Fair-faced concrete as well as preparation process and construction process thereof

Abstract

The invention relates to the technical field of building materials, in particular to fair-faced concrete and a preparation process thereof. The fair-faced concrete is prepared from the following raw materials in parts by weight: 100 to 120 parts of cement, 150 to 180 parts of sand, 200 to 240 parts of gravel, 15 to 30 parts of additive, 20 to 30 parts of admixture and 80 to 150 parts of water, wherein the cement is selected from P.042.5 ordinary Portland cement, the sand is selected from any one of natural river sand and artificial sand, the fineness modulus of the sand is greater than 2.4, the particle size of the gravel is 5-31.5 mm, and the silt content of the gravel is 1t; the content of needle-sheet-shaped broken stones is less than or equal to 15%. Cement, sand, gravel, an additive, an admixture, water and the like are used as raw materials, the cement, the sand, the gravel, the additive, the admixture and the water are put into mixing equipment to be mixed and stirred, discharging is performed after uniform mixing, and the fair-faced concrete is prepared. The invention further provides a construction process of the fair-faced concrete. The prepared fair-faced concrete has good mechanical properties, and the quality of the fair-faced concrete is effectively guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of building engineering, in particular to a kind of fair-faced concrete and a preparation process and a construction process thereof. Background Art

[0002] Fair-faced concrete is a special type of concrete among existing concretes. It refers to concrete that is directly formed in one step and has a natural texture or is only coated with a colorless protective coating. As a finishing concrete, it aims to have a clean surface, natural color, and lines that conform to the design rhythm. It can meet the requirements of various architectural shapes and has excellent decorative effects.

[0003] Compressive strength is one of the most critical mechanical performance indicators of plain concrete. For plain concrete, since it is often directly exposed as the load-bearing part of the building structure, it needs to have sufficient compressive strength to ensure the structural safety of the building during use.

[0004] Based on this, the present invention provides a kind of fair-faced concrete and its preparation process and construction process, so as to solve the technical problems mentioned above. Summary of the invention

[0005] The purpose of the present invention is to provide a kind of fair-faced concrete and its preparation process and construction process, the prepared fair-faced concrete has good mechanical properties and effectively guarantees its quality.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The first aspect of the present invention provides a plain concrete, which is composed of the following raw materials in parts by weight:

[0008] 100-120 parts of cement;

[0009] 150-180 parts of sand;

[0010] 200-240 parts of crushed stone;

[0011] 15-30 parts of admixture;

[0012] 20-30 parts of admixture;

[0013] 80-150 parts of water.

[0014] The present invention is further configured as follows: the cement is selected from P.042.5 ordinary Portland cement.

[0015] The present invention is further configured as follows: the sand is selected from any one of natural river sand and artificial sand.

[0016] The present invention is further configured as follows: the fineness modulus of the sand is greater than 2.4.

[0017] The present invention is further configured as follows: the particle size of the crushed stone is 5 to 31.5 mm, the mud content in the crushed stone is less than 1%, and the needle-like content in the crushed stone is ≤15%.

[0018] The present invention is further configured as follows: the admixture is selected from any one of a pumping agent and a polycarboxylate water reducer.

[0019] The present invention is further configured as follows: the admixture is selected from any one or more of S95 grade slag powder and fly ash.

[0020] The present invention is further configured as follows: the water is selected from any one of tap water and well water.

[0021] The second aspect of the present invention: also provides a process for preparing the above-mentioned plain concrete, comprising the following steps:

[0022] Step 1: Accurately weigh cement, sand, gravel, admixtures, additives and water and set aside;

[0023] Step 2: Put cement, sand, crushed stone, admixture, admixture and water into a mixing device for mixing and stirring, and discharge the materials after mixing evenly to prepare plain concrete.

[0024] The third aspect of the present invention is to provide a construction process for plain concrete, comprising the following steps:

[0025] Step S201, making: making a wall column template;

[0026] Step S202, erecting the formwork: installing the wall column formwork, adding horizontal diagonal braces, correcting the formwork by verticality, axis position, cross-sectional dimensions, and diagonal squareness, and tightening the supports to form a casting cavity;

[0027] Step S203, pouring: pouring plain concrete in the pouring cavity, wherein the plain concrete is obtained according to any one of claims 1 to 5;

[0028] Step S204, demoulding: after reaching the designed strength, the wall column template is removed to obtain the plain concrete wall column;

[0029] Step S205, curing: curing the plain concrete wall columns.

