The rapid development of building adhesives in the field of decorative stone has ranked first in the world in terms of annual stone production, consumption, and import and export volume. Stone products have also evolved from the initial granite and marble flooring and wall panels to various specifications of engineering boards, curved boards, spheres, columns, and lines in various shapes; Natural stone products such as thick plates, thin plates, ultra-thin stone composite plates, tombstones, countertops, stone mosaics, carvings, arts and crafts, square stones, pavement stones, and curbstones have emerged; Various artificial stone products, such as terrazzo in the form of inorganic adhesives, cultural stones, artistic poured stones, microcrystalline stones in the form of melting, solid surface materials mainly made of resin, granite mainly made of marble powder, quartz sand mainly made of quartz, etc; The surface processing forms are divided into mirror surface, matte surface, burnt surface, lychee surface, antique surface, sandblasted surface, water eroded surface, etc; The types of stone are divided into six categories and a series of products, including granite, marble, slate, limestone, sandstone, and secondary gemstones; The number of stone varieties has reached over 1500, and there are more than 300 imported stone varieties on the market. The construction and care techniques for stone materials have greatly improved, and new products and processes are constantly being developed, utilized, and promoted.
More and more building adhesives are being used in stone products. The natural properties and defects of stone require a large amount of adhesive for bonding, repairing, filling holes, sol, and bonding back nets. Adhesives are important auxiliary materials for improving the glossiness, appearance quality, and safety performance of stone. Some stone products require bonding or reinforcement treatment due to process requirements or natural cracks.
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In terms of stone application, China is gradually phasing out traditional cement bonding methods. Advanced materials and installation technologies such as cement-based adhesives and reactive resin adhesives are used for wet bonding of ground stone, avoiding quality problems such as insufficient bonding strength, stone water spots, and alkali bleeding caused by traditional cement mortar bonding; The wall stone installation adopts the dry hanging method, and the stone curtain wall structure is developing towards ecological, comfortable, and intelligent directions. The dry hanging parts are constantly improving, from the initial pin type hanging parts to T-shaped hanging parts, short groove hanging parts, through groove hanging parts, and later new hanging parts such as back bolt type, back hanging type, SE type, etc. With the application of epoxy resin dry hanging adhesive, the height of the stone curtain wall has reached 230 meters, and the maximum wind load has reached 12 kPa. In practical engineering, various surface materials such as granite, marble, limestone, sandstone, ultra-thin panels, and aluminum honeycomb composite panels have been widely used. Dry hanging and wet pasting methods are used for construction, and adhesives have become the main bonding materials, including joint fillers used for wall and floor stones and sealants used for curtain wall stones.
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At present, the most commonly used techniques for building adhesives in decorative stone products in China are mainly in the following aspects:
1. Adhesive for stone back mesh technology
The stone back mesh technology refers to the reinforcement process of bonding glass fiber mesh on the back of marble, limestone and other stones with poor strength during the entire processing to ensure that they have sufficient strength to adapt to production, processing, transportation, installation and use. The general nature of the back mesh adhesive uses unsaturated resin adhesive. During the stone construction stage, considering the adhesion problem between the stone back mesh with adhesive and the cement adhesive, the back mesh and adhesive will be removed, and the stone protective agent will be applied before paving construction. For some special types of stone, the fragmentation of stone slabs may occur after removing the back mesh. Therefore, it is necessary to retain the stone back mesh during construction. At this time, epoxy resin adhesive or cement-based adhesive is used for the back mesh. The back mesh bonded with epoxy resin adhesive requires special bonding techniques, such as sand bonding, during construction if wet bonding with cement mortar is used to enhance the bonding strength with the cement mortar. Otherwise, hollowing and other phenomena may occur after construction. For dry hanging stone, the back mesh will not affect the construction of the stone, and will enhance the front wind pressure resistance of the board, reducing the risk of detachment caused by various defects of natural stone. It is an effective measure to improve the safety performance of stone curtain walls, and epoxy resin adhesive is generally used. The durability of the back mesh bonded by unsaturated resin adhesive is poor, and it is sensitive to external factors such as water-based substances, alkaline substances, and ultraviolet radiation. Over time, it may fall off. Therefore, the back mesh bonded by unsaturated resin adhesive is only suitable for short-term fixation and reinforcement. In situations where high durability is required, epoxy resin adhesive is needed for bonding.
