In recent years, with the continuous expansion of the scale of urban construction in our country, the roof forms of residential buildings have also undergone tremendous changes. Various forms of roofs with various shapes and colors have emerged, especially in many coastal cities. The "flat to slope" project has added new highlights to the living environment of local residents. Because the color asphalt tile has the dual functions of waterproofing and decoration, and its light weight, cold construction, pollution-free, simple and fast, low cost, it is more favored by people. Recently, the Ministry of Construction issued design standards for improving the envelope structure of residential buildings, advocating energy conservation and reducing emissions, which not only helps to improve the quality of life of residents, but also further promotes the development of colored asphalt tile roofs.
However, changes in architectural design and the use of new building components have placed increasing demands on roofing waterproofing materials. In September 2009, the Ministry of Public Security and the Ministry of Housing and Construction issued the "Temporary Provisions on Fire Protection of Exterior Thermal Insulation Systems for Civil Buildings and Exterior Wall Decorations", which requires that the burning performance of exterior insulation materials including facades should be Class A and should not be low. At level B2. For roofing waterproofing materials, the development trend is to improve the flame retardant performance, while having low carbon efficiency, green environmental protection and sustainability. Among various types of roof waterproofing materials, asphalt tiles not only have excellent waterproof performance, but also have good fire safety. Existing asphalt shingle technology is mainly focused on improving the conventional performance and design structure of asphalt shingles. Few issues have been considered in terms of formula optimization, such as energy saving, fire retardant, fire retardant, and engineering application.
For flame retardant asphalt shingles, the key to its production process is the preparation of flame retardant asphalt mixtures (that is, coatings. The flame retardant asphalt mixture is prepared by adding an appropriate amount of flame retardant to the asphalt and through a certain modification process. The flame retardant asphalt material is designed, and the asphalt mixture is designed to prepare an asphalt coating material which has flame retardant performance and meets the technical requirements for use performance. The flame retardant asphalt is modified by adding a flame retardant to the asphalt The result is that the flame retardant is usually mechanically mixed with the asphalt and does not react chemically with the asphalt. The addition will have a certain effect on the performance of the asphalt, and the greater the amount of the flame retardant, the greater the impact on the performance. .
Therefore, in the preparation of flame retardant asphalt, it is necessary to control the amount of addition, select a flame retardant that has a good flame retardant effect and has a small effect on asphalt performance, and perform flame retardant modification. Some flame retardants have a synergistic effect when they are flame retardant. That is, when two flame retardants are present at the same time and have a flame retardant effect, the flame retardant effect is greater than the sum of the flame retardant effects of the two flame retardants. Therefore, you can find several flame retardants with flame retardant synergistic effect to modify the flame retardant effect to improve the flame retardant effect. At the same time, under the same flame retardant effect condition, when using a composite flame retardant with flame retardant synergy effect, It can reduce the amount of flame retardants added, thereby improving the application performance of asphalt. When a fire source or fire occurs, the flame retardant asphalt tile starts to play its role, the temperature of the flame retardant asphalt tile rises, and the flame retardant asphalt and the flame retardant are also heated at the same time, the asphalt starts to decompose, and the flame retardant begins to exert flame Effect, so that the asphalt tile achieves the flame retardant effect, reducing the loss of fire.
This project is based on the actual needs of modern construction. By optimizing asphalt base materials, modifiers, fillers, flame retardants, coating materials and production processes, the foundation of the application performance without affecting the reliability and durability of asphalt tiles In addition, it meets the flame-retardant requirements of asphalt-based materials, thereby ensuring the fire safety of asphalt shingles during use, and preparing colored flame-retardant asphalt shingles for building waterproofing with excellent performance.
First, the experimental part
1.1 Raw materials and equipment
Asphalt: 10 # petroleum asphalt, 70 # road asphalt; carcass material: glass fiber felt, polyester felt; asphalt modifier: styrene-butadiene-styrene block copolymer (CSBS), waste rubber powder; Filler: talc; flame retardant: composite flame retardant; auxiliary: organosilane coupling agent. Low-temperature refrigerators, temperature-regulating electric furnaces, ovens, high-speed dispersers, electronic tensile machines, artificial weathering test chambers, and cone calorimeters.