[0030] The present invention is further configured as follows: the wall column formwork is a square wall formwork, an arc-shaped wall formwork, a square column formwork or a petal column formwork.

[0031] The present invention is further configured as follows: in the step S203, before pouring, fill with 50mm thick cement mortar with the same composition as that of the plain concrete, and insert vibrating rods at uniform positions in the wall column formwork; during pouring, discharge the material in layers, and the height of each discharge does not exceed 50cm. The vibrating rod is vibrated and slowly lifted while discharging the material, and the vibration time and the depth of the vibrating rod inserted into the next layer of concrete are strictly controlled to be 5-10cm. The vibration time is until the plain concrete is turned over and no longer sinks and no bubbles appear on the surface.

[0032] The present invention is further configured as follows: in the step S204, when the strength of the specimen of the plain concrete reaches 3MPa, the temperature is 600-700 degrees and the formwork is removed.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] In the present invention, cement, sand, crushed stone, admixture, admixture and water are used as raw materials, and cement, sand, crushed stone, admixture, admixture and water are put into a mixing device for mixing and stirring, and the materials are discharged after being evenly mixed to prepare clear water concrete. The clear water concrete prepared by the present invention has good mechanical properties and effectively guarantees its quality. The clear water concrete and its preparation and construction process provided by the present invention have a broader market prospect and are more suitable for promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram of a process flow of a construction process of a plain concrete according to the present invention;

[0036] Figure 2 It is a structural schematic diagram of a curved wall formwork used in a construction process of plain concrete according to the present invention;

[0037] Figure 3 It is a structural schematic diagram of a square column formwork used in a construction process of plain concrete of the present invention;

[0038] Figure 4 It is a structural schematic diagram of a petal column formwork used in a construction process of fair-faced concrete according to the present invention. DETAILED DESCRIPTION

[0039] The present invention will be described in detail below in conjunction with the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional changes made by a person skilled in the art based on these embodiments are all within the scope of protection of the present invention.

[0040] The terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "the" and "the" used in the present invention and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0041] Example 1

[0042] The present embodiment provides a plain concrete, which is composed of the following raw materials in parts by weight: 100 parts of cement; 150 parts of sand; 200 parts of crushed stone; 15 parts of admixture; 20 parts of additive; and 80 parts of water.

[0043] Among them, cement is P.042.5 ordinary Portland cement, sand is natural river sand, admixture is pumping agent, admixture is S95 grade slag powder, fly ash is mixed in a mass ratio of 1:09, and tap water is used. Furthermore, the fineness modulus of sand is greater than 2.4, the particle size of crushed stone is 5mm, the mud content in crushed stone is less than 1%, and the needle-like content in crushed stone is ≤15%.

[0044] In this embodiment, it should be noted that the apparent density of the sand is 2690 kg / m3 and the bulk density is 1500 m3.

[0045] In this embodiment, it should be noted that P.042.5 ordinary Portland cement was purchased from Guangdong Qingyuan Guangying Cement Co., Ltd., the pumping agent was purchased from Sichuan Shunmei New Materials Co., Ltd., S95 grade slag powder was purchased from Xinji Gangxin New Building Materials Co., Ltd., and fly ash was purchased from Hengshui Hengguan Building Materials Co., Ltd.

[0046] In addition, this embodiment also provides a preparation process of the above-mentioned plain concrete, comprising the following steps:

[0047] Step 1: Accurately weigh cement, sand, gravel, admixtures, additives and water and set aside;

[0048] Step 2: Put cement, sand, crushed stone, admixture, admixture and water into a mixing device for mixing and stirring, and discharge the materials after mixing evenly to prepare plain concrete.

[0049] Example 2

[0050] The present embodiment provides a plain concrete, which is composed of the following raw materials in parts by weight: 105 parts of cement; 160 parts of sand; 210 parts of crushed stone; 17 parts of admixture; 22 parts of admixture; and 85 parts of water.

[0051] Among them, cement is P.042.5 ordinary Portland cement, sand is natural river sand, admixture is pumping agent, admixture is S95 grade slag powder, fly ash is mixed in a mass ratio of 1:09, and tap water is used. Furthermore, the fineness modulus of sand is greater than 2.4, the particle size of crushed stone is 5mm, the mud content in crushed stone is less than 1%, and the needle-like content in crushed stone is ≤15%.

