Dry hanging stone has reached a new level in aesthetics, durability, non-discoloration, and flatness. It overcomes the shortcomings of traditional wet pasting methods for stone materials and is increasingly widely used in the decoration of exterior walls of large city buildings. The safety and aesthetic issues caused by improper material selection and construction methods in the construction of exterior wall stone dry hanging should be highly valued by the industry. This article discusses several personal opinions on the quality control of stone dry-hanging construction after its application in this project.
01. Material quality control
Establish a sound material inspection system, and strictly inspect various materials in accordance with construction quality acceptance standards and design requirements. Special materials used should have factory certificates, inspection reports, quality assurance materials, as well as material mechanical performance tests and stone radiation testing reports. In addition to meeting the requirements of various test data available at the factory, some materials must also undergo on-site witness sampling and random inspection according to regulations. Only after passing the sampling and retesting can they be allowed to be used for construction.
1. Stone: According to design requirements, determine the variety, color, pattern, and size specifications of the stone, and strictly control and inspect its bending, tensile, and compressive strength. The water absorption rate should be less than 0.8%, and its performance such as resistance to freeze-thaw cycles should be checked. The genetic conditions of stone are complex, and many defects of the stone itself will be exposed after processing. The most common defects are hole defects, natural crushing defects, and the breakage of the board caused by sawing and transportation of raw materials. These damaged or defective boards can be restored through bonding and repair processes. Reforming bonding and filling are the two methods of plate repair used in this project.
(1) Reconstruct adhesive repair. For some damaged edges and corners, the first step is to perform splicing and restructuring bonding treatment, and for slightly larger areas, back mesh reinforcement treatment is also required. Renovation bonding generally uses special adhesives for stone materials, which have solid and liquid forms and colors such as transparent, light yellow, or other colors. This process uses epoxy resin adhesive. After 3 days of hardening and curing, it is smoothed and polished with an oilstone before use.
(2) Filling in defects. For hole defects, due to the randomness and irregularity of their distribution, manual methods are used to fill and repair these types of plates. For smaller size defect plates with holes, direct application of the adhesive solution is used to fill and repair them. For some defective boards with large hole sizes, stone powder or a mixture of stone blocks with the adhesive solution can be used to fill and repair them. The stone powder and blocks must be obtained from stone scraps of the same color variety, in order to make the color and pattern of the repaired stone as natural as possible.
2. Structural adhesive and weather-resistant adhesive: Special structural adhesive and weather-resistant adhesive that meet national or industry standards must be selected to ensure that no quality problems caused by leakage occur. If the adhesive inside the stone bonding gap is not a stone-specific adhesive, the bonding quality cannot be guaranteed, and leakage is prone to occur.
3. The main profiles for fixing stone materials, whether steel or aluminum, must meet the design requirements. Galvanized profiles should be selected for steel, and if anti-corrosion is required, reinforced treatment must be used. The electroplating layer on the surface of aluminum materials must meet the thickness requirements of national AA15 or above, and the thickness of aluminum alloy hanging parts should not be less than.
02. Control network control
Measure the axis and elevation of the structure, and verify the design dimensions of the stone facade to identify errors. Distribute the errors evenly within the control network to determine the actual setting out the size of the overall control network. Based on the adjusted control network, check and verify the deviation and quality issues of the embedded parts to determine whether they meet the installation requirements. If not, contact the design party and take corresponding remedial measures.
According to the design drawings, use a theodolite to mark the vertical control lines on the two sides of the large angle in advance, preferably at a distance of 500px from the large angle, in order to check the accuracy of the vertical hanging line at any time and ensure a smooth installation. A vertical hanging line is suitable for use φ 1.0 to φ 1.2 steel wire is preferred, with the lower and upper ends hanging on a dedicated wire hanging angle steel frame. The angle steel frame is fixed to the top of the large corner of the building with expansion bolts, and the interlayer is opened and fixed with an angle steel frame. It must be hung in a secure, accurate, and not easily touched place, and attention should be paid to protection and frequent inspection and verification to prevent displacement. Only in this way can the dry hanging stone be fully closed and the gap be connected.