1.2 Preparation process
Preparation process of flame retardant asphalt tile: unwinding and splicing of tire base, storage and drying, preparation of coating material (fire retardant asphalt mixture), impregnation of asphalt, spreading (gravel, etc.), coating, rolling cooling, gluing, cutting, Distribution, self-packing, inspection, storage. The technical formula of the flame retardant asphalt mixture is shown in Table 1.
Results and discussion
2.1 Impact of carcass materials on asphalt tile performance
On pitched roofs, asphalt tiles not only have a waterproof effect, but also give the roof a durable and beautiful geometric structure and color. The application performance of asphalt shingles, especially strength, water resistance, crack resistance and durability mainly depends on the properties of the carcass material. There are two types of carcass materials commonly used at present, such as polyacetate mat and glass fiber mat. Among them, glass fiber mat has excellent water resistance, corrosion resistance and durability, high tensile strength, good cutting performance, and dip coating high temperature molten asphalt. Exhibits better dimensional stability than polyester felt.
Experiments on the effects of two carcass materials on the performance of asphalt shingles were made. According to experimental observations, it is ideal to use glass fiber felt as the carcass material for asphalt shingles. In addition, pretreatment of glass fiber mats with a silane coupling agent can significantly improve the blending properties of glass fiber mats and asphalt, and improve its application performance.
2.2 Influence of asphalt raw materials on the performance of flame retardant asphalt mixture
Asphalt is the main component of the coating material. Its performance determines the elongation, bond strength and filler absorption of asphalt tiles. Commonly used asphalts include 10 # petroleum asphalt and 70 # road asphalt, etc. Although 10 # asphalt has a softening point It has high advantages, but because of its high wax content and high low-temperature brittleness, it cannot meet the performance requirements of asphalt tiles alone. It can be used in combination with 70 # asphalt. . Combining various indicators with the high and low temperature performance of the material, 10 "asphalt and 70 # asphalt are mixed at a ratio of 7: 3 (mass ratio), and asphalt coating materials that meet the requirements of the standard can be obtained.
2.3 Effect of asphalt modifiers on the performance of flame retardant asphalt mixtures
Asphalt modifier refers to the meltable or dispersible substance added to the asphalt or asphalt mixture, which can significantly improve and improve the performance of asphalt products. According to the chemical properties of the modifier, it can be divided into organic modifiers and inorganic Modifier. Organic modifiers often improve the physical and mechanical properties of asphalt tiles through chemical bonding or cross-linking. For example, resin modifiers can improve the high-temperature stability of asphalt. Rubber modifiers can significantly improve the low-temperature crack resistance of asphalt. Elastomer modifier has good
Good two-way modification function, and improve the high temperature stability and low temperature crack resistance of the asphalt at the same time. Among the thermoplastic elastomer material modifiers, SBS is the most commonly used modifier. SBS has excellent characteristics such as high strength and low rutness. It has the elasticity of rubber at room temperature and shows plasticity after heating. Therefore, it is very easy to perform thermoplastic processing and can be mixed with asphalt. The effect of different SBS content on the performance of flame retardant asphalt mixture is shown in Figure 1.
It can be seen from Figure 1 that the asphalt mixture modified by SBS has excellent resistance to high and low temperatures. With the addition of SBS, the softening point and low temperature flexibility of the mixture have improved. In order to reduce costs, a mixture of SBS and waste rubber powder is generally used as a modifier in production, and its ratio is controlled at about 2: 8 (mass ratio).
2.4 Effect of fillers on properties of flame retardant asphalt mixture
In the production process, inorganic modifiers mainly play a physical or mechanical support role, and are commonly called fillers. The most commonly used is talc. According to the above test results, the modified asphalt is used as the rubber compound, and different contents of talc are added as fillers to test the performance of the asphalt coating material. The results are shown in FIG. 2.
It can be seen from Figure 2 that when the talc powder content is less than 20%, there is no significant effect on the performance of asphalt shingles; when the 20% content is ≤50%, the softening point of the coating material is obvious with the increase of the filler. Increase; when the filling amount is ≥50%, the softening point level is basically unchanged, and the low temperature resistance is significantly deteriorated. Comprehensive consideration, the amount of talc powder filler should be controlled within 30% -50%, and considering the cost factor, the optimal ratio is 40%.