[0052] In this embodiment, it should be noted that the apparent density of the sand is 2690 kg / m3 and the bulk density is 1500 m3.

[0053] In this embodiment, it should be noted that P.042.5 ordinary Portland cement was purchased from Guangdong Qingyuan Guangying Cement Co., Ltd., the pumping agent was purchased from Sichuan Shunmei New Materials Co., Ltd., S95 grade slag powder was purchased from Xinji Gangxin New Building Materials Co., Ltd., and fly ash was purchased from Hengshui Hengguan Building Materials Co., Ltd.

[0054] In addition, this embodiment also provides a preparation process of the above-mentioned plain concrete, comprising the following steps:

[0055] Step 1: Accurately weigh cement, sand, gravel, admixtures, additives and water and set aside;

[0056] Step 2: Put cement, sand, crushed stone, admixture, admixture and water into a mixing device for mixing and stirring, and discharge the materials after mixing evenly to prepare plain concrete.

[0057] Example 3

[0058] The preparation process of the plain concrete provided in this embodiment is basically the same as that in Embodiment 1, except that: the specific raw material composition and the specific preparation process of the plain concrete in this embodiment are different; the specific raw material composition and the specific preparation process of the plain concrete in this embodiment are as follows:

[0059] A kind of plain concrete is composed of the following raw materials in parts by weight: 110 parts of cement; 165 parts of sand; 220 parts of crushed stone; 22 parts of admixture; 25 parts of admixture; and 115 parts of water.

[0060] Among them, cement is P.042.5 ordinary Portland cement, sand is artificial sand, admixture is pump polycarboxylate water reducer, admixture is S95 grade slag powder, water is tap water. Furthermore, the fineness modulus of sand is greater than 2.4, the particle size of crushed stone is 17mm, the mud content in crushed stone is less than 1%, and the needle-like content in crushed stone is ≤15%.

[0061] In this embodiment, it should be noted that the apparent density of the sand is 2685 kg / m3 and the bulk density is 1520 m3.

[0062] In this embodiment, it should be noted that P.042.5 ordinary Portland cement was purchased from Guangdong Qingyuan Guangying Cement Co., Ltd., polycarboxylic acid water reducer was purchased from Kunming Shengwei Concrete Admixture Co., Ltd., and S95 grade slag powder was purchased from Xinji Gangxin New Building Materials Co., Ltd.

[0063] In addition, this embodiment also provides a preparation process of the above-mentioned plain concrete, comprising the following steps:

[0064] Step 1: Accurately weigh cement, sand, gravel, admixtures, additives and water and set aside;

[0065] Step 2: Put cement, sand, crushed stone, admixture, admixture and water into a mixing device for mixing and stirring, and discharge the materials after mixing evenly to prepare plain concrete.

[0066] Example 4

[0067] The preparation process of the plain concrete provided in this embodiment is basically the same as that in Embodiment 1, except that: the specific raw material composition and the specific preparation process of the plain concrete in this embodiment are different; the specific raw material composition and the specific preparation process of the plain concrete in this embodiment are as follows:

[0068] A kind of plain concrete is composed of the following raw materials in parts by weight: 118 parts of cement; 170 parts of sand; 230 parts of crushed stone; 28 parts of admixture; 28 parts of admixture; and 140 parts of water.

[0069] Among them, cement is P.042.5 ordinary Portland cement, sand is artificial sand, admixture is pump polycarboxylate water reducer, admixture is S95 grade slag powder, water is tap water. Furthermore, the fineness modulus of sand is greater than 2.4, the particle size of crushed stone is 17mm, the mud content in crushed stone is less than 1%, and the needle-like content in crushed stone is ≤15%.

[0070] In this embodiment, it should be noted that the apparent density of the sand is 2685 kg / m3 and the bulk density is 1520 m3.

[0071] In this embodiment, it should be noted that P.042.5 ordinary Portland cement was purchased from Guangdong Qingyuan Guangying Cement Co., Ltd., polycarboxylic acid water reducer was purchased from Kunming Shengwei Concrete Admixture Co., Ltd., and S95 grade slag powder was purchased from Xinji Gangxin New Building Materials Co., Ltd.

