| To cope with the worldwide energy crisis, many countries attach importance to building energy efficiency. External Thermal Insulation Composite Systems(ETICS) are considered as an effective way to improve the thermal performance of buildings and are widely used in existing buildings.However, the durability problems such as delamination and cracking can cause defects in ETICS. Glazed Hollow Beads(GHB) thermal insulation mortar--a type of inorganic insulation material known for excellent fireproof performance and high strength--has been used in ETICS as insulation material in recent years.The durability of this ETICS under weathering effect should be assessed.Whereas current weathering test methods are based on organic insulation materials, exploring the test and evaluation methods applicable to inorganic insulation systems has important theoretical and practical significance. This study as part of National Natural Science Foundation of China(NSFC) project,proposes to determine the durability prediction method for ETICS with inorganic insulation materials by macro and micro methods. Specific studies areas follows:1. The experimental test on the durability of ETICS with GHB thermal insulation mortar under hygrothermal cycles(80 Heat- rain cycles and 5 Heat-cold cycles). During the test, thermal and strain behavior of each structural layer is monitored. Comparing the regular pattern of thermal and strain behavior of different layers(Finishing coat, Insulation layer, Substrate), showed that the intensity of temperature variation tend to change consistently; ranked from strong to weak is: Finishing coat, Insulation layer, Substrate. During the weathering test the thermal insulation effect of ETICS did not deteriorate apparently. In Heat- rain cycles, the stress of finishing coat and substrate appeared to expand with heat and contract with cold and the stress of insulation layer appeared to be opposite. In Heat- cold cycles, the stress of finishing coat and substrate also appeared to expand with heat and contract with cold, but the stress of insulation layer tend to change differently with positions on the rig.2. The experimental test on the adhesive strength of ETICS with GHB thermal insulation mortar compounded specimen under hygrothermal cycles.The regular pattern of adhesive strength under different cycles is analyzed with scanning electron microscopy(SEM) experiments to verify the microscopic deterioration mechanism of the mortar. The result showed that the number of micro cracks increased during the weathering test leading to the decrease of the adhesive strength. The adhesive strength of ETICS and that between the rendering system and insulation layer decreased by 29.41% and 23.53% after theweathering test; but the adhesive strength of both is higher than 0.1MPa which is required by the standard.3. The experimental test on the concrete compression strength of the concrete part of ETICS with GHB thermal insulation mortar compounded specimen under hygrothermal cycles. The result showed that the concrete compression strength decreased by 0.99% after the weathering test; in Heat-rain cycles it increased by 5.66% while in Heat- cold cycles decreased by 6.3%.The free flowing water froze and expanded in Heat- cold cycles caused the increase of micro cracks inside the concrete and lead to the deterioration of concrete compression strength.4. The experimental test on the heat conductivity coefficient of GHB thermal insulation mortar under hygrothermal cycles. The result showed that in Heat- rain cycles the heat conductivity coefficient decreased by 4.97% while in Heat- cold cycles increased by 1.69%. The Heat- rain cycles may have caring effects on the mortar while the Heat- cold cycles can cause freeze damage to the mortar.The conclusions obtained from the above experiments can be used as reference in future studies of weathering test methods and service life prediction of ETICS with GHB thermal insulation mortar and inorganic materials ETICS. |
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