouring is 0-30°C, for example, it can be 0°C, 2°C, 4°C, 6°C, 8°C, 10°C, 12°C, 14°C, 16°C, 18°C, 20°C, 22°C, 24°C, 26°C, 28°C or 30°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0052] Wherein, the vibration method during concrete pouring includes internal vibration and / or external vibration.

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

[0054] Furthermore, the present invention provides a molded water-reducing concrete, which is obtained by using the aforementioned construction process for reducing the pores on the surface of the plain concrete, and the pore density of the molded water-reducing concrete is ≤108m -2 , pore area density ≤ 2.316cm 2 / m 2 .

[0055] Further, in order to illustrate the good effect of removing surface pores that can be achieved by the construction process for reducing pores on the surface of plain concrete provided by the present invention, the following practical examples are used for illustration, as follows:

[0056] Example 1

[0057] This embodiment provides a construction process for reducing pores on the surface of plain concrete, the construction process comprising:

[0058] After the template paint (Changsha Yousheng YS-1 template paint) was dried for 30 minutes, the template surface was 13m 2 / kg is the dosage basis. At 10℃, high pressure spraying is carried out on a liquid standard polycarboxylate water reducer (Sika) that complies with GB 8076-2008 and has a solid content of 10%. 8305, diluted to a solid content of 10%), followed by concrete pouring, during which internal vibration, curing and demoulding are performed to obtain plain concrete.

[0059] Example 2

[0060] This embodiment provides a construction process for reducing pores on the surface of plain concrete, the construction process comprising:

[0061] After the template paint (Hunan Yipin HD-1 template paint) was dried for 35 minutes, the template surface was 14m 2 / kg is the dosage basis. At 20℃, air spraying is carried out with a liquid standard polycarboxylate water reducer (Sika) that complies with GB 8076-2008 and has a solid content of 9%. 540P, diluted to a solid content of 9%), followed by concrete pouring, during which external vibration, curing and demoulding are performed to obtain plain concrete.

[0062] Example 3

[0063] This embodiment provides a construction process for reducing pores on the surface of plain concrete, the construction process comprising:

[0064] After the template paint (Henan Lingjun LJ-1 template paint) was dried for 20 minutes, the template surface was 15m 2 / kg is the dosage basis. Apply liquid standard polycarboxylate water reducer (Sika) that complies with GB 8076-2008 and has a solid content of 12% at 15°C. 8305, diluted to a solid content of 12%), followed by concrete pouring, during which external vibration, curing and demoulding were performed to obtain plain concrete.

[0065] Example 4

[0066] This embodiment provides a construction process for reducing pores on the surface of plain concrete, the construction process comprising:

[0067] After the template paint (Changsha Yousheng YS-1 template paint) was dried for 40 minutes, the template surface was 12m 2 / kg is used as the dosage basis. A liquid standard polycarboxylate water-reducing agent (Guangdong Hongqiang CSP-18, diluted to a solid content of 8%) that complies with GB 8076-2008 is sprayed at high pressure at 25°C, and then concrete is poured. During the concrete pouring, internal vibration, curing and demoulding are carried out to obtain plain concrete.

[0068] Example 5

[0069] The only difference from Example 1 is that the water reducer used is replaced with an equal amount of Shandong Xinbaihe Chemical MZS01 calcium lignin sulfonate water reducer.

[0070] Example 6

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

[0072] Example 7

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

[0074] Example 8

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

[0076] Example 9

[0077] The only difference from Example 1 is that the water reducer used is replaced by an equal amount of Lichuanglier LC-SAF-BZ fatty acid-based high-efficiency water reducer with the same solid content.

[0078] Example 10

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

[0080] Embodiment 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 difference from Example 1 is that the amount of water reducing agent used is 10m 2 / kg.

[0084] Example 13

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

[0086] Comparative Example 1

[0087] The only difference from Example 1 is that the liquid standard polycarboxylate water-reducing agent is not sprayed on the template surface.