[0072] In addition, this embodiment also provides a preparation process of the above-mentioned plain concrete, comprising the following steps:

[0073] Step 1: Accurately weigh cement, sand, gravel, admixtures, additives and water and set aside;

[0074] Step 2: Put cement, sand, gravel, admixture, additive and water into the mixing equipment Example 5

[0075] The preparation process of the plain concrete provided in this embodiment is basically the same as that in Embodiment 1, except that: the specific raw material composition and the specific preparation process of the plain concrete in this embodiment are different; the specific raw material composition and the specific preparation process of the plain concrete in this embodiment are as follows:

[0076] A kind of plain concrete is composed of the following raw materials in parts by weight: 120 parts of cement; 180 parts of sand; 240 parts of crushed stone; 30 parts of admixture; 30 parts of admixture; and 150 parts of water.

[0077] Among them, cement is P.042.5 ordinary Portland cement, sand is natural river sand, admixture is polycarboxylate water reducer, admixture is fly ash, water is well water. Furthermore, the fineness modulus of sand is greater than 2.4, the particle size of crushed stone is 31.5mm, the mud content in crushed stone is less than 1%, and the needle-like content in crushed stone is ≤15%.

[0078] In this embodiment, it should be noted that the apparent density of the sand is 2685 kg / m3 and the bulk density is 1520 m3.

[0079] In this embodiment, it should be noted that P.042.5 ordinary Portland cement was purchased from Guangdong Qingyuan Guangying Cement Co., Ltd., polycarboxylic acid water reducer was purchased from Kunming Shengwei Concrete Admixture Co., Ltd., and fly ash was purchased from Hengshui Hengguan Building Materials Co., Ltd.

[0080] In addition, this embodiment also provides a preparation process of the above-mentioned plain concrete, comprising the following steps:

[0081] Step 1: Accurately weigh cement, sand, gravel, admixtures, additives and water and set aside;

[0082] Step 2: Put cement, sand, gravel, admixtures, additives and water into the mixing equipment

[0083] Performance test: The samples of the plain concrete provided in Examples 1 to 5 are marked as Examples 1 to 5, respectively; and the relevant properties of the plain concrete provided in Examples 1 to 5 are tested as follows:

[0084] The specimens were prepared according to JGJ55-2011 and GB50204-2015, and the strength was tested after curing for 14 days and 28 days respectively.

[0085] The obtained test data are recorded in Table 1 below:

[0086]

[0087] Table 1 Performance test results of each group of plain concrete

[0088] By comparing and analyzing the relevant data in Table 1, it can be seen that the plain concrete prepared by the present invention has good mechanical properties and effectively guarantees its quality. This shows that the plain concrete and its preparation process provided by the present invention have a broader market prospect and are more suitable for promotion.

[0089] In the present invention, cement, sand, crushed stone, admixture, additive and water are used as raw materials, and cement, sand, crushed stone, admixture, additive and water are put into a mixing device for mixing and stirring, and the materials are discharged after being evenly mixed to prepare clear water concrete. The clear water concrete prepared by the present invention has good mechanical properties and effectively guarantees its quality.

[0090] On the basis of the above technical solution, the present invention also provides a construction process using the above-mentioned plain concrete, such as Figure 1 As shown, the following steps are included:

[0091] Step S201, making: making a wall column template;

[0092] Step S202, erecting the formwork: installing the wall column formwork, adding horizontal diagonal braces, correcting the formwork by verticality, axis position, cross-sectional dimensions, and diagonal squareness, and tightening the supports to form a casting cavity;

[0093] Step S203, pouring: pouring plain concrete in the pouring cavity;

[0094] Step S204, demoulding: after reaching the designed strength, the wall column template is removed to obtain the plain concrete wall column;

[0095] Step S205, curing: curing the plain concrete wall columns.

[0096] The present invention is further configured as follows: the wall column template is a square wall template, an arc wall template, a square column template or a petal column template. The wall column template can adopt a double-layer board process, that is, an outer layer of plywood and an inner layer of plastic board.

