Abstract: The construction technology of the dry hanging (sticking) process of decorative engineering stone is relatively difficult. The dry hanging (sticking) construction is a new type of decoration that uses high-strength corrosion-resistant connection rings to install and fix the decorative stone on the surface of the building's exterior wall. The construction process, construction technology requirements are high and the operation is relatively difficult. To make stone decoration achieve the expected quality goals, it must be strictly controlled to affect its construction quality. This article combines engineering examples, conducts research and analysis, and introduces the construction technology of stone dry hanging and the key points of quality control.
With the continuous development of the economy, we have come into contact with more and more engineering projects, such as courts, procuratorates, commodity inspection, radio and television centers, etc., all of which are public buildings with dozens of floors and dozens of floors. The main building (or skirt Natural stone (granite stone) curtain wall is used for the decoration of the outer protective structure of the building and the inner wall (column) of the first floor. The decoration of stone curtain wall or the combination of stone curtain wall and glass curtain wall makes the whole building produce a strong contrast between virtual and reality, harmonious colors, unique style, solemn and elegant visual effects, adding splendor to the city.
Same as glass curtain wall project. The factors affecting the construction quality of stone curtain wall engineering are also multifaceted. The five factors of human, machine, science, law and environment have a comprehensive impact on construction quality. However, due to the particularity of stone and its dry hanging structure, its construction method and process quality influencing factors and quality control focus are different. Practice has shown that, according to the structural characteristics of the building, the requirements of the design and specifications, and the company's own technical strength, the corresponding construction technology is formulated and strictly implemented. Doing a good job of supervision and inspection is an important part of the foundation of construction technology management and quality control of stone curtain wall engineering. Combining engineering examples and taking the construction of a certain building curtain wall as a reference, the author makes some discussion on the construction technology of stone dry hanging and its quality control points.
2. Project overview
The frame-shear structure of a certain building has one basement floor, 16 floors above ground, and a height of 71m; a three-story podium with a total construction area of 37,781 square meters. The construction unit requires curtain wall decoration for the main building and the outer walls of the podium. Except for the glass curtain wall in the middle of the main building's front and back facades, the rest (including the decorative lines in the glass curtain wall) are all granite curtain walls. The granite slabs on the outer walls and the first floor cover an area of approximately 11,300 square meters. The stone curtain wall project is constructed by dry hanging method; the construction process, key parts, key procedures and construction difficulties are strictly controlled throughout the construction process.
3. Construction technology
3.1 Construction process
Set up external scaffolding to measure and set the line → install the steel structure frame → formulate the arc sleeve model template → granite drilling → install the stainless steel support and granite slab → adjust and correct, check the verticality and smoothness → the same set at the edge of the seam Masking tape → applying sealant → removing the tape, cleaning, waxing → removing the shelf → cleaning the site.
3.2 Rack requirements
The clear distance between the vertical pole and the wall is not less than 400mm, anchored with the main structure, the upper end is the same as the parapet, the middle is anchored with the floor column, the shelf is covered with safety protection boards, and the outside is protected by dense mesh nets.
3.3 Measuring and setting out
Measurement and setting-out is an important part of this stone dry hanging construction. Pay-off accuracy. Directly affect the effect of stone dry hanging. Therefore, the laying method determines the size of the construction error. We require the construction unit to check the laying off from these aspects:
(1) This project first needs to release the control line. Before the control line is cast, it is necessary to carry out the lead: that is, the original main structure axis and elevation, when the control line is cast on the floor, the center line of the building must be found first, and then cast in two directions, which can eliminate 50% cumulative error and accuracy Doubled. At this stage, a theodolite is required to draw a vertical line. Use a level to copy a horizontal line on the wall, and use a steel ruler to pull the line along the horizontal line.
(2) According to the control line, find the center line of the column net and the window, and draw one half of the required size to both sides according to the center line as the control line of the finished surface. Theodolite is used to complete the surface control line, and the error of the control line is controlled within 2mm.
(3) The control line should be protected. Without the review by quality inspectors and supervisors, no coverage is allowed. Only lines that have been reviewed and approved by the relevant technicians can be used for construction.
3.4 Steel frame construction
Large-area stone thousand hanging is realized through the steel framework to realize the force transmission, the steel framework is divided into two parts, vertical and horizontal. Vertically uses 10 channel steel, horizontally uses angle steel (L5Omm x 50mm×5mm).
First, arrange the vertical channel steel: For the base material of the brick wall, M12 bolts should be used to penetrate the brick wall. Tighten the 10mm thick, 150mm X 150mm thick steel plate with nuts on both sides of the wall, and weld the channel steel to the steel plate; for the concrete matrix, use M12 expansion bolts to fix the 150mm×150mm steel plate, and weld the channel steel to the steel plate. The vertical channel steel spacing is not more than 1500mm, and the average spacing is 100mm. Where there are concrete beams and slabs, fixed points must be added, and at least two channel steels should be arranged on the wall between the windows and each wall in order to weld the horizontal angle steel. If there is a deviation in the verticality of the partial wall, the fixed point can be leveled with steel plate. The deviation of vertical channel steel length and verticality shall not exceed 5mm.
