A styrene-acrylic emulsion (represented by A) sold on the market; sprayed polyurethane board, supplied by Shanghai Kyle, density 60 m3, with a layer of crust on the surface; polyurethane sheet, Yantai assimilation, density 4~50kg/m3, surface polymerization Cement interface layer.
2.2 Test method Test method for bonding strength of polyurethane and plastering mortar after interface treatment: Apply a layer of interface treatment material on the surface of sprayed polyurethane board, respectively, in the interface layer construction lOmin, after two hours and two d, press G149― The method of 2003 was used to form a bond strength test piece of a mortar and a polyurethane board, and then the original bond strength (7 days standard) and water-resistant bond strength (7 days standard + 7 days water immersion) of the plaster surface mortar were tested.
3 Test results and discussion 3.1 The use of dry powder interface mortar to improve the bond strength by 10%; cellulose ether, 0.2%; river sand, 44.5%; filler and other small additives, 10.3%. The test formula of the mortar is as follows: cement, 28%; FX2350, 3%; cellulose ether, 0.2%; river sand, 58.5%; filler and other small amounts of additives 10. The interface mortar is added with 22% water, and evenly spread and then scraped on the surface of the sprayed PU board. Due to the actual construction, the construction of the interface layer and the construction of the surface layer will have a certain time interval. Different manufacturers often give different requirements in the construction process. For example, some manufacturers emphasize that the interface layer is not dry when it is dry. The construction of the ash layer, while some require the construction of the plaster layer after 24 hours of construction of the interface layer. The use of interface mortar is known to improve the bond strength at the interface, but if the next layer of plastering is carried out after the interface layer is completely dried, a new bonding interface will appear between the interface layer and the plaster layer. The two layers are not well bonded, so the weak link of the bond will be between the plaster layer and the interface layer, so that the interface agent does not play its due role. In view of this, we tested the effect of the interface agent on the polyurethane surface for different time and then applied the mortar to the bonding strength of the polyurethane insulation layer. The test results are shown in Table U. Table 1 Interface mortar improves the bond strength. Layer and interface mortar layer time N interval spray PU untreated original bond strength (7 days standard) water-resistant bond strength (7 days standard + 7 days water immersion) AF-PU indicates that the damage occurred in the PU board and interface mortar The interface between the mortars (without treatment); indicating that the damage occurred inside the PU panel.
The results in Table 1 show that the bond strength between the sprayed PU board and the plastering mortar after the interface mortar treatment is greatly improved, and the construction time interval between the interface mortar and the plastering mortar has a great influence on the bond strength, and the interface mortar construction When the surface layer is applied, it is ensured that the two are wet-tightly combined in the fresh state to obtain the best bond strength. From the failure mode, as long as the test piece of the plastering mortar is applied immediately after the application of the interface mortar, the highest bond strength is achieved after 7d standardization, and the damage occurs in the polyurethane material, and the rest of the test pieces are destroyed. Occurs at the interface between the interface mortar and the polyurethane material. From the viewpoint of the bond strength after immersion in water, the water-resistant bond strength of the test piece was increased by nearly 2 times compared with other cases within 10 min. Although the damage interface of the water-resistant bond strength is between the interface mortar and the sprayed PU, the wet bond strength of 0.20 MPa is compared with the wet bond strength (>0.10 MPa) of the faced mortar and the polystyrene board in the guide. Already very high. It is only because the test PU sheet has a high tensile strength, so the damage interface does not occur inside the PU sheet.
3.2 Improvement of bond strength by using emulsion interface agent Most of the interface agents used in XPS board on the market are emulsion interface agents. The emulsion interface agent is directly roll coated on the surface of XPS board during the construction, and the emulsion is dried and formed into a film. In one process, this can increase the bond strength between the plaster and the XPS board. In order to explore the feasibility of the emulsion type interface agent for the interface treatment of PU insulation materials, we used a commercially available styrene-acrylic emulsion A as the emulsion interface agent, and tested its influence on the bond strength of the plaster. The test procedure is as follows: the PU board is sprayed with the emulsion, and after the emulsion is applied, the mortar is smeared in lOmiri, 2h and 2d, respectively, and then the original bond strength (7d standard) and water-resistant adhesion of the plaster are tested. Strength (7d standard + 7d water immersion), the formula of plastering mortar is basically the same as described in 3.1, but the dosage of rubber powder FX2350 is 3% and 6% respectively. The test results are shown in Table 2. Table 2 Different treatments of the surface of the sprayed PU board with the acrylic emulsion A interface agent. The treatment method of the coloring interface agent for the bonding strength of the plastering mortar with different rubber powders is not treated with the interface agent for 10 minutes, after the surface is rubbed for 2 hours, the surface is coated with 2d, and the surface is mixed with 3 % rubber powder, original bond strength (7d standard) AF-interface agent 2AF-PU and AF interface agent each about 50% with 3% rubber powder, water-resistant bond strength (7d standard + 7d immersion) with 6% glue Powder, original bond strength (7d standard) AF-interface agent with 6% rubber powder, water-resistant bond strength (7d standard + 7d water immersion) AF-PU indicates that the damage occurred in the PU plate and interface agent (no interface treatment) Between the mortars; the AF-interface agent indicates that the damage occurred between the plaster layer and the interface agent.