[0097] The present invention is further configured as follows: in the step S203, before pouring, fill with 50mm thick cement mortar with the same composition as that of the plain concrete, and insert vibrating rods at uniform positions in the wall column formwork; during pouring, discharge the material in layers, and the height of each discharge does not exceed 50cm. The vibrating rod is vibrated and slowly lifted while discharging the material, and the vibration time and the depth of the vibrating rod inserted into the next layer of concrete are strictly controlled to be 5-10cm. The vibration time is until the plain concrete is turned over and no longer sinks and no bubbles appear on the surface.

[0098] The present invention is further configured as follows: in the step S204, when the strength of the specimen of the plain concrete reaches 3MPa, the temperature is 600-700 degrees and the formwork is removed.

[0099] The column formwork and the wall formwork are further described below through embodiments.

[0100] Example 6

[0101] In this embodiment, the wall column formwork is a wall formwork. The specific steps are as follows.

[0102] Step S201, production: production of wall formwork.

[0103] The wall formwork can be a square wall formwork, a curved wall formwork, etc., wherein the curved wall formwork is as follows Figure 2 As shown. The template requires precise dimensions, horizontal and vertical, smooth joints, and no burr edges. The template surface layer is made of plastic board, which has a smooth, delicate and shiny surface; the lining board is made of pine or eucalyptus board, and the surface is made of phenolic resin impregnated and high-temperature hot-pressed wood plywood template. The core tube wall panel is made of a combination of steel and wood, the back ribs of the wall panel are made of specially customized reinforcement parts, and the reinforcement screws are made of 8.8 grade steel coarse teeth. The wall plugs are made of clear water concrete special wall-penetrating plastic plugs, φ18 trapezoidal screws, etc.

[0104] Step S202, erecting the formwork: installing a square wall formwork or a curved wall formwork, adding horizontal diagonal braces, correcting the formwork by verticality, axis position, cross-sectional dimensions, and diagonal squareness, and tightening the supports to form a casting cavity.

[0105] Before installing the wall formwork, check the flatness of the concrete pouring ground and strictly control the elevation to ensure the horizontality of the wall formwork. Before fixing each formwork, it is necessary to control the verticality and control line. Check and stick the special double-sided tape to ensure that the connection between the wall formworks is tight and there is no leakage. Wipe the wall formwork surface clean before assembly, and evenly apply the release agent on the surface before hoisting.

[0106] When erecting the formwork, adjust the wall formwork according to the design requirements and the actual situation of the construction site to meet the requirements. After the adjustment is completed, use bolts, reinforcements, nails, etc. to pull and fix the wall formwork.

[0107] After the wall formwork reinforcement is completed, the formwork is corrected and φ48.3×3.6mm steel pipes are used as external supports.

[0108] Step S203, pouring: pouring plain concrete in the pouring cavity.

[0109] Before pouring, check whether the joints of the wall formwork are tight and there should be no leakage during pouring; before pouring plain concrete, the wooden formwork should be watered and moistened, and there should be no water accumulation in the formwork; check whether the screws of the reinforcement parts are tightened in place to prevent the formwork from exploding. After the formwork reinforcement and correction are completed, the bottom of the wall should be sealed tightly with mortar, and it should be moistened before pouring concrete to ensure no leakage, but the sealing mortar needs to be moist. Avoid high temperature, low temperature, and rainy weather during the pouring operation to ensure that the concrete construction does not cause quality risks and visual defects due to weather reasons.

[0110] Before pouring, vibrating rods should be inserted at even positions in the wall panel, with a spacing of 3m between each two vibrating rods and obvious markings made on the vibrating rods every 1m. Insert the rods to the bottom of the wall.

[0111] In order to prevent single-point discharge from causing over-vibration of clear water concrete in some locations and excessive pressure on the wall formwork in some locations, the clear water concrete discharge needs to be circulated and evenly discharged in layers along the wall formwork in a single direction. The discharge height each time should not exceed 50cm. The vibrating rod should be vibrated at the same time as the discharge, and slowly lifted. The vibration time and the depth of the vibrating rod inserted into the next layer of concrete should be strictly controlled to ensure that the depth is 5 to 10cm. The vibration time is generally about 15s until the concrete slurry no longer sinks and no bubbles appear on the surface. Try to ensure daytime construction to avoid quality risks and visual defects caused by nighttime construction.

[0112] After pouring is completed, clean the surface slurry and seepage in time, scrape off the excessively thick cement mortar on the surface, replace it with concrete of the same proportion, control the surface elevation, smooth and polish it, and do a good job of sanitation and cleaning.