The horizontal angle steel must be welded to the vertical channel steel, so that the gravity of the hanging plate is transmitted to the wall through the vertical channel steel, but it should be noted that the angle steel must be well drilled to install the stone waist hole, and the straightness deviation of the angle steel through length is within 1.5 .
The channel steel and angle steel used in the steel frame should be galvanized anti-corrosion treatment before installation, and the welding parts should be painted with anti-rust paint twice and silver powder paint once. At the same time, the strength of the selected welding rod should be the same as the base metal.
When welding on-site, a fire hopper should be set up under the welding, reliable safety protection measures should be taken under the structural layer, and the waste debris on the scaffold should be cleaned up in time.
The steel frame should be firmly connected without chattering and deformation. The weld should be welded firmly, the expansion bolts should be firmly anchored to the wall, and there should be no looseness between the stainless steel connector and the steel frame and plate, and there should be no looseness after the external stone is installed.
3.5 Stone preparation
First use the colorimetric method to select, classify and number the color of the stone, and then set it on the bench drill with a special mold according to the design size and drawings to process mounting holes (4 on the upper and lower sides of each piece, and the depth of the hole is 30mm. Brush unsaturated resin glue and patch on the back, using one cloth and two glue method, that is, first use a wire brush and coarse sandpaper to remove the floating dust and impurities, and then brush the glue all over (the corners, especially the punched parts must be brushed in place ), then use a brush to flatten the glass fiber mesh cloth over and over again, and then brush two coats of glue, and stack them according to the number for later use.
3.6 Stone dry hanging installation
(1) Hanging line: Before installing the stone, use theodolite to pull the two vertical control lines on the left and right ends of the wall. It is best to bounce it at a position 200mm away from the corner to check the accuracy of the vertical hanging line at any time to ensure smooth installation. . The vertical hanging wire should use a steel wire hanging hammer of Φ1.0, mm to Φ1.2mm (hammer weight 8～10kg, the upper end is hung on the special hanging wire frame, it must be firm, accurate, and marked on the lower end of the control line , Pay attention to protection and frequent inspections.
(2) Bottom-layer stone bracket: starting from the bottom of m, the stone-mounted bracket should be supported on the lower end of the wall, and the upper mouth of the bracket should be on the same level.
(3) Bottom stone in place: Put a piece of stone on the corner of the bottom layer in place first, apply marble glue to the mounting holes on the upper and lower sides, and insert the connector inserts into the well aligned with the stone mounting holes, and then use a torque wrench Tighten the adjustment well, fix the board, and install the bottom stone in order.
(4)Adjustment and fixation: After the bottom stone is all in place, if the upper mouth is not flat, the levelness should be adjusted, and a corresponding double-strand copper wire pad can be placed on the bracket; to adjust the verticality, the distance between the stone upper mouth connectors can be adjusted Wall gap; finally, adjust the gap size so that the gap width is uniform and meet the design requirements of the platform (5-8mm).
(5) Top panel installation: Then, install the stone layer by layer from bottom to top as described above until the top. After the last layer of stone is installed and adjusted, the structure: the gap between the wall and the stone should be painted and waterproofed with steel wire mesh, and then a certain slope (10%) of the stone should be used as the top cover.
(6) Pasting anti-fouling strip + caulking: Use a 40-width paper tape-type self-adhesive tape to stick tightly along the edge of the stone as an anti-fouling strip: insert elastic backing strips in stone gaps; backing strips 5mm away from the decoration surface Outside. Use a caulking gun to hit neutral silica gel into the seam. But pay attention to the smoothness and interface of the stone surface.
(7) Cleaning and brushing the face agent: then tear off the anti-fouling strip. Wipe the slate with cotton yarn moistened with acetone. Mix the face paint half an hour before brushing according to the mix ratio, pay attention to the difference between the primer and the top coat, in stages Operation. Brush with a 3-inch wool brush, smooth and light-selective.
4. Key points for quality control of dry hanging construction in Shicun
4.1 Quality control of stone selection
The stone curtain wall as the outer protective structure. In addition to bearing its own weight, it also bears the influence of wind loads, earthquakes and temperature changes. Therefore, the quality of the stone must be reliable. Therefore, the supplier must provide the quality assurance certificate (national standard) required by the design and contract; the supplier should make the corresponding mechanical test report for the granite. The mechanics is called the Fuyu Design Essentials; the supplier delivers the granite Before. Self-inspection should be carried out on the external dimensions of granite, especially the thickness, concealed damage, and color, and should meet the design requirements and contract regulations. In particular, cracks in the granite are strictly prohibited; the construction party should conduct visual and actual inspections of the purchased stone walls and Observe the cracks by watering, and strictly prohibit granite that does not meet the design requirements from entering the site.