The main problem with this process currently is the disconnect between the types of adhesives and their intended use. Epoxy resin adhesives and cement-based adhesives have problems such as long curing time, high viscosity, difficulty in construction, and high cost, which often result in the use of unsaturated resin adhesives in most cases. In the application environment where the back mesh is retained, problems such as hollowing, peeling, and low strength often occur.
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2. Surface glue infiltration on stone
Stone blocks with many natural defects need to undergo surface infiltration treatment under vacuum conditions before processing large boards, which can reduce the degree of fragmentation of the board and improve the yield of the board. During the processing of stone slabs, surface infiltration treatment should also be carried out to effectively improve glossiness, compensate for defects, and increase strength. For some granite materials with coarser particlesIt can effectively eliminate the phenomenon of chicken claw lines.
The adhesive used for this process mainly has quality problems such as shrinkage and discoloration of the transparent surface adhesive required for stone materials such as cave stones, as domestic products cannot achieve the soft mirror luster of foreign products. Many marble and limestone products have experienced adhesive peeling after use, resulting in serious damage to the appearance quality of the products and affecting the engineering quality.
3. Adhesive for stone bonding and repair
A large number of natural defects in stone require the use of building adhesives for repair, small holes and cracks need to be filled with adhesives, slightly larger ones need to be repaired with their own stone powder and adhesive, and larger ones need to be repaired with stone particles, stone powder, and adhesive together. Cracks in marble and limestone stones require overall bonding, and the stone splicing process also requires bonding between panels, requiring the use of epoxy resin adhesive.
This process has many safety hazards, and many wall dry hanging projects have experienced panel detachment, mainly due to the extensive use of unsaturated resin adhesives. The relevant standards for stone specify the use of unsaturated resin adhesive in general repair situations for non structural load-bearing, limited to repairing small holes. Epoxy resin adhesive is required for fracture and process connections, as well as for connecting and reinforcing metal parts. However, due to price and process reasons, most projects use unsaturated resin adhesive for bonding, and in some cases, metal connectors are not even used. Figure 1 shows the appearance of a certain project
4. Adhesive for stone production
The current production of artificial stone mainly uses unsaturated resin adhesives and modified epoxy resin adhesives for ultra-thin stone composite panels. Due to the use of unsaturated resin adhesive as the bonding material, artificial stone products have poor resistance to UV aging, alkali and water. Once the project is applied outdoors or constructed using cement bonding method or subjected to erosion by water-based substances, quality problems such as discoloration, cracking, and warping may occur.
Ultra thin stone composite board is a new type of lightweight stone decorative material, which is made by processing stone into a thickness of 1-8 mm or thinner and compounding it with other materials. There are mainly stone ceramic composite panels, stone stone composite panels, stone glass composite panels, and stone aluminum honeycomb composite panels. The quality of the adhesive used to connect the composite layer is the key to the quality of the product, and modified epoxy resin adhesive must be used. However, due to the significant differences in adhesive properties, engineering quality problems continue to occur.
5. Adhesive for stone construction
The bonding process and filling of stone require the use of cement-based adhesives or reactive resin adhesives, mainly epoxy resin adhesives. However, due to price reasons, most construction companies still use ordinary cement mortar similar to pasting ceramic tiles to bond wall and floor stones. Some use 107 glue or 108 glue mixed with cement (commonly known as plain cement) to bond stones, causing quality problems such as hollowing and peeling in stone engineering. At the same time, the technology of domestically produced cement-based adhesives is not yet mature, while foreign products are in powder form and can be mixed in cement and sand to achieve unified water mixing. There is also a gap in bonding strength and other properties compared to foreign products or joint venture brands, and it is only suitable for bonding projects of general ground stone materials.
The joint filler used in stone bonding engineering often uses cement or sand to fill the joints, resulting in a common occurrence of black joints in stone engineering and serious contamination of the joints. In the relevant technical regulations for stone construction in our country, it is clearly stipulated that resin materials should be used as the filling material for stone. This not only allows the stone to present an overall effect through color matching, but also offsets the expansion and contraction of the stone, achieving waterproofing, pollution prevention and other purposes, greatly improving the level of stone application technology.
