| Recently, external wall insulation has formed exterior wall external insulation and exterior wall internal insulation. However, with the developing of building energy efficiency, the exterior wall internal insulation can’t catch up the requirements of energy efficiency and has been eliminated. Exterior wall external insulation has some popular formations, and external thermal insulation composite systems based on expanded polystyrene has good energy saving results, has been currently widely used as an energy-efficient building external wall insulation system.The main supporting materials of external thermal insulation composite systems based on expanded polystyrene are base coat and adhesive agent. Usually, we pick medium sand to prepare base coat, but Chongqing has rich in ultra fine sand, which modulus is less than 1.0, and more than 95% of project in Chongqing use this kind of ultra fine sand. The disadvantages of ultra-fine-sand limit it’s promoting are easy to shrink, easy to crack, lower bonding strength. So, until now so many researchers have studied how to improve the property of mortar made by ultra-fine-sand, and made a significant contribution to it. But there are still many problems remained to work out.In this paper, through studying the effect on performance of mortar with different material content, we ensure the best content of every material, and then prepare the base coat and adhesive mortar and external thermal insulation composite systems based on expanded polystyrene, and applied to engineering.In this paper, the redispersible powder and fiber were added into the mortar to improve the flexibility of mortar, join fiber and mineral admixture to improve resisting cracking of mortar, join cellulose ether to improve the adhesive property and workability of mortar. And we choose the ratio of compressive strength to flexural strength, fracture energy, impact energy to represent the flexibility of mortar. We choose air shrink and fracture index to represent the anti-crack property.The results indicate:The grading strength of cement and cement-sand ratio have a significant impact on flexibility and shrinkage of mortar, and we find that the comprehensive performances of P.O 32.5, cement-sand ratio as 1:2.6 are optimal.We choose four kinds of redispersible polymer which are widely used in ultra-fine-sand to compare their effect on work-ability, flexibility, shrinkage and adhesive property of mortar, and ensure the kind of redispersible polymer. Then ensure the optimum amount, base on the effect on performance of mortar with different redispersible polymer amount. The results indicate wacker 5044 N is superior to other redispersible polymers.Polypropylene fiber and cellulose fiber positively impact the crack resistance of mortar, we find that the comprehensive performances of mortar mixed polypropylene fiber whose length is 9mm, content is 0.10%, or mixed cellulose fiber whose content is 0.3% are optimal.HPMC is quite helpful to improve the adhesive property and water-retention rate, we find that the comprehensive performances of mortar mixed HPMC whose viscosity is 40000 MPa·s, content is 0.15% are optimal.Ash-calcium-powder takes part of cement of mortar can decreases the shrinkage, improve the adhesive property of mortar, and the replacement rate of cement should maintain 10%-15%.Expanding agent can compensate the shrinkage of mortar, but the content of it can’t exceed 6%.Through studying the effect of every material on performance of mortar, we ensure the optimum proportion, and prepare the coat base and adhesive mortar which have more excellent performance than normal ultra-fine-sand mortar. Finally, we prepare the external thermal insulation composite systems based on expanded polystyrene and apply to project. |
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