If there are inconsistent colors, concealed flaws, cracks and other poor granite quality problems. Once found, the application should be rejected and the supplier should take corresponding measures.
4.2 Quality control of expansion bolt and angle steel connection construction
The brick supplier is required to provide the mechanical test report of the expansion butterfly bolts. And meet the design requirements; the drilling rig should be kept horizontal and vertical when drilling. The drilling depth should be kept at about 6cm, and the lime sand in the hole should be blown out with wind; the inner expansion lining and inner expansion pin must be fully expanded; after the M10×45 bolt is screwed in, try to withstand the inner expansion pin. If there is any gap, fill it with glue; bolts, copper with the same fixed angle, flat washers, and spring washers must be flattened to make the angle copper close to the structural layer, and at the same time fix the screw with resin adhesive to prevent loosening; connecting piece and fixed angle steel When connecting. After adjusting the left and right sides, you must be twisted, and the nut should be fixed with a resin adhesive to prevent loosening; the owner and the supervisor should check and accept the construction of the inner expansion pin, and conduct random inspections and tests at any time and make hidden records .
4.3 Quality control of granite drilling construction
Drilling, the person who drills the eye must be performed by Gaosuo and experienced professionals. To be proficient in the operation process and technology; before drilling, the granite must be inspected for appearance, size, color, material, and fine cracks. It is strictly forbidden to use granite that does not meet the construction requirements on the wall; before drilling, you must first install the granite, adjust the horizontal up and down positions of the angle steel, and the front and rear left and right positions of the connecting piece to determine the drilling position; when drilling the elbow, you must strictly control the drilling depth. Keep the drilling depth controlled to 25mm; before installation, the construction personnel should check whether the drilling position of the drilling is correctly centered, whether there is any cracks caused by the drilling, etc., and clean the dust in the hole; the owner and the supervisor should respond Drill holes in granite for special inspection and acceptance, and make concealed records.
4.4 Quality control of granite upper wall
When installing granite on the wall, you must strictly control the size of the upper, lower, left, and right joints. Do not adjust the size of the gap arbitrarily to prevent the granite from overlapping and affecting the force system; the slate and the slab must be kept vertical, especially the light slab cannot be connected to the slab. The phenomenon of concave and convex at the joints; the construction personnel should square the diagonal (internal angle and external angle) of the slate with a smooth surface. The joint height, flatness and other quality are strictly controlled; after the pin is fixed, check whether the pin is against the upper piece of granite, and there must be a certain gap between the pin and the granite. Clean the surface and bond with strong gum to make the joints full and even. Cadmium must not be left and the next piece of granite can be installed after it has solidified; the person in charge of construction should strengthen the quality awareness education of the construction personnel and conduct technical clarification; The party shall specially assign quality personnel to conduct on-site quality inspection and conduct construction quality assessment for each part.
4.5 Quality control of caulking
The supplier is required to provide the sealant’s warranty and various index performances; the granite should be treated according to the joints before caulking. The high-pressure air of an air compressor must be used to blow off the dirt and dust on the wall (or use other methods to treat ); Strictly control the thickness of the joint. At least 6mm or more shall be stacked; the PE rod of the backing material must be made of polyethylene foam, and the pressing depth must be uniform according to the filling depth, and pressed into the joint. Do not be too loose, The number should be increased. Such as 6mm seam with 8mm bead. It is beneficial to control the filling depth; when filling the joints, tape paper must be attached to the joints to prevent the joints from polluting the granite surface; when filling the joints, the jointing agent must be continuously dense and full, and cutting corners is strictly prohibited. The filling is required to prevent water seepage; quality personnel should be specially assigned to conduct joint filling inspections and make hidden records.
Dry hanging granite is a new technology. Regardless of the mechanical system, structural connection, and quality requirements, they are different from ordinary glass curtain walls. The various management acceptance systems must be accurate and must not affect the overall quality due to problems in certain links. The acceptance system includes: ① granite appearance size, material, color and lustre acceptance; ② engineering angle steel support material acceptance; ③ concealed engineering acceptance of all links of granite installation-internal expansion construction, granite drilling and joint filling, etc.; ④ granite stone curtain wall quality acceptance evaluation .
Do a good job of dry-hanging stone curtain walls, requiring all responsible parties to carry out strict quality control in all aspects of material, construction preparation, construction process, technical (quality) management, inspection and acceptance. For stone curtain wall projects such as court buildings, due to the reasonable construction technology, accurate quality control points, effective measures, and effective construction, the construction quality is guaranteed; from the appearance, the stone surface is flat and clean, the color is consistent, the joints are dense, and the width is uniform. , The overall effect is good; the quality of the project is recognized by the owner, peers and society.