Stone is a porous, hygroscopic, unstable, and heterogeneous material that exhibits different characteristics depending on its variety, origin, layering, orientation, and the use of different materials due to its craftsmanship and purpose. Therefore, the auxiliary materials used on it should be different. However, many companies use unsaturated resin adhesive during dry hanging installation, and some increase the amount of curing agent for rapid solidification, leaving many safety hazards to the project; Some projects also used inappropriate sealants and structural adhesives, causing oil stains on the surface of the stone.
According to the development and application plan of China's stone industry, stone adhesive products have been studied and standardized as important auxiliary materials in the stone industry, and a corresponding standardized quality system has been established. The current standards for adhesive used in stone materials in China are as follows:
GB 24264— The 2009 "Adhesive for Decorative Stone" specifies various performance requirements for adhesives used in stone production and construction;
GB/T 23261— The 2009 "Building Sealants for Stone" specifies the performance requirements for sealants used in stone curtain walls;
JC 887— 2001 "Epoxy Adhesive for Dry Hanging Stone Curtain Walls" specifies the performance requirements for epoxy dry hanging adhesive for stone curtain walls;
JC/T 989— 2006 "Adhesive for non structural load-bearing stone"It specifies the performance requirements for unsaturated resin adhesive (marble adhesive) used for stone bonding and repair.
China issued and implemented JCG/T 60001 in 2007; The 2007 "Technical Regulations for Natural Stone Decoration Engineering" clarifies the technical specifications to be followed in the design, construction, installation, and acceptance of wet and dry hanging stone projects. It specifies materials such as stone, pendants, adhesives, sealants, protective agents, and cleaning agents, especially the performance of adhesives used in stone construction. The technical level is close to that of countries such as Europe and America. However, due to the lack of comprehensive standards for adhesive products for stone at that time, based on the absorption of foreign experience, the standard referenced JC/T 547— The content of the test method for the adhesive of ceramic wall and floor tiles in 2005.
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The development of building sealants, structural sealants, and bonding materials has been rapid both domestically and internationally, with relevant standards and regulations mainly applicable to building doors, windows, glass curtain walls, and ceramic bonding. Natural stone, with its unique characteristics and architectural requirements, is not suitable for all adhesives. In foreign countries, it is selected based on relevant standards and a large number of experiments on the basis of design. Based on technical discussions and exchanges with relevant foreign institutions, Europe and America have referred to the content of EN 12004:2001 "Ceramic Tile Adhesive" in the wet pasting of stone, and made local adjustments according to the characteristics of stone. The national industry standards for stone dry hanging epoxy adhesives and stone sealants that have been introduced in China are far from sufficient due to their limited scope of application, and cannot meet the actual needs and safety guarantees of various adhesives for stone. In order to standardize the technical requirements for specialized adhesives in the stone industry, guide the production, use, and application scope of such products, and ensure the safety and aesthetics of stone engineering, the standards for stone adhesives need to be further refined and improved, which will be beneficial for improving product quality. IDstone5A Stone Study Society
More and more decorative stone products are using adhesives and installed on high-rise buildings. The performance of adhesives directly affects the installation quality of stone products and endangers the safety performance of buildings. Therefore, the adhesive used in the stone industry has mandatory regulations on safety related aspects, such as bonding strength, compression shear strength, impact strength, acid and alkali resistance, UV aging resistance, high temperature resistance, earthquake resistance, freeze-thaw resistance, harmful substance content, compatibility with stone, pollution performance, etc. The scope of application includes adhesive for decorative stone bonding and repair, adhesive for stone reinforcement mesh, adhesive for installation and load-bearing, adhesive for composite stone, resin adhesive for artificial stone, etc.
The continuous development and technological progress of the stone industry have also put forward updated and higher requirements for adhesive products. How to solve the problems of durability and safety, make the surface of the stone more sturdy and wear-resistant, make the stone back mesh not only sturdy but also easy to construct, extend the service life of the stone curtain wall, and make the stone pasting construction more convenient and firm, etc. We need to work together to explore and improve various adhesives for decorative stone materials that are suitable for China's national conditions and industry development, in order to reach the international advanced technology levelTo better guide the development of China's stone industry.