The stone sticks directly to the wall. What materials are used for safe handling and how to operate them?

As a new installation technology, dry hanging stone curtain wall has reached a new level in terms of beauty, durability, anti-discoloration, flatness and so on. It overcomes the shortcomings of the traditional wet sticking stone method and is more and more widely used in the external wall decoration of large civil buildings. 1. Disadvantages of traditional wet pasting technology for stone curtain wall In the past, the installation of stone decorative plates for external and internal walls of buildings used the old technology of adding steel wire mesh on the wall, fixing the plates with copper wires and pasting cement mortar in layers. There are many disadvantages when this technology is applied to external walls, not only because of calcium bicarbonate precipitation (whitening frost) and water stains after cement mortar sticks to the board, the stone on the wall becomes discolored, forming color difference and polluting the wall surface; Moreover, due to temperature changes and other reasons, it is easy to cause quality problems such as hollowing, cracking and even falling off of the wall. For example, for the external wall decoration of Tianlong Building in Taiyuan City, 600X600mm polished rock slab of Jinan Tsinghua Port was selected. Although epoxy resin adhesive was used in the installation process, after many years of completion of 1, there was still whitening and discoloration, and some of them were empty and cracked. Therefore, the building had to take reinforcement measures, and two holes with a depth of 10cm and an upward inclination angle of15 were drilled in each granite slab. Nail φ6.5cm steel dowel, pour epoxy resin glue, and then clean it up after reinforcement. After this treatment, although the granite decorative board has been strengthened, the appearance effect is still not ideal. Another example is the granite exterior wall of the skirt building of Taiyuan Financial Building. Due to the wet sticking technology, it gradually appeared whitening, discoloration, hollowing and cracking soon after completion. 2. Principle and technology of dry hanging method of stone curtain wall In recent years, dry hanging technology of stone decorative plate has been developed and popularized. Its principle is to set the main stress points on the main structure, and fix the stone on the building through metal pendants to form a stone decorative curtain wall. At present, the concrete practices of dry hanging of engineering stone materials vary from place to place. As far as the fixing technology between the pendant and the main structure is concerned, there are two main methods: one is for the shear wall structure, the pendant can be fixed directly with expansion bolts or embedded iron pieces. Second, for the light wall structure with frame, because the wall can not directly fix the pendant, it is necessary to fix the pendant by installing a metal skeleton; As for the materials used in the metal skeleton, there are mainly two kinds of steel skeleton and aluminum skeleton. The former is low in cost, but it needs to be galvanized for corrosion protection, while the latter is expensive because it needs to use thickened or aircraft materials. Generally speaking, there are two ways to fix plates: one is bolt fixation, and the main components are pins, trays, bolts, pads and angle steel. According to the stone weight, local wind load and earthquake load, determine the model of each component. Its structure is as follows: firstly, the angle steel is fixed on the skeleton or wall by bolts, the tray is fixed by angle steel, and the stone is connected with the tray by pins. The pendant can adjust the plate up and down, back and forth in a small range to ensure the uniformity of plate joints and the flatness of the plate surface. The other is post-cutting dry hanging, also called stress-free anchoring dry hanging. The concrete method is that a group of foundation bolts with reaming at the bottom are connected with stone through convex combination and supported by metal frame, which has great advantages in safety, durability and convenience. According to the treatment method of stone flat-fell seam, the first is that the plates are naturally connected without leaving seams. The disadvantage of this method is that it is easy to limit the thermal expansion and cold contraction of plates due to temperature difference, so it is not suitable for extensive use in external walls. Second, take off the seam, plate gap is generally 5~8mm, generally evenly filled with foam rubber strip, and sealed with weather-resistant silica gel. There are three main advantages of dry hanging stone slabs: first, it can effectively avoid the phenomenon of hollowing, cracking and falling off of slabs in traditional wet sticking technology, and obviously improve the safety and durability of buildings; Second, it can completely avoid the whitening and discoloration of the surface of the traditional wet sticking process, which is conducive to keeping the curtain wall clean and beautiful; Third, to some extent, it improves the working conditions of construction workers, reduces the labor intensity, and also helps to speed up the project progress. Take the Anye Building in Taiyuan completed in 1999 as an example. The building covers a building area of 26,400 square meters, with a total height of 98.2 meters. The facade granite curtain wall is about 7,800 square meters, all of which are constructed by external dry hanging method. 635# stone in Nan 'an County, Fujian Province uses granite smooth plate, and 635# fire plate uses grid belt. At the light wall of the frame, the main keel is made of 8# channel steel, and the secondary keel is made of L50X5 angle steel. The skeleton connection is welded, and the weld height h=6mm. All skeletons are rustproof. All parts of the pendant are made of stainless steel, with 8mm gap between plates, evenly filled with foam rubber strip and sealed with weather-resistant silica gel imported from the United States. The construction process of granite curtain wall in this project is: measuring elastic line → installing skeleton → installing pendant → fixing plate → adjustment → sealant → cleaning → acceptance. In order to ensure the quality of the project, special attention should be paid to measuring and setting out, controlling, distributing and digesting the deviation of the main structure, so that the verticality and flatness of the whole skeleton are strictly controlled within the allowable range. In terms of facing, the deviation of length and width is 0.5mm, the deviation of hole position is 0.5 mm, and the deviation of hole depth is 2 mm Because of its excellent quality, the whole project of this building won the 1999 Luban Award for Chinese Architectural Engineering. 3, some practical thinking 3. 1, stone curtain wall is the external structure of the building, and the connection quality with the main building will directly affect the external resistance and safety of the stone curtain wall. Therefore, it is of positive significance to commercialize connectors. With the approval of the national industry department, professional manufacturers with production conditions will produce and supply connectors according to the construction drawings provided by the owners, which will improve the engineering quality and reduce the investment cost. 3.2, in view of the stone curtain wall is more and more widely used, and the specific practices of various projects in different places are not the same, the state should introduce technical standards for process design, construction and quality inspection as soon as possible, so that the design, construction and acceptance of stone curtain walls can be based on laws. 3.3. Although the dry hanging method of stone curtain wall has many advantages, compared with the traditional wet sticking technology, its cost is obviously high, which limits its further promotion. Therefore, in addition to mass production of pendants to effectively reduce the cost of pendants, we must also actively improve the construction technology to reduce working hours and reduce costs, so that the application of dry hanging technology for stone curtain walls is more extensive.