Fly ash roofing insulation material

At present, roofing materials have made great progress in heat insulation and waterproof performance, such as modified Zhejiang waterproofing membrane, polymer waterproofing membrane, new waterproof coating and metal composite waterproofing material, cement polystyrene board inverted insulation and waterproofing. Materials, etc., these new materials have alleviated the problem of roof leakage and energy consumption in China. However, there are two disadvantages: first, the complementarity between the waterproof material and the heat insulating material is poor; second, the roofing cost is relatively expensive. To this end, this paper successfully developed a coal ash roofing insulation material (referred to as thermal insulation material) that integrates heat insulation and waterproof functions. The material is easy to produce and construct without pollution, and can make full use of industrial waste. low. According to the Research Institute of Science and Technology Information of Hebei Province, this kind of thermal insulation material has not been reported at home and abroad.

1 Main raw materials and performance cement: 32.5 ordinary Portland cement produced by Hebei Jinniu Energy Cement Plant, initial setting time is 110min, final setting time is 186min; fly ash: Xingtai Power Plant dry discharge fly ash, its chemistry The composition is shown in Table 1; quicklime: produced by Xingtai Lime Plant No. 2, containing more than 80% (mass fraction) of CaO, and 18% of 0.126mm sieve; insulation material: waste polystyrene foam plastic pellets (Jian Fund Project: National Nature The Science Foundation funded project (20477009) called plastic granules, which has a particle size of 48 mm and an apparent density of about 21 kg/m3. In order to make plastic granules and fly ash cement cementing materials have better wettability and cohesiveness. Before the test, the surface was treated with polyvinyl formal rubber; the fatty acid waterproofing agent: self-made, adding 60 kg KOH 3 kg in the reactor, heating the reactor to 30 ° C, adding 0.5 kg of citric acid. Set the pH value to 78 for 2h, which is the fatty acid salt waterproofing agent; silicone hydrophobic agent: homemade, add 100 parts of polysiloxane 8 parts of white carbon black in the beaker, stir, heat up to 110180 ° C and keep warm for 35h And then drop it to 30C into a silicone paste, and then Add 100 parts of alkylphenol ethoxylate to 100 parts of silicone paste, 1 part of Span-60 emulsifier, 1 part of Tween-60 emulsifier, stir to heat up, dissolve the emulsifier, then add 400 parts of water and stir for 30 minutes. Silicone water repellent agent, the water repellent agent has stable performance, and is not layered at room temperature for 6 months. After it is used to treat the surface of the material, the pores and micropores are not closed, and the moisture emission inside is not affected. Respirable waterproof coating; foaming agent: polymer modified rosin soap foaming agent, homemade; fly ash activator: commercial goods.

Table 1 Chemical composition of fly ash 2 Preparation of thermal insulation material: 2:2 of cementitious material is mixed in a blender, then treated plastic pellets (the volume is 1.5 times the volume of the gelling material) and water, stirred and mixed The school 偌 ​​胧 胧 胧 胧 呐 剂 剂 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 胧 胧 胧 胧 胧 胧 胧 胧 胧 胧 胧 胧 胧 胧 胧 胧 胧 胧 胧 胧The inner layer of the plate is made of heat-insulating waterproof material, and its apparent density is 588kg/m3, and the compressive strength of 28d is 1.6MPa thermal conductivity. 12w / (mK), impermeability: 0.2MPa water pressure can be maintained for 30min impervious.

3 Results and discussion 3.1 Influence of fly ash on the strength of thermal insulation material In the case of the same amount of quicklime, plastic granules, water repellent and activator D, the influence of the amount of fly ash on the strength of thermal insulation material was investigated. see.

It can be seen that with the increase of the amount of fly ash, the pressure and bending strength of the thermal insulation material appear troughs and peaks. When the fly ash content is less than 55%, the compressive and flexural strength of the material decreases with the increase of the fly ash content, which is due to the decrease of the cement content which is the main gelation, but When the fly ash content is 55% and 65%, the compressive and flexural strengths show peaks, indicating that the fly ash has gelling activity in addition to the fine aggregate filling effect in the material. According to the experimental results and the actual needs of the material applied to the roof, it can be concluded that the fly ash content is 60%.

3.2 The effect of the activator on the compressive strength of the thermal insulation material The activator can be summarized as alkali excitation and sulfate excitation. The former is influenced by the different activators of Table 2 on the compressive strength of the thermal insulation material, and the high alkali is beneficial to destroy the fly ash. The glass phase, the latter is due to the fact that the sulfate can form a product which contributes to the strength of the aluminate phase in the fly ash. In order to investigate the effect of different activators on the compressive strength of thermal insulation materials, the fixed fly ash content is 60%, ordinary Portland cement 20%, quicklime 20%, water-to-binder ratio (mass ratio) 0.4, incorporated plastic The volume of the particles is 1.5 times the volume of the cementitious material, and the amount of the water repellent is unchanged. The test is carried out with an alkaline activator, a sulfate activator and a composite early strong activator. The results are shown in Table 2. 1) Unless otherwise specified In addition, the dosages in this article are all mass fractions.

