Insulation materials put on “fireproof jacket”

Since autumn, building fires have occurred frequently across the country, and external wall insulation materials have been pushed to the forefront. Many people believe that unqualified insulation materials are the root cause of fire accidents. In this regard, Sun Yan, a professor at Anhui Engineering University, believes that it is not appropriate to attribute all the responsibility for the fire to the insulation material, and the fire resistance of the building system structure cannot be ignored.

It is undeniable that the national building energy-saving strategy has brought endless development space for building products. Statistics show that the annual market demand for building insulation materials reaches 250 billion yuan, forming a huge market. All kinds of thermal insulation materials can be described as a hundred schools of thought contend, but there are really few products with excellent thermal insulation and flame retardant and fireproof functions.

Five performance evaluation quality is good or bad

Insulation material is a component material of building insulation system, therefore, the performance and adaptability of all components must be considered from the system point of view in the study of wall insulation and fire protection technical solutions.

Sun Yan pointed out that to judge the adaptability of a thermal insulation material to a housing construction project, the following five aspects are mainly considered from a technical point of view.

The first is thermal insulation performance. The lower the thermal conductivity of the material, the thinner the required design thickness. For thermal insulation products with a thermal conductivity greater than 0.045W (m2K), it is basically impossible to use them in buildings with high energy-saving requirements. The second is dimensional stability. The thermal insulation material should have good dimensional stability. If it is used in engineering, the board is prone to warping and deformation, which will easily lead to cracking and water seepage on the outer surface. The third is the water absorption performance. The thermal insulation performance of the thermal insulation material will decrease sharply in the state of water absorption, so the thermal insulation material used in the project should have a low water absorption rate. Nowadays, many rock wool boards, phenolic boards, and thermal insulation mortar materials are highly water-absorbent materials, and the actual thermal insulation performance is far from the theoretical effect. The fourth is quality reliability. Common insulation boards have fixed dimensions, and the insulation performance is also very stable, with reliable guarantees. The fifth is the convenience of construction. At present, many new materials do not have the corresponding convenience of construction. For example, boards such as vacuum insulation panels are difficult to cut on site, and their adaptability to the base wall is very low.

Two-way standards lead to material selection problems

However, for the use of building exterior wall insulation materials, my country has two relevant regulations: First, in 2009, the Ministry of Public Security and the Ministry of Housing and Urban-Rural Development jointly issued the "Interim Regulations on Fire Protection of Civil Building External Insulation Systems and Exterior Wall Decoration" The other is the "Notice on Further Clarifying Relevant Requirements for Fire Supervision and Management of Civil Building External Wall Thermal Insulation Materials" issued by the Fire Department of the Ministry of Public Security in 2011. According to the document, the former requires that building exterior wall insulation materials "should not be lower than B2 level (organic materials)", while the latter stipulates that only "non-combustible materials can be selected". Classification according to the combustion performance of building materials, B2 grade materials are "combustible", B1 grades are "difficult to burn", and A grade (inorganic materials) are "non-combustible". Obviously, the two documents set different standards for external wall insulation materials.

The two documents have different regulations on the use of thermal insulation materials for building exterior walls in my country, which have troubled many developers and designers since their introduction.

Shi Yong, Chief Engineer of Beijing Energy Conservation Product Technology Service Center, said that my country has not made much technological progress in Class A fireproof materials for a long time, and the level of industrial development is not high. If the use of A-grade materials is mandatory, it will be difficult for the market supply to meet the quality and quantity requirements, and if A-grade materials are not used, it violates the national policy. "In fact, the two documents are not completely opposed to the use of building exterior wall insulation materials, but the reality of the unbalanced development of A-grade materials in my country's building materials market has directly exacerbated the conflict between the two documents." Shi Yong said.

At the same time, the relevant person in charge of the engineering department of a construction team in Hebei said that the general project is to cooperate with the contractor in the form of contracting labor and materials. The investor does not strictly require the nature of the insulation material itself, but usually specifies Brands and price ranges of insulation materials. Regardless of material performance, let alone fire performance. "If Class A fireproof materials are used, the cost of the exterior wall will increase by 180-200 yuan/square meter, who will voluntarily spend more money." The person in charge said.

Two aspects promote industrial development

According to Zhang Liyu, a consultant of the Beijing Institute of Architectural Engineering, when the policy on thermal insulation materials for building exterior walls was initially formulated, thermal insulation was first required. However, in the future, buildings will become taller and more difficult to extinguish fires. Building insulation and fire protection systems should go hand in hand. Complying with policy changes and developing technical systems with better fire performance are the future direction. In other words, the fire performance requirements of the thermal insulation material and the fire resistance of the system structure are important conditions for determining the fire safety performance of the external thermal insulation system, and both are indispensable.