2.5 Effects of solvents and additives on the properties of flame retardant asphalt mixtures
In order to improve the processing and application performance of flame retardant asphalt mixtures and asphalt shingles, a certain amount of solvents and additives are often added to the mixture. The role of the solvent is mainly to dissolve the modifier and improve its dispersion and modification effect. Auxiliaries include silane coupling agents, thickeners, and anti-ultraviolet agents. Among them, silane coupling agents can improve the adhesion between asphalt and glass cloth, make the asphalt and inorganic fillers more firmly, and can significantly improve the material. Performance; Thickener can increase the surface roughness of asphalt, improve the firmness of covering materials and reduce the falling sand; Anti-ultraviolet agent can improve the aging resistance of products. In order to improve the performance of the mixture, a mixture of the above-mentioned various additives is used in this experiment, and the amount is controlled between 1% and 2%.
2.6 Effect of Flame Retardant on the Performance of Flame Retardant Asphalt Mixture
Flame retardant performance is the most important criterion for evaluating the performance of flame retardant materials. It is generally evaluated by the oxidation index (LOL). LOL> 26% means that the material cannot be burned in ordinary air, which can be considered as flame retardant. Flame retardant materials are generally not flammable by themselves or made non-flammable by adding flame retardants. Some flame retardant or non-combustible materials can be added to flammable materials to reduce the flammability of such materials. Such materials are flame retardants. However, the addition of flame retardants not only increases the cost of the material, but also reduces some of the physical properties of the asphalt. Its flame retardancy is obtained at the expense of other practical properties of the material, and sometimes even causes environmental protection during material recycling. problem. Therefore, the flame retardant performance should be determined according to various specific conditions, and the economic performance and environmental protection performance of the material should be improved as much as possible on the premise of satisfying the flame retardant performance of the material. To this end, the flame retardant performance of the flame retardant asphalt mixture is designed and optimized.
In this experiment, a compound flame retardant with a mass fraction of 25% was added, and compared with the asphalt mixture without flame retardant, the total heat release of the mixture was tested, as shown in Figure 3.
It can be seen from the figure that the addition of a flame retardant can reduce the total heat release of the asphalt mixture and reflect a certain flame retardant effect. After testing, the flame retardant asphalt tile produced by the above formula has a LOL index of 28.7 %, Has good flame retardancy and fire resistance.
Performance of flame retardant asphalt tile
The asphalt tile formula was optimized through experiments. After testing, the flame retardant asphalt tile products prepared in accordance with the appropriate proportions met the B1 fire rating. The performance test was performed on the products according to the GB / T 20474-2006 "Fiberglass Asphalt Tile" standards. Results See Table 3.
Fourth, the conclusion
1) Formula adjustment can effectively reduce the production temperature of flame retardant asphalt shingles, and does not require the use of high-shear colloid mills for processing. The process is energy-saving and less expensive, which greatly saves equipment costs for grinding and pollution control .
2) Use glass fiber felt as the carcass material, 10 # asphalt: 70 # asphalt according to 7: 3 (mass ratio) as the main material, and add 25% by mass for flame retardants, modifiers, fillers and additives. The performance of the prepared asphalt tile meets the requirements specified in GB / T 20474-2006.
3) The total heat release is an important parameter for evaluating the thermal hazard of the material in actual use. The greater the total heat release of the material, the greater the potential thermal danger. The experiment proves that the addition of flame retardant significantly reduces the heat release rate and amount of asphalt mixture and asphalt mortar. The flame retardant has a significant effect on the ignition time of the sample. After adding 25% mass fraction of flame retardant, The ignition time of the sample is obviously longer and it is difficult to ignite.
4) Asphalt roof tiles are moderately priced, easy to construct, have good overall waterproof performance, diverse colors, and different shapes. Even more prominent is that the asphalt tile is lightweight, which can reduce the construction foundation cost, and is more suitable for buildings with large roof slopes, curved and spherical roofs and other complex curved surfaces. The use of flame-retardant asphalt tiles on the building roof can ensure the fire safety of the roof.