The content of CaO in fly ash is very low, and the degree of polymerization is high. The vitreous structure of the lime ash must be disintegrated under the action of strong alkali. The pH value of the lime saturated solution at room temperature is lower than 13.2. The pH of the slurry cannot be disintegrated into the vitreous structure. The required value. Therefore, it is necessary to add a proper amount of strong alkali to the fly ash-cement system to increase the OH-concentration in the slurry. There are 18 that Na2S4 can improve the early strength of fly ash cement, and the addition of sulfate activator to fly ash can promote the conversion of hydrated calcium aluminate to produce more stable and high strength ettringite. The composite early strength activator has the above functions, and also has the function of reducing water, can promote the hydration of cement, is beneficial to the activation environment of fly ash, and can also improve the workability of the slurry and obtain dense cement stone. Therefore, the effect of the composite early strength activator on the compressive strength of the heat insulating and waterproofing material is greater than that of the alkaline activator and the sulfate activator.

3.3 Effect of fatty acid salt waterproofing agent on water impermeability and strength of thermal insulation material In the fly ash cement mixture, fatty acid salt waterproofing agent is added to make it waterproof. The effect of fatty acid salt waterproofing agent on the impervious performance and strength of thermal insulation material is shown in Table 3. Comprehensive test results, the content of fatty acid salt waterproofing agent is 4%. Table 3 fatty acid salt waterproofing agent is impervious to thermal insulation material And the effect of strength Table3Effectofpercentageof month fatate waterproofing agent can react with the cement hydration product Ca2+ to form a hydrophobic precipitation material, which is arranged in the direction of the capillary wall to form a “anti-capillary pore effect”, making the material The waterproof performance is improved. However, since the fatty acid salt water repellent is a soluble surfactant, when the amount is small, the waterproof effect is not obtained, and when the amount is too large, the waterproof property and strength of the material are lowered.

3.4 Effect of silicone water repellent on the waterproof performance of thermal insulation material After the fatty acid salt waterproofing agent is added, the silicone water repellent is sprayed on the surface of the material to make the material exhibit excellent waterproof performance. This is because the silicone water repellent has a reactive group-organopolysiloxane whose main chain structure is similar to that of the silicate structure, and thus has a strong chemical affinity between them. In addition, a small amount of reactive groups on the organopolysiloxane macromolecule react with the hydroxyl groups in the silicate substrate during the film formation process, and the organopolysiloxane having the O-Si(R2)-structure as the main chain A uniform, tightly-bonded network of siloxane membranes is formed on the surface of the porous thermal insulation board and the inner wall of the capillary, and the organic groups are arranged on the surface of the membrane to reduce the surface tension, and the water can only be on the surface thereof. Spherical droplets exist. The reduction of the surface tension of the inner wall of the capillary hole makes it difficult for water to penetrate into the inside of the heat insulation board through the capillary hole, thereby making the heat insulation board water-repellent. At the same time, the silicone hydrophobic agent is mainly composed of Si-O bond structure, and the electronegativity of SiO is different, which is close to the ionic bond, and the dissociation energy of Si-O bond is as high as 443.5 k/mol, so that the heat preservation plate is heat-resistant. , anti-oxidation, radiation resistance. The test showed that the sample with only the fatty acid salt waterproofing agent had a saturated water absorption rate of 7.6% after being immersed for 20 days. After the sample was broken, the cross section was dried and the water intrusion depth was about 4 mm. The silicone water repellent was used. After the surface was sprayed for 20 days, the saturated water absorption rate was 2.4%. After the sample was broken, the cross section was dried, and the water intrusion depth was only about 1 mm. It can be seen that the external coating of the silicone water repellent can significantly improve the waterproof performance of the thermal insulation material. After testing, the material was kept impervious to water for 30 min under 0.2 MPa water pressure.

3.5 Influence of plastic granules, fly ash and foaming agent on the thermal insulation properties of thermal insulation materials The plastic granules added to the slurry are solid materials with low thermal conductivity. The pores are mostly closed structures, and the pore diameters are mostly micron and sub-sized. Micron grade, therefore, the addition of plastic particles can improve the thermal insulation performance of the thermal insulation material; there are a large number of hollow glass microspheres and honeycombs in the fly ash, and the hollow glass microbeads are mostly in a semi-vacuum state at normal temperature, therefore, the powder Compared with other inorganic materials, coal ash also has a very low thermal conductivity, which is also beneficial to improve the thermal insulation performance of thermal insulation materials. After the addition of foaming agent, micro-closed vents are formed in the slurry which are not connected and uniformly dispersed. The thermal conductivity of the thermal insulation material is further reduced.

4 Conclusion Insulation waterproof material has the advantages of low density, high strength, good thermal insulation performance, large amount of fly ash, etc. It is an ideal roof insulation and waterproof material, which can meet the quality acceptance specification of roofing engineering (GB 50207 ―2002) standard; calculated according to the thickness of 6cm thick insulation waterproof material, the comprehensive cost is 24 yuan (RMB) / m2; the material can consume a large amount of fly ash and waste plastic granules in production, which is beneficial to waste recycling. It also protects the environment and has significant social benefits.

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