[0113] Step S204, formwork removal: after reaching the designed strength, the wall column formwork is removed to obtain a fair-faced concrete wall.

[0114] When the strength of the specimen under the same conditions reaches 3MPa, the formwork is removed at a temperature of 600-700 degrees. In particular, during winter construction, the specimen strength should not be less than 4MPa before the formwork can be removed.

[0115] Step S205, curing: curing the fair-faced concrete wall.

[0116] After demolding, timely maintenance should be carried out to reduce color difference, shrinkage cracks and other phenomena on the concrete surface.

[0117] The core tube concrete wall needs to be kept moist during the curing period to ensure the strength and durability of the concrete. You can use a sprinkler to moisten the concrete surface at least twice a day. You can install corner guards at the corners of the wall for protection, or make door pockets according to the size of the door opening for protection. The general protection height of the corner guard is 1.8-2 meters.

[0118] Example 7

[0119] In this embodiment, the wall column formwork is a column formwork.

[0120] Step S201, production: production of column formwork.

[0121] The column template can be a square column template, a petal column template, etc., among which the square column template is as follows Figure 3 As shown, the petal column template is as follows Figure 4 As shown. The template requires precise dimensions, horizontal and vertical, smooth joints, and no burr edges. The column template frame is made of steel and wood, and the surface layer is made of plastic board, which has a smooth, delicate and shiny surface; the lining board is made of pine or eucalyptus board, and the surface is made of phenolic resin impregnated, high-temperature hot-pressed wood plywood template.

[0122] Step S202, formwork erection: install column formwork, add horizontal diagonal braces, calibrate the formwork by verticality, axis position, cross-sectional dimensions, and diagonal squareness, and tighten the supports to form a casting cavity.

[0123] Before installing the column formwork, first check the axis and the outer control line of the edge to prevent deviation. During installation, first check the elevation and center line position of the foundation cushion layer, determine the control line of the template installation according to the edge line of the foundation pedestal on the cushion layer, and then accurately control the installation size and positioning of the template according to the template control line.

[0124] After the formwork is completed, the four sides of each column are individually calibrated. After verification, a line is drawn on the top, and then it is fixed, reinforced and locked.

[0125] The column formwork assembly connection can be made with φ16 full-thread high-strength bolts, which are screwed from bottom to top, and the outer steel plate is first flush and tightened in sequence, and the lower end is fixed with expansion screws according to the control line. Inclined support can be selected, such as using two φ48.3×3.6mm rack pipes for rigid support.

[0126] After assembly, use a hanging line to check the verticality of the four corners. The error should not exceed 3mm. The column casting height is the beam bottom elevation + 30mm.

[0127] Step S203, pouring: pouring plain concrete in the pouring cavity.

[0128] Before pouring, check whether the joints of the column formwork are tight and there should be no leakage during pouring; before pouring plain concrete, the wooden formwork should be watered and moistened, and there should be no water accumulation in the formwork. After the formwork reinforcement and correction are completed, the bottom of the column should be tightly sealed with mortar, and it should be moistened before pouring concrete to ensure no leakage, but the sealing mortar needs to be moistened. Avoid high temperature, low temperature, and rainy weather during pouring operations to ensure that the concrete construction does not cause quality risks and visual defects due to weather reasons.

[0129] Before pouring, fill with 50mm thick cement mortar with the same composition as the plain concrete to make the new and old concrete tightly combined to prevent quality defects at the root of the column formwork; two vibrating rods need to be inserted at even positions in the column, and the vibrating rods should be marked every 1m, and the insertion position should be to the bottom of the column formwork. In order to prevent the concrete from segregating due to the high free fall height, the pump truck hose needs to be inserted into the column formwork to ensure that the free fall height of the concrete is controlled within 3m. For column formworks above 6m, a customized extended pump pipe needs to be connected to the pump pipe.

[0130] During pouring, discharge the material in layers, and the height of each discharge should not exceed 50cm; the vibrator should be vibrated at the same time as the material is discharged, and slowly lifted. Strictly control the vibration time and the depth of the vibrator inserted into the next layer of concrete to ensure that the depth is 5-10cm. The vibration time is usually about 15s until the concrete slurry no longer sinks and no bubbles appear on the surface. Try to ensure daytime construction to avoid quality risks and visual defects caused by nighttime construction. During pouring, the sag and leakage of concrete slurry and the rusty water flowing down from the rusty steel bars should be cleaned in time.