[0088] Comparative Example 2

[0089] The only difference from Example 1 is that an equal amount of the water reducing agent is mixed into the concrete and then the concrete is poured.

[0090] The above construction process was used with C35 ordinary commercial mix (mass ratio composition was silicate cement 2.5: slag powder S95: Class C II fly ash: water: natural sand medium sand (fineness modulus = 2.5): crushed stone (5-25mm): high-performance iconic water reducer was 1:0.37:0.24:0.68:2.99:4.02:0.02), and photography and image processing software were used to combine the statistics of concrete surface pore size and pore area distribution. The formwork paint, formwork, concrete, casting process, and vibration process of each test group were completely consistent. The pore distribution results of the obtained water-reducing concrete are as shown in Table 1.

[0091] Table 1

[0092]

[0093]

[0094] As shown in Table 1, in the scheme provided by the present invention, by applying the polycarboxylate water-reducing agent, the cement slurry on the side contacting the formwork during the vibration of the concrete is more fluid, the clean slurry is easier to flow at the interface and is flattened during vibration, thereby making the interface contacting the formwork paint more flat, the holes are smaller and fewer, and the holes on the concrete surface after demolding are smaller and fewer. When the dosage of the polycarboxylate water-reducing agent and the formwork paint is too high, the effect of the two on reducing the pores on the concrete surface is no longer obvious, and the cost increases significantly. Therefore, the inflection point where the pore density and the pore area density gradually decrease with the increase in dosage is used as the recommended dosage for efficient use of brushing the formwork paint and spraying the polycarboxylate water-reducing agent.

[0095] The surface photo of the clear water concrete obtained by the construction process of Example 1 is as follows: Figure 1 As shown, the surface photo of the plain concrete obtained by the construction process of Comparative Example 1 is as follows Figure 2 As shown, the statistical diagram of the pore diameters of the surface of the plain concrete obtained by the corresponding construction processes of Example 1 and Comparative Example 1 is as follows Figure 3 As shown, the statistical diagram of the pore distribution on the surface of the plain concrete obtained by the corresponding construction process of Example 1 and Comparative Example 1 is as follows Figure 4 As shown in the figure, it can be seen that spraying polycarboxylic acid water-reducing agent on the steel formwork whose template paint has dried on the surface is beneficial to the reduction of surface pore density, pore area density and overall pore size distribution after concrete demoulding.

[0096] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to 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 further describe various possible combinations.

[0098] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A construction process for reducing pores on the surface of plain concrete, characterized in that: The construction process includes: A water reducing agent is sprayed on the surface of the formwork painted with formwork paint, and then concrete pouring, curing and demoulding are carried out in sequence to obtain plain concrete.

2. The construction process according to claim 1, characterized in that: The template coated with template paint comprises: a template obtained after the template is coated with template paint and dried for 20-40 minutes.

3. The construction process according to claim 1, characterized in that: The water reducing agent has a water reducing rate of ≥25%; Preferably, the water bleeding rate of the water reducing agent is ≤70%; Preferably, the air content of the water reducing agent is ≤6%.

4. The construction process according to claim 1, characterized in that: The solid content of the water reducing agent is 8-12%.

5. The construction process according to claim 1, characterized in that: The dosage of the water reducing agent is 12-15m 2 / kg.

6. The construction process according to claim 1, characterized in that: The concrete pouring is completed within 12 hours after the spraying is completed.

7. The construction process according to claim 1, characterized in that: The spraying method includes one of air spraying, high-pressure spraying or brushing.

8. The construction process according to claim 1, characterized in that: The working temperature of the concrete pouring is 0-30°C.

9. The construction process according to claim 1, characterized in that: The vibrating method during concrete pouring includes internal vibration and / or external vibration.

10. A water-reducing concrete, characterized in that: The water-reducing concrete is obtained by using the construction process for reducing the pores on the surface of the plain concrete as described in any one of claims 1 to 9, and the pore density of the water-reducing concrete is ≤108m -2 , pore area density ≤ 2.316cm 2 / m 2 .

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