In order to meet the requirements of expanded polystyrene board thin plaster external wall insulation technology, this paper tests the bond strength of the adhesive and the surface glue of different polymers and the impact strength and water absorption of the system. TRC-15 insulation mortar emulsion that meets industry standards.
Application of 1TRC-15 Emulsion in Polymerized Mortar 1.1 Composition of Polymer Paste The polymer mortar used in the external thermal insulation system is based on cement as the main raw material, and the filler material such as quartz sand ash powder is added, and the polymer is used. Powder or emulsion) and various short fibers are used as bonding-enhancing materials.
1.2 Polymer mortar The interaction bond strength of various materials is the main performance index of polymer mortar. Improving the strength of cement mortar is an important means to solve the anti-cracking effect of polymer mortar. The hydration and hardening of cement is a gradual process. The longer the hydration time, the more sturdy the cement mortar is. The summer is often due to the ambient temperature. The evaporation of water will shorten the hydration time of the cement, which will easily lead to the cement shrinking too fast. Cracks, while the addition of polymer mortar can avoid and reduce the occurrence of cracking.
Operational time is an important indicator of polymer to cement compatibility. Cement hydration produces a strong alkaline environment with a pH of 12 to 14 and is a destructive to the stability of the polymerization. Two-component polymer mortar is formulated at the construction site, which requires full consideration of its chemical stability and mechanical stability when selecting polymers.
TRC-15 is an acrylic elastomer emulsion synthesized by a core-shell polymerization process. Its shell layer has a hydrophilic density of bismuth carbonate. It can be used to improve the strength of cement. The crack resistance of polymer cement mortar is twofold. One is that the elastic emulsion itself has a certain anti-cracking effect, and the other is to promote the early strength of the cement to prevent shrinkage cracking and improve the impact strength of the system. The reaction mechanism is: cement hydration produces 011) 2 and carboxyl groups in the propylene emulsion to form a macromolecular network interwoven structure with ionic bonding to make hydration more complete. The more the network interlaced density is, the stronger its ionic bonding ability is, which significantly improves the strength, water resistance and crack resistance of the material. However, the proportion added in the polymer mortar should be controlled. Whether it is dry powder or water-based latex, its sealing property is derived from the film-forming process. If the amount is too high, the cement mortar will lose its respiratory function. Since the thickness of the plaster is usually only 23 1111, (the amount of polymer can be increased as appropriate.
2 Comparison of different varieties and different dosages of polymer 2.1 The raw material used 42.5R ordinary Portland cement, 40~70 mesh quartz sand and cellulose ether with viscosity of 75000mPaS, which is used for thin plastering external insulation system. Three polymers. The apparent density of polystyrene board used in the test is 20kg/m3, and other properties are in line with the industry standard. G 2.2 Basic formula. Two series of tests were carried out in this paper. The cement and cellulose ether content in the basic formula used in the test remained unchanged. Change the variety and dosage of the polymer, and adjust the amount of sand accordingly. The specific scheme is as follows: compare the effects of different varieties of polymer on mortar and system performance. The basic formula is: water 200, hydroxypropyl methylcellulose 1, cement 384, quartz sand 384, polymer 31. Compare the effect of different dosage of TRC-15 emulsion on mortar and system performance. The basic formula is: water 200, hydroxypropyl methylcellulose 1, cement 384, quartz sand 384~415, TRC-15 emulsion 0~40. 2.3 Test method Accurately weigh the raw materials according to the established formula, stir well evenly, press G The method specified in 149-2003 carries out the relevant specimen forming, curing and testing.
3 Test results and discussion 3.1 The effect of different varieties of polymer on the performance of mortar and system is tested by basic formula 1. The main properties tested include: impact strength (reflecting the crack resistance of the system); mortar and polystyrene board The original bond strength and water-resistant bond strength (reflecting the system's bond safety); water absorption (reflecting the weather resistance of the system), the test results are shown in Table 1.
It can be seen from the results in Table 1 that the effects of blending different types of polymers on the bond strength of the mortar and the performance of the system using the mortar are different. The mortar and polystyrene board to which the TRC-15 emulsion is added have good dry bond strength and water bond strength, and the system made of the mortar has a relatively high impact strength. Since TRC-15 contains hydrophobic functional groups, the water absorption of the system can also meet industry standards. The water-resistant bond strength of the mortar using the rubber powder does not meet the requirements, and the water absorption of the system also does not meet the requirements.
3.2 The effect of different amount of TRC-15 rolling liquid on mortar adhesion and system impact resistance was tested by basic formula 2. The main performance of the test included the bonding of mortar and polystyrene board with different amounts of TRC-15 emulsion. The strength and the impact strength of the system made with this mortar are shown in Table 2. Table 1 Different types of polymers for the bond strength and system water absorption and impact strength of the 14-day standard system water absorption (g / m2) 28 days standard impact strength / 28 days standard table 2TRC-15 emulsion different ft to mortar bond strength and system impact resistance performance of the color test item curing conditions and polystyrene board 14 days standard EPS board 0% damage EPS board 70% damage EPS board 100% damage bonding Strength 7 days standard + 7 days immersion EPS board 0% damage EPS board 5% damage EPS board 15% damage EPS board 20% damage impact strength / 28 days standard and polystyrene board bonding strength 7 days standard + 7 days immersion EPS board 20% damage EPS board 10% damage From the test results of Table 2, it is known that with the increase of polymer content, the impact strength of the external insulation system increases significantly, indicating the flexibility of the mortar with the amount of polymer The increase is obtained, and the bond strength between the mortar and the polystyrene board is also improved with the increase of the polymer content. However, when the amount is more than 3.1%, the dry bond strength and the water-resistant bond strength hardly increase. When the dosage of TRC-15 emulsion is more than 3.1%, the bonding strength of mortar and polystyrene board and the impact strength and water absorption of the system can meet the requirements of industry standards.
Combining Tables 1 and 2, it is found that the different varieties and dosages of the polymers have a crucial influence on the impact strength of the thin plaster external insulation system. The concept of the impact strength of the external thermal insulation system is: the maximum potential energy of the steel ball that can be withstood when the steel ball of a certain quality falls freely from a certain degree of twist to the surface of the external thermal insulation system without cracking on the surface of the system. Obviously, the impact strength is also a reflection of the system's crack resistance. We know that the biggest technical problem of the external insulation system is to prevent cracking. In order to effectively prevent cracking, it is also necessary to select a qualified mesh cloth, control the thickness of the reinforcing protective layer, control the depth of the mesh cloth in the reinforcing layer, etc., because these factors will have a significant impact on the impact strength of the system. It can be said that the higher the impact strength of the system, the better the crack resistance of the system. For the mortar used in the external thermal insulation system, it is an important technical means to give the coating system a greater degree of impact strength.
4 Conclusion There is a big difference between the performance of adding different kinds of polymer mortar and the thin plaster external insulation system made of the mortar, and the comprehensive performance of TRC-15 is more prominent.
Adding the right amount of TRC-15 emulsion can give the system excellent impact strength and bond strength with polystyrene board.
The amount of TRC-15 emulsion has a critical impact on the performance of the external insulation system. The addition of TRC-15 emulsion in the bonding mortar and plastering mortar of the external insulation system can obtain excellent bond strength and impact strength and system water absorption. .
(Finish)
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