From the perspective of adaptation policies, Zhang Liyu said that although building exterior wall insulation materials cannot comply with Class A regulations at this stage, they can be gradually improved. For example, the latest No. 046 document issued by the Ministry of Housing and Urban-Rural Development requires that public buildings higher than 50 meters need to use grade A insulation materials, and B1B2 grade insulation materials can be used below 50 meters, and fire isolation belts should be installed according to the situation. At the same time, the relationship between fire protection and heat preservation should be analyzed in detail. For example: the sunlight in the south is relatively sufficient, and a layer of paint can warm the room in winter.Polyurethane foam insulation board is a derived product. Due to poor dimensional stability, it is not much different from expanded polystyrene board. According to the composite polyurethane A-grade board with double-sided mortar coating and the test report provided by some manufacturers, the rigid foamed polyurethane board can barely pass the test for a period of time and can be used as a fireproof and thermal insulation material. will not be recognized.

Extruded polystyrene board

Best choice for interior insulation

The plate is made of polystyrene resin or its copolymer, adding a small amount of additives, and is a rigid foamed plastic product with a closed-cell structure obtained by heating and extruding.

Extruded polystyrene board is also a material that integrates waterproof and heat preservation functions. It has high rigidity, good compressive performance, and low thermal conductivity. It is very suitable for indoor insulation in roofs, floors, and basement walls. . However, this kind of board has poor vapor permeability and poor dimensional stability. Compared with inorganic adhesive mortar, the bondability is also poor. It is used for quality accidents such as system falling off and facing cracking in external wall insulation. Due to its low cost It is not cheap, and this material is not as advantageous as expanded polystyrene boards in the field of external insulation applications. Not recommended for use in external wall insulation systems.

Phenolic insulation board

Japanese architecture prefers phenolic panels

Phenolic board is a porous phenolic foam board made by mixing the condensation polymer of phenol and formaldehyde with other additives such as curing agent, foaming agent, surfactant and filler.

Phenolic boards produced abroad have good thermal insulation properties, and their thermal conductivity is lower than that of extruded polystyrene boards. Phenolic boards are widely used in sandwich insulation systems in Japan. However, the current domestic promotion efforts are small, and the production technology is relatively backward, and its thermal insulation performance is slightly worse than that of foreign products. In addition, domestically produced phenolic boards have weaknesses such as easy pulverization, low mechanical strength, brittleness, no extensibility, and high water absorption. When used in thin plastering systems for external wall insulation, there will be serious cracking and falling off of the finish. ACCIDENT.

Ash Real Gold Plate

The most successful case of modified EPS

The real gold plate is processed by phase change wrapping heat insulation energy storage technology, and has a continuous honeycomb structure for heat insulation and insulation. After modification, the fire resistance performance reaches A2 level.

Asia Cult's real gold board is the most successful modified EPS product that can be seen in China at present. The real gold board is processed by phase change wrapping heat insulation and energy storage technology, so the board itself will not burn. In fact, it is difficult for the real gold board of Asia Cuanon to achieve the real A-level fire protection. Even if the A-level performance is achieved, the price is very high. The theoretical performance of the thermal insulation board is very close to that of the graphite polystyrene board, but since no actual engineering case has been investigated, and the application history of the board is not long, its application value in terms of construction performance cannot be obtained yet.

A new material is released

Nanoporous silicon insulation material

Nanoporous silicon thermal insulation material is a new application of nanotechnology in the field of thermal insulation materials. Most of the pores inside the material are nanoscale. According to the molecular motion and collision theory, the heat transfer of gas is mainly through the high-speed molecules on the high-temperature side colliding with the low-speed molecules on the low-temperature side to transfer energy. Due to the main components in the air, the degree of freedom of nitrogen and oxygen is around 70nm. When the micropore size of the silicon dioxide particles in the nanoporous silicon insulation material is smaller than this critical size, convection is eliminated inside the material. It essentially cuts off the heat conduction of gas molecules, so that a lower thermal conductivity than that of non-convective air can be obtained. When applied, the nanoporous silicon thermal insulation material is convenient for construction and cheap, and is a new type of thermal insulation material.

Premium rock wool spray insulation coating

American super premium rockwool spray thermal insulation coating has excellent thermal insulation performance, Class A non-combustible fireproof performance, excellent sound absorption and noise reduction performance, advanced spraying construction technology and green, healthy and environmentally friendly products. The construction technology of super-fine rock wool spraying insulation layer can well solve the problem of displacement, hollowing, falling off, poor fireproof performance and the hollowing, falling off and other problems of the inorganic mortar insulation layer in the current domestic common construction method of bonding insulation boards. Disadvantages of poor thermal insulation performance. The premium rock wool raw material is collected from natural rocks without chemical additives. It is certified by UL of the United States as a Class A non-combustible building fireproof material. Its melting point exceeds 1000°C, and it has excellent high temperature resistance. It does not produce toxic smoke or molten droplets in a fire. , applied to the building structure, not only can protect the building structure, but also win time for people to escape.