From the above results, it is not difficult to see that the effect of using emulsion A as an interface agent is not satisfactory, especially the bond strength after immersion in water has dropped significantly, which is not the same as when it is used for interface treatment of XPS board. From the test results of the bond strength between the matte mortar and the sprayed PU board after different time of applying the interface agent, the rule is different from the test result when the interface mortar is used for the interface treatment. The longer the interface agent is left to dry after painting, the higher the original bond strength. In addition, although the water-resistant bond strength is slightly improved, the amount of the rubber powder in the plaster is 3% or 6%, which does not meet the requirements of the guide specified in the O.10 MPa, and the failure interface is the interface layer. The interface of the PU board indicates that the water-resistant bond strength between the interface layer and the PU sheet is the weakest point of the system for water-resistant bonding.
Comparing the test results of Table 1 and Table 2, it can be found that the one-component polymer modified cement-based interface mortar has better effect on the bond strength of the sprayed PU sheet, and the water-resistant bond strength also reaches the guideline. The specified amount is greater than. lOMPa requirements. If the surface layer is applied immediately after the construction of the one-component interface mortar, the water-resistant bonding strength of the mortar and PU board is nearly doubled compared with other treatment methods, up to 0.20 MPa. In addition, the polyurethane interface agent is In addition to improving the bonding strength with the plaster, it should also protect the polyurethane surface from yellowing and chalking under the illumination of sunlight 342.
3.3 PU board insulation system and EPS board insulation system impact strength comparison test The PU board used in the paste method specified in the guidelines refers to the board with the interface treatment layer on the surface. In the test, we used the PU board produced by Yantai Assimilation. Both the upper and lower surfaces were treated with polymer cement slurry. The PU plate has a higher compressive strength than the EPS plate, but the flexibility is lower, which may cause the impact resistance of the insulation system using the two different plates to be different. To this end, we tested the impact strength of the same insulation surface sanding and the combination of the two types of panels and the two insulation panels. The thickness of the test piece was 3mm and 5mm respectively. Position control The mesh of the mesh cloth is visible on the surface of the test piece, but the color of the mesh cloth is not visible. There are two kinds of maintenance systems for specimens: (1) standard 28d, the system is the same as G149-2003; (2) standard 14d + water 7d + standard 7d, the system and C/T 993-2006 The anti-shock curing conditions specified in the expanded polystyrene board plaster for wall insulation are the same. The test formula of plastering mortar is: cement, 28%; heavy calcium, 10%; FX2350, 3%, cellulose ether, 0.2%; air entraining agent, 0.03%; old standard sand and other small additives, 58.77%. The performance of the system is shown in Table 3. The impact strength of the system is shown in Table 4.
Table 3 Performance of the matte mortar performance test results of the compression ratio (28d standard) and the original bond strength of the PU board, MPa (7d standard). 15, destroying the water-resistant bond strength between the PU and the PU board, MPa (7d standard + 7d immersion) 0.15, destroying the impact strength of the two systems in the PU internal table 4 system impact strength / EPS board system PU board system Moisture mortar thickness 3mm (28d standard) plastering mortar thickness 5mm (28d standard) plastering mortar thickness 3mm (14d standard +7d water +7d standard) plaster mortar thickness 5mm (14d standard +7d water +7d standard The results of the impact test show that the specimens cured according to the maintenance system of G149-2003 have high impact strength, and the single-layer mesh can achieve 10 impacts without cracks. The EPS system and the PU system are almost indistinguishable. However, the impact strength of the specimens cured according to the C/T993-2006 curing system was significantly reduced, and the drop in the impact strength of the PU system was more pronounced.
The impact strength of the specimen after 7d immersion and drying treatment is much lower than that of the 28d standard curing. After 7d immersion maintenance, the secondary hydration of the unhydrated cement in the surface layer causes the strength of the plaster. Significantly increased, the flexibility is reduced, resulting in a decrease in impact resistance. This kind of anti-shock test maintenance system is consistent with the provisions of ETAG004. Compared with the 28d standard, it can reflect the impact resistance of the system after long-term use, so it is more practical.
The reason why the EPS board system exhibits higher impact strength than the PU board system after immersion maintenance may be that the EPS board is softer than the PU board, so the EPS board system is more likely to buffer the external impact. Therefore, we believe that the flexibility of the plaster for the PU sheet thin plastering insulation system should be more flexible than that of the conventional EPS thin plastering system to ensure the impact resistance and crack resistance of the system after long-term use. .
Compared with the emulsion type interface agent, the one-component polymer modified cement-based interface agent (interfacial mortar) is more suitable for the interface treatment material of the sprayed polyurethane insulation layer.
The one-component polymer modified cement-based interface agent, that is, the dry powder interface mortar, can significantly improve the bonding strength between the plastering mortar and the sprayed PU board. If the mortar layer is applied immediately after applying the interface mortar, a higher original strength can be obtained. And water resistant bond strength.
When the same plastering mortar is used, the impact strength of the PU board thin plastering insulation system after water immersion treatment is more reduced than that of the EPS thin plastering insulation system, and the plastering mortar used for this system should have better flexibility.
(Finish)
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