[0131] After the column formwork is poured, clean the surface slurry and seepage water in time, scrape off the excessively thick cement mortar on the surface, replace it with concrete of the same proportion, control the surface elevation, smooth and polish it, and do a good job of sanitation and cleaning.

[0132] Step S204, demoulding: after reaching the designed strength, the column formwork is removed to obtain a plain concrete column.

[0133] When the strength of the specimen under the same conditions reaches 3MPa, the formwork is removed at a temperature of 600-700 degrees. In particular, during winter construction, the specimen strength should not be less than 4MPa before the formwork can be removed.

[0134] Step S205, curing: curing the plain concrete column.

[0135] After demolding, timely maintenance should be carried out to reduce color difference, shrinkage cracks and other phenomena on the concrete surface.

[0136] For plain concrete, plastic film or flame-retardant straw mats are often used in combination with watering and curing. Watering should be frequently used to keep the concrete moist before demoulding and during curing, and the curing time should be no less than 7 days. If watering and curing are not possible during winter construction, a curing method combining plastic film and flame-retardant straw mats can be used, and the curing time should be no less than 14 days.

[0137] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses or adaptations of the present invention, which follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed by the present invention. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present invention are indicated by the claims of the present application.

[0138] It should be understood that the present invention is not limited to the exact construction that has been described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A kind of plain concrete, characterized in that: It is composed of the following raw materials in parts by weight: 100-120 parts of cement; 150-180 parts of sand; 200-240 parts of crushed stone; 15-30 parts of admixture; 20-30 parts of admixture; 80-150 parts of water.

2. The plain concrete according to claim 1, characterized in that: The cement is P.042.5 ordinary Portland cement, and the sand is any one of natural river sand and artificial sand.

3. A kind of fair-faced concrete according to claim 2, characterized in that: The fineness modulus of the sand is greater than 2.4, the particle size of the crushed stone is 5 to 31.5 mm, the mud content in the crushed stone is less than 1%, and the needle-like content in the crushed stone is ≤15%.

4. The plain concrete according to claim 1, characterized in that: The admixture is selected from any one of a pumping agent and a polycarboxylate water reducer.

5. The plain concrete according to claim 1, characterized in that: The admixture is selected from any one or more of S95 grade slag powder and fly ash.

6. A process for preparing the plain concrete according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step S101, accurately weigh cement, sand, gravel, admixture, additives and water for later use; Step S102, cement, sand, crushed stone, admixture, additive and water are put into a mixing device for mixing and stirring, and the materials are discharged after being evenly mixed to prepare plain concrete.

7. A construction process for fair-faced concrete, characterized in that: The following steps are involved: Step S201, making: making a wall column formwork; Step S202, erecting the formwork: installing the wall column formwork, adding horizontal diagonal braces, correcting the formwork by verticality, axis position, cross-sectional dimensions, and diagonal squareness, and tightening the supports to form a casting cavity; Step S203, pouring: pouring plain concrete in the pouring cavity, wherein the plain concrete is obtained according to any one of claims 1 to 5; Step S204, demoulding: after reaching the designed strength, the wall column template is removed to obtain the plain concrete wall column; Step S205, curing: curing the plain concrete wall columns.

8. A construction process for fair-faced concrete according to claim 7, characterized in that: The wall column formwork is a square wall formwork, an arc-shaped wall formwork, a square column formwork or a petal column formwork.

9. A construction process for fair-faced concrete according to claim 7, characterized in that: In the step S203, before pouring, fill with cement mortar with a thickness of 50 mm and the same composition as that of the plain concrete, and insert vibrating rods at uniform positions in the wall column formwork; during pouring, discharge the material in layers, and the height of each discharge does not exceed 50 cm. The vibrating rod is slowly lifted while vibrating while discharging the material, and the vibration time and the depth of the vibrating rod inserted into the next layer of concrete are strictly controlled to be 5 to 10 cm. The vibration time is until the plain concrete is turned over and no bubbles appear on the surface.

10. A construction process for fair-faced concrete according to claim 7, characterized in that: In step S204, when the strength of the specimen of the plain concrete reaches 3 MPa, the temperature is 600-700 degrees and the formwork is removed.

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